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Sample records for falciparum chloroquine resistance

  1. 3-Halo Chloroquine Derivatives Overcome Plasmodium falciparum Chloroquine Resistance Transporter-Mediated Drug Resistance in P. falciparum.

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    Edaye, Sonia; Tazoo, Dagobert; Bohle, D Scott; Georges, Elias

    2015-12-01

    Polymorphism in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) was shown to cause chloroquine resistance. In this report, we examined the antimalarial potential of novel 3-halo chloroquine derivatives (3-chloro, 3-bromo, and 3-iodo) against chloroquine-susceptible and -resistant P. falciparum. All three derivatives inhibited the proliferation of P. falciparum; with 3-iodo chloroquine being most effective. Moreover, 3-iodo chloroquine was highly effective at potentiating and reversing chloroquine toxicity of drug-susceptible and -resistant P. falciparum.

  2. Lack of Evidence for Chloroquine-Resistant Plasmodium falciparum Malaria, Leogane, Haiti

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    Neuberger, Ami; Zhong, Kathleen; Kain, Kevin C

    2012-01-01

    Plasmodium falciparum malaria in Haiti is considered chloroquine susceptible, although resistance transporter alleles associated with chloroquine resistance were recently detected. Among 49 patients with falciparum malaria, we found neither parasites carrying haplotypes associated with chloroquine resistance nor instances of chloroquine treatment failure. Continued vigilance to detect emergence of chloroquine resistance is needed. PMID:22932030

  3. Lack of evidence for chloroquine-resistant Plasmodium falciparum malaria, Leogane, Haiti.

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    Neuberger, Ami; Zhong, Kathleen; Kain, Kevin C; Schwartz, Eli

    2012-09-01

    Plasmodium falciparum malaria in Haiti is considered chloroquine susceptible, although resistance transporter alleles associated with chloroquine resistance were recently detected. Among 49 patients with falciparum malaria, we found neither parasites carrying haplotypes associated with chloroquine resistance nor instances of chloroquine treatment failure. Continued vigilance to detect emergence of chloroquine resistance is needed.

  4. High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria.

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    Ursing, Johan; Rombo, Lars; Bergqvist, Yngve; Rodrigues, Amabelia; Kofoed, Poul-Erik

    2016-04-15

    Due to development of multidrug-resistant Plasmodium falciparum new antimalarial therapies are needed. In Guinea-Bissau, routinely used triple standard-dose chloroquine remained effective for decades despite the existence of "chloroquine-resistant" P. falciparum. This study aimed to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. Standard or double-dose chloroquine was given to 892 children aged <15 years with uncomplicated malaria during 3 clinical trials (2001-2008) with ≥ 35 days follow-up. The P. falciparum resistance-conferring genotype (pfcrt 76T) and day 7 chloroquine concentrations were determined. Data were divided into age groups (<5, 5-9, and 10-14 years) because concentrations increase with age when chloroquine is prescribed according to body weight. Adequate clinical and parasitological responses were 14%, 38%, and 39% after standard-dose and 66%, 84%, and 91% after double-dose chloroquine in children aged <5, 5-9, and 10-14 years, respectively, and infected with P. falciparum genotypes conferring chloroquine resistance (n = 195, P < .001). In parallel, median chloroquine concentrations were 471, 688, and 809 nmol/L for standard-dose and 1040, 1494, and 1585 nmol/L for double-dose chloroquine. Chloroquine resistance is dose dependent and can be overcome by higher, still well-tolerated doses. © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  5. High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria

    DEFF Research Database (Denmark)

    Ursing, Johan; Rombo, Lars; Bergqvist, Yngve;

    2016-01-01

    to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. METHODS:  Standard or double-dose chloroquine was given to 892 children aged malaria during 3 clinical trials (2001-2008) with ≥35 days follow...

  6. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes

    DEFF Research Database (Denmark)

    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia

    2014-01-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated...

  7. On the mechanism of chloroquine resistance in Plasmodium falciparum.

    KAUST Repository

    Chinappi, Mauro

    2010-11-19

    Resistance to chloroquine of malaria strains is known to be associated with a parasite protein named PfCRT, the mutated form of which is able to reduce chloroquine accumulation in the digestive vacuole of the pathogen. Whether the protein mediates extrusion of the drug acting as a channel or as a carrier and which is the protonation state of its chloroquine substrate is the subject of a scientific debate. We present here an analytical approach that explores which combination of hypotheses on the mechanism of transport and the protonation state of chloroquine are consistent with available equilibrium experimental data. We show that the available experimental data are not, by themselves, sufficient to conclude whether the protein acts as a channel or as a transporter, which explains the origin of their different interpretation by different authors. Interestingly, though, each of the two models is only consistent with a subset of hypotheses on the protonation state of the transported molecule. The combination of these results with a sequence and structure analysis of PfCRT, which strongly suggests that the molecule is a carrier, indicates that the transported species is either or both the mono and di-protonated forms of chloroquine. We believe that our results, besides shedding light on the mechanism of chloroquine resistance in P. falciparum, have implications for the development of novel therapies against resistant malaria strains and demonstrate the usefulness of an approach combining systems biology strategies with structural bioinformatics and experimental data.

  8. In-vitro antimalarial activity of azithromycin against chloroquine sensitive and chloroquine resistant Plasmodium falciparum.

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    Biswas S

    2001-10-01

    Full Text Available BAKGROUND: The spread of drug resistance in Plasmodium falciparum has made the situation essential to look into new effective therapeutic agents like antibiotics. Azithromycin is a potential, chemotherapeutic agent which possesses antimalarial activity and favourable pharmacokinetic properties. It is an azalide microbiocide derived semi-synthetically from macrolide erythromycin. Like other antibiotics, the azalide azithromycin has ability to inhibit protein synthesis on 70S ribosomes. SETTINGS: Experimental study. SUBJECTS AND METHODS: The parasiticidal profile was studied in five chloroquine sensitive and five chloroquine resistant P. falciparum isolates obtained from various places of India. The antimalarial activity was evaluated in P. falciparum schizont maturation by short term culture for 24 hours and by exposing the parasites to the drug for 96 hours. Parasites synchronized at ring stage were put for culture with various concentrations of azithromycin dihydrate (0.01-40 micro/ml. RESULTS: At highest concentration (40 micro/ml, parasite growth was inhibited totally in all 10 isolates. Antimalarial activity at 96 hours was greater than at 24 hours in both chloroquine sensitive and resistant parasites, which may indicate that the inhibition of parasite growth may occur at clinically achievable concentration of the drug when parasites were exposed for several asexual cycles. CONCLUSION: Azithromycin shows a potential for eventual use alone or in combination in the treatment of chloroquine sensitive and resistant P. falciparum malaria.

  9. Polycyclic amines as chloroquine resistance modulating agents in Plasmodium falciparum.

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    Joubert, Jacques; Kapp, Erika; Taylor, Dale; Smith, Peter J; Malan, Sarel F

    2016-02-15

    Pentacycloundecylamines (PCUs) and adamantane amines, such as NGP1-01 (1) and amantadine, have shown significant channel blocking activities. They are postulated to act as chemosensitizers and circumvent the resistance of the plasmodia parasite against chloroquine (CQ) by inhibiting the p-glycoprotein efflux pump and enabling the accumulation of CQ inside the parasite digestive vacuole. Twelve polycyclic amines containing either a PCU or adamantane amine moiety conjugated to different aromatic functionalities through various tethered linkers were selected based on their channel blocking abilities and evaluated as potential chemosensitizers. Compounds 2, 4, 5 and 10 showed significant voltage-gated calcium channel (VGCC) blocking ability (IC50=0.27-35 μM) and were able to alter the CQ IC50 in differing degrees (45-81%) in the multidrug resistant Plasmodium falciparum Dd2 isolate. Among them, the PCU-dansyl amine compound (4) displayed the best potential to act as a chemosensitizer against the Dd2 strain at a 1 μM concentration (RMI=0.19) while displaying moderate antiplasmodial activity (Dd2 IC50=6.25 μM) and low in vitro cytotoxicity against a mammalian cell line (CHO, IC50=119 μM). Compounds 2 and 10 also showed some promising chemosensitizing abilities (RMI=0.36 and 0.35 respectively). A direct correlation was found between the VGCC blocking ability of these polycyclic amines and their capacity to act as CQ resistance modulating agents.

  10. No seasonal accumulation of resistant P. falciparum when high-dose chloroquine is used

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    Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia

    2009-01-01

    BACKGROUND: Potentially chloroquine resistant P. falciparum, identified by the 76T haplotype in the chloroquine resistance transporter (pfcrt 76T), are highly prevalent throughout Africa. In Guinea-Bissau, normal and double dose chloroquine have respective efficacies of 34% and 78% against P...... increase of pfcrt 76T if the high doses of CQ commonly used are effective. METHODS AND FINDINGS: P. falciparum parasite density, age, sex, the proportion of chloroquine resistance associated haplotypes pfcrt 76T and P. falciparum multidrug resistance gene 1 86Y were assessed in 988 samples collected from...... children between 2002 and 2007. There was no seasonal accumulation of any allele. During the high and low transmission periods the pfcrt 76T proportions were 24% (95% CI, 21-27%) and 26% (95% CI, 20-33%). There was no significant change of pfcrt 76T (OR 1.05, 95% CI; 0.94-1.16 p = 0.39) or pfmdr1 86Y (OR 0...

  11. Synergy of four macrolide antibiotics with chloroquine against chloroquine-resistant Plasmodium falciparum in vitro.

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    Gershon, P; Howells, R E

    1986-01-01

    The antimalarial activity of four macrolide antibiotics was investigated against the multidrug resistant K1 strain of Plasmodium falciparum in vitro. ID50 (50% inhibitory concentration) values for erythromycin, spiramycin, tylosin tartrate and oleandomycin phosphate in 48-hour assays were 1.6 X 10(-4)M, 2.5 X 10(-5)M, 1.2 X 10(-5)M and 9 X 10(-6)M respectively, and in 96 hour assays were 10(-5)M, 2.6 X 10(-6)M, 2.6 X 10(-6) and 3 X 10(-6)M, respectively. Comparable values were obtained in assays in which drug effect was quantified from either parasite counts or 14C isoleucine incorporation. Each of the four macrolides displayed synergy with chloroquine at the IC90 (90% inhibitory concentration) level, but at the IC50 level synergy was either less pronounced or absent. For each combination this difference in the degree of synergy was significant at the 95% level of confidence. In replicate assays in which 3H hypoxanthine was the marker of drug effect, synergy between chloroquine and either erythromycin or spiramycin could not be detected.

  12. Short report: polymorphisms in the chloroquine resistance transporter gene in Plasmodium falciparum isolates from Lombok, Indonesia.

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    Huaman, Maria Cecilia; Yoshinaga, Kazumi; Suryanatha, Aan; Suarsana, Nyoman; Kanbara, Hiroji

    2004-07-01

    The polymorphisms in the Plasmodium falciparum multidrug resistance 1 (pfmdr1) and P. falciparum chloroquine resistance transporter (pfcrt) genes, which are associated with chloroquine resistance, were examined in 48 P. falciparum isolates from uncomplicated malaria patients from the West Lombok District in Indonesia. The point mutation N86Y in pfmdr1 was present in 35.4% of the isolates and mutation K76T in pfcrt was found in all but one of the samples studied. Identified pfcrt haplotypes were mainly identical to the Papua New Guinea type S(agt)VMNT (42 of 48, 87.5%), and a few isolates had the Southeast Asia type CVIET (5 of 48, 10.4%). Moreover, one P. falciparum isolate harbored the K76N mutation, giving rise to the haplotype CVMNN, which was not previously reported in field isolates. Our findings suggest that chloroquine resistance in this area might have the same origin as in Papua New Guinea.

  13. Chloroquine- and sulfadoxine-pyrimethamine-resistant falciparum malaria in vivo - a pilot study in rural Zambia

    NARCIS (Netherlands)

    Bijl, HM; Kager, J; Koetsier, DW; van der Werf, TS

    2000-01-01

    BACKGROUND Chloroquine (CQ) and Sulfadoxine-Pyrimethamine (SP) are the predominantly used antimalarials in Zambia and other parts of East Africa, but increasing resistance of P. falciparum is a major concern. METHODS Seventy consecutive patients with uncomplicated falciparum malaria were enrolled.

  14. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter.

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    Petersen, Ines; Gabryszewski, Stanislaw J; Johnston, Geoffrey L; Dhingra, Satish K; Ecker, Andrea; Lewis, Rebecca E; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp P; Palatulan, Eugene; Johnson, David J; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M; Lanzer, Michael; Fidock, David A

    2015-07-01

    The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria.

  15. Neuronal monoamine reuptake inhibitors enhance in vitro susceptibility to chloroquine in resistant Plasmodium falciparum.

    OpenAIRE

    Coutaux, A F; Mooney, J. J.; Wirth, D. F.

    1994-01-01

    Chloroquine resistance in Plasmodium falciparum was reversed in vitro by the neuronal monoamine reuptake inhibitors and antidepressants desipramine, sertraline, fluoxetine, and norfluoxetine but not by carbamazepine, an antiseizure and mood-stabilizing tricyclic drug resembling desipramine which only weakly inhibits neuronal monoamine reuptake. These findings have important clinical implications for drug combination therapy.

  16. In vivo resistance to chloroquine by Plasmodium vivax and Plasmodium falciparum at Nabire, Irian Jaya, Indonesia.

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    Baird, J K; Wiady, I; Fryauff, D J; Sutanihardja, M A; Leksana, B; Widjaya, H; Kysdarmanto; Subianto, B

    1997-06-01

    A survey of resistance to chloroquine by Plasmodium vivax and P. falciparum was conducted during May 1995 at three mesoendemic villages 30 km southeast of Nabire, near the central northern coast of Irian Jaya, Indonesia. The prevalence of malaria at Urusumu (n = 157), Margajaya (n = 573), and Topo (n = 199) was 18%. 9%, and 9%, respectively, with spleen rates among children of 79%, 10%, and 27%. Infected patients among those screened formed a study population of 64 subjects eligible for a 28-day in vivo test of resistance to chloroquine. Sixty-three patients successfully completed the test; 45 males and 18 females 1-60 years of age, of whom 29 were Javanese transmigrants of five years residence in Irian Jaya and 34 were native to Irian Jaya. The seven-day day cumulative incidence of therapeutic failure for P. vivax and P. falciparum was 15% (n = 34) and 30% (n = 37). The 14- and 28-day estimates of cumulative incidence were 45% and 64% for P. vivax and 58% and 89% for P. falciparum. Almost all recurrences appeared in the face of ordinarily effective levels of chloroquine and its major metabolite, desethylchloroquine, in whole blood (> or = 100 ng/ml). Four infections by P. malariae in subjects enrolled in this study cleared by day 2 and none reappeared within 28 days. Chloroquine no longer provides effective therapy for falciparum or vivax malaria along the northern coast of Irian Jaya, Indonesia.

  17. Chloroquine resistant P. falciparum prevalence is low and unchanged between 1990 and 2005 in Guinea-Bissau

    DEFF Research Database (Denmark)

    Ursing, Johan; Schmidt, Berit Aydin; Lebbad, Marianne;

    2007-01-01

    and other genetic polymorphisms in samples from 1992, 1993, 1995, 2004 and 2005. We have also monitored drug prescriptions for febrile illnesses. The mean proportion of in vitro tests indicating chloroquine resistance was 33% (range 14-54%) with the exception of an outlying value year 2000. The proportion...... of chloroquine resistant P. falciparum detected by in vitro testing did not increase over time. Pfcrt 76T was associated with chloroquine resistance but pfmdr1 86Y was not. The mean pfcrt 76T prevalence varied between 13% and 38%. The prevalence of SNPs at Pfcrt positions 76, 271, 326 and pfmdr1 position 86 did...... of chloroquine resistant P. falciparum has not gradually increased between 1990 and 2005 in Guinea-Bissau. Chloroquine is commonly prescribed at more than double the normal dose in Guinea Bissau. It has previously been hypothesized that treatment with high doses of chloroquine may be effective. We discuss...

  18. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras

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    Gustavo A Fontecha

    2014-07-01

    Full Text Available Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76.

  19. A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras.

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    Fontecha, Gustavo A; Sanchez, Ana L; Mendoza, Meisy; Banegas, Engels; Mejía-Torres, Rosa E

    2014-07-01

    Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt "CVMNK" genotype in codons 72-76.

  20. Genetic polymorphisms in Plasmodium falciparum chloroquine resistance genes, pfcrt and pfmdr1, in North Sulawesi, Indonesia.

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    Reteng, Patrick; Vrisca, Visia; Sukarno, Inka; Djarkoni, Ilham Habib; Kalangi, Jane Angela; Jacobs, George Eduardo; Runtuwene, Lucky Ronald; Eshita, Yuki; Maeda, Ryuichiro; Suzuki, Yutaka; Mongan, Arthur Elia; Warouw, Sarah Maria; Yamagishi, Junya; Tuda, Josef

    2017-04-04

    Malaria still poses one of the major threats to human health. Development of effective antimalarial drugs has decreased this threat; however, the emergence of drug-resistant Plasmodium falciparum, a cause of Malaria, is disconcerting. The antimalarial drug chloroquine has been effectively used, but resistant parasites have spread worldwide. Interestingly, the withdrawal of the drug reportedly leads to an increased population of susceptible parasites in some cases. We examined the prevalence of genomic polymorphisms in a malaria parasite P. falciparum, associated with resistance to an antimalarial drug chloroquine, after the withdrawal of the drug from Indonesia. Blood samples were collected from 95 malaria patients in North Sulawesi, Indonesia, in 2010. Parasite DNA was extracted and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for pfcrt and pfmdr1. In parallel, multiplex amplicon sequencing for the same genes was carried out with Illumina MiSeq. Of the 59 cases diagnosed as P. falciparum infection by microscopy, PCR-RFLP analysis clearly identified the genotype 76T in pfcrt in 44 cases. Sequencing analysis validated the identified genotypes in the 44 cases and demonstrated that the haplotype in the surrounding genomic region was exclusively SVMNT. Results of pfmdr1 were successfully obtained for 51 samples, where the genotyping results obtained by the two methods were completely consistent. In pfmdr1, the 86Y mutant genotype was observed in 45 cases (88.2%). Our results suggest that the prevalence of the mutated genotypes remained dominant even 6 years after the withdrawal of chloroquine from this region. Diversified haplotype of the resistance-related locus, potentially involved in fitness costs, unauthorized usage of chloroquine, and/or a short post-withdrawal period may account for the observed high persistence of prevalence.

  1. Current understanding of the molecular basis of chloroquine-resistance in Plasmodium falciparum

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    Jiang H

    2006-01-01

    Full Text Available Chloroquine (CQ is the most successful antimalarial drug ever discovered. Unfortunately, parasites resistant to the drug eventually emerged after its large scale use and are now widespread. Although great progress in our understanding of the mechanisms of CQ action and CQ resistance (CQR has been achieved over the past two decades, including the identification of the molecules responsible for CQR (e.g., Plasmodium falciparum chloroquine resistant transporter, PfCRT many questions remain unanswered. Here we highlight recent advances in our understanding of the genetics and molecular mechanisms of CQR, with particular emphasis on the role of genes such as pfcrt and pfmdr1 in the resistance to CQ and other drugs. New drug development and applications will undoubtedly benefit from a better understanding of CQR, eventually leading to more effective malaria control measures.

  2. Survey of Plasmodium falciparum multidrug resistance-1 and chloroquine resistance transporter alleles in Haiti.

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    Elbadry, Maha A; Existe, Alexandre; Victor, Yves S; Memnon, Gladys; Fukuda, Mark; Dame, John B; Yowell, Charles A; Okech, Bernard A

    2013-11-19

    In Haiti where chloroquine (CQ) is widely used for malaria treatment, reports of resistance are scarce. However, recent identification of CQ resistance genotypes in one site is suggestive of an emerging problem. Additional studies are needed to evaluate genetic mutations associated with CQ resistance, especially in the Plasmodium falciparum multi-drug resistance-1 gene (pfmdr1) while expanding the already available information on P. falciparum CQ transporter gene (pfcrt) in Haiti. Blood samples were collected on Whatman filter cards (FTA) from eight clinics spread across Haiti. Following the confirmation of P. falciparum in the samples, PCR protocols were used to amplify regions of pfmdr1and pfcrt codons of interest, (86, 184, 1034, 1042, and 1246) and (72-76), respectively. Sequencing and site-specific restriction enzyme digestions were used to analyse these DNA fragments for the presence of single nucleotide polymorphisms (SNPs) known to confer resistance to anti-malarial drugs. P. falciparum infection was confirmed in160 samples by amplifying a segment of the P. falciparum 18S small subunit ribosomal RNA gene (pfssurrna). The sequence of pfmdr1 in 54 of these samples was determined between codons 86,184 codons 1034, 1042 and 1246. No sequence differences from that of the NF54 clone 3D7 were found among the 54 samples except at codon 184, where a non-silent mutation was found in all samples predicted to alter the amino acid sequence replacing tyrosine with phenylalanine (Y184F). This altered sequence was also confirmed by restriction enzyme digestion. The sequence of pfmdr1 at codons 86, 184, 1034 and 1042 encoded the NFSN haplotype. The sequence of pfcrt codons 72-76 from 79 samples was determined and found to encode CVMNK, consistent with a CQ sensitive genotype. The presence of the Y184F mutation in pfmdr1 of P. falciparum parasites in Haiti may have implications for resistance to antimalarial drugs. The absence of mutation in pfcrt at codon 76 among 79

  3. Chloroquine resistant Plasmodium falciparum malaria in Osogbo Nigeria: efficacy of amodiaquine + sulfadoxine-pyrimethamine and chloroquine + chlorpheniramine for treatment

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    TO Ogungbamigbe

    2008-02-01

    Full Text Available Chloroquine (CQ resistance in Plasmodium falciparum contributes to increasing malaria-attributable morbidity and mortality in Sub-Saharan Africa. Despite a change in drug policy, continued prescription of CQ did not abate. Therefore the therapeutic efficacy of CQ in uncomplicated falciparum malaria patients was assessed in a standard 28-day protocol in 116 children aged between six and 120 months in Osogbo, Southwest Nigeria. Parasitological and clinical assessments of response to treatment showed that 72 (62.1% of the patients were cured and 44 (37.9% failed the CQ treatment. High initial parasite density and young age were independent predictors for early treatment failure. Out of the 44 patients that failed CQ, 24 received amodiaquine + sulphadoxine/pyrimethamine (AQ+SP and 20 received chlorpheniramine + chloroquine (CH+CQ combinations. Mean fever clearance time in those treated with AQ+SP was not significantly different from those treated with CH+CQ (p = 0.05. There was no significant difference in the mean parasite density of the two groups. The cure rate for AQ+SP group was 92% while those of CH+CQ was 85%. There was a significant difference in parasite clearance time (p = 0.01 between the two groups. The 38% treatment failure for CQ reported in this study is higher than the 10% recommended by World Health Organization in other to effect change in antimalarial treatment policy. Hence we conclude that CQ can no more be solely relied upon for the treatment of falciparum malaria in Osogbo, Nigeria. AQ+SP and CH+CQ are effective in the treatment of acute uncomplicated malaria and may be considered as useful alternative drugs in the absence of artemisinin-based combination therapies.

  4. Confirmation of Plasmodium falciparum in vitro resistance to monodesethylamodiaquine and chloroquine in Dakar, Senegal, in 2015.

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    Diawara, Silman; Madamet, Marylin; Kounta, Mame Bou; Lo, Gora; Wade, Khalifa Ababacar; Nakoulima, Aminata; Bercion, Raymond; Amalvict, Rémy; Gueye, Mamadou Wague; Fall, Bécaye; Diatta, Bakary; Pradines, Bruno

    2017-03-16

    In response to increasing resistance to anti-malarial drugs, Senegal adopted artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria in 2006. However, resistance of Plasmodium falciparum parasites to artemisinin derivatives, characterized by delayed parasite clearance after treatment with ACT or artesunate monotherapy, has recently emerged and rapidly spread in Southeast Asia. After 10 years of stability with rates ranging from 5.6 to 11.8%, the prevalence of parasites with reduced susceptibility in vitro to monodesethylamodiaquine, the active metabolite of an ACT partner drug, increased to 30.6% in 2014 in Dakar. Additionally, after a decrease of the in vitro chloroquine resistance in Dakar in 2009-2011, the prevalence of parasites that showed in vitro chloroquine resistance increased again to approximately 50% in Dakar since 2013. The aim of this study was to follow the evolution of the susceptibility to ACT partners and other anti-malarial drugs in 2015 in Dakar. An in vitro test is the only method currently available to provide an early indication of resistance to ACT partners. Thirty-two P. falciparum isolates collected in 2015 in Dakar were analysed using a standard ex vivo assay based on an HRP2 ELISA. The prevalence of P. falciparum parasites with reduced susceptibility in vitro to monodesethylamodiaquine, chloroquine, mefloquine, doxycycline and quinine was 28.1, 46.9, 45.2, 31.2 and 9.7%, respectively. None of the parasites were resistant to lumefantrine, piperaquine, pyronaridine, dihydroartemisinin and artesunate. These results confirm an increase in the reduced susceptibility to monodesethylamodiaquine observed in 2014 in Dakar and the chloroquine resistance observed in 2013. The in vitro resistance seems to be established in Dakar. Additionally, the prevalence of parasites with reduced susceptibility to doxycycline has increased two-fold compared to 2014. The establishment of a reduced susceptibility to

  5. Sequence and gene expression of chloroquine resistance transporter (pfcrt in the association of in vitro drugs resistance of Plasmodium falciparum

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    Bray Patrick G

    2011-02-01

    Full Text Available Abstract Background Plasmodium falciparum chloroquine resistance (CQR transporter protein (PfCRT is known to be the important key of CQR. Recent studies have definitively demonstrated a link between mutations in the gene pfcrt and resistance to chloroquine in P. falciparum. Although these mutations are predictive of chloroquine resistance, they are not quantitatively predictive of the degree of resistance. Methods In this study, a total of 95 recently adapted P. falciparum isolates from Thailand were included in the analysis. Parasites were characterized for their drug susceptibility phenotypes and genotypes with respect to pfcrt. From the original 95 isolates, 20 were selected for complete pfcrt sequence analysis. Results Almost all of the parasites characterized carried the previously reported mutations K76T, A220S, Q271E, N326S, I356T and R371I. On complete sequencing, isolates were identified with novel mutations at K76A and E198K. There was a suggestion that parasites carrying E198K were less resistant than those that did not. In addition, pfcrt and pfmdr1 gene expression were investigated by real-time PCR. No relationship between the expression level of either of these genes and response to drug was observed. Conclusion Data from the present study suggest that other genes must contribute to the degree of resistance once the resistance phenotype is established through mutations in pfcrt.

  6. Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, enlarge the parasite's food vacuole and alter drug sensitivities.

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    Pulcini, Serena; Staines, Henry M; Lee, Andrew H; Shafik, Sarah H; Bouyer, Guillaume; Moore, Catherine M; Daley, Daniel A; Hoke, Matthew J; Altenhofen, Lindsey M; Painter, Heather J; Mu, Jianbing; Ferguson, David J P; Llinás, Manuel; Martin, Rowena E; Fidock, David A; Cooper, Roland A; Krishna, Sanjeev

    2015-01-01

    Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, are the major determinant of chloroquine resistance in this lethal human malaria parasite. Here, we describe P. falciparum lines subjected to selection by amantadine or blasticidin that carry PfCRT mutations (C101F or L272F), causing the development of enlarged food vacuoles. These parasites also have increased sensitivity to chloroquine and some other quinoline antimalarials, but exhibit no or minimal change in sensitivity to artemisinins, when compared with parental strains. A transgenic parasite line expressing the L272F variant of PfCRT confirmed this increased chloroquine sensitivity and enlarged food vacuole phenotype. Furthermore, the introduction of the C101F or L272F mutation into a chloroquine-resistant variant of PfCRT reduced the ability of this protein to transport chloroquine by approximately 93 and 82%, respectively, when expressed in Xenopus oocytes. These data provide, at least in part, a mechanistic explanation for the increased sensitivity of the mutant parasite lines to chloroquine. Taken together, these findings provide new insights into PfCRT function and PfCRT-mediated drug resistance, as well as the food vacuole, which is an important target of many antimalarial drugs.

  7. Assessment of the molecular marker of Plasmodium falciparum chloroquine resistance (Pfcrt) in Senegal after several years of chloroquine withdrawal.

    Science.gov (United States)

    Ndiaye, Magatte; Faye, Babacar; Tine, Roger; Ndiaye, Jean Louis; Lo, Aminata; Abiola, Annie; Dieng, Yemou; Ndiaye, Daouda; Hallett, Rachel; Alifrangis, Michael; Gaye, Oumar

    2012-10-01

    As a result of widespread antimalarial drug resistance, all African countries with endemic malaria have, in recent years, changed their malaria treatment policy. In Senegal, the health authorities changed from chloroquine (CQ) to a combination of sulfadoxine-pyrimethamine (SP) plus amodiaquine (AQ) in 2003. Since 2006, the artemisinin combination therapies (ACTs) artemether-lumefantrine (AL) and artesunate plus amodiaquine (AS/AQ) were adopted for uncomplicated malaria treatment. After several years of CQ withdrawal, the current study wished to determine the level of CQ resistance at the molecular level in selected sites in Senegal, because the scientific community is interested in using CQ again. Finger prick blood samples were collected from Plasmodium falciparum-positive children below the age of 10 years (N = 474) during cross-sectional surveys conducted in two study sites in Senegal with different malaria transmission levels. One site is in central Senegal, and the other site is in the southern part of the country. All samples were analyzed for single nucleotide polymorphisms (SNPs) in the P. falciparum CQ resistance transporter gene (Pfcrt; codons 72-76) using polymerase chain reaction (PCR) sequence-specific oligonucleotide probe (SSOP) enzyme-linked immunosorbent assay (ELISA) and real-time PCR methods. In total, the 72- to 76-codon region of Pfcrt was amplified in 449 blood samples (94.7%; 285 and 164 samples from the central and southern sites of Senegal, respectively). In both study areas, the prevalence of the Pfcrt wild-type single CVMNK haplotype was very high; in central Senegal, the prevalence was 70.5% in 2009 and 74.8% in 2010, and in southern Senegal, the prevalence was 65.4% in 2010 and 71.0% in 2011. Comparing data with older studies in Senegal, a sharp decline in the mutant type Pfcrt prevalence is evident: from 65%, 64%, and 59.5% in samples collected from various sites in 2000, 2001, and 2004 to approximately 30% in our study. A similar

  8. Falciparum malaria in the north of Laos: the occurrence and implications of the Plasmodium falciparum chloroquine resistance transporter (pfcrt) gene haplotype SVMNT

    DEFF Research Database (Denmark)

    Dittrich, Sabine; Alifrangis, Michael; Stohrer, Jörg M;

    2005-01-01

    OBJECTIVE: The Pfcrt-gene encodes a transmembrane protein located in the Plasmodium falciparum digestive vacuole. Chloroquine resistant (CQR) strains of African and Southeast Asian origin carry the Pfcrt-haplotype (c72-76) CVIET, whereas most South American and Papua New Guinean CQR stains carry...

  9. Molecular analysis of chloroquine and sulfadoxine-pyrimethamine resistance-associated alleles in Plasmodium falciparum isolates from Nicaragua.

    Science.gov (United States)

    Sridaran, Sankar; Rodriguez, Betzabe; Soto, Aida Mercedes; Macedo De Oliveira, Alexandre; Udhayakumar, Venkatachalam

    2014-05-01

    Chloroquine (CQ) is used as a first-line therapy for the treatment of Plasmodium falciparum malaria in Nicaragua. We investigated the prevalence of molecular markers associated with CQ and sulfadoxine-pyrimethamine (SP) resistance in P. falciparum isolates obtained from the North Atlantic Autonomous Region of Nicaragua. Blood spots for this study were made available from a CQ and SP drug efficacy trial conducted in 2005 and also from a surveillance study performed in 2011. Polymorphisms in P. falciparum CQ resistance transporter, dihydrofolate reductase, and dihydropteroate synthase gene loci that are associated with resistance to CQ, pyrimethamine, and sulfadoxine, respectively, were detected by DNA sequencing. In the 2005 dataset, only 2 of 53 isolates had a CQ resistance allele (CVIET), 2 of 52 had a pyrimethamine resistance allele, and 1 of 49 had a sulfadoxine resistance allele. In the 2011 dataset, none of 45 isolates analyzed had CQ or SP resistance alleles.

  10. Localized permanent epidemics: the genesis of chloroquine resistance in Plasmodium falciparum.

    Science.gov (United States)

    Verdrager, J

    1995-03-01

    Localized permanent epidemics occur when, for an indefinite period of time, there is a temporary but continuous introduction of unprotected non-immunes into the same locality of a hyperendemic area. The main epidemiological factors involved in the genesis of localized permanent epidemics were encountered in Pailin (Cambodia) the epicenter of drug resistance in Southeast Asia: a very efficient vector, Anopheles dirus, exophilic and of limited distribution with, therefore, adjacent hyperendemic and non-endemic areas; a permanent pole of attraction in the hyperendemic area: Pailin's sapphires and rubies; a temporary but continuous influx of non-immunes into the pole of attraction: continuous influx of non-immunes into the Pailin gem mining area. In the gem-mining Pailin village drug pressure was considerable: mass drug administration, a medicated salt project and permanent self-medication with very high doses, much higher doses being required to cure non-immunes with heavy infections and severe clinical attacks in epidemic situations. It appears, therefore, that the emergence of chloroquine resistance in Southeast Asia was the consequence of the localized permanent epidemics in Païlin. High level resistance was the result of continuous and intensive serial passages of P. falciparum in the non-immune subjects, large numbers of parasites being exposed to a high level of drug pressure at each passage. Similar epidemiological conditions are encountered in some parts of South America where the exophilic vector is An. nuneztovari. In Colombia, whose eastern mountains bordering Venezuela yield the most highly prized emeralds in the world, chloroquine resistance was detected at about the same time as in Southeast Asia.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Nonradioactive heteroduplex tracking assay for the detection of minority-variant chloroquine-resistant Plasmodium falciparum in Madagascar

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    Mwapasa Victor

    2009-03-01

    Full Text Available Abstract Background Strains of Plasmodium falciparum genetically resistant to chloroquine (CQ due to the presence of pfcrt 76T appear to have been recently introduced to the island of Madagascar. The prevalence of such resistant genotypes is reported to be low (P. falciparum isolates on the island. Previously, minority variant chloroquine resistant parasites were described in Malawian patients using an isotopic heteroduplex tracking assay (HTA, which can detect pfcrt 76T-bearing P. falciparum minority variants in individual patients that were undetectable by conventional PCR. However, as this assay required a radiolabeled probe, it could not be used in many resource-limited settings. Methods This study describes a digoxigenin (DIG-labeled chemiluminescent heteroduplex tracking assay (DIG-HTA to detect pfcrt 76T-bearing minority variant P. falciparum. This assay was compared to restriction fragment length polymorphism (RFLP analysis and to the isotopic HTA for detection of genetically CQ-resistant parasites in clinical samples. Results Thirty one clinical P. falciparum isolates (15 primary isolates and 16 recurrent isolates from 17 Malagasy children treated with CQ for uncomplicated malaria were genotyped for the pfcrt K76T mutation. Two (11.7% of 17 patients harboured genetically CQ-resistant P. falciparum strains after therapy as detected by HTA. RFLP analysis failed to detect any pfcrt K76T-bearing isolates. Conclusion These findings indicate that genetically CQ-resistant P. falciparum are more common than previously thought in Madagascar even though the fitness of the minority variant pfcrt 76T parasites remains unclear. In addition, HTAs for malaria drug resistance alleles are promising tools for the surveillance of anti-malarial resistance. The use of a non-radioactive label allows for the use of HTAs in malaria endemic countries.

  12. Genotyping of chloroquine resistant Plasmodium falciparum in wild caught Anopheles minimus mosquitoes in a malaria endemic area of Assam, India.

    Science.gov (United States)

    Sarma, D K; Mohapatra, P K; Bhattacharyya, D R; Mahanta, J; Prakash, A

    2014-09-01

    We validated the feasibility of using Plasmodium falciparum, the human malaria parasite, DNA present in wild caught vector mosquitoes for the characterization of chloroquine resistance status. House frequenting mosquitoes belonging to Anopheles minimus complex were collected from human dwellings in a malaria endemic area of Assam, Northeast India and DNA was extracted from the head-thorax region of individual mosquitoes. Anopheles minimus complex mosquitoes were identified to species level and screened for the presence of Plasmodium sp. using molecular tools. Nested PCR-RFLP method was used for genotyping of P. falciparum based on K76T mutation in the chloroquine resistance transporter (pfcrt) gene. Three of the 27 wild caught An. minimus mosquitoes were harbouring P. falciparum sporozoites (positivity 11.1%) and all 3 were had 76T mutation in the pfcrt gene, indicating chloroquine resistance. The approach of characterizing antimalarial resistance of malaria parasite in vector mosquitoes can potentially be used as a surveillance tool for monitoring transmission of antimalarial drug resistant parasite strains in the community.

  13. Polymorphism in the Plasmodium falciparum chloroquine-resistance transporter protein links verapamil enhancement of chloroquine sensitivity with the clinical efficacy of amodiaquine

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    Warhurst David C

    2003-09-01

    Full Text Available Abstract Background Chloroquine accumulates in the acidic digestive vacuole of the intraerythrocytic malaria parasite, and prevents the detoxication of haematin released during haemoglobin digestion. Changes in protein PfCRT in the digestive vacuole membrane of growing intra-erythrocytic stages of Plasmodium falciparum are crucial for resistance. Expressed in yeast, PfCRT resembles an anion channel. Depressed anion channel function could increase intralysosomal pH to reduce entry of basic drug, or enhanced function could reduce drug interaction with target haematin. The most important resistance-associated change is from positively-charged lysine-76 to neutral threonine which could facilitate drug efflux through a putative channel. It has been proposed that the resistance-reversing effect of verapamil is due to hydrophobic binding to the mutated PfCRT protein, and replacement of the lost positive charge, which repels the access of 4-aminoquinoline cations, thus partially restoring sensitivity. Desethylamodiaquine, the active metabolite of amodiaquine, which has significant activity in chloroquine-resistance, may also act similarly on its own. Methods Changes in physicochemical parameters in different CQ-resistant PfCRT sequences are analysed, and correlations with drug activity on lines transfected with different alleles of the pfcrt gene are examined. Results and conclusions The results support the idea that PfCRT is a channel which, in resistant parasites, can allow efflux of chloroquine from the digestive vacuole. Activity of the chloroquine/verapamil combination and of desethylamodiaquine both correlate with the mean hydrophobicity of PfCRT residues 72-76. This may partly explain clinical-resistance to amodiaquine found in the first chloroquine-resistant malaria cases from South America and enables tentative prediction of amodiaquine's clinical activity against novel haplotypes of PfCRT.

  14. Large-scale survey for novel genotypes of Plasmodium falciparum chloroquine-resistance gene pfcrt

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    Takahashi Nobuyuki

    2012-03-01

    Full Text Available Abstract Background In Plasmodium falciparum, resistance to chloroquine (CQ is conferred by a K to T mutation at amino acid position 76 (K76T in the P. falciparum CQ transporter (PfCRT. To date, at least 15 pfcrt genotypes, which are represented by combinations of five amino acids at positions 72-76, have been described in field isolates from various endemic regions. To identify novel mutant pfcrt genotypes and to reveal the genetic relatedness of pfcrt genotypes, a large-scale survey over a wide geographic area was performed. Methods Sequences for exon 2 in pfcrt, including known polymorphic sites at amino acid positions 72, 74, 75 and 76, were obtained from 256 P. falciparum isolates collected from eight endemic countries in Asia (Bangladesh, Cambodia, Lao P.D.R., the Philippines and Thailand, Melanesia (Papua New Guinea and Vanuatu and Africa (Ghana. A haplotype network was constructed based on six microsatellite markers located -29 kb to 24 kb from pfcrt in order to examine the genetic relatedness among mutant pfcrt genotypes. Results In addition to wild type (CVMNK at positions 72-76, four mutant pfcrt were identified; CVIET, CVIDT, SVMNT and CVMNT (mutated amino acids underlined. Haplotype network revealed that there were only three mutant pfcrt lineages, originating in Indochina, Philippines and Melanesia. Importantly, the Indochina lineage contained two mutant pfcrt genotypes, CVIET (n = 95 and CVIDT (n = 14, indicating that CVIDT shares a common origin with CVIET. Similarly, one major haplotype in the Melanesian lineage contained two pfcrt genotypes; SVMNT (n = 71 and CVMNT (n = 3. In Africa, all mutant pfcrt genotypes were the CVIET of the Indochina lineage, probably resulting from the intercontinental migration of CQ resistance from Southeast Asia. Conclusions The number of CQ-mutant lineages observed in this study was identical to that found in previous studies. This supports the hypothesis that the emergence of novel CQ resistance

  15. Functional Comparison of 45 Naturally Occurring Isoforms of the Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT).

    Science.gov (United States)

    Callaghan, Paul S; Hassett, Matthew R; Roepe, Paul D

    2015-08-18

    At least 53 distinct isoforms of Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein are expressed in strains or isolates of P. falciparum malarial parasites from around the globe. These parasites exhibit a range of sensitivities to chloroquine (CQ) and other drugs. Mutant PfCRT is believed to confer cytostatic CQ resistance (CQR(CS)) by transporting CQ away from its DV target (free heme released upon hemoglobin digestion). One theory is that variable CQ transport catalyzed by these different PfCRT isoforms is responsible for the range of CQ sensitivities now found for P. falciparum. Alternatively, additional mutations in drug-selected parasites, or additional functions of PfCRT, might complement PfCRT-mediated CQ transport in conferring the range of observed resistance phenotypes. To distinguish between these possibilities, we recently optimized a convenient method for measuring PfCRT-mediated CQ transport, involving heterologous expression in Saccharomyces cerevisiae. Here, we use this method to quantify drug transport activity for 45 of 53 of the naturally occurring PfCRT isoforms. Data show that variable levels of CQR likely depend upon either additional PfCRT functions or additional genetic events, including perhaps changes that influence DV membrane potential. The data also suggest that the common K76T PfCRT mutation that is often used to distinguish a P. falciparum CQR phenotype is not, in and of itself, a fully reliable indicator of CQR status.

  16. Survey of chloroquine-resistant mutations in the Plasmodium falciparum pfcrt and pfmdr-1 genes in Hadhramout, Yemen.

    Science.gov (United States)

    Bamaga, Omar A A; Mahdy, Mohammed A K; Lim, Yvonne A L

    2015-09-01

    Malaria is still a major public health problem in Yemen. More than 95% of the malaria cases are due to Plasmodium ‎falciparum‎. Recently in Yemen, the antimalarial treatment policy was changed from chloroquine (CQ) to artemisinin combination therapy (ACTs). However, CQ is still available and prescribed in the Yemeni market. The persistence of CQ resistance will be prolonged if the shift to ACT and the simultaneous withdrawal of CQ are not rigorously implemented. The aim of the current survey is to detect chloroquine-resistant mutations in P. falciparum chloroquine-resistance transporter (pfcrt) and P. falciparum multi-drug resistance-1 (pfmdr1) genes. These data will be important for future monitoring and assessment of antimalarial drug policy in Yemen. Blood specimens were collected from 735 individuals from different districts of the Hadhramout province, Yemen by house-to-house visit. Mutation-specific nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) methods were used to investigate the mutations in the pfmdr1(codons 86 and 1246) and pfcrt (codons 76, 271, 326, 356 and 371) genes. The overall prevalence of pfcrt mutations at codons 76, 271, 326 and 371 were 50.4%, 58.7%, 54.3% and 44.9%, respectively. All isolates had wild-type pfcrt 356 allele. The majority of pfmdr1 86 alleles (83.3%) and all pfmdr1 1246 alleles were wild type. There was no association between pfcrt mutations and symptomatology, gender and age groups. In conclusion, point mutations in codons 76, 271, 326 and 371 of pfcrt of P. falciparum are high suggesting a sustained high CQ resistance even after 4 years of shifting to ACTs. These findings warrant complete withdrawal of CQ use from the Yemeni market for P. falciparum and careful usage of CQ for treating Plasmodium vivax.

  17. Assessment of the molecular marker of Plasmodium falciparum chloroquine resistance (Pfcrt) in Senegal after several years of chloroquine withdrawal

    DEFF Research Database (Denmark)

    Ndiaye, Magatte; Faye, Babacar; Tine, Roger

    2012-01-01

    Abstract. As a result of widespread antimalarial drug resistance, all African countries with endemic malaria have, in recent years, changed their malaria treatment policy. In Senegal, the health authorities changed from chloroquine (CQ) to a combination of sulfadoxine-pyrimethamine (SP) plus...... susceptibility in many African countries, it may be possible to reintroduce CQ in the near future in a drug combination; it could possibly be given to non-vulnerable groups, but it demands close monitoring of possible reemergence of CQ resistance development....

  18. Quinine dimers are potent inhibitors of the Plasmodium falciparum chloroquine resistance transporter and are active against quinoline-resistant P. falciparum.

    Science.gov (United States)

    Hrycyna, Christine A; Summers, Robert L; Lehane, Adele M; Pires, Marcos M; Namanja, Hilda; Bohn, Kelsey; Kuriakose, Jerrin; Ferdig, Michael; Henrich, Philipp P; Fidock, David A; Kirk, Kiaran; Chmielewski, Jean; Martin, Rowena E

    2014-03-21

    Chloroquine (CQ) resistance in the human malaria parasite Plasmodium falciparum is primarily conferred by mutations in the "chloroquine resistance transporter" (PfCRT). The resistance-conferring form of PfCRT (PfCRT(CQR)) mediates CQ resistance by effluxing the drug from the parasite's digestive vacuole, the acidic compartment in which CQ exerts its antiplasmodial effect. PfCRT(CQR) can also decrease the parasite's susceptibility to other quinoline drugs, including the current antimalarials quinine and amodiaquine. Here we describe interactions between PfCRT(CQR) and a series of dimeric quinine molecules using a Xenopus laevis oocyte system for the heterologous expression of PfCRT and using an assay that detects the drug-associated efflux of H(+) ions from the digestive vacuole in parasites that harbor different forms of PfCRT. The antiplasmodial activities of dimers 1 and 6 were also examined in vitro (against drug-sensitive and drug-resistant strains of P. falciparum) and in vivo (against drug-sensitive P. berghei). Our data reveal that the quinine dimers are the most potent inhibitors of PfCRT(CQR) reported to date. Furthermore, the lead compounds (1 and 6) were not effluxed by PfCRT(CQR) from the digestive vacuole but instead accumulated to very high levels within this organelle. Both 1 and 6 exhibited in vitro antiplasmodial activities that were inversely correlated with CQ. Moreover, the additional parasiticidal effect exerted by 1 and 6 in the drug-resistant parasites was attributable, at least in part, to their ability to inhibit PfCRT(CQR). This highlights the potential for devising new antimalarial therapies that exploit inherent weaknesses in a key resistance mechanism of P. falciparum.

  19. Active case detection, treatment of falciparum malaria with combined chloroquine and sulphadoxine/pyrimethamine and vivax malaria with chloroquine and molecular markers of anti-malarial resistance in the Republic of Vanuatu

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    Rogers William O

    2010-04-01

    Full Text Available Abstract Background Chloroquine-resistant Plasmodium falciparum was first described in the Republic of Vanuatu in the early 1980s. In 1991, the Vanuatu Ministry of Health instituted new treatment guidelines for uncomplicated P. falciparum infection consisting of chloroquine/sulphadoxine-pyrimethamine combination therapy. Chloroquine remains the recommended treatment for Plasmodium vivax. Methods In 2005, cross-sectional blood surveys at 45 sites on Malo Island were conducted and 4,060 adults and children screened for malaria. Of those screened, 203 volunteer study subjects without malaria at the time of screening were followed for 13 weeks to observe peak seasonal incidence of infection. Another 54 subjects with malaria were followed over a 28-day period to determine efficacy of anti-malarial therapy; chloroquine alone for P. vivax and chloroquine/sulphadoxine-pyrimethamine for P. falciparum infections. Results The overall prevalence of parasitaemia by mass blood screening was 6%, equally divided between P. falciparum and P. vivax. Twenty percent and 23% of participants with patent P. vivax and P. falciparum parasitaemia, respectively, were febrile at the time of screening. In the incidence study cohort, after 2,303 person-weeks of follow-up, the incidence density of malaria was 1.3 cases per person-year with P. vivax predominating. Among individuals participating in the clinical trial, the 28-day chloroquine P. vivax cure rate was 100%. The 28-day chloroquine/sulphadoxine-pyrimethamine P. falciparum cure rate was 97%. The single treatment failure, confirmed by merozoite surface protein-2 genotyping, was classified as a day 28 late parasitological treatment failure. All P. falciparum isolates carried the Thr-76 pfcrt mutant allele and the double Asn-108 + Arg-59 dhfr mutant alleles. Dhps mutant alleles were not detected in the study sample. Conclusion Peak seasonal malaria prevalence on Malo Island reached hypoendemic levels during the study

  20. Rapid selection of Plasmodium falciparum chloroquine resistance transporter gene and multidrug resistance gene-1 haplotypes associated with past chloroquine and present artemether-lumefantrine use in Inhambane District, southern Mozambique

    DEFF Research Database (Denmark)

    Thomsen, Thomas T; Madsen, Laura B; Hansson, Helle H;

    2013-01-01

    Chloroquine (CQ) use in Mozambique was stopped in 2002 and artemether-lumefantrine (AL) was implemented in 2008. In light of no use of CQ and extensive use of AL, we determined the frequency of molecular markers of Plasmodium falciparum drug resistance/tolerance to CQ and AL in persons living...... in Linga-Linga, an isolated peninsula and in Furvela village, which is located 8 km inland. The P. falciparum chloroquine resistance transporter gene CVMNK wild type increased in frequency from 43.9% in 2009 to 66.4% in 2010 (P = 0.001), and combined P. falciparum multidrug resistance gene 1 N86-184F-D1246...... haplotype increased significantly between years (P = 0.039). The combination of P. falciparum chloroquine resistance transporter gene CVMNK and P. falciparum multidrug resistance gene NFD increased from 24.3% (2009) to 45.3% in (2010, P = 0.017). The rapid changes observed may largely be caused by decreased...

  1. Polymorphism of the Plasmodium falciparum multidrug resistance and chloroquine resistance transporter genes and in vitro susceptibility to aminoquinolines in isolates from the Peruvian Amazon.

    Science.gov (United States)

    Huaman, Maria Cecilia; Roncal, Norma; Nakazawa, Shusuke; Long, Ton That Ai; Gerena, Lucia; Garcia, Coralith; Solari, Lely; Magill, Alan J; Kanbara, Hiroji

    2004-05-01

    In vitro drug sensitivity to chloroquine (CQ), mefloquine (MQ) and quinine was investigated in 60 culture-adapted Plasmodium falciparum isolates from malaria patients in Padrecocha, a village in the Amazonian Department of Loreto, Peru. All isolates showed resistance to CQ, decreased susceptibility to quinine, and sensitivity to MQ. These isolates were examined for mutations in the P. falciparum multidrug resistance 1 (pfmdr1) and chloroquine resistance transporter (pfcrt) genes previously linked to CQ resistance. The mutations N86Y and D1246Y, two of the five mutations commonly observed in the pfmdr1 gene of CQ-resistant clones, were not found. The pfcrt mutation K76T, associated with CQ resistance, was identified in all the isolates tested. Sequence analysis of codons 72-76 in the pfcrt gene showed the haplotypes SVMNT and CVMNT.

  2. Molecular interaction of selected phytochemicals under the charged environment of Plasmodium falciparum chloroquine resistance transporter (PfCRT) model.

    Science.gov (United States)

    Patel, Saumya K; Khedkar, Vijay M; Jha, Prakash C; Jasrai, Yogesh T; Pandya, Himanshu A; George, Linz-Buoy; Highland, Hyacinth N; Skelton, Adam A

    2016-01-01

    Phytochemicals of Catharanthus roseus Linn. and Tylophora indica have been known for their inhibition of malarial parasite, Plasmodium falciparum in cell culture. Resistance to chloroquine (CQ), a widely used antimalarial drug, is due to the CQ resistance transporter (CRT) system. The present study deals with computational modeling of Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein and development of charged environment to mimic a condition of resistance. The model of PfCRT was developed using Protein homology/analogy engine (PHYRE ver 0.2) and was validated based on the results obtained using PSI-PRED. Subsequently, molecular interactions of selected phytochemicals extracted from C. roseus Linn. and T. indica were studied using multiple-iterated genetic algorithm-based docking protocol in order to investigate the translocation of these legends across the PfCRT protein. Further, molecular dynamics studies exhibiting interaction energy estimates of these compounds within the active site of the protein showed that compounds are more selective toward PfCRT. Clusters of conformations with the free energy of binding were estimated which clearly demonstrated the potential channel and by this means the translocation across the PfCRT is anticipated.

  3. Occurrence of the Southeast Asian/South American SVMNT haplotype of the chloroquine-resistance transporter gene in Plasmodium falciparum in Tanzania

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Dalgaard, Michael B; Lusingu, John P;

    2006-01-01

    Two main haplotypes, CVIET and SVMNT, of the Plasmodium falciparum chloroquine-resistance transporter gene (Pfcrt) are linked to 4-aminoquinoline resistance. The CVIET haplotype has been reported in most malaria-endemic regions, whereas the SVMNT haplotype has only been found outside Africa. We i...

  4. The antiplasmodium effects of a traditional South American remedy: Zanthoxylum chiloperone var. angustifolium against chloroquine resistant and chloroquine sensitive strains of Plasmodium falciparum

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    Gerardo Cebrian-Torrejon

    2011-08-01

    Full Text Available Zanthoxylum chiloperone var. angustifolium Engl., Rutaceae, is used in traditional medicine to treat fungal and protozoal infections in the central area of South America. Considering the increasing resistance of Plasmodium falciparum in malarial ridden areas, we explored the anti-plasmodial effects of three compounds isolated from Z. chiloperone. The pyranocoumarin transavicennol and the canthinone alkaloids, canthin-6-one and 5-methoxycanthin-6-one, were found to have IC50 on chloroquine/mefloquine resistant and sensitive strains of P. falciparum of 0.5-2.7, 2.0-5.3 and 5.1-10.4 ƒÊg/mL, respectively. Moreover, the formation of heme adducts by these compounds is described by a novel alternative method based on MS-CID methods. The alkylamide sanshool was also identified, for first time in this plant, in the dichloromethanic and ethanolic extracts and the extracts were found to be notably non-toxic and displayed good anti-plasmodial effects.

  5. In vivo and in vitro Plasmodium falciparum Resistance to Chloroquine, Amodiaquine and Quinine in the Brazilian Amazon

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    Aluisio Augusto Cotrim SEGURADO

    1997-03-01

    Full Text Available In order to study the chemoresistance of Plasmodium falciparum to commonly used antimalarial drugs in Brazil the authors have studied ten patients with falciparum malaria, acquired in the Brazilian Amazon region. Patients were submitted to in vivo study of drug sensitivity, after chemotherapy with either 4-aminoquinolines (chloroquine or amodiaquine or quinine. Adequate drug absorption was confirmed by standard urine excretion tests for antimalarials. Eight patients could be followed up to 28 days. Among these in vivo resistance (R I and R II responses was seen in all patients who received 4-amino-quinolines. One patient treated with quinine exhibited a R III response. Peripheral blood samples of the same patients were submitted to in vitro microtests for sensitivity to antimalarials. Out of nine successful tests, resistance to chloroquine and amodiaquine was found in 100% and resistance to quinine in 11.11% of isolates. Probit analysis of log dose-response was used to determine effective concentrations EC50, EC90 and EC99 to the studied drugs. Good correlation between in vivo and in vitro results was seen in six patients. The results emphasize high levels of P. falciparum resistance to 4- aminoquinolines and suggest an increase in resistance to quinine in the Brazilian Amazon region, reinforcing the need for continuous monitoring of drug sensitivity to adequate chemotherapy according to the most efficacious drug regimensResistência in vivo e in vitro do Plasmodium falciparum à cloroquina, amodiaquina e quinino na Amazônia Brasileira. Com o propósito de avaliar a resistência do Plasmodium falciparum às drogas antimaláricas, rotineiramente empregadas no Brasil, os autores acompanharam dez pacientes com malária falciparum adquirida na Amazônia brasileira. Os pacientes foram submetidos a estudo in vivo de sensibilidade a drogas, após tratamento com derivados 4-aminoquinoleínicos (cloroquina e amodiaquina ou quinino. A absorção das

  6. Polymorphism in Plasmodium falciparum Drug Transporter Proteins and Reversal of In Vitro Chloroquine Resistance by a 9,10-Dihydroethanoanthracene Derivative

    Science.gov (United States)

    Millet, Julie; Alibert, Sandrine; Torrentino-Madamet, Marylin; Rogier, Christophe; Santelli-Rouvier, Christiane; Bigot, Patricia; Mosnier, Joel; Baret, Eric; Barbe, Jacques; Parzy, Daniel; Pradines, Bruno

    2004-01-01

    BG958 reverses resistance in chloroquine-resistant isolates from different countries. Five mutations in the Plasmodium falciparum crt (pfcrt) gene resulting in the amino acid changes K76T, M74I, N75E, A220S, and R371I are systematically identified in resistance-reversed Asian, African, and Brazilian parasites which possess the pfcrt (CIET) haplotype. In combination with BG958, the activity of chloroquine is increased in parasites with the N86Y mutation in pfmdr1. PMID:15561869

  7. Dihydroethanoanthracene Derivatives as In Vitro Malarial Chloroquine Resistance Reversal Agents

    Science.gov (United States)

    Millet, Julie; Torrentino-Madamet, Marylin; Alibert, Sandrine; Rogier, Christophe; Santelli-Rouvier, Christiane; Mosnier, Joel; Baret, Eric; Barbe, Jacques; Parzy, Daniel; Pradines, Bruno

    2004-01-01

    The ability of four 9,10-dihydroethanoanthracene derivatives (BG920, BG932, BG958, and BG996), as well as verapamil and promethazine, to reverse chloroquine resistance was assessed against 24 chloroquine-resistant and 10 chloroquine-susceptible strains of Plasmodium falciparum from different countries. The 9,10-dihydroethanoanthracene derivatives clearly increase chloroquine susceptibility only in chloroquine-resistant isolates. PMID:15215144

  8. Establishment and application of a novel isothermal amplification assay for rapid detection of chloroquine resistance (K76T) in Plasmodium falciparum

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    Chahar, Madhvi; Mishra, Neelima; Anvikar, Anup; Dixit, Rajnikant; Valecha, Neena

    2017-01-01

    Chloroquine (CQ) resistance in Plasmodium falciparum is determined by the mutations in the chloroquine resistance transporter (Pfcrt) gene. The point mutation at codon 76 (K76T), which has been observed in more than 91% of P. falciparum isolates in India, is the major determinant of CQ resistance. To overcome the limitations and challenges of traditional methods, in this investigation we developed an easy to use loop mediated isothermal amplification (LAMP) protocol for rapid detection of the K76T mutation associated with CQ resistance in P. falciparum with naked eye visualization. In- house designed primers were synthesized and optimized to specifically distinguish the CQ resistant mutants of P. falciparum. The LAMP reaction was optimal at 61 °C for 60 min and calcein dye was added prior to amplification to enable visual detection. We demonstrate the detection limit of <2 ng/μl respectively, supporting the high sensitivity of this calcein based LAMP method. To the best of our knowledge this is the first report on the establishment of an easy, reliable and cost effective LAMP assay for rapid and specific detection of highly CQ resistance in P. falciparum malaria. PMID:28134241

  9. Identification of pyrimethamine- and chloroquine-resistant Plasmodium falciparum in Africa between 1984 and 1998: genotyping of archive blood samples

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    Saito-Nakano Yumiko

    2011-12-01

    Full Text Available Abstract Background Understanding the geographical distribution of drug resistance of Plasmodium falciparum is important for the effective treatment of malaria. Drug resistance has previously been inferred mainly from records of clinical resistance. However, clinical resistance is not always consistent with the parasite's genetic resistance. Thus, molecular identification of the parasite's drug resistance is required. In Africa, clinical resistance to pyrimethamine (Pyr and chloroquine (CQ was evident before 1980 but few studies investigating the genetic resistance to these drugs were conducted before the late 1990s. In this study, genotyping of genes involved in resistance to Pyr and CQ was performed using archive blood samples from Africa between 1984 and 1998. Methods Parasite DNA was extracted from P. falciparum-infected blood smears collected from travellers returning to Japan from Africa between 1984 and 1998. Genotypes of the dihydrofolate reductase gene (dhfr and CQ-resistance transporter gene (pfcrt were determined by polymerase chain reaction amplification and sequencing. Results Genotyping of dhfr and pfcrt was successful in 59 and 80 samples, respectively. One wild-type and seven mutant dhfr genotypes were identified. Three dhfr genotypes lacking the S108N mutation (NRSI, ICSI, IRSI; amino acids at positions 51, 59, 108, and 164 with mutations underlined were highly prevalent before 1994 but reduced after 1995, accompanied by an increase in genotypes with the S108N mutation. The dhfr IRNI genotype was first identified in Nigeria in 1991 in the present samples, and its frequency gradually increased. However, two double mutants (ICNI and NRNI, the latter of which was exclusively found in West Africa, were more frequent than the IRNI genotype. Only two pfcrt genotypes were found, the wild-type and a Southeast Asian type (CVIET; amino acids at positions 72-76 with mutations underlined. The CVIET genotype was already present as early as

  10. Low Prevalence of Pfcrt Resistance Alleles among Patients with Uncomplicated Falciparum Malaria in Niger Six Years after Chloroquine Withdrawal

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    Adamou Salissou

    2014-01-01

    Full Text Available Chloroquine (CQ resistance is widespread in Africa, but few data are available for Niger. Pfcrt haplotypes (aa 56–118 and ex vivo responses to CQ and amodiaquine were characterized for 26 isolates collected in South Niger from children under 15 years of age suffering from uncomplicated falciparum malaria, six years after the introduction of artemisinin-based combinations and the withdrawal of CQ. The wild-type Pfcrt haplotype CVMNK was found in 22 of the 26 isolates, with CVIET sequences observed in only three of the samples. We also describe for the first time a new CVINT haplotype. The ex vivo responses were better for CVMNK than for CVIET parasites. Pfcrt sequence data were compared with those obtained for 26 additional parasitized blood samples collected in Gabon, from an area of CQ resistance used as a control. Our findings suggest that there has been a significant decline in CQ-resistant genotypes since the previous estimates for Niger were obtained. No such decline in molecular resistance to CQ was observed in the subset of samples collected in similar conditions from Gabon. These results have important implications for public health and support the policy implemented in Niger since 2005, which aims to increase the efficacy and availability of antimalarial drugs whilst controlling the spread of resistance.

  11. Plasmodium falciparum genotypes associated with chloroquine and amodiaquine resistance in Guinea-Bissau

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    Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia

    2007-01-01

    Chloroquine is the most commonly used antimalarial in Guinea-Bissau and high doses are routinely prescribed. Blood from 497 patients treated with different doses of chloroquine or amodiaquine were genotyped. Pfcrt and pfmdr1 polymorphisms were identified. Pfmsp2 analysis identified recrudescent i...

  12. Persistence of chloroquine-resistant haplotypes of Plasmodium falciparum in children with uncomplicated Malaria in Lagos, Nigeria, four years after change of chloroquine as first-line antimalarial medicine.

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    Oladipo, Oladosu O; Wellington, Oyibo A; Sutherland, Colin J

    2015-04-28

    In Nigeria, despite the change in National malaria drug policy to artemisinin combination therapy (ACT) in 2005 due to widespread chloroquine resistance, chloroquine (CQ) is still widely used in the treatment of malaria because it is cheap, affordable and accessible. The use of ACT for the management of uncomplicated malaria is currently being promoted. The employment of genetic markers to track circulating chloroquine-resistant parasites are useful in elucidating likely poor efficacy of chloroquine, especially in settings where it is not recommended for the treatment of uncomplicated falciparum malaria. This study determined the prevalence of pfcrt haplotypes and point mutations in pfmdr1 genes four years after the change in antimalarial treatment policy from CQ to the ACTs in Lagos, a commercial city in South-West, Nigeria. This was a cross sectional study on uncomplicated malaria in children less than 12 years that presented with fever and other symptoms suggestive of malaria. Parasite DNA was extracted from 119 patients out of 251 children who were positive for Plasmodium falciparum by microscopy and amplified. The occurrence of haplotypes was investigated in pfcrt gene using probe-based qPCR and single nucleotide polymorphisms in pfmdr1 gene using nested PCR. One hundred and nine (109) of the 119 children with P falciparum infection (91.6%) harbourd parasites with the mutant pfcrt haplotype (CVIET). Out of this, 4.2% comprised a mixture of genotypes encoding CVMNK and CVIET, while 4.2% had the wild type (CVMNK). Furthermore, the frequency of point mutations in pfmdr1 was 62.2% and 69.0% for codons Y86 and F184 respectively. There were no mutations at codons 1034, 1042 and 1246 of the Pfmdr1 genes. The high frequency of the CQ-resistant haplotypes (CVIET) and mutations in Pfmdr1 associated with CQ resistance in P. falciparum among these children suggest that CQ-resistant parasites are still in circulation. Continuous use of chloroquine may continue to increase

  13. The return of chloroquine-susceptible Plasmodium falciparum malaria in Zambia.

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    Mwanza, Sydney; Joshi, Sudhaunshu; Nambozi, Michael; Chileshe, Justin; Malunga, Phidelis; Kabuya, Jean-Bertin Bukasa; Hachizovu, Sebastian; Manyando, Christine; Mulenga, Modest; Laufer, Miriam

    2016-12-05

    Plasmodium falciparum resistance to anti-malarial drugs remains a major obstacle to malaria control and elimination. The parasite has developed resistance to every anti-malarial drug introduced for wide-scale treatment. However, the spread of resistance may be reversible. Malawi was the first country to discontinue chloroquine use due to widespread resistance. Within a decade of the removal of drug pressure, the molecular marker of chloroquine-resistant malaria had disappeared and the drug was shown to have excellent clinical efficacy. Many countries have observed decreases in the prevalence of chloroquine resistance with the discontinuation of chloroquine use. In Zambia, chloroquine was used as first-line treatment for uncomplicated malaria until treatment failures led the Ministry of Health to replace it with artemether-lumefantrine in 2003. Specimens from a recent study were analysed to evaluate prevalence of chloroquine-resistant malaria in Nchelenge district a decade after chloroquine use was discontinued. Parasite DNA was extracted from dried blood spots collected by finger-prick in pregnant women who were enrolling in a clinical trial. The specimens underwent pyrosequencing to determine the genotype of the P. falciparum chloroquine resistance transporter, the gene that is associated with CQ resistance. Three-hundred and two specimens were successfully analysed. No chloroquine-resistant genotypes were detected. The study found the disappearance of chloroquine-resistant malaria after the removal of chloroquine drug pressure. Chloroquine may have a role for malaria prevention or treatment in Zambia and throughout the region in the future.

  14. Magnetic nanoparticles are highly toxic to chloroquine-resistant Plasmodium falciparum, dengue virus (DEN-2), and their mosquito vectors.

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    Murugan, Kadarkarai; Wei, Jiang; Alsalhi, Mohamad Saleh; Nicoletti, Marcello; Paulpandi, Manickam; Samidoss, Christina Mary; Dinesh, Devakumar; Chandramohan, Balamurugan; Paneerselvam, Chellasamy; Subramaniam, Jayapal; Vadivalagan, Chithravel; Wei, Hui; Amuthavalli, Pandiyan; Jaganathan, Anitha; Devanesan, Sandhanasamy; Higuchi, Akon; Kumar, Suresh; Aziz, Al Thabiani; Nataraj, Devaraj; Vaseeharan, Baskaralingam; Canale, Angelo; Benelli, Giovanni

    2017-02-01

    A main challenge in parasitology is the development of reliable tools to prevent or treat mosquito-borne diseases. We investigated the toxicity of magnetic nanoparticles (MNP) produced by Magnetospirillum gryphiswaldense (strain MSR-1) on chloroquine-resistant (CQ-r) and sensitive (CQ-s) Plasmodium falciparum, dengue virus (DEN-2), and two of their main vectors, Anopheles stephensi and Aedes aegypti, respectively. MNP were studied by Fourier-transform infrared spectroscopy and transmission electron microscopy. They were toxic to larvae and pupae of An. stephensi, LC50 ranged from 2.563 ppm (1st instar larva) to 6.430 ppm (pupa), and Ae. aegypti, LC50 ranged from 3.231 ppm (1st instar larva) to 7.545 ppm (pupa). MNP IC50 on P. falciparum were 83.32 μg ml(-1) (CQ-s) and 87.47 μg ml(-1) (CQ-r). However, the in vivo efficacy of MNP on Plasmodium berghei was low if compared to CQ-based treatments. Moderate cytotoxicity was detected on Vero cells post-treatment with MNP doses lower than 4 μg ml(-1). MNP evaluated at 2-8 μg ml(-1) inhibited DEN-2 replication inhibiting the expression of the envelope (E) protein. In conclusion, our findings represent the first report about the use of MNP in medical and veterinary entomology, proposing them as suitable materials to develop reliable tools to combat mosquito-borne diseases.

  15. Double mutation in the pfmdr1 gene is associated with emergence of chloroquine-resistant Plasmodium falciparum malaria in Eastern India.

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    Das, Sabyasachi; Mahapatra, Santanu Kar; Tripathy, Satyajit; Chattopadhyay, Sourav; Dash, Sandeep Kumar; Mandal, Debasis; Das, Balaram; Hati, Amiya Kumar; Roy, Somenath

    2014-10-01

    Malaria is a major public health problem in tropical and subtropical countries, including India. This study elucidates the cause of chloroquine treatment failure (for Plasmodium falciparum infection) before the introduction of artemisinin combination therapy. One hundred twenty-six patients were randomized to chloroquine treatment, and the therapeutic efficacy was monitored from days 1 to 28. An in vitro susceptibility test was performed with all isolates. Parasitic DNA was isolated, followed by PCR and restriction digestion of different codons of the pfcrt gene (codons 72 to 76) and the pfmdr1 gene (N86Y, Y184F, S1034C, N1042D, and D1246Y). Finally, sequencing was done to confirm the mutations. Forty-three (34.13%) early treatment failure cases and 16 (12.69%) late treatment failure cases were observed after chloroquine treatment. In vitro chloroquine resistance was found in 103 isolates (81.75%). Twenty-six (60.47%) early treatment failure cases and 6 (37.5%) late treatment failure cases were associated with the CVMNK-YYSNY allele (the underlined amino acids are those that were mutated). Moreover, the CVIEK-YYSNY allele was found in 8 early treatment failure (18.60%) and 2 late treatment failure (12.5%) cases. The presence of the wild-type pfcrt (CVMNK) and pfmdr1 (YYSNY) double mutant allele in chloroquine-nonresponsive cases was quite uncommon. In vivo chloroquine treatment failure and in vitro chloroquine resistance were strongly correlated with the CVMNK-YYSNY and CVIEK-YYSNY haplotypes (P < 0.01). Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  16. [Mutant alleles associated to chloroquine and sulfadoxine-pyrimethanime resistance in Plasmodium falciparum of the Ecuador-Peru and Ecuador-Colombia borders].

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    Arróspide, Nancy; Hijar-Guerra, Gisely; de Mora, Doménica; Diaz-Cortéz, César Eduardo; Veloz-Perez, Raúl; Gutierrez, Sonia; Cabezas-Sánchez, César

    2014-04-01

    The frequency of mutations in pfCRT and DHFR/DHPS genes of Plasmodium falciparum associated with resistance to chloroquine and sulfadoxine-pyrimethamine was evaluated in 83 strains from the districts of Esmeralda and Machala, located on the borders of Ecuador-Peru and Ecuador-Colombia in 2002. Polymerase chain reaction (PCR), conventional and its variants, was used. Mutations in the pfCRT gene were found in more than 90% of the samples from Esmeralda and Machala. For the DHFR gene, 90% of the strains were mutant samples from Esmeralda, 3 were double mutations and 1 was a triple mutation. In Machala, 25% were simple mutant forms and 75% mixed mutant forms (wild forms/mutant). In conclusion, resistance to chloroquine has been fixed in strains carrying K76T pfCRT mutation, whereas genetic imprinting for resistance to pyrimethamine is evolving, particularly in the district of Esmeralda.

  17. Evaluation of chloroquine therapy for vivax and falciparum malaria in southern Sumatra, western Indonesia

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    Laihad Ferdinand

    2010-02-01

    Full Text Available Abstract Background Chloroquine was used as first-line treatment for Plasmodium falciparum or Plasmodium vivax in Indonesia before the initial launch of artemisinin combination therapy in 2004. A study to evaluate efficacies of chloroquine against P. falciparum and P. vivax was undertaken at Lampung in southern Sumatra, western Indonesia in 2002. Methods Patients infected by P. falciparum or P. vivax were treated with 25 mg/kg chloroquine base in three daily doses over 48 hr. Finger prick blood was collected on Days 0, 2, 3, 7, 14, 21 and 28 after starting drug administration. Whole blood chloroquine and its desethyl metabolite were measured on Days-0, -3 and -28, or on the day of recurrent parasitaemia. Results 42 patients infected by P. falciparum were enrolled, and 38 fullfilled criteria for per protocol analysis. Only six of 38 (16% showed a response consistent with senstivity to chloroquine. 25 of 32 failures were confirmed resistant by demonstrating chloroquine levels on day of recurrence exceeding the minimally effective concentration (200 ng/mL whole blood. The 28-day cumulative incidence of resistance in P. falciparum was 68% (95% CI: 0.5260 - 0.8306. Thirty one patients infected by P. vivax were enrolled, and 23 were evaluable for per protocol analysis. 15 out of 23 (65% subjects had persistent or recurrent parasitaemia. Measurement of chloroquine levels confirmed all treatment failures prior to Day-15 as resistant. Beyond Day-15, 4 of 7 recurrences also had drug levels above 100 ng/mL and were classified as resistant. The 28-day cumulative incidence of chloroquine resistance in P. vivax was 43% (95% CI: 0.2715 - 0.6384. Conclusion These findings confirm persistantly high levels of resistance to chloroquine by P. falciparum in southern Sumatra, and suggest that high-grade and frequent resistance to chloroquine by P. vivax may be spreading westward in the Indonesia archipelago.

  18. Synthesis and study of effects of new 4-chloro – amodiaquine analogues against two resistant and sensitive forms to chloroquine Plasmodium Falciparum, in vitro

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    afra Khosravi

    2009-03-01

    Full Text Available Background: Resistance to chloroquine (CQ in Plasmodium falciparum malaria has become a major health concern of the developing countries.This resistance has prompted a re-examination of the pharmacology of alternative antimalarials that may be effective against resistant strains. Amodiaquine (AQ is a 4-aminoquinoline antimalarial which is effective against many chloroquine-resistant strains of P. falciparum. However, clinical use of AQ has been severely restricted because of associations with hepatotoxicity and agranulocytosis. The aim of this study was to examine the effects of replacing the 4’OH function of amodiaquine with either chlorine or fluorine. Materials and Methods: A successful four-step synthesis of a new series of 4-chloro analogues has been designed and applied to the synthesis of an array of 10 analogues. Malaria parasites were maintained in continuous culture using the method of Jensen and Trager. Cultures were grown in flasks containing human erythrocytes (2-5% with parasitemia in the range of 1% to 10% suspended in RPMI 1640 medium supplemented with 25 mM HEPES and 32 mM NaHCO3, and 10% human serum (complete medium. Cultures were gassed with a mixture of 3% O2, 6% CO2 and 91% N2 and were kept in a 30 degree temperature. Results: It is apparent that several analogues had very potent antimalarial activity against both strains of the parasite. In particular 5b, 5c and 5i were not only active in the single nanomolar range, but they also displayed little cross-resistance. Against the sensitive HB3 strain, these analogues were superior to chloroquine and slightly more potent than amodiaquine. Activity was reduced when the side-chain was large (eg. dibutyl analogue and pyridine analogues, 5g and 5j respectively. Discussion: In a four - step Process, 10 different chloro - amodiaquine were synthesized which showed (in vitro Promising effects against chloroquine resistant strains of Plasmodium falciparum. It is clear that the 4

  19. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.

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    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia; Dahal, Prabin; Nsanzabana, Christian; Moriera, Clarissa; Price, Ric N; Mårtensson, Andreas; Rosenthal, Philip J; Dorsey, Grant; Sutherland, Colin J; Guérin, Philippe; Davis, Timothy M E; Ménard, Didier; Adam, Ishag; Ademowo, George; Arze, Cesar; Baliraine, Frederick N; Berens-Riha, Nicole; Björkman, Anders; Borrmann, Steffen; Checchi, Francesco; Desai, Meghna; Dhorda, Mehul; Djimdé, Abdoulaye A; El-Sayed, Badria B; Eshetu, Teferi; Eyase, Frederick; Falade, Catherine; Faucher, Jean-François; Fröberg, Gabrielle; Grivoyannis, Anastasia; Hamour, Sally; Houzé, Sandrine; Johnson, Jacob; Kamugisha, Erasmus; Kariuki, Simon; Kiechel, Jean-René; Kironde, Fred; Kofoed, Poul-Erik; LeBras, Jacques; Malmberg, Maja; Mwai, Leah; Ngasala, Billy; Nosten, Francois; Nsobya, Samuel L; Nzila, Alexis; Oguike, Mary; Otienoburu, Sabina Dahlström; Ogutu, Bernhards; Ouédraogo, Jean-Bosco; Piola, Patrice; Rombo, Lars; Schramm, Birgit; Somé, A Fabrice; Thwing, Julie; Ursing, Johan; Wong, Rina P M; Zeynudin, Ahmed; Zongo, Issaka; Plowe, Christopher V; Sibley, Carol Hopkins

    2014-10-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine. © The American Society of Tropical Medicine and Hygiene.

  20. Survey of in vivo sensitivity to chloroquine by Plasmodium falciparum and P. vivax in Lombok, Indonesia.

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    Fryauff, D J; Baird, J K; Candradikusuma, D; Masbar, S; Sutamihardja, M A; Leksana, B; Tuti, S; Marwoto, H; Richie, T; Romzan, A

    1997-02-01

    A malariometric survey was conducted in 14 villages of Sekotong district, in Lombok, Indonesia during October 1994. Point prevalence of malaria ranged from 0% to 15% in the surveyed villages, averaging 6% overall, and Plasmodium falciparum accounted for 63% of the infections. Forty-nine patients with uncomplicated malaria and parasite counts ranging from 40 to 10,800 asexual forms/microliter were enrolled in a 28-day in vivo test of chloroquine sensitivity. All subjects received a supervised therapeutic regimen of chloroquine (25 mg base/kg over a 48-hr period) and parasitemia and symptoms were closely monitored for 28 days. Asexual parasites were eliminated within four days in the 29 P. falciparum and 20 P. vivax study patients enrolled. The cumulative incidence of therapeutic failure (recurrent symptomatic parasitemia) among P. falciparum cases at days 7, 14, and 28 was 7%, 10%, and 14% (4 of 29), respectively. However in all four cases, parasitemias recurred against chloroquine blood levels below the minimally effective concentration (MEC) of 200 ng/ml and do not confirm chloroquine resistance. All 20 P. vivax parasitemias were sensitive to chloroquine and the blood remained clear, with the exception of one case in which an asymptomatic parasitemia appeared on day 28. Parasitemias by P. falciparum and P. vivax that were observed before supervised therapy, but in the presence of whole blood chloroquine above normally suppressive MEC levels, suggest resistance to suppressive or prophylactic regimens of chloroquine.

  1. High frequency of Plasmodium falciparum chloroquine resistance marker (pfcrt T76 mutation in Yemen: An urgent need to re-examine malaria drug policy

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    Al-Mekhlafi Hesham M

    2011-05-01

    Full Text Available Abstract Background Malaria remains a significant health problem in Yemen with Plasmodium falciparum being the predominant species which is responsible for 90% of the malaria cases. Despite serious concerns regarding increasing drug resistance, chloroquine is still used for the prevention and treatment of malaria in Yemen. This study was carried out to determine the prevalence of choloroquine resistance (CQR of P. falciparum isolated from Yemen based on the pfcrt T76 mutation. Methods A cross-sectional study was carried out among 511 participants from four governorates in Yemen. Blood samples were screened using microscopic and species-specific nested PCR based on the 18S rRNA gene to detect and identify Plasmodium species. Blood samples positive for P. falciparum were used for detecting the pfcrt T76 mutation using nested-PCR. Results The prevalence of pfcrt T76 mutation was 81.5% (66 of 81 isolates. Coastal areas/foothills had higher prevalence of pfcrt T76 mutation compared to highland areas (90.5% vs 71.8% (p = 0.031. The pfcrt T76 mutation had a significant association with parasitaemia (p = 0.045. Univariate analysis shows a significant association of pfcrt T76 mutation with people aged > 10 years (OR = 9, 95% CI = 2.3 - 36.2, p = 0.001, low household income (OR = 5, 95% CI = 1.3 - 19.5, p = 0.027, no insecticide spray (OR = 3.7, 95% CI = 1.16 - 11.86, p = 0.025 and not sleeping under insecticide treated nets (ITNs (OR = 4.8, 95% CI = 1.38 - 16.78, p = 0.01. Logistic regression model confirmed age > 10 years and low household income as predictors of pfcrt T76 mutation in Yemen P. falciparum isolates. Conclusions The high prevalence of pfcrt T76 mutation in Yemen could be a predictive marker for the prevalence of P. falciparum CQR. This finding shows the necessity for an in-vivo therapeutic efficacy test for CQ. P. falciparum CQR should be addressed in the national strategy to control malaria.

  2. In Vitro and Molecular Surveillance for Antimalarial Drug Resistance in Plasmodium falciparum Parasites in Western Kenya Reveals Sustained Artemisinin Sensitivity and Increased Chloroquine Sensitivity.

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    Lucchi, Naomi W; Komino, Franklin; Okoth, Sheila Akinyi; Goldman, Ira; Onyona, Philip; Wiegand, Ryan E; Juma, Elizabeth; Shi, Ya Ping; Barnwell, John W; Udhayakumar, Venkatachalam; Kariuki, Simon

    2015-12-01

    Malaria control is hindered by the evolution and spread of resistance to antimalarials, necessitating multiple changes to drug policies over time. A comprehensive antimalarial drug resistance surveillance program is vital for detecting the potential emergence of resistance to antimalarials, including current artemisinin-based combination therapies. An antimalarial drug resistance surveillance study involving 203 Plasmodium falciparum malaria-positive children was conducted in western Kenya between 2010 and 2013. Specimens from enrolled children were analyzed in vitro for sensitivity to chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ), lumefantrine, and artemisinin derivatives (artesunate and dihydroartemisinin) and for drug resistance allele polymorphisms in P. falciparum crt (Pfcrt), Pfmdr-1, and the K13 propeller domain (K13). We observed a significant increase in the proportion of samples with the Pfcrt wild-type (CVMNK) genotype, from 61.2% in 2010 to 93.0% in 2013 (P < 0.0001), and higher proportions of parasites with elevated sensitivity to CQ in vitro. The majority of isolates harbored the wild-type N allele in Pfmdr-1 codon 86 (93.5%), with only 7 (3.50%) samples with the N86Y mutant allele (the mutant nucleotide is underlined). Likewise, most isolates harbored the wild-type Pfmdr-1 D1246 allele (79.8%), with only 12 (6.38%) specimens with the D1246Y mutant allele and 26 (13.8%) with mixed alleles. All the samples had a single copy of the Pfmdr-1 gene (mean of 0.907 ± 0.141 copies). None of the sequenced parasites had mutations in K13. Our results suggest that artemisinin is likely to remain highly efficacious and that CQ sensitivity appears to be on the rise in western Kenya.

  3. Distribution pattern of Plasmodium falciparum chloroquine transporter (pfcrt) gene haplotypes in Sri Lanka 1996-2006

    DEFF Research Database (Denmark)

    Zhang, Jenny J; Senaratne, Tharanga N; Daniels, Rachel

    2011-01-01

    Abstract. Widespread antimalarial resistance has been a barrier to malaria elimination efforts in Sri Lanka. Analysis of genetic markers in historic parasites may uncover trends in the spread of resistance. We examined the frequency of Plasmodium falciparum chloroquine transporter (pfcrt; codons 72...

  4. Chloroquine clinical failures in P. falciparum malaria are associated with mutant Pfmdr-1, not Pfcrt in Madagascar.

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    Valérie Andriantsoanirina

    Full Text Available Molecular studies have demonstrated that mutations in the Plasmodium falciparum chloroquine resistance transporter gene (Pfcrt play a major role in chloroquine resistance, while mutations in P. falciparum multidrug resistance gene (Pfmdr-1 act as modulator. In Madagascar, the high rate of chloroquine treatment failure (44% appears disconnected from the overall level of in vitro CQ susceptibility (prevalence of CQ-resistant parasites 60% of isolates, but did not explore their association with P. falciparum chloroquine resistance. To document the association of Pfmdr-1 alleles with chloroquine resistance in Madagascar, 249 P. falciparum samples collected from patients enrolled in a chloroquine in vivo efficacy study were genotyped in Pfcrt/Pfmdr-1 genes as well as the estimation of the Pfmdr-1 copy number. Except 2 isolates, all samples displayed a wild-type Pfcrt allele without Pfmdr-1 amplification. Chloroquine treatment failures were significantly associated with Pfmdr-1 86Y mutant codon (OR = 4.6. The cumulative incidence of recurrence of patients carrying the Pfmdr-1 86Y mutation at day 0 (21 days was shorter than patients carrying Pfmdr-1 86N wild type codon (28 days. In an independent set of 90 selected isolates, in vitro susceptibility to chloroquine was not associated with Pfmdr-1 polymorphisms. Analysis of two microsatellites flanking Pfmdr-1 allele showed that mutations occurred on multiple genetic backgrounds. In Madagascar, Pfmdr-1 polymorphism is associated with late chloroquine clinical failures and unrelated with in vitro susceptibility or Pfcrt genotype. These results highlight the limits of the current in vitro tests routinely used to monitor CQ drug resistance in this unique context. Gaining insight about the mechanisms that regulate polymorphism in Pfmdr1 remains important, particularly regarding the evolution and spread of Pfmdr-1 alleles in P. falciparum populations under changing drug pressure which may have important

  5. In vitro evaluation of verapamil and other modulating agents in Brazilian chloroquine-resistant Plasmodium falciparum isolates Avaliação in vitro do verapamil e de outros agentes moduladores em isolados de Plasmodium falciparum resistentes à cloroquina

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    Carla M.S. Menezes

    2003-01-01

    Full Text Available Verapamil, was assayed to record its modulating effect upon Brazilian Plasmodium falciparum isolates resistant to chloroquine. Other cardiovascular drugs known to be modulating agents in resistant malaria and/or multidrug-resistant neoplasias, including nifedipine, nitrendipine, diltiazem and propranolol, were also evaluated. Concentrations similar to those for cardiovascular therapy were used in the in vitro microtechnique for antimalarial drug susceptibility. Intrinsic antiplasmodial activity was observed from the lowest concentrations without a significant modulating action. Other reported modulating agents, such as the antipsychotic drug trifluoperazine and the antidepressants desipramine and imipramine, demonstrated similar responses under the same experimental conditions. Results suggest a much higher susceptibility of Brazilian strains, as well as an indifferent behaviour in relation to modulating agents.Verapamil foi ensaiado quanto ao efeito modulador em isolados brasileiros de Plasmodium falciparum resistentes à cloroquina. Outros agentes cardiovasculares, considerados como moduladores da resistência em malária e/ou em neoplasias multiresistentes a fármacos, como nifedipino, nitrendipino, diltiazem e propranolol foram ensaiados quanto ao mesmo efeito. Concentrações semelhantes às da terapia cardiovascular foram empregadas no ensaio de microtécnica de sensibilidade para fármacos antimaláricos. Atividade antiplasmódica intrínsica foi observada desde as menores concentrações, sem, entretanto, ocorrência de modulação significativa da resistência. Sob as mesmas condições experimentais, respostas semelhantes foram observadas para outros agentes moduladores conhecidos como o antipsicótico trifluoperazina e os antidepressivos desipramina e imipramina. Em conjunto, estes resultados sugerem alta sensibilidade e comportamento indiferente de cepas brasileiras ao efeito de agentes moduladores da resistência.

  6. [Sensitivity in vitro of Plasmodium falciparum to chloroquine, pyronaridine, artesunate and piperaquine in south Yunnan].

    Science.gov (United States)

    Yang, H L; Yang, P F; Liu, D Q; Liu, R J; Dong, Y; Zhang, C Y; Cao, D Q; He, H

    1992-01-01

    The sensitivity of P. falciparum to chloroquine, pyronaridine, artesunate and piperaquine (CQ, PD, AT, PQ) was assayed using in vitro microtechnique in south Yunnan in 1990. The resistance rates were 98.7% (75/76), 27.6% (16/58), 13.8% (9/65) and 97.7% (43/44) respectively, and ID50 were 125.0, 19.0, 4.7 and 243.3 nmol/L, respectively. The resistance rate against CQ showed no change as compared to the rates against CQ 5 and 9 years ago; but the ID50 was lower. CQ-resistant P. falciparum showed a marked cross-resistance to PQ, but not to PD and AT. AT-resistant P. falciparum exhibited cross-resistance to the above-mentioned three drugs. PD-resistant P. falciparum showed no cross resistance to AT, but showed cross resistance to CQ and PQ. In comparison with chloroquine-coated plates, the plates coated with pyronaridine, artesunate or piperaquine gave similar results as the former, which were shown by the rise in schizont inhibition rates along with the rise in drug concentration. It indicates that pyronaridine-, artesunate-, and piperaquine-coated plates can be used in the assay of sensitivity of P. falciparum to the three drugs.

  7. Efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in Honduras.

    Science.gov (United States)

    Mejia Torres, Rosa Elena; Banegas, Engels Ilich; Mendoza, Meisy; Diaz, Cesar; Bucheli, Sandra Tamara Mancero; Fontecha, Gustavo A; Alam, Md Tauqeer; Goldman, Ira; Udhayakumar, Venkatachalam; Zambrano, Jose Orlinder Nicolas

    2013-05-01

    Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization-World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.

  8. Using a genome-scale metabolic network model to elucidate the mechanism of chloroquine action in Plasmodium falciparum

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    Shivendra G. Tewari

    2017-08-01

    Full Text Available Chloroquine, long the default first-line treatment against malaria, is now abandoned in large parts of the world because of widespread drug-resistance in Plasmodium falciparum. In spite of its importance as a cost-effective and efficient drug, a coherent understanding of the cellular mechanisms affected by chloroquine and how they influence the fitness and survival of the parasite remains elusive. Here, we used a systems biology approach to integrate genome-scale transcriptomics to map out the effects of chloroquine, identify targeted metabolic pathways, and translate these findings into mechanistic insights. Specifically, we first developed a method that integrates transcriptomic and metabolomic data, which we independently validated against a recently published set of such data for Krebs-cycle mutants of P. falciparum. We then used the method to calculate the effect of chloroquine treatment on the metabolic flux profiles of P. falciparum during the intraerythrocytic developmental cycle. The model predicted dose-dependent inhibition of DNA replication, in agreement with earlier experimental results for both drug-sensitive and drug-resistant P. falciparum strains. Our simulations also corroborated experimental findings that suggest differences in chloroquine sensitivity between ring- and schizont-stage P. falciparum. Our analysis also suggests that metabolic fluxes that govern reduced thioredoxin and phosphoenolpyruvate synthesis are significantly decreased and are pivotal to chloroquine-based inhibition of P. falciparum DNA replication. The consequences of impaired phosphoenolpyruvate synthesis and redox metabolism are reduced carbon fixation and increased oxidative stress, respectively, both of which eventually facilitate killing of the parasite. Our analysis suggests that a combination of chloroquine (or an analogue and another drug, which inhibits carbon fixation and/or increases oxidative stress, should increase the clearance of P. falciparum

  9. Similar efficacy and tolerability of double-dose chloroquine and artemether-lumefantrine for treatment of Plasmodium falciparum infection in Guinea-Bissau: a randomized trial

    DEFF Research Database (Denmark)

    Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia

    2011-01-01

    In 2008, Guinea-Bissau introduced artemether-lumefantrine for treatment of uncomplicated malaria. Previously, 3 times the standard dose of chloroquine, that was probably efficacious against Plasmodium falciparum with the resistance-associated chloroquine-resistance transporter (pfcrt) 76T allele...

  10. The Association of K76T Mutation in Pfcrt Gene and Chloroquine Treatment Failure in Uncomplicated Plasmodium falciparum Malaria in a Cohort of Nigerian Children

    Science.gov (United States)

    Umar, R. A.; Hassan, S. W.; Ladan, M. J.; Nma Jiya, M.; Abubakar, M. K.; Nata`Ala, U.

    The aim of this study was to evaluate the association of K76T mutation in Pfcrt gene and chloroquine treatment failure following reports that the efficacy of chloroquine in the treatment of uncomplicated falciparum malaria in Africa is seriously compromised by high levels of drug resistance. The occurrence of mutation on codon 76 of Plasmodium falciparum chloroquine resistance transporter (Pfcrt) gene has been associated with development of resistance to chloroquine. We investigated the association of K76T mutation in Pfcrt gene in malaria-infected blood samples from a cohort of Nigerian children with uncomplicated falciparum malaria treated with chloroquine and its association with clinical (in vivo) resistance. The Pfcrt T76 allele was very significantly associated with resistance to chloroquine (Fischer exact test: p = 0.0001). We conclude that K76T mutation in Pfcrt gene is significantly associated with chloroquine resistance and that it could be used as a population marker for chloroquine resistance in this part of the country

  11. A purine analog synergizes with chloroquine (CQ by targeting Plasmodium falciparum Hsp90 (PfHsp90.

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    Dea Shahinas

    Full Text Available BACKGROUND: Drug resistance, absence of an effective vaccine, and inadequate public health measures are major impediments to controlling Plasmodium falciparum malaria worldwide. The development of antimalarials to which resistance is less likely is paramount. To this end, we have exploited the chaperone function of P. falciparum Hsp90 (PfHsp90 that serves to facilitate the expression of resistance determinants. METHODS: The affinity and activity of a purine analogue Hsp90 inhibitor (PU-H71 on PfHsp90 was determined using surface plasmon resonance (SPR studies and an ATPase activity assay, respectively. In vitro, antimalarial activity was quantified using flow cytometry. Interactors of PfHsp90 were determined by LC-MS/MS. In vivo studies were conducted using the Plasmodium berghei infection mouse model. RESULTS: PU-H71 exhibited antimalarial activity in the nanomolar range, displayed synergistic activity with chloroquine in vitro. Affinity studies reveal that the PfHsp90 interacts either directly or indirectly with the P. falciparum chloroquine resistance transporter (PfCRT responsible for chloroquine resistance. PU-H71 synergized with chloroquine in the P.berghei mouse model of malaria to reduce parasitemia and improve survival. CONCLUSIONS: We propose that the interaction of PfHsp90 with PfCRT may account for the observed antimalarial synergy and that PU-H71 is an effective adjunct for combination therapy.

  12. Patterns of chloroquine use and resistance in sub-Saharan Africa: a systematic review of household survey and molecular data

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    Venkatesan Meera

    2011-05-01

    Full Text Available Abstract Background As a result of widespread chloroquine and sulphadoxine-pyrimethamine (SP resistance, 90% of sub-Saharan African countries had adopted policies of artemisinin-based combination therapy (ACT for treatment of uncomplicated malaria by 2007. In Malawi, cessation of chloroquine use was followed by the re-emergence of chloroquine-susceptible malaria. It was expected that introduction of ACT would lead to a return in chloroquine susceptibility throughout Africa, but this has not yet widely occurred. This observation suggests that there is continuing use of ineffective anti-malarials in Africa and that persistent chloroquine-resistant malaria is due to ongoing drug pressure despite national policy changes. Methods To estimate drug use on a national level, 2006-2007 Demographic Health Survey and Multiple Indicator Cluster Survey data from 21 African countries were analysed. Resistance data were compiled by systematic review of the published literature on the prevalence of the Plasmodium falciparum chloroquine resistance transporter polymorphism at codon 76, which causes chloroquine resistance. Results Chloroquine was the most common anti-malarial used according to surveys from 14 of 21 countries analysed, predominantly in West Africa. SP was most commonly reported in two of 21 countries. Among eight countries with longitudinal molecular resistance data, the four countries where the highest proportion of children treated for fever received chloroquine (Uganda, Burkina Faso, Guinea Bissau, and Mali also showed no significant declines in the prevalence of chloroquine-resistant infections. The three countries with low or decreasing chloroquine use among children who reported fever treatment (Malawi, Kenya, and Tanzania had statistically significant declines in the prevalence of chloroquine resistance. Conclusions This study demonstrates that in 2006-2007, chloroquine and SP continued to be used at high rates in many African countries. In

  13. Atovaquone and proguanil hydrochloride compared with chloroquine or pyrimethamine/sulfadoxine for treatment of acute Plasmodium falciparum malaria in Peru

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    Llanos-Cuentas A.

    2001-01-01

    Full Text Available The efficacy and safety of a fixed-dose combination of atovaquone and proguanil hydrochloride (MalaroneTM were compared with chloroquine or pyrimethamine/sulfadoxine in patients with acute falciparum malaria in northern Peru. Patients were initially randomized to receive 1,000 mg atovaquone and 400 mg proguanil hydrochloride daily for 3 days (n=15 or 1,500 mg chloroquine (base over a 3 day period (n=14 (phase 1. The cure rate with chloroquine was lower than expected and patients were subsequently randomized to receive a single dose of 75 mg pyrimethamine and 1,500 mg sulfadoxine (n=9 or atovaquone/proguanil as before (n=5 (phase 2. In phase 1, atovaquone/proguanil was significantly more effective than chloroquine (cure rate 100% [14/14] versus 8% [1/13], P<0.0001. In phase 2, atovaquone/proguanil and pyrimethamine/sulfadoxine were both highly effective (cure rates 100% [5/5] and 100% [7/7]. There were no significant differences between treatment groups in parasite or fever clearance times. Adverse events were typical of malarial symptoms and did not differ significantly between groups. Overall efficacy of atovaquone/proguanil was 100% for treatment of acute falciparum malaria in a region with a high prevalence of chloroquine resistance.

  14. Genetics of chloroquine-resistant malaria: a haplotypic view

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    Gauri Awasthi

    2013-12-01

    Full Text Available The development and rapid spread of chloroquine resistance (CQR in Plasmodium falciparum have triggered the identification of several genetic target(s in the P. falciparum genome. In particular, mutations in the Pfcrt gene, specifically, K76T and mutations in three other amino acids in the region adjoining K76 (residues 72, 74, 75 and 76, are considered to be highly related to CQR. These various mutations form several different haplotypes and Pfcrt gene polymorphisms and the global distribution of the different CQR- Pfcrt haplotypes in endemic and non-endemic regions of P. falciparum malaria have been the subject of extensive study. Despite the fact that the Pfcrt gene is considered to be the primary CQR gene in P. falciparum , several studies have suggested that this may not be the case. Furthermore, there is a poor correlation between the evolutionary implications of the Pfcrt haplotypes and the inferred migration of CQR P. falciparum based on CQR epidemiological surveillance data. The present paper aims to clarify the existing knowledge on the genetic basis of the different CQR- Pfcrt haplotypes that are prevalent in worldwide populations based on the published literature and to analyse the data to generate hypotheses on the genetics and evolution of CQR malaria.

  15. Chloroquine-resistant Plasmodium vivax in transmigration settlements of West Kalimantan, Indonesia.

    Science.gov (United States)

    Fryauff, D J; Tuti, S; Mardi, A; Masbar, S; Patipelohi, R; Leksana, B; Kain, K C; Bangs, M J; Richie, T L; Baird, J K

    1998-10-01

    Malariometric surveys were conducted during July 1996 in native Dayak villages and predominantly Javanese transmigration settlements in Ketapang district of West Kalimantan, Indonesia. Malaria prevalence ranged from 0.9% to 2.7% in Dayak villages and from 1% to 20% in the transmigration settlements. Plasmodium falciparum accounted for 67% of the cases among Dayaks but P. vivax was dominant among transmigrants, accounting for more than 72% of the infections. Chloroquine sensitivity/resistance was assessed by 28-day in vivo testing of uncomplicated malaria infections and measurement of chloroquine blood levels in cases where parasitemias reappeared within the 28-day test period. Resistance was based on the appearance of asexual parasites against chloroquine plus desethylchloroquine levels exceeding the minimally effective whole blood concentrations proposed for sensitive parasite strains (P. vivax, 100 ng/ml; P. falciparum, 200 ng/ml). All parasitemias cleared initially within four days of beginning supervised chloroquine therapy (25 mg base/kg over a 48-hr period), but asexual parasites reappeared within 28 days in 27 of 52 P. vivax and three of 12 P. falciparum cases. Chloroquine blood levels at the time of recurrent parasitemias revealed resistance in 12 of the 27 P. vivax cases and in one of the three P. falciparum cases. Genotypes of nine of the 12 recurrent P. vivax isolates matched with their primary isolates and ruled out reinfection. These findings establish the presence of chloroquine-resistant P. vivax on the island of Borneo. The pattern of malaria and the high frequency of chloroquine resistance by P. vivax at the West Kalimantan location may relate to demographic, ecologic, agricultural, and socioeconomic changes associated with transmigration.

  16. High prevalence of drug-resistance mutations in Plasmodium falciparum and Plasmodium vivax in southern Ethiopia

    OpenAIRE

    Schunk, Mirjam; Kumma, Wondimagegn P.; Barreto Miranda, Isabel; Maha E. Osman; Roewer, Susanne; Alano, Abraham; Loescher, Thomas; Bienzle, Ulrich; Mockenhaupt, Frank P

    2006-01-01

    Background: In Ethiopia, malaria is caused by both Plasmodium falciparum and Plasmodium vivax. Drug resistance of P. falciparum to sulfadoxine-pyrimethamine (SP) and chloroquine (CQ) is frequent and intense in some areas. Methods: In 100 patients with uncomplicated malaria from Dilla, southern Ethiopia, P. falciparum dhfr and dhps mutations as well as P. vivax dhfr polymorphisms associated with resistance to SP and P. falciparum pfcrt and pfmdr1 mutations conferring CQ resistance were assesse...

  17. A simple, high-throughput method to detect Plasmodium falciparum single nucleotide polymorphisms in the dihydrofolate reductase, dihydropteroate synthase, and P. falciparum chloroquine resistance transporter genes using polymerase chain reaction- and enzyme-linked immunosorbent

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Enosse, Sonia; Pearce, Richard;

    2005-01-01

    . However, to be a practical tool in the surveillance of drug resistance, simpler methods for high-throughput haplotyping are warranted. Here we describe a quick and simple technique that detects dhfr, dhps, and Pfcrt SNPs using polymerase chain reaction (PCR)- and enzyme-linked immunosorbent assay (ELISA...... the SNPs of dhfr, dhps, and Pfcrt with high specificity. The SSOP-ELISA compared well with a standard PCR-restriction fragment length polymorphism procedure, and gave identical positive results in more than 90% of the P. falciparum slide-positive samples tested. The SSOP-ELISA of all dhfr, dhps, or Pfcrt...

  18. Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt.

    OpenAIRE

    Pelleau, Stéphane; Moss, Eli L; Dhingra, Satish K.; Volney, Béatrice; Casteras, Jessica; Gabryszewski, Stanislaw J.; Volkman, Sarah K.; Wirth, Dyann F.; Legrand, Eric; David A Fidock; Neafsey, Daniel E; Musset, Lise

    2015-01-01

    International audience; In regions with high malaria endemicity, the withdrawal of chloroquine (CQ) as first-line treatment of Plasmodium falciparum infections has typically led to the restoration of CQ susceptibility through the reexpansion of the wild-type (WT) allele K76 of the chloroquine resistance transporter gene (pfcrt) at the expense of less fit mutant alleles carrying the CQ resistance (CQR) marker K76T. In low-transmission settings, such as South America, drug resistance mutations ...

  19. Trends in chloroquine resistance marker, Pfcrt-K76T mutation ten years after chloroquine withdrawal in Tanzania

    DEFF Research Database (Denmark)

    Mohammed, Asia; Ndaro, Arnold; Kalinga, Akili;

    2013-01-01

    , continued to be used in intermittent preventive treatment of malaria in pregnancy (IPTp) despite reports of high levels of resistance to SP due to the lack of alternatives to SP for IPTp. Recent reports have indicated recovery of CQ-susceptibility in Malawi, Kenya, Mozambique, and Tanzania based......Plasmodium falciparum resistance to anti-malarial drugs remains a major obstacle to the control of malaria. In 2001 Tanzania replaced chloroquine (CQ) with sulphadoxine-pyrimethamine (SP) as first-line drug, which in turn was replaced by artemisinin combination therapy in 2006. SP has however...

  20. A simple, high-throughput method to detect Plasmodium falciparum single nucleotide polymorphisms in the dihydrofolate reductase, dihydropteroate synthase, and P. falciparum chloroquine resistance transporter genes using polymerase chain reaction- and enzyme-linked immunosorbent

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Enosse, Sonia; Pearce, Richard

    2005-01-01

    . However, to be a practical tool in the surveillance of drug resistance, simpler methods for high-throughput haplotyping are warranted. Here we describe a quick and simple technique that detects dhfr, dhps, and Pfcrt SNPs using polymerase chain reaction (PCR)- and enzyme-linked immunosorbent assay (ELISA......)-based technology. Biotinylated PCR products of dhfr, dhps, or Pfcrt were captured on streptavidin-coated microtiter plates and sequence-specific oligonucleotide probes (SSOPs) were hybridized with the PCR products. A stringent washing procedure enabled detection of remaining bound SSOPs and distinguished between...... the SNPs of dhfr, dhps, and Pfcrt with high specificity. The SSOP-ELISA compared well with a standard PCR-restriction fragment length polymorphism procedure, and gave identical positive results in more than 90% of the P. falciparum slide-positive samples tested. The SSOP-ELISA of all dhfr, dhps, or Pfcrt...

  1. Dynamics of pfcrt alleles CVMNK and CVIET in chloroquine-treated Sudanese patients infected with Plasmodium falciparum

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    Warhurst David C

    2010-03-01

    Full Text Available Abstract Background Parasite resistance to the anti-malarial drug chloroquine is common in eastern Sudan. Dynamic within-host changes in the relative abundance of both sensitive and resistant Plasmodium falciparum parasites were examined in a cohort of chloroquine-treated patients presenting with uncomplicated falciparum malaria, using a novel allele-specific quantitative approach. Methods Treatment outcomes were determined for 93 patients of all ages in a per protocol cohort using a modified 14-day WHO protocol. Parasite DNA samples at days 0, 1, 2, 3, 7 and 14 following treatment were analysed using real-time quantitative PCR methods that distinguished resistant and sensitive genotypes at amino acids 72 - 76 of the pfcrt locus. Results Chloroquine treatment was not efficacious, and of 93 assessable patients, only 10 individuals (10.7%; 95% C.I. 4.34 - 17.2% enjoyed an adequate clinical and parasitological response. Resistant parasites with the haplotype CVIET at codons 72-76 of the pfcrt locus were dominant in the starting population. Chloroquine sensitive parasites with the haplotype CVMNK were detected in 19 individuals prior to treatment (20.43%; 95% C.I. 5.14 - 18.5%. In these patients, CQ treatment rapidly selected CVIET parasites, and this haplotype overwhelmingly dominated the parasite population in each individual by day 2 after treatment. Conclusions Such rapid intra-host selection of particular genotypes after the introduction of drug will cause frequent misidentification of parasite genotypes present in the starting population. This will have a potentially serious confounding effect on clinical trials which employ PCR-corrected estimates of treatment failure, as resistant parasites below the detection threshold in the pre-treatment sample can be erroneously classified as "new" infections during follow-up, over-estimating drug efficacy.

  2. Chloroquine-resistant Plasmodium vivax malaria in Debre Zeit, Ethiopia

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    Muchohi Simon

    2008-10-01

    Full Text Available Abstract Background Plasmodium vivax accounts for about 40% of all malaria infection in Ethiopia. Chloroquine (CQ is the first line treatment for confirmed P. vivax malaria in the country. The first report of CQ treatment failure in P. vivax was from Debre Zeit, which suggested the presence of chloroquine resistance. Methods An in vivo drug efficacy study was conducted in Debre Zeit from June to August 2006. Eighty-seven patients with microscopically confirmed P. vivax malaria, aged between 8 months and 52 years, were recruited and treated under supervision with CQ (25 mg/kg over three days. Clinical and parasitological parameters were assessed during the 28 day follow-up period. CQ and desethylchloroquine (DCQ blood and serum concentrations were determined with high performance liquid chromatography (HPLC in patients who showed recurrent parasitaemia. Results Of the 87 patients recruited in the study, one was lost to follow-up and three were excluded due to P. falciparum infection during follow-up. A total of 83 (95% of the study participants completed the follow-up. On enrolment, 39.8% had documented fever and 60.2% had a history of fever. The geometric mean parasite density of the patients was 7045 parasites/μl. Among these, four patients had recurrent parasitaemia on Day 28. The blood CQ plus DCQ concentrations of these four patients were all above the minimal effective concentration (> 100 ng/ml. Conclusion Chloroquine-resistant P. vivax parasites are emerging in Debre Zeit, Ethiopia. A multi-centre national survey is needed to better understand the extent of P. vivax resistance to CQ in Ethiopia.

  3. Effects of chloroquine and sulfadoxine/pyrimethamine on gametocytes in patients with uncomplicated Plasmodium falciparum malaria in Colombia

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    Lyda Osorio

    2002-12-01

    Full Text Available The effect of antimalarials on gametocytes can influence transmission and the spread of drug resistance. In order to further understand this relationship, we determined the proportion of gametocyte carriers over time post-treatment in patients with uncomplicated Plasmodium falciparum malaria who were treated with either chloroquine (CQ or sulfadoxine/pyrimethamine (SP. The overall proportion of gametocyte carriers was high (85% and not statistically significantly different between the CQ and SP treatment groups. However, an increased risk of carrying gametocytes on day 14 of follow up (1.26 95% CI 1.10-1.45 was found among patients having therapeutic failure to CQ compared with patients having an adequate therapeutic response. This finding confirms and extends reports of increased risk of gametocytaemia among CQ resistant P. falciparum.

  4. Using a Genome-Scale Metabolic Network Model to Elucidate the Mechanism of Chloroquine Action in Plasmodium falciparum

    Science.gov (United States)

    2017-03-22

    Parasitology: Drugs and Drug Resistance journal homepage: www.elsevier .com/locate/ i jpddrUsing a genome-scale metabolic network model to elucidate...the mechanism of chloroquine action in Plasmodium falciparum Shivendra G. Tewari a , *, Sean T. Prigge b, Jaques Reifman a , Anders Wallqvist a , * a ...authors. E-mail addresses: stewari@bhsai.org (S.G. (S.T. Prigge), jaques.reifman.civ@mail.mil (J. Reifma mil ( A . Wallqvist). http://dx.doi.org/10.1016

  5. In vitro antiplasmodial activity of marine sponge Clathria vulpina extract against chloroquine sensitive Plasmodium falciparum

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    Sundaram Prasanna Kumar

    2014-02-01

    Full Text Available Objective: To explore the antiplasmodial potential of marine sponge Clathria vulpina (C. vulpina against chloroquine sensitive Plasmodium falciparum (P. falciparum. Methods: The marine sponge C. vulpina was collected from Thondi coast, authenticated and subjected for extraction by soaking in ethanol:water mixture (3:1 ratio. The percentage of extract was calculated. Filter sterilized extracts (100, 50, 25, 12.5, 6.25, 3.125 μg/mL were screened for antiplasmodial activity against chloroquine sensitive P. falciparum. The extract was also tested for its hemolytic activity. Results: The percentage yield of extract of C. vulpina was found to be 4.8%. The crude extract of C. vulpina showed excellent antiplasmodial activity (IC 50=14.75 μg/mL which was highly comparable to the positive control chloroquine (IC50=7 μg/mL. Statistical analysis reveals that the significant antiplasmodial activity (P<0.05 was observed between the concentrations and the time of exposure. The chemical injury to erythrocytes was also carried out, which showed that there were no morphological changes in erythrocytes by the ethanolic extracts of sponges after 48 h of incubation. The extract showed slight hemolytic activity which almost equal to chloroquine at 100 μg/mL concentration (1.023%. Conclusions: The marine sponge C. vulpina can be used as a putative antiplasmodial drug after completing successful clinical trials.

  6. Assessment of Therapeutic Response of Plasmodium vivax and Plasmodium falciparum to Chloroquine in a Malaria Transmission Free Area in Colombia

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    Castillo Carmen Manuela

    2002-01-01

    Full Text Available In order to determine the frequency of therapeutic failures to chloroquine (CQ in patients with malaria due to either Plasmodium falciparum or P. vivax, and to explore the usefulness of a malaria-free city as a sentinel site to monitor the emergence of drug resistance, 53 patients (44 infected with P. vivax and 9 with P. falciparum were evaluated at the Laboratory of Parasitology, Universidad del Valle in Cali, Colombia. Patients received 25 mg/kg of CQ divided in three doses over 48 h; they were followed during 28 days according to WHO/PAHO protocols. While therapeutic failures to CQ in the P. vivax group were not detected, the proportion of therapeutic failures in the P. falciparum group was high (78% and consistent with the reports from endemic areas in Colombia. The diverse origin of cases presenting therapeutic failure confirmed that P. falciparum resistant to CQ is widespread in Colombia, and further supports the change in the national antimalarial drug scheme. Monitoring of drug resistance in malaria free areas would be useful to identify sites requiring efficacy evaluation, and in some situations could be the most appropriate alternative to collect information from endemic areas where therapeutic efficacy studies are not feasible.

  7. Creation of cloned strains of chloroquine-resistant Plasmodium falciparum from Yunnan, China with resistance to dihydroartemisinin%云南省抗氯喹恶性疟原虫双氢青蒿素抗性株体外培育与单克隆品系的建立

    Institute of Scientific and Technical Information of China (English)

    杨亚明; 李雪平; 张苍林; 李奔福; 刘慧; 李丽

    2013-01-01

    目的 建立云南省恶性疟原虫抗双氢青蒿素的单克隆品系,为开展恶性疟原虫对青蒿素类的抗药性研究奠定基础. 方法 体外长期连续培养恶性疟原虫,采用体外间断双氢青蒿素药物刺激法对恶性疟原虫株进行抗药性培育,待达到一定抗药性后采用有限稀释法对虫株进行克隆,采用体外微量法测定克隆虫株对双氢青蒿素、青蒿素、氯喹的敏感性,并对其生物学特性进行鉴定. 结果 获得2个云南氯喹抗性恶性疟原虫对双氢青蒿素抗性的单克隆品系C10和H6,IC50值分别为39.01 nmol/L和26.91 nmol/L. 结论 经过8次体外间断药物刺激和筛选,获得2株恶性疟双氢青蒿素抗性单克隆品系,其药物耐受性水平与现场抗性株接近.%Objectives To establish monoclonal strains of Plasmodium falciparum from Yunnan Province with resistance to dihydroartemisinin and to lay the foundation for study of the resistance of P.falciparum to artemisinin-based drugs.Methods Strains of P.falciparum were cultured via long-term continuous in vitro culturing.Strains were intermittently challenged with dihydroartemisinin in vitro.After the strains developed a certain level of resistance to dihydroartemisinin according to a microtest assay,they were cloned using a limited dilution.Biological characteristics of sensitivity to dihydroartemisinin,artemisinin,and chloroquine in vitro were identified.Results Two monoclonal strains of dihydroartemisinin-resistant P.falciparum were obtained from chloroquine resistant P.falciparum originating in Yunnan.The IC50 of the C10 cloned strain was 39.01nmol/L and the IC50 of the H6 cloned strain was 26.91 nmol/L.Conclusion Two monoclonal strains of dihydroartemisinin-resistant P.falciparum were obtained after the parasites were intermittently challenged with 8 rounds of dihydroartemisinin in vitro.These strains had a level of drug resistance close to that of resistant strains from Yunnan.

  8. In vitro sensitivity of chloroquine sensitive and resistant Plasmodium falciparum to artemisinin antimalarials%恶性疟原虫氯喹敏感株与抗性株对青蒿素类药物体外敏感性的研究

    Institute of Scientific and Technical Information of China (English)

    黄芳; 冯晓平; 周水森; 汤林华

    2008-01-01

    目的 测定恶性疟原虫氯喹敏感株与抗性株对青蒿素类药物的体外敏感性. 方法 运用体外微量法与酶联免疫吸附试验(enzyme-linked immunosorbent assay,ELISA)测定青蒿琥酯、蒿甲醚及双氢青蒿素等3种青蒿素类抗疟药物对体外培养的恶性疟原虫氯喹敏感株与氯喹抗性株的体外敏感性,并比较两种方法测定的IC50值. 结果 体外微量法测定的3种药物对恶性疟原虫氯喹敏感株的IC50值依次为3.12 nmol/L、4.30 nmol/L、2.18 nmol/L,对恶性疟原虫氯喹抗性株的IC50值依次为4.31nmol/L、3.90 nmol/L、3.17 nmol/L;同时,将体外微量法与ELISA法所获的结果进行相关性分析,两种方法结果基本一致(r2=0.93,P<0.001). 结论 恶性疟原虫氯喹抗性株对青蒿素类药物无明显的交叉抗性;ELISA法可用于恶性疟原虫对抗疟药物的体外敏感性检测.%Objective To test the sensitivity of chloroquine sensitive and resistant Plasmodium falciparum to artemisinin anfimalarials. Method The responses of chloroquine sensitive and resistant P.falciparum to artemisinin antimalarials including artesunate,artemether and dihydroartemisinin were determined with Rieckmann s in vitro micro-technique and enzyme-linked immunosorbent assay(ELISA).The values of 50%inhibition of parasitemia(IC50)were compared with above two methods. Results The IC50 of artemisinin antimalarials in chloroquine sensitive P.falciparum were 3.12 nmoL/L,4.30 nmol/L,2.18 nmol/L respectively,while that in chloroquine resistant P. falciparum were 4.31nmol/L,3.90 nmol/L,3.17 nmol/L.The results obtained with both techniques were similar or identical by correlation analysis(r2=0.93,P<0.001).Conclusions There were no apparent cross-resistance of chloroquine resistant P.falciparum to artemisinin antimalarials.The ELISA test would be suitable for testing antimalarial drugs sensitivitv in vitro.

  9. Identification of a mutant PfCRT-mediated chloroquine tolerance phenotype in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Stephanie G Valderramos

    2010-05-01

    Full Text Available Mutant forms of the Plasmodium falciparum transporter PfCRT constitute the key determinant of parasite resistance to chloroquine (CQ, the former first-line antimalarial, and are ubiquitous to infections that fail CQ treatment. However, treatment can often be successful in individuals harboring mutant pfcrt alleles, raising questions about the role of host immunity or pharmacokinetics vs. the parasite genetic background in contributing to treatment outcomes. To examine whether the parasite genetic background dictates the degree of mutant pfcrt-mediated CQ resistance, we replaced the wild type pfcrt allele in three CQ-sensitive strains with mutant pfcrt of the 7G8 allelic type prevalent in South America, the Oceanic region and India. Recombinant clones exhibited strain-dependent CQ responses that ranged from high-level resistance to an incremental shift that did not meet CQ resistance criteria. Nonetheless, even in the most susceptible clones, 7G8 mutant pfcrt enabled parasites to tolerate CQ pressure and recrudesce in vitro after treatment with high concentrations of CQ. 7G8 mutant pfcrt was found to significantly impact parasite responses to other antimalarials used in artemisinin-based combination therapies, in a strain-dependent manner. We also report clinical isolates from French Guiana that harbor mutant pfcrt, identical or related to the 7G8 haplotype, and manifest a CQ tolerance phenotype. One isolate, H209, harbored a novel PfCRT C350R mutation and demonstrated reduced quinine and artemisinin susceptibility. Our data: 1 suggest that high-level CQR is a complex biological process dependent on the presence of mutant pfcrt; 2 implicate a role for variant pfcrt alleles in modulating parasite susceptibility to other clinically important antimalarials; and 3 uncover the existence of a phenotype of CQ tolerance in some strains harboring mutant pfcrt.

  10. A thirteen-year analysis of Plasmodium falciparum populations reveals high conservation of the mutant pfcrt haplotype despite the withdrawal of chloroquine from national treatment guidelines in Gabon

    NARCIS (Netherlands)

    M. Frank; N. Lehners; P.I. Mayengue; J. Gabor; M. Dal-Bianco; D.U. Kombila; G.M. Ngoma; C. Supan; B. Lell; F. Ntoumi; M.P. Grobusch; K. Dietz; P.G. Kremsner

    2011-01-01

    Chloroquine resistance (CR) decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR) conferring mutant pfcrt allele and its associated chromosomal haplotype were determined be

  11. Tracking Origins and Spread of Sulfadoxine-Resistant Plasmodium falciparum dhps Alleles in Thailand▿

    OpenAIRE

    Alam, Md Tauqeer; Vinayak, Sumiti; Congpuong, Kanungnit; Wongsrichanalai, Chansuda; Satimai, Wichai; Slutsker, Laurence; Escalante, Ananias A.; Barnwell, John W.; Udhayakumar, Venkatachalam

    2010-01-01

    The emergence and spread of drug-resistant Plasmodium falciparum have been a major impediment for the control of malaria worldwide. Earlier studies have shown that similar to chloroquine (CQ) resistance, high levels of pyrimethamine resistance in P. falciparum originated independently 4 to 5 times globally, including one origin at the Thailand-Cambodia border. In this study we describe the origins and spread of sulfadoxine-resistance-conferring dihydropteroate synthase (dhps) alleles in Thail...

  12. Changes in Plasmodium falciparum gametocytaemia in children with chloroquine-sensitive asexual infections

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    Sowunmi A.

    2003-12-01

    Full Text Available A non-compartmental pharmacokinetic model was used to describe the changes in gametocytaemia in nine children with chloroquine-sensitive Plasmodium falciparum malaria in whom asexual parasitaemia cleared within 72 h of chloroquine treatment. Peak gametocytaemia was 74 ± 19.9 (se, range 24-198, géométrie mean 58 sf (sexual forms/ul. Time to peak gametocytaemia was 43.2 ± 14.4, range 0-120 h. Following peak gametocytaemia, gametocytes persisted in blood for a period of 168-504 h. The décline from peak gametocytaemia was exponential with a half-life of gametocytaemia of 43.2 ± 20.4, range 1 3.1-206 h. The mean pre-treatment sex ratio was male-biased and remained so til! complete elimination of gametocytaemia. Peak microgametocytaemia, area under the curve of microgametocytaemia versus time, and the half-life of microgametocytaemia were significantly higher than those of macrogametocytaemia. The volume of blood completely cleared of macrogametocytaemia per unit time was significantly higher than that of microgametocytaemia. Macrogametocytes are cleared from the circulation faster than microgametocytes but chloroquine treatment of chloroquine-sensitive infections has little or no significant effect on gametocyte sex ratios in this group of children.

  13. Rapid detection of Pfcrt and Pfmdr1 mutations in Plasmodium falciparum isolates by FRET and in vivo response to chloroquine among children from Osogbo, Nigeria

    Directory of Open Access Journals (Sweden)

    Fendel Rolf

    2007-04-01

    Full Text Available Abstract Background Chloroquine (CQ has been in use in Africa for a long time. Because of misuse, this drug has now lost its efficacy due to the emergence of resistance strains in most parts of Africa. Recently, it was shown that after chloroquine has been withdrawn from the market, chloroquine-sensitive Plasmodium falciparum re-emerged and chloroquine could again be used successfully as an antimalarial. Surveillance of parasite populations is, therefore, important to decide whether chloroquine could be re-introduced. Methods To estimate the prevalence of the most pivotal polymorphisms, including Pfcrt K76T, Pfmdr1 N86Y and Pfmdr1 Y184F mutations, and their contributions to the outcome of CQ treatment, isolates from Osogbo Western Nigeria were tested using the Fluorescence Resonance Energy Transfer (FRET method on a real-time PCR instrument. Results 116 children with acute uncomplicated P. falciparum malaria infections were treated with the standard dosage of CQ and followed-up for 28 days. Blood samples were collected on filter paper at enrollment and during follow-up for identification of parasite carrying the chloroquine resistant transporter (pfcrt and P. falciparum-multi drug resistance (pfmdr1 gene mutations. Parasitological assessment of response to treatment showed that 62% of the patients were cured and 38% failed the CQ treatment. The presence of single mutant pfcrt (T76 alleles (P = 0.003 and in combination with mutant pfmdr1 Y86 (P = 0.028 was significantly associated with in vivo CQR. No other mutation on its own or in combinations was significantly associated with treatment outcome. Mutant pfcrt was more prevalent in both pre- and post-treatment isolates. No association was observed between age or initial level of parasitaemia and chloroquine treatment outcome. Conclusion The result established the usefulness and accuracy of real time PCR in pfcrt and pfmdr1 mutation detection and also give further evidence to the reliability of

  14. Therapeutic efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum in Haiti after many decades of its use.

    Science.gov (United States)

    Okech, Bernard A; Existe, Alexandre; Romain, Jean R; Memnon, Gladys; Victor, Yves Saint; de Rochars, Madsen Beau; Fukuda, Mark

    2015-03-01

    Chloroquine (CQ) has been used for malaria treatment in Haiti for several decades, but reports of CQ resistance are scarce. The efficacy of CQ in patients with uncomplicated Plasmodium falciparum undergoing treatment in Haiti was evaluated. Malaria patients were enrolled, treated with CQ, and monitored over a 42-day period. The treatment outcomes were evaluated on day 28 by microscopy. The P. falciparum slide-confirmed rate was 9.5% (121 of 1,277). Malaria infection was seasonal, with peak observations between October and January; 88% (107 of 121) of patients consented to participate. Sixty patients successfully completed the 42-day follow-up, whereas 47 patients withdrew consent or were lost to follow-up. The mean parasite density declined rapidly within the first few days after treatment. Seven patients did not clear their malaria infections and were clinically asymptomatic; therefore, they were considered late parasitological failures. About 90% (95% confidence interval = 84.20-97.90) of patients had no detectable parasitemia by day 28 and remained malaria-free to day 42. Testing for recrudescence, reinfection, and CQ serum levels was not done in the seven patients, and therefore, their CQ resistance status is unresolved. CQ resistance surveillance by patient follow-up, in vitro drug sensitivity studies, and molecular markers is urgently needed in Haiti. © The American Society of Tropical Medicine and Hygiene.

  15. Short report: therapeutic efficacy of chloroquine combined with primaquine against Plasmodium falciparum in northeastern Papua, Indonesia.

    Science.gov (United States)

    Baird, J Kevin; Wiady, Iwa; Sutanihardja, Awalludin; Suradi; Purnomo; Basri, Hasan; Sekartuti; Ayomi, Ester; Fryauff, David J; Hoffman, Stephen L

    2002-06-01

    Chloroquine combined with primaquine was evaluated for therapy of uncomplicated malaria caused by Plasmodium falciparum in nonimmune Javanese migrants to northeastern Papua, Indonesia. Subjects were randomized to treatment with standard chloroquine therapy (25 mg/kg in 3 doses over the course of 48 hours) with 30 mg primaquine administered daily for 28 days (n = 25) or a placebo of primaquine (n = 28). The 14-day cumulative incidence of therapeutic failure was 56% with primaquine and 79% with placebo (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.1-1.3; P = 0.08). Primaquine administered daily created a marginally significant improvement in therapeutic efficacy at day 14, but not at day 7 (20% versus 36%; OR, 0.2; 95% CI, 0.1-1.8; P = 0.2) or day 28 (82% versus 93%; OR, 0.31; 95% Cl, 0.04-2.1; P = 0.23). This report corroborates studies suggesting that therapeutic doses of primaquine exert no discernible effect on parasitemia by P. falciparum.

  16. INDUCTION OF DRUG RESISTANCE IN PLASMODIUM FALCIPARUM: AN INTERMITTENT DRUG EXPOSURE METHOD

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    M.Nateghpour

    1998-03-01

    Full Text Available The production of experimentally induced drug resistance in the laboratory provides valuable opportunities for investigators to study the nature and genetics of drug resistance mechanisms to a given agent, patterns of cross resistance and the mode of action of drugs. At the beginning the continuous drug exposure was chosen as a standard procedure to produce drug— resistant strains of P. falciparum,.but later on some other methods were also applied. An intermittent drug exposure method as a novel procedure has been introduced in this study. Intermittent exposure of chloroquine resistant Kl and chloroquine sensitive T9.96 strains of P. falciparum to halofantrine culminated in a relatively rapid reduction in sensitivity to the drug. The response of halofantrifle - resistnat K1HF and T9.96 strains and parent parasites to halofantrifle, inefloquine, quinine and chloroquine was determined. The results indicated that the effectiveness of halofantrine to K1HF and T9.96HF strains decreased 9 and 3 folds respectively, compared to the parent parasites. Cross -resistance occurred among halofantrine. mefloquine and quinine. Halofantrine resistance was associated with enhanced chloroquine sensitivity in the strain derived from chloroquine - resistant K1 strain, hut not in the strain derived from chloroquine - sensitive T9.96 parasites.

  17. Combating multidrug-resistant Plasmodium falciparum malaria.

    Science.gov (United States)

    Thu, Aung Myint; Phyo, Aung Pyae; Landier, Jordi; Parker, Daniel M; Nosten, François H

    2017-08-01

    Over the past 50 years, Plasmodium falciparum has developed resistance against all antimalarial drugs used against it: chloroquine, sulphadoxine-pyrimethamine, quinine, piperaquine and mefloquine. More recently, resistance to the artemisinin derivatives and the resulting failure of artemisinin-based combination therapy (ACT) are threatening all major gains made in malaria control. Each time resistance has developed progressively, with delayed clearance of parasites first emerging only in a few regions, increasing in prevalence and geographic range, and then ultimately resulting in the complete failure of that antimalarial. Drawing from this repeated historical chain of events, this article presents context-specific approaches for combating drug-resistant P. falciparum malaria. The approaches begin with a context of drug-sensitive parasites and focus on the prevention of the emergence of drug resistance. Next, the approaches address a scenario in which resistance has emerged and is increasing in prevalence and geographic extent, with interventions focused on disrupting transmission through vector control, early diagnosis and treatment, and the use of new combination therapies. Elimination is also presented as an approach for addressing the imminent failure of all available antimalarials. The final drug resistance context presented is one in which all available antimalarials have failed; leaving only personal protection and the use of new antimalarials (or new combinations of antimalarials) as a viable strategy for dealing with complete resistance. All effective strategies and contexts require a multipronged, holistic approach. © 2017 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

  18. Characterization of the commercially-available fluorescent chloroquine-BODIPY conjugate, LynxTag-CQGREEN, as a marker for chloroquine resistance and uptake in a 96-well plate assay.

    Directory of Open Access Journals (Sweden)

    Cheryl C Y Loh

    Full Text Available Chloroquine was a cheap, extremely effective drug against Plasmodium falciparum until resistance arose. One approach to reversing resistance is the inhibition of chloroquine efflux from its site of action, the parasite digestive vacuole. Chloroquine accumulation studies have traditionally relied on radiolabelled chloroquine, which poses several challenges. There is a need for development of a safe and biologically relevant substitute. We report here a commercially-available green fluorescent chloroquine-BODIPY conjugate, LynxTag-CQGREEN, as a proxy for chloroquine accumulation. This compound localized to the digestive vacuole of the parasite as observed under confocal microscopy, and inhibited growth of chloroquine-sensitive strain 3D7 more extensively than in the resistant strains 7G8 and K1. Microplate reader measurements indicated suppression of LynxTag-CQGREEN efflux after pretreatment of parasites with known reversal agents. Microsomes carrying either sensitive- or resistant-type PfCRT were assayed for uptake; resistant-type PfCRT exhibited increased accumulation of LynxTag-CQGREEN, which was suppressed by pretreatment with known chemosensitizers. Eight laboratory strains and twelve clinical isolates were sequenced for PfCRT and Pgh1 haplotypes previously reported to contribute to drug resistance, and pfmdr1 copy number and chloroquine IC50s were determined. These data were compared with LynxTag-CQGREEN uptake/fluorescence by multiple linear regression to identify genetic correlates of uptake. Uptake of the compound correlated with the logIC50 of chloroquine and, more weakly, a mutation in Pgh1, F1226Y.

  19. Low level genotypic chloroquine resistance near Malawi's northern border with Tanzania.

    Science.gov (United States)

    Bridges, Daniel J; Molyneux, Malcolm; Nkhoma, Standwell

    2009-09-01

    We conducted a prevalence study of mutations in Plasmodium falciparum that are associated with antimalarial drug resistance at a rural site in Karonga near Malawi's northern border with Tanzania. We found a higher prevalence of the key chloroquine resistance-conferring mutation in the pfcrt gene (K76T) at this site in comparison with the prevalence in Blantyre, a city in the south of Malawi, far from an international border (9%vs. 0%; P Malawi was recently reported to be over 50%. Our findings suggest a considerable 'leakage' of parasite antimalarial drug resistance across the border between two countries with different national malaria control policies and with different levels of resistance. Neighbouring countries should consider implementing common regional rather than national malaria treatment policies to prevent the spread of antimalarial drug resistance alleles across their borders.

  20. High level of resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine in children in Tanzania

    DEFF Research Database (Denmark)

    Rønn, A M; Msangeni, H A; Mhina, J

    1996-01-01

    In many areas of tropical Africa affected by chloroquine-resistant Plasmodium falciparum, a combination of sulfadoxine and pyrimethamine (S-P) is used for alternative medication, especially in young children. In Magoda village in Muheza District, north-eastern Tanzania, 38 children 1-10 years...

  1. Safety, Immunogenicity, and Protective Efficacy of Intradermal Immunization with Aseptic, Purified, Cryopreserved Plasmodium falciparum Sporozoites in Volunteers Under Chloroquine Prophylaxis : A Randomized Controlled Trial

    NARCIS (Netherlands)

    G.J.H. Baestians (Guido); M.P.A. van Meer (Maurits); A. Scholzen (Anja); J.M. Obiero (Joshua); M. Vatanshenassan (Mansoureh); T. van Grinsven (Tim); B.K.L. Sim (B. Kim Lee); P.F. Billingsley (Peter); E.R. James (Eric); A. Gunasekera (Anusha); E.M. Bijker (Else); G-J. van Gemert (Geert-Jan); M. van de Vegte-Bolmer (Magda); W. Graumans (Wouter); C.C. Hermsen (Cornelus); Q. de Mast (Quirijn); A.J.A.M. van der Ven (André); S.L. Hoffman (Stephen); R.W. Sauerwein (Robert)

    2015-01-01

    markdownabstractImmunization of volunteers under chloroquine prophylaxis by bites of *Plasmodium falciparum* sporozoite (PfSPZ)–infected mosquitoes induces > 90% protection against controlled human malaria infection (CHMI). We studied intradermal immunization with cryopreserved, infectious PfSPZ in

  2. Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Bushman, Mary; Morton, Lindsay; Duah, Nancy; Quashie, Neils; Abuaku, Benjamin; Koram, Kwadwo A; Dimbu, Pedro Rafael; Plucinski, Mateusz; Gutman, Julie; Lyaruu, Peter; Kachur, S Patrick; de Roode, Jacobus C; Udhayakumar, Venkatachalam

    2016-03-16

    Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures.

  3. A non-radioactive DAPI-based high-throughput in vitro assay to assess Plasmodium falciparum responsiveness to antimalarials--increased sensitivity of P. falciparum to chloroquine in Senegal.

    Science.gov (United States)

    Ndiaye, Daouda; Patel, Vishal; Demas, Allison; LeRoux, Michele; Ndir, Omar; Mboup, Souleymane; Clardy, Jon; Lakshmanan, Viswanathan; Daily, Johanna P; Wirth, Dyann F

    2010-02-01

    The spread of Plasmodium falciparum drug resistance is outpacing new antimalarial development and compromising effective malaria treatment. Combination therapy is widely implemented to prolong the effectiveness of currently approved antimalarials. To maximize utility of available drugs, periodic monitoring of drug efficacy and gathering of accurate information regarding parasite-sensitivity changes are essential. We describe a high-throughput, non-radioactive, field-based assay to evaluate in vitro antimalarial drug sensitivity of P. falciparum isolates from 40 Senegalese patients. Compared with earlier years, we found a significant decrease in chloroquine in vitro and in genotypic resistances (> 50% and > 65%, respectively, in previous studies) with only 23% of isolates showing resistance. This is possibly caused by a withdrawal of chloroquine from Senegal in 2002. We also found a range of artemisinin responses. Prevalence of drug resistance is dynamic and varies by region. Therefore, the implementation of non-radioactive, robust, high-throughput antimalarial sensitivity assays is critical for defining region-specific prophylaxis and treatment guidelines.

  4. A Non-Radioactive DAPI-based High-Throughput In Vitro Assay to Assess Plasmodium falciparum Responsiveness to Antimalarials—Increased Sensitivity of P. falciparum to Chloroquine in Senegal

    Science.gov (United States)

    Ndiaye, Daouda; Patel, Vishal; Demas, Allison; LeRoux, Michele; Ndir, Omar; Mboup, Souleymane; Clardy, Jon; Lakshmanan, Viswanathan; Daily, Johanna P.; Wirth, Dyann F.

    2010-01-01

    The spread of Plasmodium falciparum drug resistance is outpacing new antimalarial development and compromising effective malaria treatment. Combination therapy is widely implemented to prolong the effectiveness of currently approved antimalarials. To maximize utility of available drugs, periodic monitoring of drug efficacy and gathering of accurate information regarding parasite-sensitivity changes are essential. We describe a high-throughput, non-radioactive, field-based assay to evaluate in vitro antimalarial drug sensitivity of P. falciparum isolates from 40 Senegalese patients. Compared with earlier years, we found a significant decrease in chloroquine in vitro and in genotypic resistances (> 50% and > 65%, respectively, in previous studies) with only 23% of isolates showing resistance. This is possibly caused by a withdrawal of chloroquine from Senegal in 2002. We also found a range of artemisinin responses. Prevalence of drug resistance is dynamic and varies by region. Therefore, the implementation of non-radioactive, robust, high-throughput antimalarial sensitivity assays is critical for defining region-specific prophylaxis and treatment guidelines. PMID:20133997

  5. Artemisinin-Resistant Plasmodium falciparum Malaria.

    Science.gov (United States)

    Fairhurst, Rick M; Dondorp, Arjen M

    2016-06-01

    For more than five decades, Southeast Asia (SEA) has been fertile ground for the emergence of drug-resistant Plasmodium falciparum malaria. After generating parasites resistant to chloroquine, sulfadoxine, pyrimethamine, quinine, and mefloquine, this region has now spawned parasites resistant to artemisinins, the world's most potent antimalarial drugs. In areas where artemisinin resistance is prevalent, artemisinin combination therapies (ACTs)-the first-line treatments for malaria-are failing fast. This worrisome development threatens to make malaria practically untreatable in SEA, and threatens to compromise global endeavors to eliminate this disease. A recent series of clinical, in vitro, genomics, and transcriptomics studies in SEA have defined in vivo and in vitro phenotypes of artemisinin resistance, identified its causal genetic determinant, explored its molecular mechanism, and assessed its clinical impact. Specifically, these studies have established that artemisinin resistance manifests as slow parasite clearance in patients and increased survival of early-ring-stage parasites in vitro; is caused by single nucleotide polymorphisms in the parasite's K13 gene, is associated with an upregulated "unfolded protein response" pathway that may antagonize the pro-oxidant activity of artemisinins, and selects for partner drug resistance that rapidly leads to ACT failures. In SEA, clinical studies are urgently needed to monitor ACT efficacy where K13 mutations are prevalent, test whether new combinations of currently available drugs cure ACT failures, and advance new antimalarial compounds through preclinical pipelines and into clinical trials. Intensifying these efforts should help to forestall the spread of artemisinin and partner drug resistance from SEA to sub-Saharan Africa, where the world's malaria transmission, morbidity, and mortality rates are highest.

  6. Molecular surveillance of drug resistance through imported isolates of Plasmodium falciparum in Europe

    DEFF Research Database (Denmark)

    Jelinek, Tomas; Peyerl-Hoffmann, Gabriele; Mühlberger, Nikolai;

    2002-01-01

    BACKGROUND: Results from numerous studies point convincingly to correlations between mutations at selected genes and phenotypic resistance to antimalarials in Plasmodium falciparum isolates. In order to move molecular assays for point mutations on resistance-related genes into the realm of applied...... tools for surveillance, we investigated a selection of P. falciparum isolates that were imported during the year 2001 into Europe to study the prevalence of resistance-associated point mutations at relevant codons. In particular, we tested for parasites which were developing resistance to antifolates...... and chloroquine. The screening results were used to map the prevalence of mutations and, thus, levels of potential drug resistance in endemic areas world-wide. RESULTS: 337 isolates have been tested so far. Prevalence of mutations that are associated with resistance to chloroquine on the pfcrt and pfmdr genes...

  7. Polymorphisms in Pfcrt and Pfmdr-1 genes after five years withdrawal of chloroquine for the treatment of Plasmodium falciparum malaria in West Bengal, India.

    Science.gov (United States)

    Chatterjee, Moytrey; Ganguly, Swagata; Saha, Pabitra; Guha, Subhasish Kamal; Basu, Nandita; Bera, Dilip K; Maji, Ardhendu Kumar

    2016-10-01

    The emergence of resistant power against different antimalarial agents particularly by Plasmodium falciparum is a challenge to combat malaria. Regular monitoring is essential not only to determine the efficacy and development of resistance by the parasite but also to detect early sign of regaining sensitivity to any anti-malarial agent that has been withdrawn for a long period. Studies on molecular markers associated with antimalarial drug resistance of prevailing Plasmodium population play an important role in this aspect. The present protocol was designed to study the polymorphisms in pfcrt and pfmdr-1 gene to determine any sign of regaining sensitivity to chloroquine among P. falciparum after five years of artemisinin combination therapy (ACT) implementation. Clinical isolates were collected from P. falciparum positive patients attending the malaria clinic of Calcutta School of Tropical Medicine during December 2014 to December 2015. Genomic parasitic DNA was extracted and subjected to sequencing of pfcrt and pfmdr-1 gene directly from purified PCR products. A total of 89 isolates were sequenced for pfcrt and 73 isolates for pfmdr-1 genes. In pfcrt gene mutant K76T was detected in all isolates and all were SVMNT haplotype. Out of three important polymorphisms in pfmdr-1 gene mutant Y184F was detected among all isolates. One synonymous G182G and one non-synonymous S232F/Y, mutation were detected in 99% isolates. All isolates carrying mutant K76T in pfcrt gene, considered as hall mark for CQ resistance, indicate that there is no sign of regaining CQ sensitivity among the prevailing P. falciparum population of the study area after five years of ACT implementation. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Drug resistance and genetic diversity of Plasmodium falciparum parasites from suriname.

    Science.gov (United States)

    Peek, Ron; VAN Gool, Tom; Panchoe, Daynand; Greve, Sophie; Bus, Ellen; Resida, Lesley

    2005-11-01

    Plasmodium falciparum in Suriname was studied for the presence of drug resistance and genetic variation in blood samples of 86 patients with symptomatic malaria. Drug resistance was predicted by determining point mutations in the chloroquine resistance marker of the P. falciparum chloroquine resistance transporter (pfcrt) gene (codon 76) and the pyrimethamine-sulfadoxine resistance markers in the dihydrofolate reductase (dhfr) gene (codons 16, 51, 59, 108, and 164) and dihydropteroate synthase (dhps) gene (codons 436, 437, 540, 581, and 613). Genetic variability was determined by sequence analysis of the polymorphic segments of the merozoite surface protein 2 (msp-2) and glutamate-rich protein (glurp) genes. Mutations in the pfcrt, dhps, and dhfr genes were found in all samples tested, suggesting that resistance to chloroquine and antifolate drugs is present at a high frequency. A low number of alleles was found for the msp-2 and glurp genes. This indicates limited genetic diversity and, based on geographic data, a genetically homogeneous P. falciparum population in Suriname.

  9. In vitro evaluation of the antiplasmodial activity of Dendropanax morbifera against chloroquine-sensitive strains of Plasmodium falciparum.

    Science.gov (United States)

    Chung, Ill-Min; Kim, Min-Young; Park, Sun-Dong; Park, Won-Hwan; Moon, Hyung-In

    2009-11-01

    Dendropanax morbifera Leveille (Araliaceae) is well known in Korea traditional medicine for a variety of diseases. The methanol extract of the lower stem parts of D. morbifera was investigated for its activity against chloroquine-sensitive strains of Plasmodium falciparum using the parasite lactate dehydrogenase assay method. Two cycloartane-type glycosides oleifoliosides A (1) and B (2), and dendropanoxide (3), beta-amyrin (4), alpha-amyrin (5) have been isolated from the stem parts of D. morbifera. All five compounds were evaluated for in vitro antiplasmodial activities as well as their cytotoxic potential on SK-OV-3 cancer cell lines. Compounds 2 and 3 showed notable growth inhibitory activity against chloroquine-sensitive strains of Plasmodium falciparum with IC(50) values of 6.2 and 5.3 microm. This compound showed no significant cytotoxicity (IC(50) > 150 microm) evaluated using SK-OV-3 cancer cell lines. This is the first report on the antiplasmodial activity of the compounds from D. morbifera.

  10. Synergistic activity of chloroquine with fluconazole against fluconazole-resistant isolates of Candida species.

    Science.gov (United States)

    Li, Yali; Wan, Zhe; Liu, Wei; Li, Ruoyu

    2015-02-01

    The in vitro activity of chloroquine and the interactions of chloroquine combined with fluconazole against 37 Candida isolates were tested using the broth microdilution, disk diffusion, and Etest susceptibility tests. Synergistic effect was detected with 6 of 9 fluconazole-resistant Candida albicans isolates, with Candida krusei ATCC 6258, and with all 12 fluconazole-resistant Candida tropicalis isolates.

  11. Polymorphisms of the oxidant enzymes glutathione S-transferase and glutathione reductase and their association with resistance ofPlasmodium falciparum isolates to antimalarial drugs

    Institute of Scientific and Technical Information of China (English)

    Raewadee Wisedpanichkij; Wanna Chaicharoenkul; Poonuch Mahamad; Prapichaya Prompradit; Kesara Na-Bangchang

    2010-01-01

    Objective:To investigate the association between amplification of the two regulatory genes controlling glutathione(GSH)levels, glutathione reductase(PfGR)and glutathione S-transferase (PfGST) genes and sensitivity ofPlasmodium falciparum (P. falciparum)isolates collected from different malaria endemic areas of Thailand to standard antimalarial drugs.Methods: A total of70P. falciparum isolates were collected from endemic areas of multi-drug resistance (Tak, Chantaburi and Ranong Provinces) during the year2008-2009. The in vitro assessment of antimalarial activity ofP. falciparumclones (K1- and Dd2 chloroquine resistant and3D7-chloroquine sensitive) and isolates to chloroquine, quinine, mefloquine and arteusnate was performed based onSYBR Green modified assay.Results:68 (97.14%), 11 (15.71%) and28 (40%) isolates respectively were classified as chloroquine-, quinine- and mefloquine-resistant isolates. With this limited number ofP. falciparum isolates included in the analysis, no significant association between amplification ofPfGST gene and sensitivity of the parasite to chloroquine, quinine, mefloquine and quinine was found. Based onPCR analysis,Dd2, K1 and3D7clones all contained only one copy of thePfGST gene. All isolates (70) also carried only one copy number of PfGST gene. There appears to be an association between amplification ofPfGR gene and chloroquine resistance. The3D7and Dd2 clones were found to carry only onePfGR gene copy, whereas the K1 clone carried two gene copies.Conclusions: Chloroquine resistance is likely to be a consequence of multi-factors and enzymes in theGSH system may be partly involved. Larger number of parasite isolates are required to increase power of the hypothesis testing in order to confirm the involvement of both genes as well as other genes implicated in glutathione metabolism in conferring chloroquine resistance.

  12. Methylene blue inhibits the asexual development of vivax malaria parasites from a region of increasing chloroquine resistance.

    Science.gov (United States)

    Suwanarusk, Rossarin; Russell, Bruce; Ong, Alice; Sriprawat, Kanlaya; Chu, Cindy S; PyaePhyo, Aung; Malleret, Benoit; Nosten, François; Renia, Laurent

    2015-01-01

    Methylene blue, once discarded due to its unsettling yet mild side effects, has now found a renewed place in the pharmacopoeia of modern medicine. The continued spread of drug-resistant Plasmodium vivax and Plasmodium falciparum has also led to a recent re-examination of methylene blue's potent antimalarial properties. Here we examine the ex vivo susceptibility profile of Plasmodium spp. isolates to methylene blue; the isolates were from a region on the Thai-Myanmar border where there are increasing rates of failure when treating vivax malaria with chloroquine. To do this we used a newly developed ex vivo susceptibility assay utilizing flow cytometry and a portable flow cytometer with a near-UV laser. P. vivax (median methylene blue IC50 3.1 nM, IQR 1.7-4.3 nM) and P. falciparum (median methylene blue IC50 1.8 nM, IQR 1.6-2.3 nM) are susceptible to methylene blue treatment at physiologically relevant levels. Unfortunately, the addition of chloroquine to combination treatments with methylene blue significantly reduces the ex vivo effectiveness of this molecule. Our data support further efforts to employ methylene blue as a safe, low-cost antimalarial to treat drug-resistant malaria. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. Potential contribution of prescription practices to the emergence and spread of chloroquine resistance in south-west Nigeria: caution in the use of artemisinin combination therapy

    Directory of Open Access Journals (Sweden)

    Ogundahunsi Olumide A

    2009-12-01

    Full Text Available Abstract Background Prescription practices have been shown to influence the emergence of anti-malarial drug resistance. Thus efforts in this study were devoted to evaluating the prescribing practices prior to introduction of the artemisinin based combination therapy (ACT in Nigeria and its potential contribution to emergence of chloroquine resistant malaria in south-west Nigeria, in order to forestall a similar situation with the ACT. Methods A retrospective quantitative study was designed to examine case records of patients treated for malaria in either a government or a private hospital in Ibadan, south-west Nigeria, over a 20-year period, cutting across three phases of resistance to chloroquine in Nigeria: pre-resistance, emerging resistance and dissemination of resistance. Patient prescriptions were examined for use of anti-malarial drugs, sub-therapeutic doses of chloroquine, co-administration of anti-histamines with chloroquine. Descriptive statistics of frequency and percentage were used to describe trends in the parameters assessed using EPI-info. Results Case record files of 2,529 patients were examined. Chloroquine was the main drug used in treatment of malaria throughout the periods studied, with frequency of prescription at both sites ranging from 91.4% to 98.3% during the pre-resistance years. It was administered as standard doses during the pre resistance years. Anti-histamines, especially promethazine, were routinely co-administered with chloroquine at this period too. However, the practice of prescribing sub-therapeutic doses of chloroquine at the private health care facility coincided with the latter phase of emerging resistance and phase of dissemination of resistance. Frequency of prescription of sub-therapeutic doses increased from 6.7% in 1983 (pre-resistance years to 43.6% in 1997 (dissemination of resistance phase at the private health care facility. Frequency of co-administration of anti-histamines with chloroquine also

  14. High frequency of Plasmodium falciparum CICNI/SGEAA and CVIET haplotypes without association with resistance to sulfadoxine/pyrimethamine and chloroquine combination in the Daraweesh area, in Sudan

    DEFF Research Database (Denmark)

    A-Elbasit, I E; Khalil, I F; Elbashir, M I

    2008-01-01

    , 50%; TF 55%) were not associated with TF. In contrast to other studies in Africa, the triple 51I/59R/108N mutation was rare (0.6%). In addition, the pfcrt CVIET haplotype (93%) was found to be associated with the CICNI/SGEAA haplotype. Finally, these data represent a baseline for SP resistance...

  15. Plasmodium falciparum drug resistance in Angola

    OpenAIRE

    Fançony, Cláudia; Brito, Miguel; Gil, Jose Pedro

    2016-01-01

    Facing chloroquine drug resistance, Angola promptly adopted artemisinin-based combination therapy as the first-line to treat malaria. Currently, the country aims to consolidate malaria control, while preparing for the elimination of the disease, along with others African countries in the region. However, the remarkable capacity of Plasmodium to develop drug resistance represents an alarming threat for those achievements. Herein, the available, but relatively scarce and dispersed, information ...

  16. Identification and deconvolution of cross-resistance signals from antimalarial compounds using multidrug-resistant Plasmodium falciparum strains.

    Science.gov (United States)

    Chugh, Monika; Scheurer, Christian; Sax, Sibylle; Bilsland, Elizabeth; van Schalkwyk, Donelly A; Wicht, Kathryn J; Hofmann, Natalie; Sharma, Anil; Bashyam, Sridevi; Singh, Shivendra; Oliver, Stephen G; Egan, Timothy J; Malhotra, Pawan; Sutherland, Colin J; Beck, Hans-Peter; Wittlin, Sergio; Spangenberg, Thomas; Ding, Xavier C

    2015-02-01

    Plasmodium falciparum, the most deadly agent of malaria, displays a wide variety of resistance mechanisms in the field. The ability of antimalarial compounds in development to overcome these must therefore be carefully evaluated to ensure uncompromised activity against real-life parasites. We report here on the selection and phenotypic as well as genotypic characterization of a panel of sensitive and multidrug-resistant P. falciparum strains that can be used to optimally identify and deconvolute the cross-resistance signals from an extended panel of investigational antimalarials. As a case study, the effectiveness of the selected panel of strains was demonstrated using the 1,2,4-oxadiazole series, a newly identified antimalarial series of compounds with in vitro activity against P. falciparum at nanomolar concentrations. This series of compounds was to be found inactive against several multidrug-resistant strains, and the deconvolution of this signal implicated pfcrt, the genetic determinant of chloroquine resistance. Targeted mode-of-action studies further suggested that this new chemical series might act as falcipain 2 inhibitors, substantiating the suggestion that these compounds have a site of action similar to that of chloroquine but a distinct mode of action. New antimalarials must overcome existing resistance and, ideally, prevent its de novo appearance. The panel of strains reported here, which includes recently collected as well as standard laboratory-adapted field isolates, is able to efficiently detect and precisely characterize cross-resistance and, as such, can contribute to the faster development of new, effective antimalarial drugs.

  17. Molecular characterisation of drug-resistant Plasmodium falciparum from Thailand

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    Gil José

    2002-10-01

    Full Text Available Abstract Background The increasing levels of Plasmodium falciparum resistance to chloroquine (CQ in Thailand have led to the use of alternative antimalarials, which are at present also becoming ineffective. In this context, any strategies that help improve the surveillance of drug resistance, become crucial in overcoming the problem. Methods In the present study, we have established the in vitro sensitivity to CQ, mefloquine (MF, quinine (QUIN and amodiaquine (AMQ of 52 P. falciparum isolates collected in Thailand, and assessed the prevalence of four putative genetic polymorphisms of drug resistance, pfcrt K76T, pfmdr1 N86Y, pfmdr1 D1042N and pfmdr1 Y1246D, by PCR-RFLP. Results The percentage of isolates resistant to CQ, MF, and AMQ was 96% (50/52, 62% (32/52, and 58% (18/31, respectively, while all parasites were found to be sensitive to QUIN. In addition, 41 (79% of the isolates assayed were resistant simultaneously to more than one drug; 25 to CQ and MF, 9 to CQ and AMQ, and 7 to all three drugs, CQ, MF and AMQ. There were two significant associations between drug sensitivity and presence of particular molecular markers, i CQ resistance / pfcrt 76T (P = 0.001, and ii MF resistance / pfmdr1 86N (P Conclusions i In Thailand, the high levels of CQ pressure have led to strong selection of the pfcrt 76T polymorphism and ii pfmdr1 86N appears to be a good predictor of in vitro MF resistance.

  18. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

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    Sumiti Vinayak

    2010-03-01

    Full Text Available The Thailand-Cambodia border is the epicenter for drug-resistant falciparum malaria. Previous studies have shown that chloroquine (CQ and pyrimethamine resistance originated in this region and eventually spread to other Asian countries and Africa. However, there is a dearth in understanding the origin and evolution of dhps alleles associated with sulfadoxine resistance. The present study was designed to reveal the origin(s of sulfadoxine resistance in Cambodia and its evolutionary relationship to African and South American dhps alleles. We sequenced 234 Cambodian Plasmodium falciparum isolates for the dhps codons S436A/F, A437G, K540E, A581G and A613S/T implicated in sulfadoxine resistance. We also genotyped 10 microsatellite loci around dhps to determine the genetic backgrounds of various alleles and compared them with the backgrounds of alleles prevalent in Africa and South America. In addition to previously known highly-resistant triple mutant dhps alleles SGEGA and AGEAA (codons 436, 437, 540, 581, 613 are sequentially indicated, a large proportion of the isolates (19.3% contained a 540N mutation in association with 437G/581G yielding a previously unreported triple mutant allele, SGNGA. Microsatellite data strongly suggest the strength of selection was greater on triple mutant dhps alleles followed by the double and single mutants. We provide evidence for at least three independent origins for the double mutants, one each for the SGKGA, AGKAA and SGEAA alleles. Our data suggest that the triple mutant allele SGEGA and the novel allele SGNGA have common origin on the SGKGA background, whereas the AGEAA triple mutant was derived from AGKAA on multiple, albeit limited, genetic backgrounds. The SGEAA did not share haplotypes with any of the triple mutants. Comparative analysis of the microsatellite haplotypes flanking dhps alleles from Cambodia, Kenya, Cameroon and Venezuela revealed an independent origin of sulfadoxine resistant alleles in each

  19. Origin and evolution of sulfadoxine resistant Plasmodium falciparum.

    Science.gov (United States)

    Vinayak, Sumiti; Alam, Md Tauqeer; Mixson-Hayden, Tonya; McCollum, Andrea M; Sem, Rithy; Shah, Naman K; Lim, Pharath; Muth, Sinuon; Rogers, William O; Fandeur, Thierry; Barnwell, John W; Escalante, Ananias A; Wongsrichanalai, Chansuda; Ariey, Frederick; Meshnick, Steven R; Udhayakumar, Venkatachalam

    2010-03-26

    The Thailand-Cambodia border is the epicenter for drug-resistant falciparum malaria. Previous studies have shown that chloroquine (CQ) and pyrimethamine resistance originated in this region and eventually spread to other Asian countries and Africa. However, there is a dearth in understanding the origin and evolution of dhps alleles associated with sulfadoxine resistance. The present study was designed to reveal the origin(s) of sulfadoxine resistance in Cambodia and its evolutionary relationship to African and South American dhps alleles. We sequenced 234 Cambodian Plasmodium falciparum isolates for the dhps codons S436A/F, A437G, K540E, A581G and A613S/T implicated in sulfadoxine resistance. We also genotyped 10 microsatellite loci around dhps to determine the genetic backgrounds of various alleles and compared them with the backgrounds of alleles prevalent in Africa and South America. In addition to previously known highly-resistant triple mutant dhps alleles SGEGA and AGEAA (codons 436, 437, 540, 581, 613 are sequentially indicated), a large proportion of the isolates (19.3%) contained a 540N mutation in association with 437G/581G yielding a previously unreported triple mutant allele, SGNGA. Microsatellite data strongly suggest the strength of selection was greater on triple mutant dhps alleles followed by the double and single mutants. We provide evidence for at least three independent origins for the double mutants, one each for the SGKGA, AGKAA and SGEAA alleles. Our data suggest that the triple mutant allele SGEGA and the novel allele SGNGA have common origin on the SGKGA background, whereas the AGEAA triple mutant was derived from AGKAA on multiple, albeit limited, genetic backgrounds. The SGEAA did not share haplotypes with any of the triple mutants. Comparative analysis of the microsatellite haplotypes flanking dhps alleles from Cambodia, Kenya, Cameroon and Venezuela revealed an independent origin of sulfadoxine resistant alleles in each of these regions.

  20. Combinatorial Genetic Modeling of pfcrt-Mediated Drug Resistance Evolution in Plasmodium falciparum.

    Science.gov (United States)

    Gabryszewski, Stanislaw J; Modchang, Charin; Musset, Lise; Chookajorn, Thanat; Fidock, David A

    2016-06-01

    The emergence of drug resistance continuously threatens global control of infectious diseases, including malaria caused by the protozoan parasite Plasmodium falciparum A critical parasite determinant is the P. falciparum chloroquine resistance transporter (PfCRT), the primary mediator of chloroquine (CQ) resistance (CQR), and a pleiotropic modulator of susceptibility to several first-line artemisinin-based combination therapy partner drugs. Aside from the validated CQR molecular marker K76T, P. falciparum parasites have acquired at least three additional pfcrt mutations, whose contributions to resistance and fitness have been heretofore unclear. Focusing on the quadruple-mutant Ecuadorian PfCRT haplotype Ecu1110 (K76T/A220S/N326D/I356L), we genetically modified the pfcrt locus of isogenic, asexual blood stage P. falciparum parasites using zinc-finger nucleases, producing all possible combinations of intermediate pfcrt alleles. Our analysis included the related quintuple-mutant PfCRT haplotype 7G8 (Ecu1110 + C72S) that is widespread throughout South America and the Western Pacific. Drug susceptibilities and in vitro growth profiles of our combinatorial pfcrt-modified parasites were used to simulate the mutational trajectories accessible to parasites as they evolved CQR. Our results uncover unique contributions to parasite drug resistance and growth for mutations beyond K76T and predict critical roles for the CQ metabolite monodesethyl-CQ and the related quinoline-type drug amodiaquine in driving mutant pfcrt evolution. Modeling outputs further highlight the influence of parasite proliferation rates alongside gains in drug resistance in dictating successful trajectories. Our findings suggest that P. falciparum parasites have navigated constrained pfcrt adaptive landscapes by means of probabilistically rare mutational bursts that led to the infrequent emergence of pfcrt alleles in the field.

  1. Prevalence of resistance associated polymorphisms in Plasmodium falciparum field isolates from southern Pakistan

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    Beg Mohammad A

    2011-01-01

    Full Text Available Abstract Background Scarce data are available on Plasmodium falciparum anti-malarial drug resistance in Pakistan. The aim of this study was, therefore, to determine the prevalence of P. falciparum resistance associated polymorphisms in field isolates from southern Pakistan. Methods Blood samples from 244 patients with blood-slide confirmed P. falciparum mono-infections were collected between 2005-2007. Single nucleotide polymorphisms in the P. falciparum chloroquine resistance transporter (pfcrt K76T, multi drug resistance (pfmdr1 N86Y, dihydrofolate reductase (pfdhfr A16V, N51I, C59R, S108N, I164L and dihydropteroate synthetase (pfdhps A436S, G437A and E540K genes and pfmdr1 gene copy numbers were determined using PCR based methods. Results The prevalence of pfcrt 76T and pfmdr1 86Y was 93% and 57%, respectively. The prevalence of pfdhfr double mutations 59R + 108N/51R + 108N was 92%. The pfdhfr triple mutation (51I, 59R, 108N occurred in 3% of samples. The pfdhfr (51I, 59R, 108N and pfdhps (437G, 540E quintuple mutation was found in one isolate. Pfdhps 437G was observed in 51% and 540E in 1% of the isolates. One isolate had two pfmdr1 copies and carried the pfmdr1 86Y and pfcrt 76T alleles. Conclusions The results indicate high prevalence of in vivo resistance to chloroquine, whereas high grade resistance to sulphadoxine-pyrimethamine does not appear to be widespread among P. falciparum in southern Pakistan.

  2. Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt.

    Science.gov (United States)

    Pelleau, Stéphane; Moss, Eli L; Dhingra, Satish K; Volney, Béatrice; Casteras, Jessica; Gabryszewski, Stanislaw J; Volkman, Sarah K; Wirth, Dyann F; Legrand, Eric; Fidock, David A; Neafsey, Daniel E; Musset, Lise

    2015-09-15

    In regions with high malaria endemicity, the withdrawal of chloroquine (CQ) as first-line treatment of Plasmodium falciparum infections has typically led to the restoration of CQ susceptibility through the reexpansion of the wild-type (WT) allele K76 of the chloroquine resistance transporter gene (pfcrt) at the expense of less fit mutant alleles carrying the CQ resistance (CQR) marker K76T. In low-transmission settings, such as South America, drug resistance mutations can attain 100% prevalence, thereby precluding the return of WT parasites after the complete removal of drug pressure. In French Guiana, despite the fixation of the K76T allele, the prevalence of CQR isolates progressively dropped from >90% to <30% during 17 y after CQ withdrawal in 1995. Using a genome-wide association study with CQ-sensitive (CQS) and CQR isolates, we have identified a single mutation in pfcrt encoding a C350R substitution that is associated with the restoration of CQ susceptibility. Genome editing of the CQR reference strain 7G8 to incorporate PfCRT C350R caused a complete loss of CQR. A retrospective molecular survey on 580 isolates collected from 1997 to 2012 identified all C350R mutant parasites as being CQS. This mutation emerged in 2002 and rapidly spread throughout the P. falciparum population. The C350R allele is also associated with a significant decrease in piperaquine susceptibility in vitro, suggesting that piperaquine pressure in addition to potential fitness costs associated with the 7G8-type CQR pfcrt allele may have selected for this mutation. These findings have important implications for understanding the evolutionary dynamics of antimalarial drug resistance.

  3. Overcoming Chloroquine Resistance in Malaria: Design, Synthesis, and Structure-Activity Relationships of Novel Hybrid Compounds.

    Science.gov (United States)

    Boudhar, Aicha; Ng, Xiao Wei; Loh, Chiew Yee; Chia, Wan Ni; Tan, Zhi Ming; Nosten, Francois; Dymock, Brian W; Tan, Kevin S W

    2016-05-01

    Resistance to antimalarial therapies, including artemisinin, has emerged as a significant challenge. Reversal of acquired resistance can be achieved using agents that resensitize resistant parasites to a previously efficacious therapy. Building on our initial work describing novel chemoreversal agents (CRAs) that resensitize resistant parasites to chloroquine (CQ), we herein report new hybrid single agents as an innovative strategy in the battle against resistant malaria. Synthetically linking a CRA scaffold to chloroquine produces hybrid compounds with restored potency toward a range of resistant malaria parasites. A preferred compound, compound 35, showed broad activity and good potency against seven strains resistant to chloroquine and artemisinin. Assessment of aqueous solubility, membrane permeability, and in vitro toxicity in a hepatocyte line and a cardiomyocyte line indicates that compound 35 has a good therapeutic window and favorable drug-like properties. This study provides initial support for CQ-CRA hybrid compounds as a potential treatment for resistant malaria.

  4. Molecular surveillance as monitoring tool for drug-resistant Plasmodium falciparum in Suriname.

    Science.gov (United States)

    Adhin, Malti R; Labadie-Bracho, Mergiory; Bretas, Gustavo

    2013-08-01

    The aim of this translational study was to show the use of molecular surveillance for polymorphisms and copy number as a monitoring tool to track the emergence and dynamics of Plasmodium falciparum drug resistance. A molecular baseline for Suriname was established in 2005, with P. falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance (pfmdr1) markers and copy number in 40 samples. The baseline results revealed the existence of a uniformly distributed mutated genotype corresponding with the fully mefloquine-sensitive 7G8-like genotype (Y184F, S1034C, N1042D, and D1246Y) and a fixed pfmdr1 N86 haplotype. All samples harbored the pivotal pfcrtK76T mutation, showing that chloroquine reintroduction should not yet be contemplated in Suriname. After 5 years, 40 samples were assessed to trace temporal changes in the status of pfmdr1 polymorphisms and copy number and showed minor genetic alterations in the pfmdr1 gene and no significant changes in copy number, thus providing scientific support for prolongation of the current drug policy in Suriname.

  5. Antimalarial drug resistance of Plasmodium falciparum in India: changes over time and space

    OpenAIRE

    Shah, Naman K.; Dhillon, Gajender P S; Dash, Adtiya P; Arora, Usha; Meshnick, Steven R.; Valecha, Neena

    2011-01-01

    After the launch of the National Malaria Control Programme in 1953, the number of malaria cases reported in India fell to an all-time low of 0·1 million in 1965. However, the initial success could not be maintained and a resurgence of malaria began in the late 1960s. Resistance of Plasmodium falciparum to chloroquine was first reported in 1973 and increases in antimalarial resistance, along with rapid urbanisation and labour migration, complicated the challenge that India’s large geographical...

  6. Evidence That Mutant PfCRT Facilitates the Transmission to Mosquitoes of Chloroquine-Treated Plasmodium Gametocytes

    OpenAIRE

    Ecker, Andrea; Lakshmanan, Viswanathan; Sinnis, Photini; Coppens, Isabelle; Fidock, David A

    2011-01-01

    Resistance of the human malarial parasite Plasmodium falciparum to the antimalarial drug chloroquine has rapidly spread from several independent origins and is now widely prevalent throughout the majority of malaria-endemic areas. Field studies have suggested that chloroquine-resistant strains might be more infective to mosquito vectors. To test the hypothesis that the primary chloroquine resistance determinant, mutations in PfCRT, facilitates parasite transmission under drug pressure, we hav...

  7. REVERSAL OF HALOFANTRINE RESISTANCE IN PLASMODIUM FALCIPARUM BY PENFLURIDOL IN VITRO

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    M. Nateghpour

    1998-10-01

    Full Text Available Penfluridol, a neuroleptic drug, considerably reversed halofantrine resistance in T9.96HF halofantrine resistant strain of Plasmodium falicparum (originally chloroquine sensitive parasites, but not in K1HF halofantrine resistant strain (originally chloroquine resistant parasites

  8. Resistance of infection by Plasmodium vivax to chloroquine in Bolivia.

    Science.gov (United States)

    Añez, Arletta; Moscoso, Manuel; Laguna, Ángel; Garnica, Cecilia; Melgar, Viviana; Cuba, Mauren; Gutierrez, Sonia; Ascaso, Carlos

    2015-07-01

    Chloroquine (CQ) over three days plus primaquine (PQ) for seven days is the treatment of choice of infections by Plasmodium vivax in Bolivia, where 95% of the cases of malaria are attributed to this species. The aim of this study was to evaluate the therapeutic efficacy of CQ in this setting. Patients in the Amazon region of northern Bolivia, were included in the study from May to November 2011 and the therapeutic efficacy of CQ was evaluated over a 28-day follow-up period. Patients with P. vivax mono-infection received 25 mg/Kg body weight of CQ over three days. The concentrations of CQ + desethylchloroquine (DCQ) in blood were determined at days 7 and 28 of follow up; at follow-up and on the day of treatment failure was administered PQ. One hundred patients fulfilled the inclusion criteria, two were lost to follow up and another two were later excluded for protocol violation. Of the 96 patients who completed the follow up 10 showed TF; one presented continued parasitaemia until day 7 of follow up, three on day 21 and six on day 28 of follow up. The geometric mean of CQ + DCQ on day 7 was 321.7 ng/ml (range 197-535 ng/ml). In six patients with TF the CQ + DCQ concentrations in blood on the day of TF were >100 ng/ml. The rate of resistance was 6.5%. The present study demonstrates the presence of resistance to CQ in the treatment of malaria by P. vivax in the Amazon region of Bolivia. New clinical trials are needed to establish alternative treatments against these parasites in this region of South America.

  9. Prevalence of molecular markers of anti-malarial drug resistance in Plasmodium vivax and Plasmodium falciparum in two districts of Nepal

    DEFF Research Database (Denmark)

    Ranjitkar, Samir; Schousboe, Mette L; Thomsen, Thomas

    2011-01-01

    ABSTRACT: BACKGROUND: Sulphadoxine-pyrimethamine (SP) and chloroquine (CQ) have been used in treatment of falciparum and vivax malaria in Nepal. Recently, resistance to both drugs have necessitated a change towards artemisinin combination therapy (ACT) against Plasmodium falciparum in highly...... endemic areas. However, SP is still used against P. falciparum infections in low endemic areas while CQ is used in suspected cases in areas with lack of diagnostic facilities. This study examines the prevalence of molecular markers of P. falciparum and Plasmodium vivax CQ and SP resistance to determine...... if high levels of in vivo resistance are reflected at molecular level as well. METHODS: Finger prick blood samples (n=189) were collected from malaria positive patients from two high endemic districts and analysed for single nucleotide polymorphisms (SNPs) in the resistance related genes of P. falciparum...

  10. Licochalcone A, a new antimalarial agent, inhibits in vitro growth of the human malaria parasite Plasmodium falciparum and protects mice from em>P. yoelii infection

    DEFF Research Database (Denmark)

    Chen, M; Theander, T G; Christensen, S B;

    1994-01-01

    Licochalcone A, isolated from Chinese licorice roots, inhibited the in vitro growth of both chloroquine-susceptible (3D7) and chloroquine-resistant (Dd2) Plasmodium falciparum strains in a [3H]hypoxanthine uptake assay. The growth inhibition of the chloroquine-resistant strain by licochalcone A w...

  11. Treatment of erythrocytes with the 2-cys peroxiredoxin inhibitor, Conoidin A, prevents the growth of Plasmodium falciparum and enhances parasite sensitivity to chloroquine.

    Directory of Open Access Journals (Sweden)

    Mariana Brizuela

    Full Text Available The human erythrocyte contains an abundance of the thiol-dependant peroxidase Peroxiredoxin-2 (Prx2, which protects the cell from the pro-oxidant environment it encounters during its 120 days of life in the blood stream. In malarial infections, the Plasmodium parasite invades red cells and imports Prx2 during intraerythrocytic development, presumably to supplement in its own degradation of peroxides generated during cell metabolism, especially hemoglobin (Hb digestion. Here we demonstrate that an irreversible Prx2 inhibitor, Conoidin A (2,3-bis(bromomethyl-1,4-dioxide-quinoxaline; BBMQ, has potent cytocidal activity against cultured P. falciparum. Parasite growth was also inhibited in red cells that were treated with BBMQ and then washed prior to parasite infection. These cells remained susceptible to merozoite invasion, but failed to support normal intraerythrocytic development. In addition the potency of chloroquine (CQ, an antimalarial drug that prevents the detoxification of Hb-derived heme, was significantly enhanced in the presence of BBMQ. CQ IC50 values decreased an order of magnitude when parasites were either co-incubated with BBMQ, or introduced into BBMQ-pretreated cells; these effects were equivalent for both drug-resistant and drug-sensitive parasite lines. Together these results indicate that treatment of red cells with BBMQ renders them incapable of supporting parasite growth and increases parasite sensitivity to CQ. We also propose that molecules such as BBMQ that target host cell proteins may constitute a novel host-directed therapeutic approach for treating malaria.

  12. Plasmodium falciparum drug resistance in Angola.

    Science.gov (United States)

    Fançony, Cláudia; Brito, Miguel; Gil, Jose Pedro

    2016-02-09

    Facing chloroquine drug resistance, Angola promptly adopted artemisinin-based combination therapy as the first-line to treat malaria. Currently, the country aims to consolidate malaria control, while preparing for the elimination of the disease, along with others African countries in the region. However, the remarkable capacity of Plasmodium to develop drug resistance represents an alarming threat for those achievements. Herein, the available, but relatively scarce and dispersed, information on malaria drug resistance in Angola, is reviewed and discussed. The review aims to inform but also to encourage future research studies that monitor and update the information on anti-malarial drug efficacy and prevalence of molecular markers of drug resistance, key fields in the context and objectives of elimination.

  13. Assessment of Plasmodium falciparum resistance to ferroquine (SSR97193 in field isolates and in W2 strain under pressure

    Directory of Open Access Journals (Sweden)

    Pradines Bruno

    2006-02-01

    Full Text Available Abstract Background Ferroquine (FQ, or SSR97193, is a novel antimalarial drug currently in phase I clinical trials. FQ is a unique organometallic compound designed to overcome the chloroquine (CQ resistance problem. FQ revealed to be equally active on CQ-sensitive and CQ-resistant Plasmodium falciparum laboratory strains and field isolates. FQ is also curative on rodent malaria parasites. As FQ will be tested in patients, the potential for resistance to this drug was evaluated. Methods The relationship between CQ-resistant transporter gene genotype and susceptibility to FQ were studied in 33 Cambodian P. falciparum field isolates previously studied for their in vitro response to CQ. In parallel, the ability of the CQ-resistant strain W2, to become resistant to FQ under drug pressure was assessed. Results The IC50 values for FQ in field isolates were found to be unrelated to mutations occurring in the P. falciparum chloroquine resistance transporter (PfCRT or to the level of expression of the corresponding mRNA. In vitro, under a drug pressure of 100 nM of FQ, transient survival was observed in only one of two experiments. Conclusion Field isolates studies and experimental drug pressure experiments showed that FQ overcomes CQ resistance, which reinforces the potential of this compound as a new antimalarial drug.

  14. Tracking origins and spread of sulfadoxine-resistant Plasmodium falciparum dhps alleles in Thailand.

    Science.gov (United States)

    Alam, Md Tauqeer; Vinayak, Sumiti; Congpuong, Kanungnit; Wongsrichanalai, Chansuda; Satimai, Wichai; Slutsker, Laurence; Escalante, Ananias A; Barnwell, John W; Udhayakumar, Venkatachalam

    2011-01-01

    The emergence and spread of drug-resistant Plasmodium falciparum have been a major impediment for the control of malaria worldwide. Earlier studies have shown that similar to chloroquine (CQ) resistance, high levels of pyrimethamine resistance in P. falciparum originated independently 4 to 5 times globally, including one origin at the Thailand-Cambodia border. In this study we describe the origins and spread of sulfadoxine-resistance-conferring dihydropteroate synthase (dhps) alleles in Thailand. The dhps mutations and flanking microsatellite loci were genotyped for P. falciparum isolates collected from 11 Thai provinces along the Burma, Cambodia, and Malaysia borders. Results indicated that resistant dhps alleles were fixed in Thailand, predominantly being the SGEGA, AGEAA, and SGNGA triple mutants and the AGKAA double mutant (mutated codons are underlined). These alleles had different geographical distributions. The SGEGA alleles were found mostly at the Burma border, while the SGNGA alleles occurred mainly at the Cambodia border and nearby provinces. Microsatellite data suggested that there were two major genetic lineages of the triple mutants in Thailand, one common for SGEGA/SGNGA alleles and another one independent for AGEAA. Importantly, the newly reported SGNGA alleles possibly originated at the Thailand-Cambodia border. All parasites in the Yala province (Malaysia border) had AGKAA alleles with almost identical flanking microsatellites haplotypes. They were also identical at putatively neutral loci on chromosomes 2 and 3, suggesting a clonal nature of the parasite population in Yala. In summary, this study suggests multiple and independent origins of resistant dhps alleles in Thailand.

  15. The efficacy of sulfadoxine-pyrimethamine alone and in combination with chloroquine for malaria treatment in rural Eastern Sudan: the interrelation between resistance, age and gametocytogenesis

    DEFF Research Database (Denmark)

    A-Elbasit, Ishraga E; Elbashir, Mustafa I; Khalil, Insaf F;

    2006-01-01

    OBJECTIVE: To compare the efficacy of sulfadoxine-pyremethamine (SP)+chloroquine (CQ) combination treatment against falciparum malaria with SP treatment alone. METHOD: In-vivo study of 254 patients with uncomplicated Plasmodium falciparum malaria in rural eastern Sudan, where the population is semi......-immune. RESULTS: Sulfadoxine-pyremethamine treatment alone cured 68.3% (41/60) and SP+CQ cured 63.4% (123/194). Early and late treatment failures occurred in both treatment groups. Host age (as a marker for immunity) and parasite gametocytogenesis (as a marker for transmissibility) were significantly associated...... with SP resistance. Patients who were cured were significantly older (median age 21 years) than patients whose treatment failed (median age 12 years). Gametocyte production was significantly higher in patients with treatment failure (0.72 vs 0.45) and associated with younger age. Gametocyte counts were...

  16. Apoptosis of erythrocytic stage parasites of Plasmodium berghei chloroquine-resistant strain

    Institute of Scientific and Technical Information of China (English)

    CHEN Ke-qiang; SONG Guan-hong

    2002-01-01

    Objective: To explore the characteristics of crisis state at erythrocytic stage of Plasmodium berghei chloroquine-resistant (RC) strain. Methods: Agarose electrophoresis, optical and transmission electron microscopes were used. Patterns of genomic DNA structures and ultra-structures of the erythrocytic parasites were observed in ICA mice (infected with the RC strain) during rising and declining of parasitemia. Results: During the declining parasitemia, the erythrocytic stage parasites of the RC strain showed round or oval appearance with intact plasma membrane and shrank nuclei with no metabolic window, mitochondria or other membranaceous structures. Their DNA electrophoretogram revealed a ladder pattern which evidently differed from the parasites of the RC strain in the rising parasitemia and the chloroquine-sensitive (N) strain.Conclusion: The crisis state of the erythrocytic stage parasites of the P. berghei chloroquine-resistant (RC)strain is characterized by apoptosis.

  17. Pretreatment blood concentrations of chloroquine in patients with malaria infection: relation to response to treatment

    DEFF Research Database (Denmark)

    Quashie, Neils Ben; Akanmori, Bartholomew D; Goka, Bamenla Q

    2005-01-01

    Resistance of Plasmodium falciparum to chloroquine has been reported in many areas in Ghana. Most of these reports, which are from hospital-based studies, indicate RI and RII rather than RIII type of resistance. Since high pretreatment levels of chloroquine have also been measured in patients...... with treatment outcomes in 231 paediatric malaria patients, referred to a major hospital in Ghana. The rate of parasite clearance and prevalence of recrudescence, 14 days post-treatment, were determined for each patient. Results from this study showed no correlation between pretreatment chloroquine levels...... and day 0 parasitaemia. Two hundred and seven patients (89.6 per cent) had parasites that were sensitive to chloroquine whilst 24 (10.4 per cent) had resistant parasites. Of the latter group 17, six, and one patients had P. falciparum parasites, which were resistant at RI, RII and RIII levels...

  18. Multiple origins of Plasmodium falciparum dihydropteroate synthetase mutant alleles associated with sulfadoxine resistance in India.

    Science.gov (United States)

    Lumb, Vanshika; Das, Manoj K; Singh, Neeru; Dev, Vas; Khan, Wajihullah; Sharma, Yagya D

    2011-06-01

    With the spread of chloroquine (CQ)-resistant malaria in India, sulfadoxine-pyrimethamine (SP) alone or in combination with artesunate is used as an alternative antimalarial drug. Due to continuous drug pressure, the Plasmodium falciparum parasite is exhibiting resistance to antifolates because of mutations in candidate genes dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps). Our earlier study on flanking microsatellite markers of dhfr mutant alleles from India had shown a single origin of the pyrimethamine resistance and some minor haplotypes which shared haplotypes with Southeast Asian (Thailand) strains. In the present study, we have analyzed 193 of these Indian P. falciparum isolates for 15 microsatellite loci around dhps to investigate the genetic lineages of the mutant dhps alleles in different parts of the country. Eighty-one of these samples had mutant dhps alleles, of which 62 were from Andaman and Nicobar Islands and the remaining 19 were from mainland India. Of 112 isolates with a wild-type dhps allele, 109 were from mainland India and only 3 were from Andaman and Nicobar Islands. Consistent with the model of selection, the mean expected heterozygosity (H(e)) around mutant dhps alleles (H(e) = 0.55; n = 81) associated with sulfadoxine resistance was lower (P ≤ 0.05) than the mean H(e) around the wild-type dhps allele (H(e) = 0.80; n = 112). There was more genetic diversity in flanking microsatellites of dhps than dhfr among these isolates, which confirms the assertion that dhps mutations are at a very early stage of fixation in the parasite population. Microsatellite haplotypes around various mutant dhps alleles suggest that the resistant dhps alleles have multiple independent origins in India, especially in Andaman and Nicobar Islands. Determining the genetic lineages of the resistant dhps alleles on Andaman and Nicobar Islands and mainland India is significant, given the role of Asia in the intercontinental spread of chloroquine

  19. Plasmodium falciparum In Vitro Resistance to Monodesethylamodiaquine, Dakar, Senegal, 2014.

    Science.gov (United States)

    Fall, Bécaye; Madamet, Marylin; Camara, Cheikhou; Amalvict, Rémy; Fall, Mansour; Nakoulima, Aminata; Diatta, Bakary; Diémé, Yaya; Wade, Boubacar; Pradines, Bruno

    2016-05-01

    We successfully cultured 36 Plasmodium falciparum isolates from blood samples of 44 malaria patients admitted to the Hôpital Principal de Dakar (Dakar, Senegal) during August-December 2014. The prevalence of isolates with in vitro reduced susceptibility was 30.6% for monodesethylamodiaquine, 52.8% for chloroquine, 44.1% for mefloquine, 16.7% for doxycycline, 11.8% for piperaquine, 8.3% for artesunate, 5.9% for pyronaridine, 2.8% for quinine and dihydroartemisinin, and 0.0% for lumefantrine. The prevalence of isolates with reduced in vitro susceptibility to the artemisinin-based combination therapy partner monodesethylamodiaquine increased from 5.6% in 2013 to 30.6% in 2014. Because of the increased prevalence of P. falciparum parasites with impaired in vitro susceptibility to monodesethylamodiaquine, the implementation of in vitro and in vivo surveillance of all artemisinin-based combination therapy partners is warranted.

  20. Chloroquine treatment of severe malaria in children. Pharmacokinetics, toxicity, and new dosage recommendations.

    Science.gov (United States)

    White, N J; Miller, K D; Churchill, F C; Berry, C; Brown, J; Williams, S B; Greenwood, B M

    1988-12-01

    Although empirical regimens of parenteral chloroquine have been used extensively to treat severe malaria for 40 years, recent recommendations state that parenteral chloroquine should no longer be used because of potential toxicity. We studied prospectively the pharmacokinetics and toxicity of seven chloroquine regimens in 58 Gambian children with severe chloroquine-sensitive falciparum malaria. In all regimens the total cumulative dose was 25 mg of chloroquine base per kilogram of body weight. Chloroquine was rapidly absorbed after either intramuscular or subcutaneous administration (5 mg of base per kilogram every 12 hours), producing high peak blood concentrations but transient hypotension in 5 of 18 patients (28 percent). Intermittent intravenous infusion (5 mg of base per kilogram over 4 hours, repeated every 12 hours) also produced wide fluctuations in chloroquine levels, suggesting incomplete distribution from a small central compartment. Continuous infusion (0.83 mg of base per kilogram per hour for 30 hours) and smaller, more frequent intramuscular or subcutaneous injections of chloroquine (3.5 mg of base per kilogram every 6 hours) produced smoother blood-concentration profiles with lower early peak levels and no adverse cardiovascular or neurologic effects. Chloroquine given by nasogastric tube (initial dose, 10 mg of base per kilogram) was absorbed well, even in comatose children. We conclude that simple alterations in dosage and frequency of administration can give parenteral chloroquine an acceptable therapeutic ratio and reinstate it as the treatment of choice for severe malaria in areas where chloroquine resistance is not a major problem.

  1. A thirteen-year analysis of Plasmodium falciparum populations reveals high conservation of the mutant pfcrt haplotype despite the withdrawal of chloroquine from national treatment guidelines in Gabon.

    Science.gov (United States)

    Frank, Matthias; Lehners, Nicola; Mayengue, Pembe I; Gabor, Julian; Dal-Bianco, Matthias; Kombila, David U; Ngoma, Ghyslain Mombo; Supan, Christian; Lell, Bertrand; Ntoumi, Francine; Grobusch, Martin P; Dietz, Klaus; Kremsner, Peter G

    2011-10-17

    Chloroquine resistance (CR) decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR) conferring mutant pfcrt allele and its associated chromosomal haplotype were determined before and after the change in Gabonese national treatment guidelines from chloroquine (CQ) to artesunate plus amodiaquine (AQ) in 2003. The prevalence of the wild type pfcrt allele was assessed in 144 isolates from the years 2005 - 07 by PCR fragment restriction digest and direct sequencing. For haplotype analysis of the chromosomal regions flanking the pfcrt locus, microsatellite analysis was done on a total of 145 isolates obtained in 1995/96 (43 isolates), 2002 (47 isolates) and 2005 - 07 (55 isolates). The prevalence of the mutant pfcrt allele decreased from 100% in the years 1995/96 and 2002 to 97% in 2005 - 07. Haplotype analysis showed that in 1995/96 79% of the isolates carried the same microsatellite alleles in a chromosomal fragment spanning 39 kb surrounding the pfcrt locus. In 2002 and 2005 - 07 the prevalence of this haplotype was 62% and 58%, respectively. Pfcrt haplotype analysis showed that all wild type alleles were CVMNK. Four years after the withdrawal of CQ from national treatment guidelines the prevalence of the mutant pfcrt allele remains at 97%. The data suggest that the combination of artesunate plus AQ may result in continued selection for the mutant pfcrt haplotype even after discontinuance of CQ usage.

  2. A thirteen-year analysis of Plasmodium falciparum populations reveals high conservation of the mutant pfcrt haplotype despite the withdrawal of chloroquine from national treatment guidelines in Gabon

    Directory of Open Access Journals (Sweden)

    Ngoma Ghyslain

    2011-10-01

    Full Text Available Abstract Background Chloroquine resistance (CR decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR conferring mutant pfcrt allele and its associated chromosomal haplotype were determined before and after the change in Gabonese national treatment guidelines from chloroquine (CQ to artesunate plus amodiaquine (AQ in 2003. Methods The prevalence of the wild type pfcrt allele was assessed in 144 isolates from the years 2005 - 07 by PCR fragment restriction digest and direct sequencing. For haplotype analysis of the chromosomal regions flanking the pfcrt locus, microsatellite analysis was done on a total of 145 isolates obtained in 1995/96 (43 isolates, 2002 (47 isolates and 2005 - 07 (55 isolates. Results The prevalence of the mutant pfcrt allele decreased from 100% in the years 1995/96 and 2002 to 97% in 2005 - 07. Haplotype analysis showed that in 1995/96 79% of the isolates carried the same microsatellite alleles in a chromosomal fragment spanning 39 kb surrounding the pfcrt locus. In 2002 and 2005 - 07 the prevalence of this haplotype was 62% and 58%, respectively. Pfcrt haplotype analysis showed that all wild type alleles were CVMNK. Conclusion Four years after the withdrawal of CQ from national treatment guidelines the prevalence of the mutant pfcrt allele remains at 97%. The data suggest that the combination of artesunate plus AQ may result in continued selection for the mutant pfcrt haplotype even after discontinuance of CQ usage.

  3. In Vitro Sensitivity of Plasmodium falciparum Isolates from China-Myanmar Border Region to Chloroquine,Piperaquine and Pyronaridine%中缅边境地区恶性疟原虫对氯喹、哌喹、咯萘啶敏感性的体外测定

    Institute of Scientific and Technical Information of China (English)

    张苍林; 周红宁; 王剑; 刘慧

    2012-01-01

    目的 了解中缅边境地区恶性疟原虫(Plasmodium falciparum)对氯喹、哌喹和咯萘啶敏感性的变化.方法 2009年9~12月在中缅边境的缅甸拉咱市采集了51份恶性疟血样,采用Rieckmann体外微量测定法进行药物敏感性测定. 结果 敏感性测定结果有效的42份血样中,其恶性疟原虫对氯喹、哌喹和咯萘啶的抗性率分别为95.2%、7.1%和54.8%,半数抑制量(ID50)分别为320.5、128.2和96.0 nmol/L.在抗咯萘啶的23份血样中,对氯喹和哌喹的交叉抗性率分别为91.3% (21/23)和13.0% (3/23);抗氯喹的40份血样中,对哌喹和咯萘啶的交叉抗性率分别为7.5% (3/40)和52.5% (21/40);抗哌喹的3份血样中,对氯喹和咯萘啶的交叉抗性率均为100%.结论 在缅甸拉咱市调查点流行的恶性疟原虫对氯喹已普遍产生抗性,约半数对咯萘啶具有抗性,多数对哌喹则敏感.%Objective To assess the in vitro sensitivity of Plasmodium falciparum to chloroquine, piperaquine and pyronaridine in China-Myanmar border area. Methods Fifty-one blood specimens of P. Falcipamm isolates were collected from Laza City of Myanmar during September to December in 2009, and the sensitivity of the parasites to the drugs was detected by Rieckmann's in vitro microtest. Results Among the 42 blood samples with valid results of sensitivity test, the resistance rate to chloroquine, piperaquine and pyronaridine was 95.2%, 7.1%, and 54.8%, with a corresponding 50% inhibition dose (ID50 ) of 320.5, 128.2, and 96.0nmol/L, respectively. Pyronaridine-resistant P. Falcipamm exhibited some degree of cross-resistance to chloroquine [91.3%(21/23)] and piperaquine [13.0% (3/23)], and chloroquine-resistant P. Falciparum showed cross-resistance to piperaquine [7.5%(3/40)] and pyronaridine [52.5%(21/40) ]. High level of cross-resistance was present to chloroquine (100%) and pyronaridine (100%) in piperaquineresistant P. Falciparum. Conclusion In Laza City, P. Falciparum

  4. Emerging Plasmodium vivax resistance to chloroquine in South America: an overview

    Directory of Open Access Journals (Sweden)

    Lígia Antunes Gonçalves

    2014-08-01

    Full Text Available The global emergence of Plasmodium vivax strains resistant to chloroquine (CQ since the late 1980s is complicating the current international efforts for malaria control and elimination. Furthermore, CQ-resistant vivax malaria has already reached an alarming prevalence in Indonesia, East Timor and Papua New Guinea. More recently, in vivo studies have documented CQ-resistant P. vivax infections in Guyana, Peru and Brazil. Here, we summarise the available data on CQ resistance across P. vivax-endemic areas of Latin America by combining published in vivo and in vitro studies. We also review the current knowledge regarding the molecular mechanisms of CQ resistance in P. vivax and the prospects for developing and standardising reliable molecular markers of drug resistance. Finally, we discuss how the Worldwide Antimalarial Resistance Network, an international collaborative effort involving malaria experts from all continents, might contribute to the current regional efforts to map CQ-resistant vivax malaria in South America.

  5. Prevalence of the molecular marker of chloroquine resistance (pfcrt ...

    African Journals Online (AJOL)

    We monitored the resistance pattern 5 years after withdrawal of CQ, using the pfcrt K76T mutation as a ... The World Health Organization (WHO) currently advocates the .... A clinical trial later confirmed that these changes in the prevalence.

  6. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Zaid O. Ibraheem

    2014-01-01

    Full Text Available Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter and pfcrt (Plasmodium falciparum chloroquine resistance transporter which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system and members of drug metabolite transporter (DMT family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs.

  7. Ex Vivo Drug Susceptibility Testing and Molecular Profiling of Clinical Plasmodium falciparum Isolates from Cambodia from 2008 to 2013 Suggest Emerging Piperaquine Resistance.

    Science.gov (United States)

    Chaorattanakawee, Suwanna; Saunders, David L; Sea, Darapiseth; Chanarat, Nitima; Yingyuen, Kritsanai; Sundrakes, Siratchana; Saingam, Piyaporn; Buathong, Nillawan; Sriwichai, Sabaithip; Chann, Soklyda; Se, Youry; Yom, You; Heng, Thay Kheng; Kong, Nareth; Kuntawunginn, Worachet; Tangthongchaiwiriya, Kuntida; Jacob, Christopher; Takala-Harrison, Shannon; Plowe, Christopher; Lin, Jessica T; Chuor, Char Meng; Prom, Satharath; Tyner, Stuart D; Gosi, Panita; Teja-Isavadharm, Paktiya; Lon, Chanthap; Lanteri, Charlotte A

    2015-08-01

    Cambodia's first-line artemisinin combination therapy, dihydroartemisinin-piperaquine (DHA-PPQ), is no longer sufficiently curative against multidrug-resistant Plasmodium falciparum malaria at some Thai-Cambodian border regions. We report recent (2008 to 2013) drug resistance trends in 753 isolates from northern, western, and southern Cambodia by surveying for ex vivo drug susceptibility and molecular drug resistance markers to guide the selection of an effective alternative to DHA-PPQ. Over the last 3 study years, PPQ susceptibility declined dramatically (geomean 50% inhibitory concentration [IC50] increased from 12.8 to 29.6 nM), while mefloquine (MQ) sensitivity doubled (67.1 to 26 nM) in northern Cambodia. These changes in drug susceptibility were significantly associated with a decreased prevalence of P. falciparum multidrug resistance 1 gene (Pfmdr1) multiple copy isolates and coincided with the timing of replacing artesunate-mefloquine (AS-MQ) with DHA-PPQ as the first-line therapy. Widespread chloroquine resistance was suggested by all isolates being of the P. falciparum chloroquine resistance transporter gene CVIET haplotype. Nearly all isolates collected from the most recent years had P. falciparum kelch13 mutations, indicative of artemisinin resistance. Ex vivo bioassay measurements of antimalarial activity in plasma indicated 20% of patients recently took antimalarials, and their plasma had activity (median of 49.8 nM DHA equivalents) suggestive of substantial in vivo drug pressure. Overall, our findings suggest DHA-PPQ failures are associated with emerging PPQ resistance in a background of artemisinin resistance. The observed connection between drug policy changes and significant reduction in PPQ susceptibility with mitigation of MQ resistance supports reintroduction of AS-MQ, in conjunction with monitoring of the P. falciparum mdr1 copy number, as a stop-gap measure in areas of DHA-PPQ failure.

  8. In Vitro Increase in Chloroquine Accumulation Induced by Dihydroethano- and Ethenoanthracene Derivatives in Plasmodium falciparum-Parasitized Erythrocytes

    Science.gov (United States)

    Pradines, Bruno; Alibert, Sandrine; Houdoin, Carole; Santelli-Rouvier, Christiane; Mosnier, Joel; Fusai, Thierry; Rogier, Christophe; Barbe, Jacques; Parzy, Daniel

    2002-01-01

    The effects of a series of dihydroethano- and ethenoanthracene derivatives on chloroquine (CQ) accumulation in CQ-susceptible strain 3D7 and CQ-resistant clone W2 were assessed. The levels of CQ accumulation increased little or none in CQ-susceptible strain 3D7 and generally increased markedly in CQ-resistant strain W2. At 10 μM, 28 compounds yielded cellular accumulation ratios (CARs) greater than that observed with CQ alone in W2. At 10 μM, in strain W2, 21 of 31 compounds had CQ CARs two or more times higher than that of CQ alone, 15 of 31 compounds had CQ CARs three or more times higher than that of CQ alone, 13 of 31 compounds had CQ CARs four or more times higher than that of CQ alone, and 9 of 31 compounds had CQ CARs five or more times higher than that of CQ alone. At 1 μM, 17 of 31 compounds had CQ CARs two or more times higher than that of CQ alone, 12 of 31 compounds had CQ CARs three or more times higher than that of CQ alone, 6 of 31 compounds had CQ CARs four or more times higher than that of CQ alone, and 3 of 31 compounds had CQ CARs five or more times higher than that of CQ alone. At 1 μM, 17 of 31 compounds were more potent inducers of CQ accumulation than verapamil and 12 of 31 compounds were more potent inducers of CQ accumulation than promethazine. The nature of the basic group seems to be associated with increases in the levels of CQ accumulation. At 1 and 10 μM, 10 of 14 and 13 of 14 compounds with amino group (amines and diamines), respectively, had CARs ≥3, while at 1 and 10 μM, only 1 of the 13 derivatives with amido groups had CARs ≥3. Among 12 of the 31 compounds which were more active inducers of CQ accumulation than promethazine at 1 μM, 10 had amino groups and 1 had an amido group. PMID:12069956

  9. Risk of drug resistance in Plasmodium falciparum malaria therapy-a systematic review and meta-analysis.

    Science.gov (United States)

    Zhou, Li-Juan; Xia, Jing; Wei, Hai-Xia; Liu, Xiao-Jun; Peng, Hong-Juan

    2017-02-01

    Plasmodium falciparum is responsible for the vast majority of the morbidity and mortality associated with malaria infection globally. Although a number of studies have reported the emergence of drug resistance in different therapies for P. falciparum infection, the degree of the drug resistance in different antimalarials is still unclear. This research investigated the risk of drug resistance in the therapies with different medications based on meta-analyses. Relevant original randomized control trials (RCTs) were searched in all available electronic databases. Pooled relative risks (RRs) with 95% confidence intervals (95% CIs) were used to evaluate the risk of drug resistance resulting from different treatments. Seventy-eight studies were included in the meta-analysis to compare drug resistance in the treatment of P. falciparum infections and yielded the following results: chloroquine (CQ) > sulfadoxine-pyrimethamine (SP) (RR = 3.67, p  artemether + lumefantrine (AL) (RR = 2.94, p  artemisinin-based combination therapies (ACTs) (RR = 1.93, p < 0.001); no significant difference was found in amodiaquine (AQ) vs. SP, AS + AQ vs. AS + SP, AS + AQ vs. AL, or AS + MQ vs. AL. These results presented a global view for the current status of antimalarial drug resistance and provided a guidance for choice of antimalarials for efficient treatment and prolonging the life span of the current effective antimalarial drugs.

  10. Malaria chemoprophylaxis in travellers to east Africa: a comparative prospective study of chloroquine plus proguanil with chloroquine plus sulfadoxine-pyrimethamine

    DEFF Research Database (Denmark)

    Fogh, S; Schapira, A; Bygbjerg, Ib Christian

    1988-01-01

    As malaria caused by Plasmodium falciparum has become resistant to chloroquine alternative drug regimens need to be developed. The prophylactic efficacy against malaria and the side effects of chloroquine phosphate 500 mg weekly with proguanil hydrochloride 200 mg daily was compared...... with the efficacy of chloroquine 500 mg weekly with sulfadoxine 500 mg-pyrimethamine 25 mg weekly in a randomised study of Scandinavian travellers to Kenya and Tanzania during 1984-5. A total of 767 subjects (416 male and 351 female; 384 taking chloroquine phosphate with proguanil hydrochloride and 383 taking...... chloroquine with sulfadoxine-pyrimethamine) completed a diary on the breakthrough of malaria and the side effects of treatment while taking the drugs. They were also asked to make thick blood films when symptoms like those of malaria occurred, which were sent to and analysed in Denmark. Four subjects taking...

  11. [Research Progress on Artemisinin Resistance in Plasmodium falciparum].

    Science.gov (United States)

    Zhang, Yi-long; Pan, Wei-qing

    2015-12-01

    Artemisinin (ART) is a novel and effective antimalarial drug discovered in China. As recommended by the World Health Organization, the ART-based combination therapies (ACTs) have become the first-line drugs for the treatment of falciparum malaria. ART and its derivatives have contributed greatly to the effective control of malaria globally, leading to yearly decrease of malaria morbidity and mortality. However, there have recently been several reports on the resistance of Plasmodium falciparum to ART in Southeast Asia. This is deemed a serious threat to the global malaria control programs. In this paper, we reviewed recent research progress on ART resistance to P. falciparum, including new tools for resistance measurement, resistance-associated molecular markers, and the origin and spread of the ART-resistant parasite strains.

  12. Evidence that mutant PfCRT facilitates the transmission to mosquitoes of chloroquine-treated Plasmodium gametocytes.

    Science.gov (United States)

    Ecker, Andrea; Lakshmanan, Viswanathan; Sinnis, Photini; Coppens, Isabelle; Fidock, David A

    2011-01-15

    Resistance of the human malarial parasite Plasmodium falciparum to the antimalarial drug chloroquine has rapidly spread from several independent origins and is now widely prevalent throughout the majority of malaria-endemic areas. Field studies have suggested that chloroquine-resistant strains might be more infective to mosquito vectors. To test the hypothesis that the primary chloroquine resistance determinant, mutations in PfCRT, facilitates parasite transmission under drug pressure, we have introduced a mutant or wild-type pfcrt allele into the rodent model malarial parasite Plasmodium berghei. Our results show that mutant PfCRT from the chloroquine-resistant 7G8 strain has no effect on asexual blood stage chloroquine susceptibility in vivo or ex vivo but confers a significant selective advantage in competitive mosquito infections in the presence of this drug, by protecting immature gametocytes from its lethal action. Enhanced infectivity to mosquitoes may have been a key factor driving the worldwide spread of mutant pfcrt.

  13. The roles of the pfcrt 76T and pfmdr1 86Y mutations, immunity and the initial level of parasitaemia, in predicting the outcome of chloroquine treatment in two areas with different transmission intensities

    DEFF Research Database (Denmark)

    Khalil, I F; Alifrangis, M; Tarimo, D S

    2005-01-01

    , and the ability to clear P. falciparum parasites carrying the key chloroquine-resistance (CQR) mutations, pfcrt 76T and pfmdr1 86Y. Identical CQ-efficacy trials were performed in 51 young children (aged

  14. Microsatellite polymorphism within pfcrt provides evidence of continuing evolution of chloroquine-resistant alleles in Papua New Guinea

    Directory of Open Access Journals (Sweden)

    Sharma Yagya D

    2007-03-01

    Full Text Available Abstract Background Polymorphism in the pfcrt gene underlies Plasmodium falciparum chloroquine resistance (CQR, as sensitive strains consistently carry lysine (K, while CQR strains carry threonine (T at the codon 76. Previous studies have shown that microsatellite (MS haplotype variation can be used to study the evolution of CQR polymorphism and to characterize intra- and inter-population dispersal of CQR in Papua New Guinea (PNG. Methods Here, following identification of new polymorphic MS in introns 2 and 3 within the pfcrt gene (msint2 and msint3, respectively, locus-by-locus and haplotype heterozygosity (H analyses were performed to determine the distribution of this intronic polymorphism among pfcrt chloroquine-sensitive and CQR alleles. Results For MS flanking the pfcrt CQR allele, H ranged from 0.07 (B5M77, -18 kb to 0.094 (9B12, +2 kb suggesting that CQ selection pressure was responsible for strong homogenisation of this gene locus. In a survey of 206 pfcrt-SVMNT allele-containing field samples from malaria-endemic regions of PNG, H for msint2 was 0.201. This observation suggests that pfcrt msint2 exhibits a higher level of diversity than what is expected from the analyses of pfcrt flanking MS. Further analyses showed that one of the three haplotypes present in the early 1980's samples has become the predominant haplotype (frequency = 0.901 in CQR parasite populations collected after 1995 from three PNG sites, when CQR had spread throughout malaria-endemic regions of PNG. Apparent localized diversification of pfcrt haplotypes at each site was also observed among samples collected after 1995, where minor CQR-associated haplotypes were found to be unique to each site. Conclusion In this study, a higher level of diversity at MS loci within the pfcrt gene was observed when compared with the level of diversity at pfcrt flanking MS. While pfcrt (K76T and its immediate flanking region indicate homogenisation in PNG CQR parasite populations

  15. Enhanced combination therapy effect on paclitaxel-resistant carcinoma by chloroquine co-delivery via liposomes

    Directory of Open Access Journals (Sweden)

    Gao MH

    2015-10-01

    Full Text Available Menghua Gao,1 Yuzhen Xu,1 Liyan Qiu2,3 1College of Pharmaceutical Sciences, 2Ministry of Education (MOE Key Laboratory of Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 3Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People’s Republic of China Abstract: A novel composite liposomal system co-encapsulating paclitaxel (PTX with chloroquine phosphate (CQ was designed for treating PTX-resistant carcinoma. It was confirmed that liposomal CQ can sensitize PTX by means of autophagy inhibition and competitively binding with multidrug-resistance transporters. Furthermore, according to the in vitro cytotoxicity and apoptosis assay, real-time observation of cellular uptake, and in vivo tissue distribution study, co-encapsulation of PTX and CQ in liposomes was validated as superior to the mixture of PTX liposome plus CQ liposome due to the simultaneous delivery and synergetic effect of the two drugs. Consequently, this composite liposome achieved significantly stronger anticancer efficacy in vivo than the PTX liposome plus CQ liposome mixture. This study helps to guide and enlighten ongoing and future clinical trials about the optimal administration modes for drug combination therapy. Keywords: paclitaxel, chloroquine, liposome, drug resistance, combination therapy

  16. Discordance in drug resistance-associated mutation patterns in marker genes of Plasmodium falciparum and Plasmodium knowlesi during coinfections.

    Science.gov (United States)

    Tyagi, Rupesh K; Das, Manoj K; Singh, Shiv S; Sharma, Yagya D

    2013-05-01

    Human Plasmodium knowlesi infections have been reported from several South-East Asian countries, excluding India, but its drug susceptibility profile in mixed-infection cases remains unknown. The chloroquine resistance transporter (CRT) and dihydrofolate reductase (DHFR) genes of P. knowlesi and other Plasmodium species were sequenced from clinical isolates obtained from malaria patients living in the Andaman and Nicobar Islands, India. The merozoite surface protein-1 and 18S rRNA genes of P. knowlesi were also sequenced from these isolates. Among 445 samples analysed, only 53 of them had P. knowlesi-specific gene sequences. While 3 of the 53 cases (5.66%) had P. knowlesi monoinfection, the rest were coinfected with Plasmodium falciparum (86.79%, n = 46) or Plasmodium vivax (7.55%, n = 4), but none with Plasmodium malariae or Plasmodium ovale. There was discordance in the drug resistance-associated mutations among the coinfecting Plasmodium species. This is because the P. knowlesi isolates contained wild-type sequences, while P. falciparum isolates had mutations in the CRT and DHFR marker genes associated with a higher level of chloroquine and antifolate drug resistance, respectively. The mutation pattern indicates that the same patient, having a mixed infection, may be harbouring the drug-susceptible P. knowlesi parasite and a highly drug-resistant P. falciparum parasite. A larger human population in South-East Asia may be at risk of P. knowlesi infection than reported so far. The different drug susceptibility genotypes of P. knowlesi from its coinfecting Plasmodium species in mixed infections adds a new dimension to the malaria control programme, requiring formulation of an appropriate drug policy.

  17. The evolution of drug-resistant malaria

    OpenAIRE

    Plowe, Christopher V.

    2008-01-01

    Molecular epidemiological investigations have uncovered the patterns of emergence and global spread of Plasmodium falciparum resistance to chloroquine and sulfadoxine-pyrimethamine. Malaria parasites highly resistant to chloroquine and pyrimethamine spread from Asian origins to Africa, at great cost to human health and life. If artemisinin-resistant falciparum malaria follows the same pattern, renewed efforts to eliminate and eradicate malaria will be gravely threatened. This paper, adapted f...

  18. Identification of chloroquine resistance Pfcrt-K76T and determination of Pfmdr1-N86Y copy number by SYBR Green I qPCR

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    Addimas Tajebe

    2015-03-01

    Conclusions: The study showed high prevalence level and fixation of Pfcrt, 76T mutation after chloroquine withdrawal. The prevalence of Pfmdr1 copy number variant suggested that the presence of modulating factor for emergence of Plasmodium falciparum strains with higher copy numbers. However, the prevalence level was not statistically significant.

  19. Plasmodium falciparum Drug-Resistant Haplotypes and Population Structure in Postearthquake Haiti, 2010.

    Science.gov (United States)

    Morton, Lindsay Carol; Huber, Curtis; Okoth, Sheila Akinyi; Griffing, Sean; Lucchi, Naomi; Ljolje, Dragan; Boncy, Jacques; Oscar, Roland; Townes, David; McMorrow, Meredith; Chang, Michelle A; Udhayakumar, Venkatachalam; Barnwell, John W

    2016-10-05

    Chloroquine (CQ) remains the first-line treatment of malaria in Haiti. Given the challenges of conducting in vivo drug efficacy trials in low-endemic settings like Haiti, molecular surveillance for drug resistance markers is a reasonable approach for detecting resistant parasites. In this study, 349 blood spots were collected from suspected malaria cases in areas in and around Port-au-Prince from March to July 2010. Among them, 121 samples that were Plasmodium falciparum positive by polymerase chain reaction were genotyped for drug-resistant pfcrt, pfdhfr, pfdhps, and pfmdr1 alleles. Among the 108 samples that were successfully sequenced for CQ resistant markers in pfcrt, 107 were wild type (CVMNK), whereas one sample carried a CQ-resistant allele (CVIET). Neutral microsatellite genotyping revealed that the CQ-resistant isolate was distinct from all other samples in this study. Furthermore, the remaining parasite specimens appeared to be genetically distinct from other reported Central and South American populations. © The American Society of Tropical Medicine and Hygiene.

  20. Plasmodium falciparum Malaria, Southern Algeria, 2007

    OpenAIRE

    Boubidi, Saïd C; Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria.

  1. Plasmodium falciparum Malaria, Southern Algeria, 2007

    Science.gov (United States)

    Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria. PMID:20113565

  2. Plasmodium falciparum Malaria, Southern Algeria, 2007

    OpenAIRE

    Boubidi, Saïd C; Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria.

  3. Evaluation of dihydrofolate reductase and dihydropteroate synthetase genotypes that confer resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum in Haiti.

    Science.gov (United States)

    Carter, Tamar E; Warner, Megan; Mulligan, Connie J; Existe, Alexander; Victor, Yves S; Memnon, Gladys; Boncy, Jacques; Oscar, Roland; Fukuda, Mark M; Okech, Bernard A

    2012-08-13

    Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ) as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR) and sulphadoxine (SDX) treatment combination (SP), have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Thirty-three percent (20/61) of the samples carried a mutation at codon 108 (S108N) of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540) examined. No significant difference was observed between samples collected in urban vs rural sites (Welch's T-test p-value = 0.53 and permutations p-value = 0.59). This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These results have important implications for ongoing discussions on

  4. Evaluation of dihydrofolate reductase and dihydropteroate synthetase genotypes that confer resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum in Haiti

    Directory of Open Access Journals (Sweden)

    Carter Tamar E

    2012-08-01

    Full Text Available Abstract Background Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR and sulphadoxine (SDX treatment combination (SP, have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr and dihydropteroate synthetase (dhps genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. Methods DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Results Thirty-three percent (20/61 of the samples carried a mutation at codon 108 (S108N of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540 examined. No significant difference was observed between samples collected in urban vs rural sites (Welch’s T-test p-value = 0.53 and permutations p-value = 0.59. Conclusion This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These

  5. Complex polymorphisms in the Plasmodium falciparum multidrug resistance protein 2 gene and its contribution to antimalarial response.

    Science.gov (United States)

    Veiga, Maria Isabel; Osório, Nuno S; Ferreira, Pedro Eduardo; Franzén, Oscar; Dahlstrom, Sabina; Lum, J Koji; Nosten, Francois; Gil, José Pedro

    2014-12-01

    Plasmodium falciparum has the capacity to escape the actions of essentially all antimalarial drugs. ATP-binding cassette (ABC) transporter proteins are known to cause multidrug resistance in a large range of organisms, including the Apicomplexa parasites. P. falciparum genome analysis has revealed two genes coding for the multidrug resistance protein (MRP) type of ABC transporters: Pfmrp1, previously associated with decreased parasite drug susceptibility, and the poorly studied Pfmrp2. The role of Pfmrp2 polymorphisms in modulating sensitivity to antimalarial drugs has not been established. We herein report a comprehensive account of the Pfmrp2 genetic variability in 46 isolates from Thailand. A notably high frequency of 2.8 single nucleotide polymorphisms (SNPs)/kb was identified for this gene, including some novel SNPs. Additionally, we found that Pfmrp2 harbors a significant number of microindels, some previously not reported. We also investigated the potential association of the identified Pfmrp2 polymorphisms with altered in vitro susceptibility to several antimalarials used in artemisinin-based combination therapy and with parasite clearance time. Association analysis suggested Pfmrp2 polymorphisms modulate the parasite's in vitro response to quinoline antimalarials, including chloroquine, piperaquine, and mefloquine, and association with in vivo parasite clearance. In conclusion, our study reveals that the Pfmrp2 gene is the most diverse ABC transporter known in P. falciparum with a potential role in antimalarial drug resistance.

  6. Enhanced combination therapy effect on paclitaxel-resistant carcinoma by chloroquine co-delivery via liposomes.

    Science.gov (United States)

    Gao, Menghua; Xu, Yuzhen; Qiu, Liyan

    2015-01-01

    A novel composite liposomal system co-encapsulating paclitaxel (PTX) with chloroquine phosphate (CQ) was designed for treating PTX-resistant carcinoma. It was confirmed that liposomal CQ can sensitize PTX by means of autophagy inhibition and competitively binding with multidrug-resistance transporters. Furthermore, according to the in vitro cytotoxicity and apoptosis assay, real-time observation of cellular uptake, and in vivo tissue distribution study, co-encapsulation of PTX and CQ in liposomes was validated as superior to the mixture of PTX liposome plus CQ liposome due to the simultaneous delivery and synergetic effect of the two drugs. Consequently, this composite liposome achieved significantly stronger anticancer efficacy in vivo than the PTX liposome plus CQ liposome mixture. This study helps to guide and enlighten ongoing and future clinical trials about the optimal administration modes for drug combination therapy.

  7. A Method for Amplicon Deep Sequencing of Drug Resistance Genes in Plasmodium falciparum Clinical Isolates from India.

    Science.gov (United States)

    Rao, Pavitra N; Uplekar, Swapna; Kayal, Sriti; Mallick, Prashant K; Bandyopadhyay, Nabamita; Kale, Sonal; Singh, Om P; Mohanty, Akshaya; Mohanty, Sanjib; Wassmer, Samuel C; Carlton, Jane M

    2016-06-01

    A major challenge to global malaria control and elimination is early detection and containment of emerging drug resistance. Next-generation sequencing (NGS) methods provide the resolution, scalability, and sensitivity required for high-throughput surveillance of molecular markers of drug resistance. We have developed an amplicon sequencing method on the Ion Torrent PGM platform for targeted resequencing of a panel of six Plasmodium falciparum genes implicated in resistance to first-line antimalarial therapy, including artemisinin combination therapy, chloroquine, and sulfadoxine-pyrimethamine. The protocol was optimized using 12 geographically diverse P. falciparum reference strains and successfully applied to multiplexed sequencing of 16 clinical isolates from India. The sequencing results from the reference strains showed 100% concordance with previously reported drug resistance-associated mutations. Single-nucleotide polymorphisms (SNPs) in clinical isolates revealed a number of known resistance-associated mutations and other nonsynonymous mutations that have not been implicated in drug resistance. SNP positions containing multiple allelic variants were used to identify three clinical samples containing mixed genotypes indicative of multiclonal infections. The amplicon sequencing protocol has been designed for the benchtop Ion Torrent PGM platform and can be operated with minimal bioinformatics infrastructure, making it ideal for use in countries that are endemic for the disease to facilitate routine large-scale surveillance of the emergence of drug resistance and to ensure continued success of the malaria treatment policy.

  8. Assessment of Markers of Antimalarial Drug Resistance in Plasmodium falciparum Isolates from Pregnant Women in Lagos, Nigeria.

    Directory of Open Access Journals (Sweden)

    Chimere Obiora Agomo

    Full Text Available The use of antimalarial drugs for prevention and treatment is a major strategy in the prevention of malaria in pregnancy. Although sulphadoxine-pyrimethamine (SP is currently recommended for intermittent preventive treatment of malaria during pregnancy in Nigeria, previously used drugs for prophylaxis such as chloroquine (CQ and pyrimethamine are accessible as they are purchased over the counter. This study describes the markers of absence or presence of resistance to quinoline (Pfcrt and Pfmdr 1 and type 1 antifolate antimalarial medicines (Pfdhfr.Plasmodium falciparum-positive dried blood spots from pregnant women attending antenatal clinics for the first time during current pregnancy were investigated for the presence of mutations at codons 72-76 of Plasmodium falciparum chloroquine resistance transporter (Pfcrt gene by real time polymerase chain reaction (PCR using haplotype-specific probes. PCR followed by sequence analysis was used to identify mutations at codons 86, 184, 1034, 1042 and 1246 of P. falciparum multi-drug resistance-1 (Pfmdr1 gene; and codons 16, 50, 51, 59, 108, 140 and 164 of Pfdhfr gene.Two haplotypes of Pfcrt (n = 54 were observed: CVMNK 13(24.2% and CVIET 41 (75.9% of the samples. The SVMNT haplotype was absent in this population. The Pfmdr1 (n = 28 haplotypes were NYSND 15(53.6%, YYSND 5(17.9%, NFSND 6(21.4% and YFSND 2(7.1%. The Pfdhfr (n = 15 were ACNCSVI 4(26.7%, and ACICNSVI 1(6.7% and ACIRNVI 10 (66.7%. The rate of occurrence of Pfcrt 76T, Pfdhfr108N, Pfmdr186Y and 184F were 75.9%, 73.3%, 25% and 28.1% respectively. The Pfmdr1 86Y was associated with low parasitaemia (median = 71 parasites/μl, P = 0.024 while Pfcrt 76T was associated with young maternal age (mean 24.1 ± 4.5 years; P = 0.006. The median parasitaemia were similar (P>0.05 in wild and mutant strains of Pfcrt 76, Pfmdr1 184 and Pfdhfr 108. There was no association between gravidity or gestational age of the women and presence of mutations in the Pfcrt

  9. Targeting Plasmodium falciparum Hsp90: Towards Reversing Antimalarial Resistance

    Directory of Open Access Journals (Sweden)

    Dea Shahinas

    2013-02-01

    Full Text Available Malaria continues to exact a great human toll in tropical settings. Antimalarial resistance is rife and the parasite inexorably develops mechanisms to outwit our best drugs, including the now first-line choice, artesunate. Novel strategies to circumvent resistance are needed. Here we detail drug development focusing on heat shock protein 90 and its central role as a chaperone. A growing body of evidence supports the role for Hsp90 inhibitors as adjunctive drugs able to restore susceptibility to traditionally efficacious compounds like chloroquine.

  10. Genetic diversity of Plasmodium falciparum and distribution of drug resistance haplotypes in Yemen

    Science.gov (United States)

    2013-01-01

    Background Despite evident success of malaria control in many sites in the Arabian Peninsula, malaria remains endemic in a few spots, in Yemen and south-west of Saudi Arabia. In addition to local transmission, imported malaria sustains an extra source of parasites that can challenge the strengths of local control strategies. This study examined the genetic diversity of Plasmodium falciparum in Yemen and mutations of drug resistant genes, to elucidate parasite structure and distribution of drug resistance genotypes in the region. Methods Five polymorphic loci (MSP-2, Pfg377 and three microsatellites on chromosome 8) not involved in anti-malarial drug resistance, and four drug resistant genes (pfcrt, pfmdr1, dhfr and dhps) were genotyped in 108 P. falciparum isolates collected in three sites in Yemen: Dhamar, Hodeidah and Taiz. Results High diversity was seen in non-drug genes, pfg377 (He = 0.66), msp-2 (He = 0.80) and three microsatellites on chr 8, 7.7 kb (He = 0.88), 4.3 kb (He = 0.77) and 0.8 kb (He = 0.71). There was a high level of mixed-genotype infections (57%), with an average 1.8 genotypes per patient. No linkage disequilibrium was seen between drug resistant genes and the non-drug markers (p < 0.05). Genetic differentiation between populations was low (most pair-wise FST values <0.03), indicating extensive gene flow between the parasites in the three sites. There was a high prevalence of mutations in pfmdr1, pfcrt and dhfr; with four mutant pfmdr1 genotypes (NFCDD[57%], NFSND[21%], YFCDD[13%] and YFSND[8% ]), two mutant pfcrt genotypes (CVIET[89%] and SVMNT[4%]) and one mutant dhfr genotype (ICNI[53.7%]). However, no dhps mutations were detected. Conclusion The high diversity of P. falciparum in Yemen is indicative of a large parasite reservoir, which represents a challenge to control efforts. The presence of two distinct pfcrt genotype, CVIET and SVMNT, suggests that chloroquine resistance can possibly be related to a migratory

  11. In vitro evaluation of quinidine sensitivity in brazilian Plasmodium falciparum isolates: comparative analysis to quinine and chloroquine Avaliação da sensibilidade in vitro à quinidina em isolados brasileiros de Plasmodium falciparum: análise comparativa à quinina e à cloroquina

    Directory of Open Access Journals (Sweden)

    Carla M. S. MENEZES

    2001-08-01

    Full Text Available Falciparum malaria represents a serious and an increasing world public health problem due to the acquired parasite's resistance to the most available drugs. In some endemic areas, quinidine, a diastereoisomer of the antimalarial quinine, has been employed for replacing the latter. In order to evaluate the use of quinidine as an alternative to the increasing loss of quinine effectiveness in Brazilian P. falciparum strains, as has been observed in the Amazon area, we have assayed quinidine, quinine and chloroquine. The in vitro microtechnique was employed. All isolates showed to be highly resistant to chloroquine. Resistance to quinine was not noted although high MIC (minimal inhibitory concentration values have been observed. These data corroborate the decreasing sensitivity to quinine in strains from Brazil. Quinidine showed IC50 from 0.053 to 4.577 mumol/L of blood while IC50 from 0.053 to 8.132 mumol/L of blood was estimated for quinine. Moreover, clearance of the parasitemia was observed in concentrations lower than that used for quinidine in antiarrhythmic therapy, confirming our previous data. The results were similar to African isolate.Malária falciparum representa grave e crescente problema de saúde pública mundial, dada a resistência do parasito à maioria dos fármacos disponíveis. Em algumas áreas endêmicas, a quinidina, diastereoisômero do antimalárico quinina, vem sendo empregada em substituição a este último. Com o objetivo de avaliar o emprego da quinidina como alternativa à perda crescente de sensibilidade de cepas brasileiras de P. falciparum à quinina, como o observado na região Amazônica, realizamos ensaio comparativo entre quinidina, quinina e cloroquina. A técnica in vitro do microteste de sensibilidade foi utilizada. Todos os isolados mostraram-se altamente resistentes à cloroquina. Resistência à quinina não foi observada, embora altos valores de CMI (concentração mínima inibitória tenham sido

  12. CHLOROQUINE SENSITIVITY OF PLASMODIUM FALCIPARUM IN BERAKIT, BINTAN ISLAND, SUMATRA, AFTER MASS CHEMOPROPHYLAXIS THROUGH COMMUNITY PARTICIPATION, AND ITS SOCIOLOGICAL STUDIES

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    Wita Pribadi

    2012-09-01

    Full Text Available Profilaksis minggguan dengan klorokuin yang dilakukan secara massal melalui peran serta masyarakat telah dilakukan pada penduduk RK I di desa Berakit, Bintan, Propinsi Riau, Sumatra selama dua tahun (¡983-1985. Delapan tahun kemudian (¡993, pemeriksaan sensitivitas Plasmodium falciparum terhadap klorokuin in vivo dan in vitro dilakukan di RK I untuk mengetahui apakah pemberian klorokuin setiap minggu pada penduduk secara massal selama 2 tahun mempunyai dampak terhadap timbulnya resistensi P. falciparum terhadap obat tersebut di RK I atau dapat menyebar­luaskan resistensi klorokuin. Penelitian sosial dilakukan untuk mendapatkan informasi melalui pemeriksaan pengetahuan, sikap dan perilaku (KAP tentang malaria pada penduduk RK II di desa Berakit. RK II letaknya bersebelahan dengan RK I yang penduduknya telah diwawancara dan diberi penyuluhan kesehatan dengan "learning module" tentang malaria, dan. apakah hal ini mempengaruhi situasi/keadaan malaria di RK II. Hasil penelitian malariometrik di RK I dan RK II menunjukkan angka limpa dan angka parasit menurun secara bermakna, bila dibandingkan dengan hasil pada tahun 1991 tetapi di RK I tidak berbeda bermakna dibandingkan dengan hasil tahun 1995. Dari pemeriksaan 644 sediaan darah dari RK I dan RK II untuk tes sensitivitas, prevalensi parasitnya adalah 8.2 % (53/644 dan 58.5 % kasus positif adalah P. falciparum dan infeksi campur, selebihnya adalah P. vivax (41.5 %. Sayang sekali, hanya satu infeksi P. falciparum yang memenuhi syarat untuk tes dengan hasil S/R I in vivo 7 hari yang disederhanakan. Tes mikro in vitro menunjukkan resistensi (R terhadap klorokuin dan masih sensitif (S terhadap obat malaria lain (kina, S-P, meftokuin.Hasil pemeriksaan sosiologis menunjukkan adanya pengaruh"learning module" mengenai penyakit malaria sebanyak 20 % responden di RK II yang mempunyai sikap dan perilaku yang positif, bila dibandingkan dengan penelitian di RK II tahun 1991 sebesar 27.9 % dan tahun 1995

  13. CHLOROQUINE SENSITIVITY OF PLASMODIUM FALCIPARUM IN BERAKIT, BINTAN ISLAND, SUMATRA, AFTER MASS CHEMOPROPHYLAXIS THROUGH COMMUNITY PARTICIPATION, AND ITS SOCIOLOGICAL STUDIES

    Directory of Open Access Journals (Sweden)

    Wita Pribadi

    2012-09-01

    Full Text Available Profilaksis minggguan dengan klorokuin yang dilakukan secara massal melalui peran serta masyarakat telah dilakukan pada penduduk RK I di desa Berakit, Bintan, Propinsi Riau, Sumatra selama dua tahun (¡983-1985. Delapan tahun kemudian (¡993, pemeriksaan sensitivitas Plasmodium falciparum terhadap klorokuin in vivo dan in vitro dilakukan di RK I untuk mengetahui apakah pemberian klorokuin setiap minggu pada penduduk secara massal selama 2 tahun mempunyai dampak terhadap timbulnya resistensi P. falciparum terhadap obat tersebut di RK I atau dapat menyebar­luaskan resistensi klorokuin. Penelitian sosial dilakukan untuk mendapatkan informasi melalui pemeriksaan pengetahuan, sikap dan perilaku (KAP tentang malaria pada penduduk RK II di desa Berakit. RK II letaknya bersebelahan dengan RK I yang penduduknya telah diwawancara dan diberi penyuluhan kesehatan dengan "learning module" tentang malaria, dan. apakah hal ini mempengaruhi situasi/keadaan malaria di RK II. Hasil penelitian malariometrik di RK I dan RK II menunjukkan angka limpa dan angka parasit menurun secara bermakna, bila dibandingkan dengan hasil pada tahun 1991 tetapi di RK I tidak berbeda bermakna dibandingkan dengan hasil tahun 1995. Dari pemeriksaan 644 sediaan darah dari RK I dan RK II untuk tes sensitivitas, prevalensi parasitnya adalah 8.2 % (53/644 dan 58.5 % kasus positif adalah P. falciparum dan infeksi campur, selebihnya adalah P. vivax (41.5 %. Sayang sekali, hanya satu infeksi P. falciparum yang memenuhi syarat untuk tes dengan hasil S/R I in vivo 7 hari yang disederhanakan. Tes mikro in vitro menunjukkan resistensi (R terhadap klorokuin dan masih sensitif (S terhadap obat malaria lain (kina, S-P, meftokuin.Hasil pemeriksaan sosiologis menunjukkan adanya pengaruh"learning module" mengenai penyakit malaria sebanyak 20 % responden di RK II yang mempunyai sikap dan perilaku yang positif, bila dibandingkan dengan penelitian di RK II tahun 1991 sebesar 27.9 % dan tahun 1995

  14. A longitudinal trial comparing chloroquine as monotherapy or in combination with artesunate, azithromycin or atovaquone-proguanil to treat malaria.

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    Miriam K Laufer

    Full Text Available BACKGROUND: The predominance of chloroquine-susceptible falciparum malaria in Malawi more than a decade after chloroquine's withdrawal permits contemplation of re-introducing chloroquine for targeted uses. We aimed to compare the ability of different partner drugs to preserve chloroquine efficacy and prevent the re-emergence of resistance. METHODOLOGY/PRINCIPAL FINDINGS: Children with uncomplicated malaria were enrolled at a government health center in Blantyre, Malawi. Participants were randomized to receive chloroquine alone or combined with artesunate, azithromycin or atovaquone-proguanil for all episodes of uncomplicated malaria for one year. The primary outcome was incidence of clinical malaria. Secondary endpoints included treatment efficacy, and incidence of the chloroquine resistance marker pfcrt T76 and of anemia. Of the 640 children enrolled, 628 were included in the intention-to-treat analysis. Malaria incidence (95% confidence interval was 0.59 (.46-.74, .61 (.49-.76, .63 (.50-.79 and .68 (.54-.86 episodes/person-year for group randomized to receive chloroquine alone or in combination with artesunate, azithromycin or atovaquone-proguanil respectively and the differences were not statistically significant. Treatment efficacy for first episodes was 100% for chloroquine monotherapy and 97.9% for subsequent episodes of malaria. Similar results were seen in each of the chloroquine combination groups. The incidence of pfcrt T76 in pure form was 0%; mixed infections with both K76 and T76 were found in two out of 911 infections. Young children treated with chloroquine-azithromycin had higher hemoglobin concentrations at the study's end than did those in the chloroquine monotherapy group. CONCLUSION/SIGNIFICANCE: Sustained chloroquine efficacy with repeated treatment supports the eventual re-introduction of chloroquine combinations for targeted uses such as intermittent preventive treatment. TRIAL REGISTRATION: ClinicalTrials.gov NCT00379821.

  15. Molecular monitoring of Plasmodium falciparum resistance to artemisinin in Tanzania

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    Genton Blaise

    2006-12-01

    Full Text Available Abstract Artemisinin-based combination therapies (ACTs are recommended for use against uncomplicated malaria in areas of multi-drug resistant malaria, such as sub-Saharan Africa. However, their long-term usefulness in these high transmission areas remains unclear. It has been suggested that documentation of the S769N PfATPase6 mutations may indicate an emergence of artemisinin resistance of Plasmodium falciparum in the field. The present study assessed PfATPase6 mutations (S769N and A623E in 615 asymptomatic P. falciparum infections in Tanzania but no mutant genotype was detected. This observation suggests that resistance to artemisinin has not yet been selected in Tanzania, supporting the Ministry of Health's decision to adopt artemether+lumefantrine as first-line malaria treatment. The findings recommend further studies to assess PfATPase6 mutations in sentinel sites and verify their usefulness in monitoring emergency of ACT resistance.

  16. HUBUNGAN SENSISTIVITAS PLASMODIUM FALCIPARUM TERHADAP KOMBINASI PIRIMETAMIN/SULFADOKSIN DAN KLOROKUIN SECARA IN VITRO

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    Sahat Ompusunggu

    2012-09-01

    Full Text Available An in vitro sensitivity test was conducted to study the sensitivity of Plasmodium falciparum against chloroquine and pyrimethamine/sulphadoxine combination. The relationship between sensitivity of the parasite to the two drugs was also studied. A total of 72 patients from five localities were examined during 1984-1985. Test against chloroquine was conduc­ted according to WHO method, while against pyrimethamine/sulphadoxine combination, a modified method of Nguyen Dinh and Payne and Eastham and Rieckmann was used. The results showed that there is no relationship between the sensitivity of P. falciparum against pyrimethamine/ sulphadoxine combination and chloroquine. It can be concluded that in case of chloroquine resistant P. falciparum, pyrimethamine/sulphadoxine combination could be applied as an alternative chemotherapy.

  17. Treatment of falciparum malaria in the age of drug resistance

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    Shanks G

    2006-01-01

    Full Text Available The growing problem of drug resistance has greatly complicated the treatment for falciparum malaria. Whereaschloroquine and sulfadoxine/pyrimethamine could once cure most infections, this is no longer true and requiresexamination of alternative regimens. Not all treatment failures are drug resistant and other issues such asexpired antimalarials and patient compliance need to be considered. Continuation of a failing treatment policyafter drug resistance is established suppresses infections rather than curing them, leading to increasedtransmission of malaria, promotion of epidemics and loss of public confidence in malaria control programs.Antifolate drug resistance (i.e. pyrimethamine means that new combinations are urgently needed particularlybecause addition of a single drug to an already failing regimen is rarely effective for very long. Atovaquone/proguanil and mefloquine have been used against multiple drug resistant falciparum malaria with resistance toeach having been documented soon after drug introduction. Drug combinations delay further transmission ofresistant parasites by increasing cure rates and inhibiting formation of gametocytes. Most currentlyrecommended drug combinations for falciparum malaria are variants of artemisinin combination therapy wherea rapidly acting artemisinin compound is combined with a longer half-life drug of a different class. Artemisininsused include dihydroartemisinin, artesunate, artemether and companion drugs include mefloquine, amodiaquine,sulfadoxine/pyrimethamine, lumefantrine, piperaquine, pyronaridine, chlorproguanil/dapsone. The standard ofcare must be to cure malaria by killing the last parasite. Combination antimalarial treatment is vital not only tothe successful treatment of individual patients but also for public health control of malaria.

  18. Artemisinin resistance in Plasmodium falciparum: A process linked to dormancy?

    Science.gov (United States)

    Cheng, Qin; Kyle, Dennis E; Gatton, Michelle L

    2012-12-01

    Artemisinin (ART) based combination therapy (ACT) is used as the first line treatment of uncomplicated falciparum malaria in over 100 countries and is the cornerstone of malaria control and elimination programs in these areas. However, despite the high potency and rapid parasite killing action of ART derivatives there is a high rate of recrudescence associated with ART monotherapy and recrudescence is not uncommon even when ACT is used. Compounding this problem are reports that some parasites in Cambodia, a known foci of drug resistance, have decreased in vivo sensitivity to ART. This raises serious concerns for the development of ART resistance in the field even though no major phenotypic and genotypic changes have yet been identified in these parasites. In this article we review available data on the characteristics of ART, its effects on Plasmodium falciparum parasites and present a hypothesis to explain the high rate of recrudescence associated with this potent class of drugs and the current enigma surrounding ART resistance.

  19. In silico attempt for adduct agent(s) against malaria: Combination of chloroquine with alkaloids of Adhatoda vasica.

    Science.gov (United States)

    Swain, Shasank S; Sahu, Mahesh C; Padhy, Rabindra N

    2015-10-01

    With the aim of controlling drug resistant Plasmodium falciparum, a computational attempt of designing novel adduct antimalarial drugs through the molecular docking method of combining chloroquine with five alkaloids, individually is presented. These alkaloids were obtained from the medicinal plant, Adhatoda vasica. From the obtained individual docking values of important derivatives of quinine and chloroquine, as well as, individual alkaloids and adduct agents of chloroquine with Adhatoda alkaloids as ligands, it was discernible that the 'adduct agent-1 with chloroquine and adhatodine' combination had the minimum energy of interaction, as the docking score value of -11.144 kcal/mol against the target protein, triosephosphate isomerase (TIM), the key enzyme of glycolytic pathway. Drug resistance of P. falciparum is due to a mutation in the polypeptide of TIM. Moratorium of mutant TIM would disrupt the metabolism during the control of the drug resistant P. falciparum. This in silico work helped to locate the 'adduct agent-1 with chloroquine and adhatodine', which could be taken up by pharmacology for further development of this compound as a new drug against drug resistant Plasmodium.

  20. The novel oxygenated chalcone, 2,4-dimethoxy-4'-butoxychalcone, exhibits potent activity against human malaria parasite Plasmodium falciparum in vitro and rodent parasites Plasmodium berghei and Plasmodium yoelii in vivo

    DEFF Research Database (Denmark)

    Chen, M; Brøgger Christensen, S; Zhai, L

    1997-01-01

    growth of both a chloroquine-susceptible (3D7) and a chloroquine-resistant (Dd2) strain of Plasmodium falciparum in a [3H]hypoxanthine uptake assay. The in vivo activity of 2,4mbc was tested in mice infected with Plasmodium berghei or Plasmodium yoelii and in rats infected with P. berghei. 2,4mbc...

  1. Submicroscopic gametocytes and the transmission of antifolate-resistant Plasmodium falciparum in Western Kenya.

    NARCIS (Netherlands)

    Oesterholt, M.J.A.M.; Alifrangis, M.; Sutherland, C.J.; Omar, S.A.; Sawa, P.; Howitt, C.; Gouagna, L.C.; Sauerwein, R.W.; Bousema, T.

    2009-01-01

    BACKGROUND: Single nucleotide polymorphisms (SNPs) in the dhfr and dhps genes are associated with sulphadoxine-pyrimethamine (SP) treatment failure and gametocyte carriage. This may result in enhanced transmission of mutant malaria parasites, as previously shown for chloroquine resistant parasites.

  2. Identification of chloroquine resistance Pfcrt-K76T and determination of Pfmdr1-N86Y copy number by SYBR Green I qPCR

    Institute of Scientific and Technical Information of China (English)

    Addimas; Tajebe; Mulugeta; Aemero; Kimani; Francis; Gabriel; Magoma

    2015-01-01

    Objective:To identify prevalence of chloroquine resistance point mutation at(Pfcrt,K76T)and(Pfindr1.N86Y) copy number variation.Methods:SYBR Green I based real time PCR was used.One hundred and thirty-three samples were analyzed for(Pfcrt,K76T) and(Pfmdr1.N86Y) copy number from dried blood spot.Parasite DNA was extracted using high pure DNA preparation kit.The amplification of DNA was done by using AccuPower 2* GreenStar ’’ qPCR Master mix.For quantification purpose a new primer pair was designed for 178 base pair template from complete genome sequence of Plasmodium falciparum strain 3D7 at NCBI.Absolute quantification method was used to determine the Pfmdr1-N86 Y copy number variations.Standard curve was built from strain3D7 gDNA since it has single copy of Pfindr1 per haploid genome.The known positive controls with single and multi-copy number of Pfindr1 gene were included in each experiment.The copy number ratio of the samples to the standard calibrator was made to obtain the fold difference among the samples with respect to copy number variation.Results:Out of 133 samples 73(54.89%) were confirmed as mutant(Pfcrt,76T) and the remaining 60(45.11%) were genotyped as wild type(Pfcrt,K76).The(Pfindr1.N86Y) copy number variation was determined for 133 clinical samples.Out of these samples 61(45.86%)had single copy and the remaining 72(54.14%) had multi-copy numbers higher than 1.5 copies per genome.Thirty-four(25.56%) multi-copies were between 1.5 and 2.5 copies per genome while 38(28.57%) were more than 2.5 copies per genome.The minimum and maximum copies per genome were 0.474 and 4.741.respectively.Conclusions:The study showed high prevalence level and fixation of Pfcrt.76 T mutation after chloroquine withdrawal.The prevalence of Pfindr1 copy number variant suggested that the presence of modulating factor for emergence of Plasmodium falciparum strains with higher copy numbers.However,the prevalence level was not statistically significant.

  3. Prevalence of molecular markers of Plasmodium falciparum drug resistance in Dakar, Senegal

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    Wurtz Nathalie

    2012-06-01

    Full Text Available Abstract Background As a result of the widespread resistance to chloroquine and sulphadoxine-pyrimethamine, artemisinin-based combination therapy (ACT (including artemether-lumefantrine and artesunate-amodiaquine has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Intermittent preventive treatments with anti-malarial drugs based on sulphadoxine-pyrimethamine are also given to children or pregnant women once per month during the transmission season. Since 2006, there have been very few reports on the susceptibility of Plasmodium falciparum to anti-malarial drugs. To estimate the prevalence of resistance to several anti-malarial drugs since the introduction of the widespread use of ACT, the presence of molecular markers associated with resistance to chloroquine and sulphadoxine-pyrimethamine was assessed in local isolates at the military hospital of Dakar. Methods The prevalence of genetic polymorphisms in genes associated with anti-malarial drug resistance, i.e., Pfcrt, Pfdhfr, Pfdhps and Pfmdr1, and the copy number of Pfmdr1 were evaluated for a panel of 174 isolates collected from patients recruited at the military hospital of Dakar from 14 October 2009 to 19 January 2010. Results The Pfcrt 76T mutation was identified in 37.2% of the samples. The Pfmdr1 86Y and 184F mutations were found in 16.6% and 67.6% of the tested samples, respectively. Twenty-eight of the 29 isolates with the 86Y mutation were also mutated at codon 184. Only one isolate (0.6% had two copies of Pfmdr1. The Pfdhfr 108N/T, 51I and 59R mutations were identified in 82.4%, 83.5% and 74.1% of the samples, respectively. The double mutant (108N and 51I was detected in 83.5% of the isolates, and the triple mutant (108N, 51I and 59R was detected in 75.3%. The Pfdhps 437G, 436F/A and 613S mutations were found in 40.2%, 35.1% and 1.8% of the samples, respectively. There was no double mutant (437G and 540E or no quintuple mutant (Pfdhfr 108N, 51I and 59R

  4. Battling the malaria iceberg with chloroquine in India.

    Science.gov (United States)

    Sharma, Vinod P

    2007-08-07

    The National Vector Borne Disease Control Programme (NVBDCP) of the Ministry of Health, Government of India is reporting about 2 million parasite positive cases each year, although case incidence is 30-fold or more under-estimated. Forty five to fifty percent of Plasmodium infections are caused by Plasmodium falciparum, the killer parasite. Anti-malaria drug policy (2007) of the NVBDC recommends chloroquine (CQ) as the first line of drug for the treatment of all malarias. In a Primary Health Centre (PHC) reporting 10% or more cases of CQ resistance in P. falciparum, ACT blister pack is recommended and, so far, the policy has been adopted in 261 PHCs of 71 districts. The NVBDCP still depends on CQ to combat malaria and, as a result, P. falciparum has taken deep roots in malaria-endemic regions, causing unacceptable levels of morbidity and mortality. This policy was a subject of criticism in recent Nature and Lancet articles questioning the World Bank's decision to supply CQ to the NVBDCP. Continuation of an outdated drug in the treatment of P. falciparum is counterproductive in fighting drug resistant malaria and in the containment of P. falciparum. Switchover to Artemisinin-based Combination Therapy (ACT) in the treatment of all P. falciparum cases, ban on artemisinin monotherapy and effective vector control (treated nets/efficient insecticide spraying) would be a rational approach to malaria control in India.

  5. Battling the malaria iceberg with chloroquine in India

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    Sharma Vinod P

    2007-08-01

    Full Text Available Abstract The National Vector Borne Disease Control Programme (NVBDCP of the Ministry of Health, Government of India is reporting about 2 million parasite positive cases each year, although case incidence is 30-fold or more under-estimated. Forty five to fifty percent of Plasmodium infections are caused by Plasmodium falciparum, the killer parasite. Anti-malaria drug policy (2007 of the NVBDC recommends chloroquine (CQ as the first line of drug for the treatment of all malarias. In a Primary Health Centre (PHC reporting 10% or more cases of CQ resistance in P. falciparum, ACT blister pack is recommended and, so far, the policy has been adopted in 261 PHCs of 71 districts. The NVBDCP still depends on CQ to combat malaria and, as a result, P. falciparum has taken deep roots in malaria-endemic regions, causing unacceptable levels of morbidity and mortality. This policy was a subject of criticism in recent Nature and Lancet articles questioning the World Bank's decision to supply CQ to the NVBDCP. Continuation of an outdated drug in the treatment of P. falciparum is counterproductive in fighting drug resistant malaria and in the containment of P. falciparum. Switchover to Artemisinin-based Combination Therapy (ACT in the treatment of all P. falciparum cases, ban on artemisinin monotherapy and effective vector control (treated nets/efficient insecticide spraying would be a rational approach to malaria control in India.

  6. Chloroquine enhances gefitinib cytotoxicity in gefitinib-resistant nonsmall cell lung cancer cells.

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    Mei-Chuan Tang

    Full Text Available Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs, including gefitinib, are effective for non-small cell lung cancer (NSCLC patients with EGFR mutations. However, these patients eventually develop resistance to EGFR-TKI. The goal of the present study was to investigate the involvement of autophagy in gefitinib resistance. We developed gefitinib-resistant cells (PC-9/gef from PC-9 cells (containing exon 19 deletion EGFR after long-term exposure in gefitinib. PC-9/gef cells (B4 and E3 were 200-fold more resistant to gefitinib than PC-9/wt cells. Compared with PC-9/wt cells, both PC-9/gefB4 and PC-9/gefE3 cells demonstrated higher basal LC3-II levels which were inhibited by 3-methyladenine (3-MA, an autophagy inhibitor and potentiated by chloroquine (CQ, an inhibitor of autophagolysosomes formation, indicating elevated autophagy in PC-9/gef cells. 3-MA and CQ concentration-dependently inhibited cell survival of both PC-9wt and PC-9/gef cells, suggesting that autophagy may be pro-survival. Furthermore, gefitinib increased LC3-II levels and autolysosome formation in both PC-9/wt cells and PC-9/gef cells. In PC-9/wt cells, CQ potentiated the cytotoxicity by low gefitinib (3 nM. Moreover, CQ overcame the acquired gefitinib resistance in PC-9/gef cells by enhancing gefitinib-induced cytotoxicity, activation of caspase 3 and poly (ADP-ribose polymerase cleavage. Using an in vivo model xenografting with PC-9/wt and PC-9/gefB4 cells, oral administration of gefitinib (50 mg/kg completely inhibited the tumor growth of PC-9/wt but not PC-9/gefB4cells. Combination of CQ (75 mg/kg, i.p. and gefitinib was more effective than gefitinib alone in reducing the tumor growth of PC-9/gefB4. Our data suggest that inhibition of autophagy may be a therapeutic strategy to overcome acquired resistance of gefitinib in EGFR mutation NSCLC patients.

  7. Genotyping of Plasmodium falciparum using antigenic polymorphic markers and to study anti-malarial drug resistance markers in malaria endemic areas of Bangladesh

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    Akter Jasmin

    2012-11-01

    Full Text Available Abstract Background In the past many regions of Bangladesh were hyperendemic for malaria. Malaria control in the 1960s to 1970s eliminated malaria from the plains but in the Chittagong Hill Tracts remained a difficult to control reservoir. The Chittagong Hill Tracts have areas with between 1 and 10% annual malaria rates, predominately 90-95% Plasmodium falciparum. In Southeast Asia, multiplicity of infection for hypo-endemic regions has been approximately 1.5. Few studies on the genetic diversity of P. falciparum have been performed in Bangladesh. Anderson et al. performed a study in Khagrachari, northern Chittagong Hill Tracts in 2002 on 203 patients and found that parasites had a multiplicity of infection of 1.3 by MSP-1, MSP-2 and GLURP genotyping. A total of 94% of the isolates had the K76T Pfcrt chloroquine resistant genotype, and 70% showed the N86Y Pfmdr1 genotype. Antifolate drug resistant genotypes were high with 99% and 73% of parasites having two or more mutations at the dhfr or dhps loci. Methods Nested and real-time polymerase chain reaction (PCR methods were used to genotype P. falciparum using antigenic polymorphic markers and to study anti-malarial drug resistance markers in malaria endemic areas of Bangladesh. Results The analysis of polymorphic and drug resistant genotype on 33 paired recrudescent infections after drug treatment in the period 2004 to 2008 in the Chittagong Hill Tracts, which is just prior to countrywide provision of artemisinin combination therapy. Overall the multiplicity of infection for MSP-1 was 2.7 with a slightly smaller parasite diversity post-treatment. The 13 monoclonal infections by both GLURP and MSP-1 were evenly divided between pre- and post-treatment. The MSP-1 MAD block was most frequent in 66 of the samples. The prevalence of the K76T PfCRT chloroquine resistant allele was approximately 82% of the samples, while the resistant Pfmdr1 N86Y was present in 33% of the samples. Interestingly, the post

  8. Caspar controls resistance to Plasmodium falciparum in diverse anopheline species.

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    Lindsey S Garver

    2009-03-01

    Full Text Available Immune responses mounted by the malaria vector Anopheles gambiae are largely regulated by the Toll and Imd (immune deficiency pathways via the NF-kappaB transcription factors Rel1 and Rel2, which are controlled by the negative regulators Cactus and Caspar, respectively. Rel1- and Rel2-dependent transcription in A. gambiae has been shown to be particularly critical to the mosquito's ability to manage infection with the rodent malaria parasite Plasmodium berghei. Using RNA interference to deplete the negative regulators of these pathways, we found that Rel2 controls resistance of A. gambiae to the human malaria parasite Plasmodium falciparum, whereas Rel 1 activation reduced infection levels. The universal relevance of this defense system across Anopheles species was established by showing that caspar silencing also prevents the development of P. falciparum in the major malaria vectors of Asia and South America, A. stephensi and A. albimanus, respectively. Parallel studies suggest that while Imd pathway activation is most effective against P. falciparum, the Toll pathway is most efficient against P. berghei, highlighting a significant discrepancy between the human pathogen and its rodent model. High throughput gene expression analyses identified a plethora of genes regulated by the activation of the two Rel factors and revealed that the Toll pathway played a more diverse role in mosquito biology than the Imd pathway, which was more immunity-specific. Further analyses of key anti-Plasmodium factors suggest they may be responsible for the Imd pathway-mediated resistance phenotype. Additionally, we found that the fitness cost caused by Rel2 activation through caspar gene silencing was undetectable in sugar-fed, blood-fed, and P. falciparum-infected female A. gambiae, while activation of the Toll pathway's Rel1 had a major impact. This study describes for the first time a single gene that influences an immune mechanism that is able to abort

  9. Caspar controls resistance to Plasmodium falciparum in diverse anopheline species.

    Science.gov (United States)

    Garver, Lindsey S; Dong, Yuemei; Dimopoulos, George

    2009-03-01

    Immune responses mounted by the malaria vector Anopheles gambiae are largely regulated by the Toll and Imd (immune deficiency) pathways via the NF-kappaB transcription factors Rel1 and Rel2, which are controlled by the negative regulators Cactus and Caspar, respectively. Rel1- and Rel2-dependent transcription in A. gambiae has been shown to be particularly critical to the mosquito's ability to manage infection with the rodent malaria parasite Plasmodium berghei. Using RNA interference to deplete the negative regulators of these pathways, we found that Rel2 controls resistance of A. gambiae to the human malaria parasite Plasmodium falciparum, whereas Rel 1 activation reduced infection levels. The universal relevance of this defense system across Anopheles species was established by showing that caspar silencing also prevents the development of P. falciparum in the major malaria vectors of Asia and South America, A. stephensi and A. albimanus, respectively. Parallel studies suggest that while Imd pathway activation is most effective against P. falciparum, the Toll pathway is most efficient against P. berghei, highlighting a significant discrepancy between the human pathogen and its rodent model. High throughput gene expression analyses identified a plethora of genes regulated by the activation of the two Rel factors and revealed that the Toll pathway played a more diverse role in mosquito biology than the Imd pathway, which was more immunity-specific. Further analyses of key anti-Plasmodium factors suggest they may be responsible for the Imd pathway-mediated resistance phenotype. Additionally, we found that the fitness cost caused by Rel2 activation through caspar gene silencing was undetectable in sugar-fed, blood-fed, and P. falciparum-infected female A. gambiae, while activation of the Toll pathway's Rel1 had a major impact. This study describes for the first time a single gene that influences an immune mechanism that is able to abort development of P. falciparum

  10. Treatment of Plasmodium falciparum malaria with mefloquine alone or in combination with i.v. quinine at the Department of Communicable and Tropical Diseases, Rigshospitalet, Copenhagen 1982-1988

    DEFF Research Database (Denmark)

    Magnussen, P; Bygbjerg, Ib Christian

    1990-01-01

    At the Department of Communicable and Tropical Diseases, Rigshospitalet, Denmark, mefloquine has been used since 1982 for the treatment of patients with suspected or verified chloroquine and sulfadoxine-pyrimethamine resistant P. falciparum malaria. Eighty-one patients treated with mefloquine...... and effective for the treatment of P. falciparum malaria and is recommended for treatment of worldwide acquired P. falciparum malaria, although patients should be monitored closely to disclose resistance....

  11. A molecular mechanism of artemisinin resistance in Plasmodium falciparum malaria.

    Science.gov (United States)

    Mbengue, Alassane; Bhattacharjee, Souvik; Pandharkar, Trupti; Liu, Haining; Estiu, Guillermina; Stahelin, Robert V; Rizk, Shahir S; Njimoh, Dieudonne L; Ryan, Yana; Chotivanich, Kesinee; Nguon, Chea; Ghorbal, Mehdi; Lopez-Rubio, Jose-Juan; Pfrender, Michael; Emrich, Scott; Mohandas, Narla; Dondorp, Arjen M; Wiest, Olaf; Haldar, Kasturi

    2015-04-30

    Artemisinins are the cornerstone of anti-malarial drugs. Emergence and spread of resistance to them raises risk of wiping out recent gains achieved in reducing worldwide malaria burden and threatens future malaria control and elimination on a global level. Genome-wide association studies (GWAS) have revealed parasite genetic loci associated with artemisinin resistance. However, there is no consensus on biochemical targets of artemisinin. Whether and how these targets interact with genes identified by GWAS, remains unknown. Here we provide biochemical and cellular evidence that artemisinins are potent inhibitors of Plasmodium falciparum phosphatidylinositol-3-kinase (PfPI3K), revealing an unexpected mechanism of action. In resistant clinical strains, increased PfPI3K was associated with the C580Y mutation in P. falciparum Kelch13 (PfKelch13), a primary marker of artemisinin resistance. Polyubiquitination of PfPI3K and its binding to PfKelch13 were reduced by the PfKelch13 mutation, which limited proteolysis of PfPI3K and thus increased levels of the kinase, as well as its lipid product phosphatidylinositol-3-phosphate (PI3P). We find PI3P levels to be predictive of artemisinin resistance in both clinical and engineered laboratory parasites as well as across non-isogenic strains. Elevated PI3P induced artemisinin resistance in absence of PfKelch13 mutations, but remained responsive to regulation by PfKelch13. Evidence is presented for PI3P-dependent signalling in which transgenic expression of an additional kinase confers resistance. Together these data present PI3P as the key mediator of artemisinin resistance and the sole PfPI3K as an important target for malaria elimination.

  12. Amplification of a Gene Related to Mammalian mdr Genes in Drug-Resistant Plasmodium falciparum

    Science.gov (United States)

    Wilson, Craig M.; Serrano, Adelfa E.; Wasley, Annemarie; Bogenschutz, Michael P.; Shankar, Anuraj H.; Wirth, Dyann F.

    1989-06-01

    The malaria parasite Plasmodium falciparum contains at least two genes related to the mammalian multiple drug resistance genes, and at least one of the P. falciparum genes is expressed at a higher level and is present in higher copy number in a strain that is resistant to multiple drugs than in a strain that is sensitive to the drugs.

  13. Molecular evidence of increased resistance to anti-folate drugs in Plasmodium falciparum in North-East India: a signal for potential failure of artemisinin plus sulphadoxine-pyrimethamine combination therapy.

    Science.gov (United States)

    Mohapatra, Pradyumna Kishore; Sarma, Devojit Kumar; Prakash, Anil; Bora, Khukumoni; Ahmed, Md Atique; Sarma, Bibhas; Goswami, Basanta Kumar; Bhattacharyya, Dibya Ranjan; Mahanta, Jagadish

    2014-01-01

    North-east India, being a corridor to South-east Asia, is believed to play an important role in transmitting drug resistant Plasmodium falciparum malaria to India and South Asia. North-east India was the first place in India to record the emergence of drug resistance to chloroquine as well as sulphadoxine/pyrimethamine. Presently chloroquine resistance is widespread all over the North-east India and resistance to other anti-malarials is increasing. In this study both in vivo therapeutic efficacy and molecular assays were used to screen the spectrum of drug resistance to chloroquine and sulphadoxine/pyrimethamine in the circulating P. falciparum strains. A total of 220 P. falciparum positives subjects were enrolled in the study for therapeutic assessment of chloroquine and sulphadoxine/pyrimethamine and assessment of point mutations conferring resistances to these drugs were carried out by genotyping the isolates following standard methods. Overall clinical failures in sulphadoxine/pyrimethamine and chloroquine were found 12.6 and 69.5% respectively, while overall treatment failures recorded were 13.7 and 81.5% in the two arms. Nearly all (99.0%) the isolates had mutant pfcrt genotype (76 T), while 68% had mutant pfmdr-1 genotype (86 Y). Mutation in dhps 437 codon was the most prevalent one while dhfr codon 108 showed 100% mutation. A total of 23 unique haplotypes at the dhps locus and 7 at dhfr locus were found while dhps-dhfr combined loci revealed 49 unique haplotypes. Prevalence of double, triple and quadruple mutations were common while 1 haplotype was found with all five mutated codons (F/AGEGS/T) at dhps locus. Detection of quadruple mutants (51 I/59 R/108 N/164 L) in the present study, earlier recorded from Car Nicobar Island, India only, indicates the presence of high levels of resistance to sulphadoxine/pyrimethamine in north-east India. Associations between resistant haplotypes and the clinical outcomes and emerging resistance in sulphadoxine

  14. A molecular marker of artemisinin-resistant Plasmodium falciparum malaria

    Science.gov (United States)

    Ariey, Frédéric; Witkowski, Benoit; Amaratunga, Chanaki; Beghain, Johann; Langlois, Anne-Claire; Khim, Nimol; Kim, Saorin; Duru, Valentine; Bouchier, Christiane; Ma, Laurence; Lim, Pharath; Leang, Rithea; Duong, Socheat; Sreng, Sokunthea; Suon, Seila; Chuor, Char Meng; Bout, Denis Mey; Ménard, Sandie; Rogers, William O.; Genton, Blaise; Fandeur, Thierry; Miotto, Olivo; Ringwald, Pascal; Le Bras, Jacques; Berry, Antoine; Barale, Jean-Christophe; Fairhurst, Rick M.; Benoit-Vical, Françoise; Mercereau-Puijalon, Odile; Ménard, Didier

    2014-01-01

    Plasmodium falciparum resistance to artemisinin derivatives in southeast Asia threatens malaria control and elimination activities worldwide. To monitor the spread of artemisinin resistance, a molecular marker is urgently needed. Here, using whole-genome sequencing of an artemisinin-resistant parasite line from Africa and clinical parasite isolates from Cambodia, we associate mutations in the PF3D7_1343700 kelch propeller domain (`K13-propeller') with artemisinin resistance in vitro and in vivo. Mutant K13-propeller alleles cluster in Cambodian provinces where resistance is prevalent, and the increasing frequency of a dominant mutant K13-propeller allele correlates with the recent spread of resistance in western Cambodia. Strong correlations between the presence of a mutant allele, in vitro parasite survival rates and in vivo parasite clearance rates indicate that K13-propeller mutations are important determinants of artemisinin resistance. K13-propeller polymorphism constitutes a useful molecular marker for large-scale surveillance efforts to contain artemisinin resistance in the Greater Mekong Subregion and prevent its global spread.

  15. Analysis of chloroquine resistance transporter (CRT) isoforms and orthologues in S. cerevisiae yeast.

    Science.gov (United States)

    Baro, Nicholas K; Pooput, Chaya; Roepe, Paul D

    2011-08-01

    Previous work from our laboratory optimized MeOH-inducible expression of the P. falciparum malarial parasite transporter PfCRT in P. pastoris yeast. These strains are useful for many experiments but do not allow for inducible protein expression under ambient growth conditions. We have therefore optimized galactose-inducible expression of PfCRT in S. cerevisiae yeast. We find that expression of PfCRT confers CQ hypersensitivity to growing yeast and that this is due to plasma membrane localization of the transporter. We use quantitative analyses of growth rates to compare hypersensitivity for yeast expressing various PfCRT isoforms. We also report successful high level inducible expression of the P. vivax orthologue, PvCRT, and compare CQ hypersensitivity for PvCRT vs PfCRT expressing yeast. We test the hypothesis that hypersensitivity is due to increased transport of CQ into yeast expressing the transporters via direct (3)H-CQ transport experiments and analyze the effect that membrane potential has on transport. The data suggest important new tools for rapid functional screening of PfCRT and PvCRT isoforms and provide further evidence for a model wherein membrane potential promotes charged CQ transport by PfCRT. Data also support our previous conclusion that wild type PfCRT is capable of CQ transport and provide a basis for understanding the lack of correspondence between PvCRT mutations and resistance to CQ in the important malarial parasite P. vivax.

  16. The efficacy of artemether in the treatment of Plasmodium falciparum malaria in Sudan

    DEFF Research Database (Denmark)

    Elhassan, I M; Satti, G H; Ali, A E

    1994-01-01

    The efficacy of artemether (a qinghaosu derivative) administered intramuscularly for the treatment of Plasmodium falciparum malaria was compared to quinine in an open randomized trial including 54 patients in eastern Sudan, where chloroquine resistance is common. The artemether treatment (5 d...

  17. Resistência in vitro de cepas do Plasmodium falciparum isoladas no sul do estado do Pará, em diferentes períodos: emergência de casos de multirresistência

    Directory of Open Access Journals (Sweden)

    A. A. Couto

    1993-03-01

    Full Text Available O presente estudo avalia a resposta de cepas de Plasmodium falciparum às drogas antimaláricas, através de testes in vitro, isoladas em 7 municípios do sul do Estado do Pará. Foram efetuados 69 testes para cloroquina e mefloquina, 62 para amodiaquina e 61 para quinino. Os resultados mostram elevada resistência para cloroquina (71%, relativamente baixa resistência para amodiaquina com (25,8% e para o quinino apenas 8,2%. Mefloquina revela ampla sensibilidade (100%, mas, demonstrando perda da mesma quando comparada em dois períodos distintos. Evidenciou-se também cepas multirresistentes em dois dos municípios estudados.The responses of Plasmodium falciparum to antimalarial drugs were evaluated through the in vitro test using blood sample collected from patients of 7 municipalities of the south of Pará State. Sixty nine microtests for chloroquine and mefloquine, 62 for amodiaquine and 61 for quinine were pet formed. The results showed a high resistance for chloroquine (71%, a relatively low resistance level for amodiaquine (25.8% and little resistance to quinine (8.2%. For mefloquine 100% of sensitivity was found.

  18. Targeting protein translation, RNA splicing, and degradation by morpholino-based conjugates in Plasmodium falciparum.

    Science.gov (United States)

    Garg, Aprajita; Wesolowski, Donna; Alonso, Dulce; Deitsch, Kirk W; Ben Mamoun, Choukri; Altman, Sidney

    2015-09-22

    Identification and genetic validation of new targets from available genome sequences are critical steps toward the development of new potent and selective antimalarials. However, no methods are currently available for large-scale functional analysis of the Plasmodium falciparum genome. Here we present evidence for successful use of morpholino oligomers (MO) to mediate degradation of target mRNAs or to inhibit RNA splicing or translation of several genes of P. falciparum involved in chloroquine transport, apicoplast biogenesis, and phospholipid biosynthesis. Consistent with their role in the parasite life cycle, down-regulation of these essential genes resulted in inhibition of parasite development. We show that a MO conjugate that targets the chloroquine-resistant transporter PfCRT is effective against chloroquine-sensitive and -resistant parasites, causes enlarged digestive vacuoles, and renders chloroquine-resistant strains more sensitive to chloroquine. Similarly, we show that a MO conjugate that targets the PfDXR involved in apicoplast biogenesis inhibits parasite growth and that this defect can be rescued by addition of isopentenyl pyrophosphate. MO-based gene regulation is a viable alternative approach to functional analysis of the P. falciparum genome.

  19. Resistência "in vivo" do Plasmodium falciparum às 4-amino - quinoleínas e à associação sulfadoxina-pirimetamina: I - estudo de Porto Velho, Rondônia, 1983

    Directory of Open Access Journals (Sweden)

    Santiago Reyes

    1985-09-01

    Full Text Available Através da prova de 7 dias foi estudado o grau de resistência do Plasmodium falciparum à cloroquina, amodiaquina e sulfadoxina-pirimetamina em Porto Velho, Estado de Rondônia, Brasil. Não se observaram diferenças significativas nas médias de parasitas nos dias de seguimento e nas proporções de resistência entre os três medicamentos testados, fazendo com que os autores recomendem a manutenção das 4-aminoquinoleínas como drogas a serem usadas atualmente em infecções não graves por P. falciparum na área de Porto Velho.The authors studied the levei of resistance of Plasmodium falciparum malaria to chloroquine, amodiaquine and the combination of sulfadoxine and pyrimethamine in the City of Porto Velho, State Capital of Rondônia, Brazil. Using a seven day observation test they did not find signiftcant differences in the parasite count averages in the follow-up as well as in the proportions of resistance to the three drugs. Based upon theseflndings they recommend the maintenance of the 4-aminoquinolines in treating uncomplicated forms of falciparum malaria in the area of Porto Velho.

  20. Molecular markers associated with resistance to commonly used antimalarial drugs among Plasmodium falciparum isolates from a malaria-endemic area in Taiz governorate-Yemen during the transmission season.

    Science.gov (United States)

    Alareqi, Lina M Q; Mahdy, Mohammed A K; Lau, Yee-Ling; Fong, Mun-Yik; Abdul-Ghani, Rashad; Mahmud, Rohela

    2016-10-01

    Since 2005, artesunate (AS) plus sulfadoxine/pyrimethamine (SP) combination has been adopted as the first-line treatment for uncomplicated malaria in Yemen in response to the high level of Plasmodium falciparum resistance to chloroquine (CQ). Therefore, the aim of the present study was to determine the frequency distribution of molecular markers associated with resistance to CQ and AS plus SP combination among P. falciparum isolates from a malaria-endemic area in Taiz governorate, Yemen. Fifty P. falciparum isolates were collected during a cross-sectional study in Mawza district, Taiz, in the period from October 2013 to April 2014. The isolates were investigated for drug resistance-associated molecular markers in five genes, including P. falciparum CQ resistance transporter (pfcrt) 76T and P. falciparum multidrug resistance 1 (pfmdr1) 86Y as markers of resistance to CQ, mutations in the Kelch 13 (K13) propeller domain for resistance to AS, and P. falciparum dihydrofolate reductase (pfdhfr) and P. falciparum dihydropteroate synthase (pfdhps) genes for resistance to SP. Nested polymerase chain reaction was used to amplify target genes in DNA extracts of the isolates followed by restriction fragment length polymorphism for detecting 76T and 86Y mutations in pfcrt and pfmdr1, respectively, and by DNA sequencing for detecting mutations in K13, pfdhfr and pfdhps. All the investigated isolates from Mawza district were harboring the pfcrt 76T mutant and the pfmdr1 N86 wild-type alleles. The pfdhfr 51I/108N double mutant allele was found in 2.2% (1/45) of the isolates; however, no mutations were detected at codons 436, 437, 540, 581 and 613 of pfdhps. All P. falciparum isolates that were successfully sequenced (n=47) showed the K13 Y493, R539, I543 and C580 wild-type alleles. In conclusion, the pfcrt 76T mutant allele is fixed in the study area about six years after the official withdrawal of CQ, possibly indicating its over-the-counter availability and continued use as a

  1. Fighting drug-resistant Plasmodium falciparum: the challenge of artemisinin resistance.

    Science.gov (United States)

    Wongsrichanalai, C; Sibley, C H

    2013-10-01

    Following a decade-long scale up of malaria control through vector control interventions, the introduction of rapid diagnostic tests and highly efficacious Artemisinin-based Combination Therapy (ACT) along with other measures, global malaria incidence declined significantly. The recent development of artemisinin resistance on the Cambodia-Thailand border, however, is of great concern. This review encompasses the background of artemisinin resistance in Plasmodium falciparum, its situation, especially in the Greater Mekong Sub-region (GMS), and the responses taken to overcome this resistance. The difficulties in defining resistance are presented, particularly the necessity of measuring the clinical response to artemisinins using the slow parasite-clearance phenotype. Efforts to understand the molecular basis of artemisinin resistance and the search for molecular markers are reviewed. The markers, once identified, can be applied as an efficient tool for resistance surveillance. Despite the limitation of current surveillance methods, it is important to continue vigilance for artemisinin resistance. The therapeutic efficacy "in vivo study" network for monitoring antimalarial resistance in the GMS has been strengthened. GMS countries are working together in response to artemisinin resistance and aim to eliminate all P. falciparum parasites. These efforts are crucial since a resurgence of malaria due to drug and/or insecticide resistance, program cuts, lack of political support and donor fatigue could set back malaria control success in the sub-region and threaten malaria control and elimination if resistance spreads to other regions.

  2. In vivo drug resistance of falciparum malaria in mining areas of Venezuela.

    Science.gov (United States)

    Aché, A; Escorihuela, M; Vivas, E; Páez, E; Miranda, L; Matos, A; Pérez, W; Díaz, O; Izarra, E

    2002-09-01

    The Lot Quality Assurance Double-Sampling Plan (LQADSP) technique was used in three areas, Maripa, Kilómetro 88 and Ikabaru, to assess the efficacy of antimalarials used routinely by the Venezuelan Malaria Programme. The use of chloroquine (25 mg/kg), chloroquine (40 mg/kg) and the combination of sulfadoxine (500 mg) and pyrimethamine (25 mg) registered treatment failures above the threshold level of 25% in Maripa and Kilómertro 88. In Ikabaru the use of chloroquine (40 mg/kg) did not surpass that quality level and could possibly be less than 10%. Quinine (30 mg/kg) was totally effective in curing patients in all three areas. The use of this technique seems adequate for rapid field evaluations and in this case for providing appropriate information to assist this health programme. However, whilst being an ideal technique for surveying areas in which considerable variation may exist among lots and particularly for Plasmodium falciparum infections in these areas, repeated surveys should be carried out in the same areas over time to monitor changes in the susceptibility of this parasite to first-, second- and third-line drugs. In that way, national drug policies can be modified adequately.

  3. [Is Plasmodium falciparum, the parasite responsible for tropical malaria, resistant to fansidar?].

    Science.gov (United States)

    Holzer, B; Keller, H; Frossard, E; Stürchler, D

    1980-03-01

    A world-wide increase of malaria infections is observed. Malaria is imported into Switzerland mainly by tourists and recently by refugees from South East Asia. The strains of P. falciparum resistant to treatment are of increasing importance. A patient with P. falciparum infection from Cambodia is reported, who suffered from three episodes of malaria recrudescence within ten weeks, in spite of adequate therapy with quinine and Fansidar. The definition, the significance and the geographical distribution of resistances and the possible cause for a P. falciparum recrudescence are discussed. For the treatment of repeating recrudescence quinine and Fansidar are recommended, followed by a suppressive Fansidar prophylaxy for 4--8 weeks.

  4. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine in Guinea-Bissau between 2003 and 2012.

    Science.gov (United States)

    Jovel, Irina Tatiana; Kofoed, Poul-Erik; Rombo, Lars; Rodrigues, Amabelia; Ursing, Johan

    2015-02-01

    In 2008, artemether-lumefantrine was introduced in Guinea-Bissau, West Africa, but quinine has also been commonly prescribed for the treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine have been described. P. falciparum chloroquine resistance transporter (pfcrt) K76T, pfmdr1 gene copy numbers, pfmdr1 polymorphisms N86Y and Y184F, and pfmdr1 sequences 1034 to 1246 were determined using PCR-based methods. Blood samples came from virtually all (n=1,806) childrenquinine and despite a fitness cost linked to pfcrt 76T. (The studies reported here were registered at ClinicalTrials.gov under registration no. NCT00137514 [PSB-2001-chl-amo], NCT00137566 [PSB-2004-paracetamol], NCT00426439 [PSB-2006-coartem], NCT01157689 [AL-eff 2010], and NCT01704508 [Eurartesim 2012].).

  5. A modified Plasmodium falciparum growth inhibition assay (GIA) to assess activity of plasma from malaria endemic areas.

    Science.gov (United States)

    Mlambo, Godfree; Kumar, Nirbhay

    2007-02-01

    Plasma samples from patients undergoing treatment in malaria endemic countries often contain anti-malaria drugs, that may overstate effects of specific antibodies in growth inhibition assays (GIA). We describe a modified assay that uses drug resistant P. falciparum parasites (W2) that circumvents the requirement for dialyzing samples that may likely contain drugs such as chloroquine and sulfadoxine/pyrimethamine (SP).

  6. Simplified Reversed Chloroquines To Overcome Malaria Resistance to Quinoline-Based Drugs.

    Science.gov (United States)

    Gunsaru, Bornface; Burgess, Steven J; Morrill, Westin; Kelly, Jane X; Shomloo, Shawheen; Smilkstein, Martin J; Liebman, Katherine; Peyton, David H

    2017-05-01

    Building on our earlier work of attaching a chemosensitizer (reversal agent) to a known drug pharmacophore, we have now expanded the structure-activity relationship study to include simplified versions of the chemosensitizer. The change from two aromatic rings in this head group to a single ring does not appear to detrimentally affect the antimalarial activity of the compounds. Data from in vitro heme binding and β-hematin inhibition assays suggest that the single aromatic RCQ compounds retain activities against Plasmodium falciparum similar to those of CQ, although other mechanisms of action may be relevant to their activities. Copyright © 2017 Gunsaru et al.

  7. Effects of Low Dose of Ketotifen and Chloroquine Combination on the Ultrastructure of Chloroquine Resistant Strain of Plasmodium Yoelii%低剂量氯喹和酮替酚联合作用下疟原虫的超微结构研究

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    46 inbred NIH mice were infected by chloroquine resistant strain of Plasmodium yoelii. The ultrastructure changes were observed under the administration of ketotifen(10mg· kg- 1· d- 1 ) and chloroquine( 10mg. kg-1 · d- 1 ) combination and one after another respectively. The effect of taking ketotifen and chloroquine combination showed that parasites died rapidly with a few of intermittent membranes and vacuoles. The effect of taking two kinds of drugs one after another showed that there were exceedingly rich membranes, concentric arrangement structures similar to rough endo-reticulum and conspiciously blocking of the formation of food vacuoles.

  8. A cross-sectional survey of Plasmodium falciparum pfcrt mutant haplotypes in the Democratic Republic of Congo.

    Science.gov (United States)

    Antonia, Alejandro L; Taylor, Steve M; Janko, Mark; Emch, Michael; Tshefu, Antoinette K; Meshnick, Steven R

    2014-06-01

    In the Democratic Republic of the Congo (DRC), artesunate-amodiaquine is first-line therapy for falciparum malaria; little is known about the prevalence of molecular markers of parasite drug resistance. Across the DRC, we genotyped 166 parasites in Plasmodium falciparum chloroquine resistance transporter (pfcrt) using polymerase chain reaction (PCR) and sequencing. Of these parasites, 73 (44%) parasites were pure wild-type CVMNK, 55 (31%) parasites were chloroquine-resistant CVIET: , 35 (21.1%) parasites were mixed CVMNK and CVIET: , and 3 parasites were other genotypes. Ninety-two infections (55.4%) harbored the pfcrt K76T: substitution that is highly correlated with chloroquine failure. The amodiaquine-resistant S: VMNT: haplotype was absent. Geographically, pfcrt haplotypes were not clearly clustered. Chloroquine accounted for 19.4% of antimalarial use, and amodiaquine accounted for 15.3% of antimalarial use; there were no associations between drug use and mutant haplotype prevalence. In the DRC, our molecular survey indicates that resistance to chloroquine is substantial but that resistance to amodiaquine is absent. These contrasting findings highlight the need for molecular surveillance of drug resistance to inform malaria control policies.

  9. Biological and haematological safety profile of oral amodiaquine and chloroquine in healthy volunteers with or without Plasmodium falciparum infection in northeast Tanzania

    DEFF Research Database (Denmark)

    Massaga, J J; Lusingu, J P; Makunde, R

    2008-01-01

    morbidity in infants. Volunteers were stratified according to parasitaemia status and randomly assigned 20 participants each arm to three days treatment with either AQ or chloroquine (CQ). The level of difference of selected haematological and hepatological values pre-and post-trial were marginal and within......-immune healthy adult male volunteers with and without malaria parasites. The objective was to collect data on biological and haematological safety, tolerability, and parasitological efficacy to serve as baseline in the evaluation of the effectiveness of AQ preventive intermittent treatment against malaria......-treated volunteers. The findings indicate that there was no agranulocytosis or hepatic toxicity suggesting that AQ may pose no public health risk in its wide therapeutic dosage uses. Larger studies are needed to exclude rare adverse effects....

  10. Drug resistance. K13-propeller mutations confer artemisinin resistance in Plasmodium falciparum clinical isolates.

    Science.gov (United States)

    Straimer, Judith; Gnädig, Nina F; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D; Urnov, Fyodor D; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M; Ménard, Didier; Fidock, David A

    2015-01-23

    The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites.

  11. [Progress in researches on molecular markers of Plasmodium falciparum drug resistance].

    Science.gov (United States)

    Zhang, Mei-hua; Lu, Feng; Cao, Jun; Gao, Qi

    2015-06-01

    Effective chemotherapy is the mainstay of malaria control. However, it is undergoing the serious threat by resis- tance of falciparum malaria to antimalarial drugs. In recent years, with the development of molecular biology technology, molec- ular markers have been widely used to monitor antimalarial drug resistance. This paper reviews the researches on the common molecular markers related to Plasmodiumfalciparum drug resistance.

  12. Malaria Epidemic and Drug Resistance, Djibouti

    OpenAIRE

    Rogier, Christophe; Pradines, Bruno; Bogreau, H.; Koeck, Jean-Louis; Kamil, Mohamed-Ali; Mercereau-Puijalon, Odile

    2005-01-01

    Analysis of Plasmodium falciparum isolates collected before, during, and after a 1999 malaria epidemic in Djibouti shows that, despite a high prevalence of resistance to chloroquine, the epidemic cannot be attributed to a sudden increase in drug resistance of local parasite populations.

  13. Chloroquine-induced pruritus

    Directory of Open Access Journals (Sweden)

    Aghahowa S

    2010-01-01

    Full Text Available Chloroquine-induced pruritus remains one of the most common side-effects in the use of chloroquine in the prophylaxis and treatment of uncomplicated malaria before the advent of artemisinin-based combination therapies. It has been reported to vary from a tolerable to intolerable intensity among susceptible individuals resulting in disruption of treatment and development of resistance to the drug thus leading to therapeutic failures as reported. This scourge is quite challenging due to the complex physiologic mechanism that has not been fully elucidated. Factors observed to be responsible in the induction of pruritus such as age, race, heredity, density of parasitaemia; impurities in formulations, plasmodial specie, dosage form and metabolites have been discussed in this review. Efforts to ameliorate this burden have necessitated the use of drugs of diverse pharmacological classes such as antihistamines, corticosteroids and multivitamins either alone or as a combination. This review is to look into the use of chloroquine retrospectively, and consider its re-introduction due to its safety. Efficacy can be attained if the pruritic effect is resolved.

  14. Antiplasmodial activity of certain medicinal plants against chloroquine resistant Plasmodium berghei infected white albino BALB/c mice.

    Science.gov (United States)

    Rajendran, C; Begam, M; Kumar, Dharmendra; Baruah, Indra; Gogoi, H K; Srivastava, R B; Veer, Vijay

    2014-06-01

    In the present study of antimalarial efficacy, aqueous extracts of leaves and unripe fruits of Psidium guajava, leaves of Ocimum sanctum and leaves of Murraya koenigii are evaluated against Plasmodium berghei (chloroquine resistant NK65 strain) infected white albino BALB/c mice. A 7 days oral administration was adopted with different dosage viz., 350 mg, 750 mg and 1,000 mg/kg body weight as treatment schedule along with parasite (Group I) and drug control with Chloroquine, 50 mg/kg body weight (Group II). All the parts were extracted based on the decoction method, which is commonly seen among the villagers/tribes as their usual method of preparation of decoction for most of the ailments. The antimalarial activities were evaluated from the giemsa stained blood smears collected from different treated groups of mice used in this experiment. The antiplasmodial effect that is percent parasitaemia and percent suppression (values in parenthesis) showed by the treated groups of mice at 350 mg/kg b. wt. by the aqueous extracts of P. guajava leaves (Group III) was 19.8 ± 1.22 (73.7 %), P. guajava unripe fruits (Group IV) was 52.7 ± 2.19 (30.0 %), leaves of O. sanctum (Group V) was 64.0 ± 0.73 (15.1 %) and leaves of M. koenigii (Group VI) was 28.9 ± 0.81 (61.6 %) whereas at 750 mg/kg b. wt., it all showed 10.3 ± 0.7 (80.2 %), 26.3 ± 0.52 (65.1 %), 42.0 ± 0.47 (44.2 %) and 14.9 ± 0.46 (71.5 %) whereas at 1,000 mg/kg b. wt. dose, it all showed 9.2 ± 0.39 (85.8 %), 25.6 ± 0.40 (62.0 %), 41.8 ± 0.29 (35.5 %) and 14.0 ± 0.42 (76.9 %) respectively.

  15. Sensitization of multidrug-resistant malignant cells by liposomes co-encapsulating doxorubicin and chloroquine through autophagic inhibition.

    Science.gov (United States)

    Gao, Menghua; Xu, Yuzhen; Qiu, Liyan

    2017-06-01

    Adenosine triphosphate (ATP)-binding cassette (ABC) transporters play a key role in the development of multidrug resistance (MDR) in cancer cells. P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) are important proteins in this superfamily which are widely expressed on the membranes of multidrug resistance (MDR) cancer cells. Besides, upregulation of cellular autophagic responses is considered a contributing factor for MDR in cancer cells. We designed a liposome system co-encapsulating a chemotherapeutic drug (doxorubicin hydrochloride, DOX) and a typical autophagy inhibitior (chloroquine phosphate, CQ) at a weight ratio of 1:2 and investigated its drug resistance reversal mechanism. MTT assay showed that the IC50 of DOX/CQ co-encapsulated liposome in DOX-resistant human breast cancer cells (MCF7/ADR) was 4.7 ± 0.2 μM, 5.7-fold less than that of free DOX (26.9 ± 1.9  μM), whereas it was 19.5-fold in doxorubicin-resistant human acute myelocytic leukemia cancer cells (HL60/ADR) (DOX/CQ co-encapsulated liposome 1.2 ± 0.1 μM, free DOX 23.4 ± 2.8 μM). The cellular uptake of DOX increased upon addition of free CQ, indicating that CQ may interact with P-gp and MRP1; however, the expressions of P-gp and MRP1 remained unchanged. In contrast, the expression of the autophagy-related protein LC3-II increased remarkably. Therefore, the mechanism of MDR reversal may be closely related to autophagic inhibition. Evaluation of anti-tumor activity was achieved in an MCF-7/ADR multicellular tumor spheroid model and transgenic zebrafish model. DOX/CQ co-encapsulated liposome exerted a better anti-tumor effect in both models than that of liposomal DOX or DOX alone. These findings suggest that encapsulating CQ with DOX in liposomes significantly improves the sensitivity of DOX in DOX-resistant cancer cells.

  16. Resistência in vivo do Plasmodium falciparum às 4-aminoquinoleínas e à associação sulfadoxina-pirimetamina: II - estudo de imperatriz, Maranhão, 1983-1984

    Directory of Open Access Journals (Sweden)

    Afonso Dinis Costa Passos

    1987-06-01

    Full Text Available Através da prova de 7 dias foram estudadas as respostas terapêuticas de 96 pacientes com malária falciparum não grave atendidos pela SUCAM em Imperatriz, Maranhão. Esses pacientes foram distribuídos aleatoriamente em três grupos de estudo, tendo o primeiro recebido cloroquina, o segundo amodiaquina e o terceiro a associação sulfadoxina-pirimetamina. Mesmo sem evidenciar significância estatística ao nível de 5% de probabilidade, as diferenças observadas nas respostas as 3 drogas apontam para a associação sulfadoxina-pirimetamina como a que produziu melhores resultados terapêuticos. Recomenda-se a monitorização contínua da resistência nas áreas malarígenas criticas.The in vivo drug response of 96 patients with falciparum malaria was studied to chloroquine, amodiaquine or the combination of sulfadoxine and pyrimethamine, in Imperatriz, State of Maranhão, Brasil. The patients were randomly assigned to the three study groups and followed for seven days. Better results were obtained with the association sulfadoxine-pyrimethamine, although no statistically significant differences were observed. The need of continous surveillance of P. falciparum drug resistance in areas of high levels of transmission is emphasised.

  17. Plasmodium falciparum kelch 13: a potential molecular marker for tackling artemisinin-resistant malaria parasites.

    Science.gov (United States)

    Mita, Toshihiro; Tachibana, Shin-Ichiro; Hashimoto, Muneaki; Hirai, Makoto

    2016-01-01

    Although artemisinin combination therapies have been deployed as a first-line treatment for uncomplicated malaria in almost all endemic countries, artemisinin-resistant parasites have emerged and have gradually spread across the Greater Mekong subregions. There is growing concern that the resistant parasites may migrate to or emerge indigenously in sub-Saharan Africa, which might provoke a global increase in malaria-associated morbidity and mortality. Therefore, development of molecular markers that enable identification of artemisinin resistance with high sensitivity is urgently required to combat this issue. In 2014, a potential artemisinin-resistance responsible gene, Plasmodium falciparum kelch13, was discovered. Here, we review the genetic features of P. falciparum kelch13 and discuss its related resistant mechanisms and potential as a molecular marker.

  18. [Drug sensitivity of falciparum malaria imported into France in 1995].

    Science.gov (United States)

    Longuet, C; Ramiliarisoa, O; Thor, R; Bouchaud, O; Basco, L K; Doury, J C; Le Bras, J

    1997-01-01

    The National Reference Centre for Malaria Chemosusceptibility (CNRCP) and the Tropical Medicine Institute of the Health Department for the Army (IMTSSA) monitor the chemosusceptibility of falciparum malaria introduced in France. In 1995, 353 isolates of P. falciparum are sent to the CNRCP and IMTSSA from malaria cases presenting in 49 civil and military hospitals distributed all over the french country. The patients are mostly Africans living in France and have mainly stayed in West Africa. Half of them did not take any chemoprophylaxis and a quarter took only chloroquine more or less regularly. The curative treatment, when known, is halofantrine alone in 52% of cases and quinine alone in 28% of cases. Three halofantrine failures are reported including 1 incorrect regimen and 4 quinine failures including 3 incorrect regimens. In 1995, in vitro resistance of P. falciparum isolates imported in France to the chemoprophylactic and therapeutic drugs is not worsening. In vitro quinine resistance is rare (1/108), mefloquine resistance (2/20) and halofantrine resistance (12/211) are limited, cycloguanil resistance (42/185) is stable and chloroquine resistance (84/230) is even decreasing (less selective pressure in Africa?).

  19. The implication of dihydrofolate reductase and dihydropteroate synthetase gene mutations in modification of Plasmodium falciparum characteristics

    DEFF Research Database (Denmark)

    A-Elbasit, Ishraga E; Alifrangis, Michael; Khalil, Insaf F

    2007-01-01

    the effects of dhfr/dhps mutations on parasite characteristics other than SP resistance. METHOD: Parasite infections obtained from 153 Sudanese patients with uncomplicated falciparum malaria treated with SP or SP + chloroquine, were successfully genotyped at nine codons in the dhfr/dhps genes by PCR......BACKGROUND: The Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) are enzymes of central importance in parasite metabolism. The dhfr and dhps gene mutations are known to be associated with sulphadoxine/pyrimethamine (SP) resistance. OBJECTIVE: To investigate...

  20. Independent origin of Plasmodium falciparum antifolate super-resistance, Uganda, Tanzania, and Ethiopia

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Nag, Sidsel; Schousboe, Mette L

    2014-01-01

    Super-resistant Plasmodium falciparum threatens the effectiveness of sulfadoxine-pyrimethamine in intermittent preventive treatment for malaria during pregnancy. It is characterized by the A581G Pfdhps mutation on a background of the double-mutant Pfdhps and the triple-mutant Pfdhfr. Using sample...

  1. Engineered resistance to Plasmodium falciparum development in transgenic Anopheles stephensi.

    Directory of Open Access Journals (Sweden)

    Alison T Isaacs

    2011-04-01

    Full Text Available Transposon-mediated transformation was used to produce Anopheles stephensi that express single-chain antibodies (scFvs designed to target the human malaria parasite, Plasmodium falciparum. The scFvs, m1C3, m4B7, and m2A10, are derived from mouse monoclonal antibodies that inhibit either ookinete invasion of the midgut or sporozoite invasion of salivary glands. The scFvs that target the parasite surface, m4B7 and m2A10, were fused to an Anopheles gambiae antimicrobial peptide, Cecropin A. Previously-characterized Anopheles cis-acting DNA regulatory elements were included in the transgenes to coordinate scFv production with parasite development. Gene amplification and immunoblot analyses showed promoter-specific increases in transgene expression in blood-fed females. Transgenic mosquito lines expressing each of the scFv genes had significantly lower infection levels than controls when challenged with P. falciparum.

  2. Increased pfmdr1 gene copy number and the decline in pfcrt and pfmdr1 resistance alleles in Ghanaian Plasmodium falciparum isolates after the change of anti-malarial drug treatment policy.

    Science.gov (United States)

    Duah, Nancy O; Matrevi, Sena A; de Souza, Dziedzom K; Binnah, Daniel D; Tamakloe, Mary M; Opoku, Vera S; Onwona, Christiana O; Narh, Charles A; Quashie, Neils B; Abuaku, Benjamin; Duplessis, Christopher; Kronmann, Karl C; Koram, Kwadwo A

    2013-10-30

    With the introduction of artemisinin-based combination therapy (ACT) in 2005, monitoring of anti-malarial drug efficacy, which includes the use of molecular tools to detect known genetic markers of parasite resistance, is important for first-hand information on the changes in parasite susceptibility to drugs in Ghana. This study investigated the Plasmodium falciparum multidrug resistance gene (pfmdr1) copy number, mutations and the chloroquine resistance transporter gene (pfcrt) mutations in Ghanaian isolates collected in seven years to detect the trends in prevalence of mutations. Archived filter paper blood blots collected from children aged below five years with uncomplicated malaria in 2003-2010 at sentinel sites were used. Using quantitative real-time polymerase chain reaction (qRT-PCR), 756 samples were assessed for pfmdr1 gene copy number. PCR and restriction fragment length polymorphism (RFLP) were used to detect alleles of pfmdr1 86 in 1,102 samples, pfmdr1 184, 1034, 1042 and 1246 in 832 samples and pfcrt 76 in 1,063 samples. Merozoite surface protein 2 (msp2) genotyping was done to select monoclonal infections for copy number analysis. The percentage of isolates with increased pfmdr1 copy number were 4, 27, 9, and 18% for 2003-04, 2005-06, 2007-08 and 2010, respectively. Significant increasing trends for prevalence of pfmdr1 N86 (×(2) = 96.31, p resistance has been reported. The decreasing trend in the prevalence of chloroquine resistance markers after change of treatment policy presents the possibility for future introduction of chloroquine as prophylaxis for malaria risk groups such as children and pregnant women in Ghana.

  3. Carriage of chloroquine-resistant parasites and delay of effective treatment increase the risk of severe malaria in Gambian children.

    NARCIS (Netherlands)

    Meerman, L.; Ord, R.; Bousema, T.; Niekerk, M. van; Osman, E.; Hallett, R.; Pinder, M.; Walraven, G.E.; Sutherland, C.J.

    2005-01-01

    Two hundred thirty-four Gambian children with severe falciparum malaria who were admitted to the pediatric ward of a rural district hospital each were matched for age with a same-sex control subject presenting as an outpatient with uncomplicated falciparum malaria. Severe malarial anemia (SMA) was t

  4. Susceptibility of Colombian Plasmodium falciparum isolates to 4-aminoquinolines and the definition of amodiaquine resistance in vitro

    Directory of Open Access Journals (Sweden)

    Diego F Echeverry

    2006-05-01

    Full Text Available There are wide variations in the threshold used to define in vitro resistance of Plasmodium falciparum to amodiaquine (AQ, probably due to differences in methodology and interpretation. In vitro susceptibility data of Colombian P. falciparum strains to AQ and N-desethylamodiaquine is used to illustrate the need to standardized methodologies and compare inhibitory concentrations, instead of resistant/susceptible phenotypes, when studying the mechanisms of resistance to AQ and monitoring drug susceptibility trends in the field.

  5. Comparative assessment on the prevalence of mutations in the Plasmodium falciparum drug-resistant genes in two different ecotypes of Odisha state, India.

    Science.gov (United States)

    Kar, Narayani Prasad; Chauhan, Kshipra; Nanda, Nutan; Kumar, Ashwani; Carlton, Jane M; Das, Aparup

    2016-07-01

    Considering malaria as a local and focal disease, epidemiological understanding of different ecotypes of malaria can help in devising novel control measures. One of the major hurdles in malaria control lies on the evolution and dispersal of the drug-resistant malaria parasite, Plasmodium falciparum. We herewith present data on genetic variation at the Single Nucleotide Polymorphism (SNP) level in four different genes of P. falciparum (Pfcrt, Pfmdr1, Pfdhfr, and Pfdhps) that confer resistance to different antimalarials in two different eco-epidemiological settings, i.e. Hilly-Forest (HF) and Riverine-Plain (RP), in a high malaria endemic district of Odisha state, India. Greater frequency of antimalarial resistance conferring SNPs and haplotypes was observed in all four genes in P. falciparum, and Pfdhps was the most variable gene among the four. No significant genetic differentiation could be observed in isolates from HF and RP ecotypes. Twelve novel, hitherto unreported nucleotide mutations could be observed in the Pfmdr1 and Pfdhps genes. While the Pfdhps gene presented highest haplotype diversity, the Pfcrt gene displayed the highest nucleotide diversity. When the data on all the four genes were complied, the isolates from HF ecotype were found to harbour higher average nucleotide diversity than those coming from RP ecotype. High and positive Tajima's D values were obtained for the Pfcrt and Pfdhfr genes in isolates from both the HF and RP ecotypes, with statistically significant deviation from neutrality in the RP ecotype. Different patterns of Linkage Disequilibrium (LD) among SNPs located in different drug-resistant genes were found in the isolates collected from HF and RP ecotypes. Whereas in the HF ecotype, SNPs in the Pfmdr1 and Pfdhfr were significantly associated, in the RP ecotype, SNPs located in Pfcrt were associated with Pfmdr1, Pfdhfr and Pfdhps. These findings provide a baseline understanding on how different micro eco-epidemiological settings

  6. Mutations in the Plasmodium falciparum Cyclic Amine Resistance Locus (PfCARL Confer Multidrug Resistance

    Directory of Open Access Journals (Sweden)

    Gregory LaMonte

    2016-07-01

    Full Text Available Mutations in the Plasmodium falciparum cyclic amine resistance locus (PfCARL are associated with parasite resistance to the imidazolopiperazines, a potent class of novel antimalarial compounds that display both prophylactic and transmission-blocking activity, in addition to activity against blood-stage parasites. Here, we show that pfcarl encodes a protein, with a predicted molecular weight of 153 kDa, that localizes to the cis-Golgi apparatus of the parasite in both asexual and sexual blood stages. Utilizing clustered regularly interspaced short palindromic repeat (CRISPR-mediated gene introduction of 5 variants (L830V, S1076N/I, V1103L, and I1139K, we demonstrate that mutations in pfcarl are sufficient to generate resistance against the imidazolopiperazines in both asexual and sexual blood-stage parasites. We further determined that the mutant PfCARL protein confers resistance to several structurally unrelated compounds. These data suggest that PfCARL modulates the levels of small-molecule inhibitors that affect Golgi-related processes, such as protein sorting or membrane trafficking, and is therefore an important mechanism of resistance in malaria parasites.

  7. Chloroquine Phosphate Oral

    Science.gov (United States)

    Chloroquine phosphate is in a class of drugs called antimalarials and amebicides. It is used to prevent and treat ... Chloroquine phosphate comes as a tablet to take by mouth. For prevention of malaria in adults, one dose is ...

  8. Tracing the origins and signatures of selection of antifolate resistance in island populations of Plasmodium falciparum

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    Pinto João

    2010-06-01

    Full Text Available Abstract Background Resistance of the malaria parasite Plasmodium falciparum to sulfadoxine-pyrimethamine (SP has evolved worldwide. In the archipelago of São Tomé and Principe (STP, West Africa, although SP resistance is highly prevalent the drug is still in use in particular circumstances. To address the evolutionary origins of SP resistance in these islands, we genotyped point mutations at P. falciparum dhfr and dhps genes and analysed microsatellites flanking those genes. Methods Blood samples were collected in July and December 2004 in three localities of São Tomé Island and one in Principe Island. Species-specific nested-PCR was used to identify P. falciparum infected samples. Subsequently, SNPs at the dhfr and dhps genes were identified through PCR-RFLP. Isolates were also analysed for three microsatellite loci flanking the dhfr gene, three loci flanking dhps and four loci located at putative neutral genomic regions. Results An increase of resistance-associated mutations at dhfr and dhps was observed, in particular for the dhfr/dhps quintuple mutant, associated with clinical SP failure. Analysis of flanking microsatellites suggests multiple independent introductions for dhfr and dhps mutant haplotypes, possibly from West Africa. A reduced genetic diversity and increased differentiation at flanking microsatellites when compared to neutral loci is consistent with a selective sweep for resistant alleles at both loci. Conclusions This study provides additional evidence for the crucial role of gene flow and drug selective pressures in the rapid spread of SP resistance in P. falciparum populations, from only a few mutation events giving rise to resistance-associated mutants. It also highlights the importance of human migration in the spread of drug resistant malaria parasites, as the distance between the islands and mainland is not consistent with mosquito-mediated parasite dispersal.

  9. Molecular surveillance of antimalarial drug resistance related genes in Plasmodium falciparum isolates from Eritrea.

    Science.gov (United States)

    Menegon, Michela; Nurahmed, Abduselam M; Talha, Albadawi A; Nour, Bakri Y M; Severini, Carlo

    2016-05-01

    The introduction of artemisinin-based combination therapy has led to extraordinary results in malaria control, however the recent emergence of partial resistance to artemisinin therapy in Southeast Asia jeopardizes these successes. This study aimed at investigating resistance to the antimalarial drugs by evaluating the polymorphisms in the PfK13, Pfcrt and Pfmdr1 genes in Plasmodium falciparum isolates obtained from patients in Eritrea.

  10. Treatment of Plasmodium falciparum malaria with mefloquine alone or in combination with i.v. quinine at the Department of Communicable and Tropical Diseases, Rigshospitalet, Copenhagen 1982-1988

    DEFF Research Database (Denmark)

    Magnussen, P; Bygbjerg, Ib Christian

    1990-01-01

    At the Department of Communicable and Tropical Diseases, Rigshospitalet, Denmark, mefloquine has been used since 1982 for the treatment of patients with suspected or verified chloroquine and sulfadoxine-pyrimethamine resistant P. falciparum malaria. Eighty-one patients treated with mefloquine are...

  11. Dihydroartemisinin-piperaquine resistance in Plasmodium falciparum malaria in Cambodia: a multisite prospective cohort study.

    Science.gov (United States)

    Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Dek, Dalin; Try, Vorleak; Amato, Roberto; Blessborn, Daniel; Song, Lijiang; Tullo, Gregory S; Fay, Michael P; Anderson, Jennifer M; Tarning, Joel; Fairhurst, Rick M

    2016-03-01

    Artemisinin resistance in Plasmodium falciparum threatens to reduce the efficacy of artemisinin combination therapies (ACTs), thus compromising global efforts to eliminate malaria. Recent treatment failures with dihydroartemisinin-piperaquine, the current first-line ACT in Cambodia, suggest that piperaquine resistance may be emerging in this country. We explored the relation between artemisinin resistance and dihydroartemisinin-piperaquine failures, and sought to confirm the presence of piperaquine-resistant P falciparum infections in Cambodia. In this prospective cohort study, we enrolled patients aged 2-65 years with uncomplicated P falciparum malaria in three Cambodian provinces: Pursat, Preah Vihear, and Ratanakiri. Participants were given standard 3-day courses of dihydroartemisinin-piperaquine. Peripheral blood parasite densities were measured until parasites cleared and then weekly to 63 days. The primary outcome was recrudescent P falciparum parasitaemia within 63 days. We measured piperaquine plasma concentrations at baseline, 7 days, and day of recrudescence. We assessed phenotypic and genotypic markers of drug resistance in parasite isolates. The study is registered with ClinicalTrials.gov, number NCT01736319. Between Sept 4, 2012, and Dec 31, 2013, we enrolled 241 participants. In Pursat, where artemisinin resistance is entrenched, 37 (46%) of 81 patients had parasite recrudescence. In Preah Vihear, where artemisinin resistance is emerging, ten (16%) of 63 patients had recrudescence and in Ratanakiri, where artemisinin resistance is rare, one (2%) of 60 patients did. Patients with recrudescent P falciparum infections were more likely to have detectable piperaquine plasma concentrations at baseline compared with non-recrudescent patients, but did not differ significantly in age, initial parasite density, or piperaquine plasma concentrations at 7 days. Recrudescent parasites had a higher prevalence of kelch13 mutations, higher piperaquine 50% inhibitory

  12. Dihydroartemisinin–piperaquine resistance in Plasmodium falciparum malaria in Cambodia: a multisite prospective cohort study

    Science.gov (United States)

    Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Dek, Dalin; Try, Vorleak; Amato, Roberto; Blessborn, Daniel; Song, Lijiang; Tullo, Gregory S; Fay, Michael P; Anderson, Jennifer M; Tarning, Joel; Fairhurst, Rick M

    2016-01-01

    Background Artemisinin resistance in Plasmodium falciparum threatens to reduce the efficacy of artemisinin combination therapies (ACTs), thus compromising global efforts to eliminate malaria. Recent treatment failures with dihydroartemisinin-piperaquine, the current first-line ACT in Cambodia, suggest that piperaquine resistance may be emerging in this country. We explored the relation between artemisinin resistance and dihydroartemisinin–piperaquine failures, and sought to confirm the presence of piperaquine-resistant P falciparum infections in Cambodia. Methods In this prospective cohort study, we enrolled patients aged 2–65 years with uncomplicated P falciparum malaria in three Cambodian provinces: Pursat, Preah Vihear, and Ratanakiri. Participants were given standard 3-day courses of dihydroartemisinin–piperaquine. Peripheral blood parasite densities were measured until parasites cleared and then weekly to 63 days. The primary outcome was recrudescent P falciparum parasitaemia within 63 days. We measured piperaquine plasma concentrations at baseline, 7 days, and day of recrudescence. We assessed phenotypic and genotypic markers of drug resistance in parasite isolates. The study is registered with ClinicalTrials.gov, number NCT01736319. Findings Between Sept 4, 2012, and Dec 31, 2013, we enrolled 241 participants. In Pursat, where artemisinin resistance is entrenched, 37 (46%) of 81 patients had parasite recrudescence. In Preah Vihear, where artemisinin resistance is emerging, ten (16%) of 63 patients had recrudescence and in Ratanakiri, where artemisinin resistance is rare, one (2%) of 60 patients did. Patients with recrudescent P falciparum infections were more likely to have detectable piperaquine plasma concentrations at baseline compared with non-recrudescent patients, but did not differ significantly in age, initial parasite density, or piperaquine plasma concentrations at 7 days. Recrudescent parasites had a higher prevalence of kelch13 mutations

  13. Monitoring the drug-sensitivity of Plasmodium falciparum in coastal towns in Madagascar by use of in vitro chemosensitivity and mutation detection tests

    Directory of Open Access Journals (Sweden)

    Rason M.A.

    2002-09-01

    Full Text Available The dissemination of mutant and resistant strains of Plasmodium falciparum makes a considerable contribution to the spread of drug-resistant malaria. Populations around harbours and airports could be particularly exposed to Plasmodium isolates introduced with imported cases of malaria. The use of chloroquine as well as the use of and sulfadoxine/pyrimethamine is currently an effective method for treating uncomplicated cases of malaria in Madagascar. As part of a monitoring programme, in vitro methods were used to assess the sensitivity of P. falciparum isolates in two coastal towns in Madagascar: Mahajanga on the west coast and Toamasina on the east coast. All of the isolates from both sites were sensitive to amodiaquine, quinine, pyrimethamine and cycloguanil. All of the isolates from Mahajanga were sensitive to chloroquine (n = 25; mean IC50 = 22.6 nM, 95 % confidence interval: 16.8-28.7 nM, whereas three of the isolates from Toamasina were resistant to chloroquine (n = 18; mean IC50 = 66.3 nM; 95 % confidence interval : 42.6-90 nM, The frequency of the Pfcrt Thr-76 and the dhfr Asn- 108 mutations was estimated by PCR/RFLP. The 43 P. falciparum isolates examined, including the three in vitro chloroquine-resistant isolates from Toamasina were all wild-type (Lys-76. Phenotyping and genotyping studies suggested that the prevalence of chloroquine- and pyrimethamine-resistant isolates and of mutant strains of P. falciparum is very low. These results showed that in vitro test and genotyping of resistance markers approaches could be successfully used to monitor the emergence of drug-resistant malaria and to try to alleviate the lack of medical teams able to carry out in vivo test. The possible hazard/risk associated with imported cases of malaria is discussed.

  14. 间日疟原虫氯喹抗性研究进展%Research progress on Plasmodium vivax chloroquine resistance

    Institute of Scientific and Technical Information of China (English)

    李江艳; 李倩; 方强

    2014-01-01

    Malaria remains a serious public health problem,especially in developing countries. With the deepening of the un-derstanding of vivax malaria,Plasmodium vivax is also attracting more and more attention. An effective drug treatment is the foun-dation of controlling or even eliminating malaria. In recent years,more and more reports of chloroquine-resistance Plasmodium vivax have been reported. Plasmodium vivax chloroquine resistance has been a focus problem in vivax malaria prevention and treat-ment. In this paper,the research progress on distribution situation,detection methods and molecular markers of Plasmodium vivax chloroquine resistance is summarized.%疟疾仍然是一个严重危害人类健康的公共卫生问题,尤其多见于发展中国家。随着认识的深入,间日疟也获得越来越多的重视。有效的药物治疗是控制疟疾甚至消除疟疾的基石,近年来已有越来越多的间日疟原虫氯喹抗性报道,间日疟原虫氯喹抗性已成为间日疟防治中一个备受关注的问题。本文就间日疟原虫氯喹抗性的分布现状、体内外检测方法和分子检测标志物研究进展进行初步总结。

  15. Multiple origins and regional dispersal of resistant dhps in African Plasmodium falciparum malaria.

    Directory of Open Access Journals (Sweden)

    Richard J Pearce

    2009-04-01

    Full Text Available Although the molecular basis of resistance to a number of common antimalarial drugs is well known, a geographic description of the emergence and dispersal of resistance mutations across Africa has not been attempted. To that end we have characterised the evolutionary origins of antifolate resistance mutations in the dihydropteroate synthase (dhps gene and mapped their contemporary distribution.We used microsatellite polymorphism flanking the dhps gene to determine which resistance alleles shared common ancestry and found five major lineages each of which had a unique geographical distribution. The extent to which allelic lineages were shared among 20 African Plasmodium falciparum populations revealed five major geographical groupings. Resistance lineages were common to all sites within these regions. The most marked differentiation was between east and west African P. falciparum, in which resistance alleles were not only of different ancestry but also carried different resistance mutations.Resistant dhps has emerged independently in multiple sites in Africa during the past 10-20 years. Our data show the molecular basis of resistance differs between east and west Africa, which is likely to translate into differing antifolate sensitivity. We have also demonstrated that the dispersal patterns of resistance lineages give unique insights into recent parasite migration patterns.

  16. Plasmodium vivax resistance to chloroquine (R2 and mefloquine (R3 in Brazilian Amazon region Resistência do Plasmodium vivax pela cloroquina (R2 e mefloquina (R3 na amazônia Brasileira

    Directory of Open Access Journals (Sweden)

    Maria das Graças C. Alecrim

    1999-02-01

    Full Text Available We report for the first time a patient with malaria due to Plasmodium vivax who showed R2 resistance to chloroquine and R3 resistance to mefloquine in the Brazilian Amazon region based on WHO clinical criteria for diagnosis of malaria resistance. Failure was observed with unsupervised oral chloroquine, chloroquine under rigorous supervision and mefloquine in the same scheme. Finally, the patient was cured with oral artesunate.Estamos relatando pela primeira vez um paciente com malária por Plasmodium vivax que mostrou resistência R2 à cloroquina e resistência R3 à mefloquina na Amazônia brasileira, de acordo com os critérios clínicos da OMS para resistência da malária. A falha foi observada com cloroquina oral, não supervisionada, cloroquina oral administrada sob rigorosa supervisão e com mefloquina no mesmo esquema. A paciente curou com o artesunato oral.

  17. Effects ofPlasmodium falciparum-infected erythrocytes on matrix metalloproteinase-9 regulation in human microvascular endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Sarah D Alessandro; Nicoletta Basilico; Mauro Prato

    2013-01-01

    Objective:To investigate the regulation of matrix metalloproteinases(MMPs) and tissue inhibitors of metalloproteinases(TIMPs) in human microvascular endothelium(HMEC-1) exposed to erythrocytes infected by different strains ofPlasmodium falciparum (P. falciparum).Methods:HMEC-1 cells were co-incubated for72 h with erythrocytes infected by late stage trophozoite of D10(chloroquine-sensitive) orW2(chloroquine-resistant)P. falciparum strains.Cell supernatants were then collected and the levels of pro- or active gelatinasesMMP-9 andMMP-2 were evaluated by gelatin zymography and densitometry.The release of pro-MMP-9,MMP-3,MMP-1 andTIMP-1 proteins was analyzed by western blotting and densitometry.Results:Infected erythrocytes inducedde novo proMMP-9 andMMP-9 release.Neither basal levels of proMMP-2 were altered, nor activeMMP-2 was found.MMP-3 andMMP-1 secretion was significantly enhanced, whereas basalTIMP-1 was unaffected.All effects were similar for both strains. Conclusions:P. falciparum parasites, either chloroquine-sensitive or -resistant, induce the release of activeMMP-9 protein from human microvascular endothelium, by impairing balances between proMMP-9 and its inhibitor, and by enhancing the levels of its activators.This work provides new evidence onMMP involvement in malaria, pointing atMMP-9 as a possible target in adjuvant therapy.

  18. The anti-malarial chloroquine overcomes Primary resistance and restores sensitivity to Trastuzumab in HER2-positive breast cancer

    Science.gov (United States)

    Cufí, Sílvia; Vazquez-Martin, Alejandro; Oliveras-Ferraros, Cristina; Corominas-Faja, Bruna; Cuyàs, Elisabet; López-Bonet, Eugeni; Martin-Castillo, Begoña; Joven, Jorge; Menendez, Javier A.

    2013-01-01

    Autophagy may control the de novo refractoriness of HER2 gene-amplified breast carcinomas to the monoclonal antibody trastuzumab (Herceptin). Tumor cells originally obtained from a patient who rapidly progressed on trastuzumab ab initio display increased cellular levels of the LC3-II protein—a finding that correlates with increased numbers of autophagosomes—and decreased levels of the autophagy receptor p62/SQSTM1, a protein selectively degraded by autophagy. Trastuzumab-refractory cells are in a state of “autophagy addiction” because genetic ablation of autophagy-specific genes (ATG8, ATG5, ATG12) notably reduces intrinsic refractoriness to trastuzumab. When the anti-malarial lysosomotropic drug chloroquine impedes autophagic resolution of the accumulation of autophagolysosomes formed in the presence of trastuzumab, cells commit to die by apoptosis. Accordingly, combination treatment with trastuzumab and chloroquine radically suppresses tumor growth by > 90% in a tumor xenograft completely refractory to trastuzumab. Adding chloroquine to trastuzumab-based regimens may therefore improve outcomes among women with autophagy-addicted HER2-positive breast cancer. PMID:23965851

  19. The molecular basis of antifolate resistance in Plasmodium falciparum: looking beyond point mutations.

    Science.gov (United States)

    Heinberg, Adina; Kirkman, Laura

    2015-04-01

    Drugs that target the folate-synthesis pathway have a long history of effectiveness against a variety of pathogens. As antimalarials, the antifolates were safe and well tolerated, but resistance emerged quickly and has persisted even with decreased drug pressure. The primary determinants of resistance in Plasmodium falciparum are well-described point mutations in the enzymes dihydropteroate synthase and dihydrofolate reductase targeted by the combination sulfadoxine-pyrimethamine. Recent work has highlighted the contributions of additional parasite adaptation to antifolate resistance. In fact, the evolution of antifolate-resistant parasites is multifaceted and complex. Gene amplification of the first enzyme in the parasite folate synthesis pathway, GTP-cyclohydrolase, is strongly associated with resistant parasites and potentially contributes to persistence of resistant parasites. Further understanding of how parasites adjust flux through the folate pathway is important to the further development of alternative agents targeting this crucial synthesis pathway.

  20. Plasmodium falciparum field isolates from areas of repeated emergence of drug resistant malaria show no evidence of hypermutator phenotype.

    Science.gov (United States)

    Brown, Tyler S; Jacob, Christopher G; Silva, Joana C; Takala-Harrison, Shannon; Djimdé, Abdoulaye; Dondorp, Arjen M; Fukuda, Mark; Noedl, Harald; Nyunt, Myaing Myaing; Kyaw, Myat Phone; Mayxay, Mayfong; Hien, Tran Tinh; Plowe, Christopher V; Cummings, Michael P

    2015-03-01

    Multiple transcontinental waves of drug resistance in Plasmodium falciparum have originated in Southeast Asia before spreading westward, first into the rest of Asia and then to sub-Saharan Africa. In vitro studies have suggested that hypermutator P. falciparum parasites may exist in Southeast Asia and that an increased rate of acquisition of new mutations in these parasites may explain the repeated emergence of drug resistance in Southeast Asia. This study is the first to test the hypermutator hypothesis using field isolates. Using genome-wide SNP data from human P. falciparum infections in Southeast Asia and West Africa and a test for relative rate differences we found no evidence of increased relative substitution rates in P. falciparum isolates from Southeast Asia. Instead, we found significantly increased substitution rates in Mali and Bangladesh populations relative to those in populations from Southeast Asia. Additionally we found no association between increased relative substitution rates and parasite clearance following treatment with artemisinin derivatives.

  1. Chloroquine is grossly under dosed in young children with malaria

    DEFF Research Database (Denmark)

    Ursing, Johan; Eksborg, Staffan; Rombo, Lars

    2014-01-01

    BACKGROUND: Plasmodium falciparum malaria is treated with 25 mg/kg of chloroquine (CQ) irrespective of age. Theoretically, CQ should be dosed according to body surface area (BSA). The effect of dosing CQ according to BSA has not been determined but doubling the dose per kg doubled the efficacy of...

  2. Antimalarial drug resistance in Bangladesh, 1996-2012.

    Science.gov (United States)

    Haque, Ubydul; Glass, Gregory E; Haque, Waziul; Islam, Nazrul; Roy, Shyamal; Karim, Jahirul; Noedl, Harald

    2013-12-01

    Malaria remains an important health problem in Bangladesh, with approximately 14 million people at risk. Antimalarial drug resistance is a major obstacle to the control of malaria in endemic countries. In 2012, Bangladesh reported an estimated 29 522 malaria episodes, of which 94% were reported as being caused by Plasmodium falciparum. In this study, we reviewed and summarized antimalarial drug resistance data from Bangladesh published until June 2013. We searched published sources for data referring to any type of P. falciparum drug resistance (in vivo, in vitro, or molecular) and found 169 articles published in peer-reviewed journals. Of these, 143 articles were excluded because they did not meet our inclusion criteria. After detailed review of the remaining 26 articles, 14 were selected for evaluation. Published studies indicate that P. falciparum shows varying levels of resistance to chloroquine, mefloquine and sulfadoxine-pyrimethamine. Combination therapy of chloroquine and primaquine has proven ineffective and combinations of sulfadoxine-pyrimethamine with either quinine or chloroquine have also shown poor efficacy. Recent studies indicate that artemisinin derivatives, such as artesunate, remain highly efficacious in treating P. falciparum malaria. Available data suggest that artemisinins, quinine, doxycyline, mefloquine-artesunate and azithromycin-artesunate combination therapy remain efficacious in the treatment of P. falciparum malaria in Bangladesh.

  3. Historical shifts in Brazilian P. falciparum population structure and drug resistance alleles.

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    Sean M Griffing

    Full Text Available Previous work suggests that Brazilian Plasmodium falciparum has limited genetic diversity and a history of bottlenecks, multiple reintroductions due to human migration, and clonal expansions. We hypothesized that Brazilian P. falciparum would exhibit clonal structure. We examined isolates collected across two decades from Amapá, Rondônia, and Pará state (n = 190. By examining more microsatellites markers on more chromosomes than previous studies, we hoped to define the extent of low diversity, linkage disequilibrium, bottlenecks, population structure, and parasite migration within Brazil. We used retrospective genotyping of samples from the 1980s and 1990s to explore the population genetics of SP resistant dhfr and dhps alleles. We tested an existing hypothesis that the triple mutant dhfr mutations 50R/51I/108N and 51I/108N/164L developed in southern Amazon from a single origin of common or similar parasites. We found that Brazilian P. falciparum had limited genetic diversity and isolation by distance was rejected, which suggests it underwent bottlenecks followed by migration between sites. Unlike Peru, there appeared to be gene flow across the Brazilian Amazon basin. We were unable to divide parasite populations by clonal lineages and pairwise FST were common. Most parasite diversity was found within sites in the Brazilian Amazon, according to AMOVA. Our results challenge the hypothesis that triple mutant alleles arose from a single lineage in the Southern Amazon. SP resistance, at both the double and triple mutant stages, developed twice and potentially in different regions of the Brazilian Amazon. We would have required samples from before the 1980s to describe how SP resistance spread across the basin or describe the complex internal migration of Brazilian parasites after the colonization efforts of past decades. The Brazilian Amazon basin may have sufficient internal migration for drug resistance reported in any particular region to

  4. Targeting the cell stress response of Plasmodium falciparum to overcome artemisinin resistance.

    Science.gov (United States)

    Dogovski, Con; Xie, Stanley C; Burgio, Gaetan; Bridgford, Jess; Mok, Sachel; McCaw, James M; Chotivanich, Kesinee; Kenny, Shannon; Gnädig, Nina; Straimer, Judith; Bozdech, Zbynek; Fidock, David A; Simpson, Julie A; Dondorp, Arjen M; Foote, Simon; Klonis, Nectarios; Tilley, Leann

    2015-04-01

    Successful control of falciparum malaria depends greatly on treatment with artemisinin combination therapies. Thus, reports that resistance to artemisinins (ARTs) has emerged, and that the prevalence of this resistance is increasing, are alarming. ART resistance has recently been linked to mutations in the K13 propeller protein. We undertook a detailed kinetic analysis of the drug responses of K13 wild-type and mutant isolates of Plasmodium falciparum sourced from a region in Cambodia (Pailin). We demonstrate that ART treatment induces growth retardation and an accumulation of ubiquitinated proteins, indicative of a cellular stress response that engages the ubiquitin/proteasome system. We show that resistant parasites exhibit lower levels of ubiquitinated proteins and delayed onset of cell death, indicating an enhanced cell stress response. We found that the stress response can be targeted by inhibiting the proteasome. Accordingly, clinically used proteasome inhibitors strongly synergize ART activity against both sensitive and resistant parasites, including isogenic lines expressing mutant or wild-type K13. Synergy is also observed against Plasmodium berghei in vivo. We developed a detailed model of parasite responses that enables us to infer, for the first time, in vivo parasite clearance profiles from in vitro assessments of ART sensitivity. We provide evidence that the clinical marker of resistance (delayed parasite clearance) is an indirect measure of drug efficacy because of the persistence of unviable parasites with unchanged morphology in the circulation, and we suggest alternative approaches for the direct measurement of viability. Our model predicts that extending current three-day ART treatment courses to four days, or splitting the doses, will efficiently clear resistant parasite infections. This work provides a rationale for improving the detection of ART resistance in the field and for treatment strategies that can be employed in areas with ART

  5. Monitoring of clinical efficacy and in vitro sensitivity of Plasmodium vivax to chloroquine in area along Thai Myanmar border during 2009-2010

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    Rungsihirunrat Kanchana

    2011-02-01

    Full Text Available Abstract Background In Thailand, the proportion of Plasmodium vivax infection has become equal to Plasmodium falciparum. Reports of a trend of gradual decline of in vitro sensitivity of P. vivax to chloroquine in some areas of the country, together with accumulating evidences of chloroquine resistance P. vivax in other parts of the world, emphasize the need for closely and continuously monitoring clinical efficacy in conjunction with in vitro sensitivity of P. vivax isolates. Methods The study was conducted at Mae Tao clinic for migrant workers, Tak Province during March 2008 - August 2009. A total of 130 patients (17 Thais and 113 Burmeses; 64 males and 66 females with mono-infection of P. vivax malaria, aged between 15-60 years and weighing more than 40 kg, were included in the study. Patients received treatment with chloroquine (2,000 mg chloroquine phosphate over three days and the anti-relapse drug primaquine (15 mg for 14 days. In vitro sensitivity of P. vivax isolates was evaluated by schizont maturation inhibition assay. Results All patients showed satisfactory response to treatment. The cure rate was virtually 100% within the follow-up period of 42 days. Neither recurrence of P. vivax parasitaemia nor appearance of P. falciparum occurred during the investigation period. In vitro data showed a stable sensitivity of chloroquine in this area since 2006. Geometric mean and median (95% CI values of IC50 for chloroquine were 100.1 and 134.7 (1.1-264.9 nM, respectively. Conclusion In vivo results suggest that the standard regimen of chloroquine was still very effective for the treatment of blood infections with P. vivax in the Thai-Myanmar border area. In vitro sensitivity data however, raise the possibility of potential advent of resistance in the future. Regular monitoring of the chloroquine sensitivity of P. vivax is essential to facilitate the early recognition of treatment failures and to expedite the formulation of appropriate changes to

  6. Comprehensive study of proteasome inhibitors against Plasmodium falciparum laboratory strains and field isolates from Gabon

    Directory of Open Access Journals (Sweden)

    Kremsner Peter G

    2008-09-01

    Full Text Available Abstract Background The emergence and spread of Plasmodium falciparum resistance to almost all available antimalarial drugs necessitates the search for new chemotherapeutic compounds. The ubiquitin/proteasome system plays a major role in overall protein turnover, especially in fast dividing eukaryotic cells including plasmodia. Previous studies show that the 20S proteasome is expressed and catalytically active in plasmodia and treatment with proteasome inhibitors arrests parasite growth. This is the first comprehensive screening of proteasome inhibitors with different chemical modes of action against laboratory strains of P. falciparum. Subsequently, a selection of inhibitors was tested in field isolates from Lambaréné, Gabon. Methods Epoxomicin, YU101, YU102, MG132, MG115, Z-L3-VS, Ada-Ahx3-L3-VS, lactacystin, bortezomib (Velcade®, gliotoxin, PR11 and PR39 were tested and compared to chloroquine- and artesunate-activities in a standardized in vitro drug susceptibility assay against P. falciparum laboratory strains 3D7, D10 and Dd2. Freshly obtained field isolates from Lambaréné, Gabon, were used to measure the activity of chloroquine, artesunate, epoxomicin, MG132, lactacystin and bortezomib. Parasite growth was detected through histidine-rich protein 2 (HRP2 production. Raw data were fitted by a four-parameter logistic model and individual inhibitory concentrations (50%, 90%, and 99% were calculated. Results Amongst all proteasome inhibitors tested, epoxomicin showed the highest activity in chloroquine-susceptible (IC50: 6.8 nM [3D7], 1.7 nM [D10] and in chloroquine-resistant laboratory strains (IC50: 10.4 nM [Dd2] as well as in field isolates (IC50: 8.5 nM. The comparator drug artesunate was even more active (IC50: 1.0 nM, whereas all strains were chloroquine-resistant (IC50: 113 nM. Conclusion The peptide α',β'-epoxyketone epoxomicin is highly active against P. falciparum regardless the grade of the parasite's chloroquine

  7. The Role of ABC Proteins in Drug-Resistant Breast Cancer Cells

    Science.gov (United States)

    2007-04-01

    mefloquine (A), quinine (B), chloroquine (C), and verapamil (D) profiles of wildtype (squares, solid line), Dd2 (triangles, dashed line), and 7G8 (circles...Nosten F, and Krishna S. (2004) Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number. Lancet 364 438-447. Reed MB

  8. Artemisinin Resistance-Associated Polymorphisms at the K13-Propeller Locus Are Absent in Plasmodium falciparum Isolates from Haiti

    Science.gov (United States)

    Carter, Tamar E.; Boulter, Alexis; Existe, Alexandre; Romain, Jean R.; St. Victor, Jean Yves; Mulligan, Connie J.; Okech, Bernard A.

    2015-01-01

    Antimalarial drugs are a key tool in malaria elimination programs. With the emergence of artemisinin resistance in southeast Asia, an effort to identify molecular markers for surveillance of resistant malaria parasites is underway. Non-synonymous mutations in the kelch propeller domain (K13-propeller) in Plasmodium falciparum have been associated with artemisinin resistance in samples from southeast Asia, but additional studies are needed to characterize this locus in other P. falciparum populations with different levels of artemisinin use. Here, we sequenced the K13-propeller locus in 82 samples from Haiti, where limited government oversight of non-governmental organizations may have resulted in low-level use of artemisinin-based combination therapies. We detected a single-nucleotide polymorphism (SNP) at nucleotide 1,359 in a single isolate. Our results contribute to our understanding of the global genomic diversity of the K13-propeller locus in P. falciparum populations. PMID:25646258

  9. 伯氏疟原虫氯喹抗性逆转的实验观察%Search for reverser of chloroquine-resistance in Plasmodium berghei

    Institute of Scientific and Technical Information of China (English)

    吴嘉彤; 兰勤娴; 王琴美; 潘星清

    2010-01-01

    Objective To search for reverser of chloroquine-resistance in Plasmodium berghei (P.berghei) ANKA. Methods Seventy-two healthy Kunming mice were each infected with chloroquine sensitive (CS) or chloroquine resistance (CR) P. berghei ANKA respectively, then treated with various schedule of reversal agents C-2832 、D-6182 or ketotifen(Ket) respectively with or without co-administration of low dose (5%ED90) of chloroquine (CQ). Schedule 1: mice infected with CS were randomly distributed into 4 groups, 6 mice in each group, 30 min after infection,then treated i.g. with D-6182, C-2832, Ket or 0. 1% gum tragacanth(control) respectively for 5 consecutive days. The parasitemia of each experiment group was then determined by routine microscopic examination on blood smears from the tail blood of each mouse from D1 to D7.Schedule 2:mice infected with CR were randomly distriduted into 8 groups, 6 mice in each group, 3 d after infection, then treated i.g. with D-6182, C-2832, Ket, chloroquine or 0. 1% gum tragacanth (control) with or without co-administration of 12 mg/(kg · d) chloroquine (5% ED90) 2 h after the first administration for 5 consecutive days. The parasitemia of each experiment group was then determined microscopically by examination on blood smears from the tail blood of each mouse from D4 to D7. The reduction rates of each group were calculated and compared between the groups with or without treatment of reverser. Results 1. The parasitemia of mice infected with CS was going up daily from D1 to D4 and reached the peak on D4 in all groups administered with 80 mg/(kg · d) D-6182, 120 mg/(kg · d) C-2832 or 10 mg/(kg · d) Ket for5 d. From D5 the parasitemia kept going up in control group while it kept at the level of D4 in all treated groups. 2. Chloroquine 12 mg/(kg · d) administered i.g. 2 h after administration of C-2832 or D-6182 or Ket for 5 d(D3-D7) could reach 97.77%, 99.28% or 96.73% of reduction rate of parasitemia on D4 and 99.81%, 98.87% or 100

  10. Therapeutic efficacy of artesunate in the treatment of uncomplicated Plasmodium falciparum malaria and anti-malarial, drug-resistance marker polymorphisms in populations near the China-Myanmar border

    Directory of Open Access Journals (Sweden)

    Huang Fang

    2012-08-01

    Full Text Available Abstract Background The aim of this study was to evaluate the clinical outcome after seven-day artesunate monotherapy for uncomplicated Plasmodium falciparum malaria in Yingjiang County along the China-Myanmar border and investigate genetic polymorphisms in the P. falciparum chloroquine-resistance transporter (pfcrt, multidrug resistance 1 (pfmdr1, dihydrofolate reductase (pfdhfr, dihydropteroate synthase (pfdhps and ATPase (pfatp6 genes. Methods Patients ≥ one year of age with fever (axillary temperature ≥37.5°C or history of fever and P. falciparum mono-infection were included. Patients received anti-malarial treatment with artesunate (total dose of 16 mg/kg over seven days by directly observed therapy. After a 28-day follow-up, treatment efficacy and effectiveness were assessed based on clinical and parasitological outcomes. Treatment failure was defined as recrudescence of the original parasite and distinguished with new infection confirmed by PCR. Analysis of gene mutation and amplification were performed by nested polymerase chain reaction. Results Sixty-five patients were enrolled; 10 withdrew from the study, and six were lost to follow-up. All but two patients demonstrated adequate clinical and parasitological response; 12 had detectable parasitaemia on day 3. These two patients were confirmed to be new infection by PCR. The efficacy of artesunate was 95.9%. The pfcrt mutation in codon 76 was found in all isolates (100%, and mutations in codons 71 and 72 were found in 4.8% of parasite isolates. No mutation of pfmdr1 (codons 86 or 1246 was found. Among all samples, 5.1% were wild type for pfdhfr, whereas the other samples had mutations in four codons (51, 59, 108 and 164, and mutations in pfdhps (codons 436, 437, 540 and 581 were found in all isolates. No samples had mutations in pfatp6 codons 623 or 769, but two new mutations (N683K and R756K were found in 4.6% and 9.2% of parasite isolates, respectively. Conclusion Plasmodium

  11. Heterologous Protection against Malaria after Immunization with Plasmodium falciparum Sporozoites

    NARCIS (Netherlands)

    Schats, R.; Bijker, E.M.; Gemert, G.J.A. van; Graumans, W.; Vegte-Bolmer, M. van de; Lieshout, L. van; Haks, M.C.; Hermsen, C.C.; Scholzen, A.; Visser, L.G.; Sauerwein, R.W.

    2015-01-01

    BACKGROUND: Sterile protection in >90% of volunteers against homologous Plasmodium falciparum infection has been achieved only using the controlled human malaria infection (CHMI) model. This efficient model involves whole parasite immunizations under chloroquine prophylaxis (CPS-immunization),

  12. A better resolution for integrating methods for monitoring Plasmodium falciparum resistance to antimalarial drugs.

    Science.gov (United States)

    Abdul-Ghani, Rashad; Al-Maktari, Mohamed T; Al-Shibani, Latifa A; Allam, Amal F

    2014-09-01

    Effective chemotherapy is the mainstay of malaria control. However, resistance of falciparum malaria to antimalarial drugs compromised the efforts to eliminate the disease and led to the resurgence of malaria epidemics. Three main approaches are used to monitor antimalarial drug efficacy and drug resistance; namely, in vivo trials, in vitro/ex vivo assays and molecular markers of drug resistance. Each approach has its implications of use as well as its advantages and drawbacks. Therefore, there is a need to use an integrated approach that would give the utmost effect to detect resistance as early as its emergence and to track it once spread. Such integration becomes increasingly needed in the era of artemisinin-based combination therapy as a forward action to deter resistance. The existence of regional and global networks for the standardization of methodology, provision of high quality reagents for the assessment of antimalarial drug resistance and dissemination of open-access data would help in approaching an integrated resistance surveillance system on a global scale.

  13. Developing artemisinin based drug combinations for the treatment of drug resistant falciparum malaria: A review

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    Olliaro P

    2004-01-01

    Full Text Available The emergence and spread of drug resistant malaria represents a considerable challenge to controlling malaria. To date, malaria control has relied heavily on a comparatively small number of chemically related drugs, belonging to either the quinoline or the antifolate groups. Only recently have the artemisinin derivatives been used but mostly in south east Asia. Experience has shown that resistance eventually curtails the life-span of antimalarial drugs. Controlling resistance is key to ensuring that the investment put into developing new antimalarial drugs is not wasted. Current efforts focus on research into new compounds with novel mechanisms of action, and on measures to prevent or delay resistance when drugs are introduced. Drug discovery and development are long, risky and costly ventures. Antimalarial drug development has traditionally been slow but now various private and public institutions are at work to discover and develop new compounds. Today, the antimalarial development pipeline is looking reasonably healthy. Most development relies on the quinoline, antifolate and artemisinin compounds. There is a pressing need to have effective, easy to use, affordable drugs that will last a long time. Drug combinations that have independent modes of action are seen as a way of enhancing efficacy while ensuring mutual protection against resistance. Most research work has focused on the use of artesunate combined with currently used standard drugs, namely, mefloquine, amodiaquine, sulfadoxine/pyrimethamine, and chloroquine. There is clear evidence that combinations improve efficacy without increasing toxicity. However, the absolute cure rates that are achieved by combinations vary widely and depend on the level of resistance of the standard drug. From these studies, further work is underway to produce fixed dose combinations that will be packaged in blister packs. This review will summarise current antimalarial drug developments and outline recent

  14. Fitness trade-offs in the evolution of dihydrofolate reductase and drug resistance in Plasmodium falciparum.

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    Marna S Costanzo

    Full Text Available BACKGROUND: Patterns of emerging drug resistance reflect the underlying adaptive landscapes for specific drugs. In Plasmodium falciparum, the parasite that causes the most serious form of malaria, antifolate drugs inhibit the function of essential enzymes in the folate pathway. However, a handful of mutations in the gene coding for one such enzyme, dihydrofolate reductase, confer drug resistance. Understanding how evolution proceeds from drug susceptibility to drug resistance is critical if new antifolate treatments are to have sustained usefulness. METHODOLOGY/PRINCIPAL FINDINGS: We use a transgenic yeast expression system to build on previous studies that described the adaptive landscape for the antifolate drug pyrimethamine, and we describe the most likely evolutionary trajectories for the evolution of drug resistance to the antifolate chlorcycloguanil. We find that the adaptive landscape for chlorcycloguanil is multi-peaked, not all highly resistant alleles are equally accessible by evolution, and there are both commonalities and differences in adaptive landscapes for chlorcycloguanil and pyrimethamine. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that cross-resistance between drugs targeting the same enzyme reflect the fitness landscapes associated with each particular drug and the position of the genotype on both landscapes. The possible public health implications of these findings are discussed.

  15. Polymorphisms in the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) genes of Plasmodium falciparum and in vivo resistance to sulphadoxine/pyrimethamine in isolates from Tanzania

    DEFF Research Database (Denmark)

    Jelinek, T; Rønn, A M; Lemnge, M M

    1998-01-01

    The efficacy of sulphadoxine/pyrimethamine (S/P) in treatment of uncomplicated falciparum malaria in Africa is increasingly compromised by development of resistance. The occurrence of mutations associated with the active site sequence in the Plasmodium falciparum genes coding for dihydrofolate...

  16. Chemotherapy and drug resistance status of malaria parasite in northeast India

    Institute of Scientific and Technical Information of China (English)

    Diganta Goswami; Indra Baruah; Sunil Dhiman; Bipul Rabha; Vijay Veer; Lokendra Singh; Dhirendra Kumar Sharma

    2013-01-01

    India reports the highest number of malaria cases in Southeast Asia, of which Plasmodiumfalciparum contribute more than half of the cases every year. North eastern states of India contribute only 3.96% of country’s population but account for >10% of total reported malaria cases, 11% of Plasmodium falciparum cases and 20% of malaria related deaths annually. In India, chloroquine resistance was reported for the first time from northeast region and since then chloroquine treatment failure is being reported from many parts of the region. Increased chloroquine treatment failure has led to change of the drug policy to artemisinin combination therapy as first line of malaria treatment in the region. However, replacing chloroquine to artemisinin combination therapy has not shown significant difference in the overall malaria incidence in the region. The present review addresses the current malaria situation of northeastern region of India in the light of antimalarials drug resistance.

  17. Spread of artemisinin-resistant Plasmodium falciparum in Myanmar: a cross-sectional survey of the K13 molecular marker.

    Science.gov (United States)

    Tun, Kyaw M; Imwong, Mallika; Lwin, Khin M; Win, Aye A; Hlaing, Tin M; Hlaing, Thaung; Lin, Khin; Kyaw, Myat P; Plewes, Katherine; Faiz, M Abul; Dhorda, Mehul; Cheah, Phaik Yeong; Pukrittayakamee, Sasithon; Ashley, Elizabeth A; Anderson, Tim J C; Nair, Shalini; McDew-White, Marina; Flegg, Jennifer A; Grist, Eric P M; Guerin, Philippe; Maude, Richard J; Smithuis, Frank; Dondorp, Arjen M; Day, Nicholas P J; Nosten, François; White, Nicholas J; Woodrow, Charles J

    2015-04-01

    Emergence of artemisinin resistance in southeast Asia poses a serious threat to the global control of Plasmodium falciparum malaria. Discovery of the K13 marker has transformed approaches to the monitoring of artemisinin resistance, allowing introduction of molecular surveillance in remote areas through analysis of DNA. We aimed to assess the spread of artemisinin-resistant P falciparum in Myanmar by determining the relative prevalence of P falciparum parasites carrying K13-propeller mutations. We did this cross-sectional survey at malaria treatment centres at 55 sites in ten administrative regions in Myanmar, and in relevant border regions in Thailand and Bangladesh, between January, 2013, and September, 2014. K13 sequences from P falciparum infections were obtained mainly by passive case detection. We entered data into two geostatistical models to produce predictive maps of the estimated prevalence of mutations of the K13 propeller region across Myanmar. Overall, 371 (39%) of 940 samples carried a K13-propeller mutation. We recorded 26 different mutations, including nine mutations not described previously in southeast Asia. In seven (70%) of the ten administrative regions of Myanmar, the combined K13-mutation prevalence was more than 20%. Geospatial mapping showed that the overall prevalence of K13 mutations exceeded 10% in much of the east and north of the country. In Homalin, Sagaing Region, 25 km from the Indian border, 21 (47%) of 45 parasite samples carried K13-propeller mutations. Artemisinin resistance extends across much of Myanmar. We recorded P falciparum parasites carrying K13-propeller mutations at high prevalence next to the northwestern border with India. Appropriate therapeutic regimens should be tested urgently and implemented comprehensively if spread of artemisinin resistance to other regions is to be avoided. Wellcome Trust-Mahidol University-Oxford Tropical Medicine Research Programme and the Bill & Melinda Gates Foundation. Copyright © 2015

  18. [Therapeutic response of Plasmodium vivax to chloroquine in Bolivia].

    Science.gov (United States)

    Añez, Arletta; Navarro-Costa, Dennis; Yucra, Omar; Garnica, Cecilia; Melgar, Viviana; Moscoso, Manuel; Arteaga, Ricardo; Nakao, Gladys

    2012-01-01

    Knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance. The therapeutic efficacy of chloroquine as treatment was evaluated for uncomplicated Plasmodium vivax malaria in Bolivia. An in vivo efficacy study of chloroquine was undertaken in three regions of Bolivia--Riberalta, Guayaramerín and Yacuiba. Two hundred and twenty-three patients (84, 80, and 59 in the three regions, respectively) aged over 5 years old were administered with chloroquine (25 mg/kg/three days) and followed for 28 days. Blood levels of chloroquine and desethylchloroquine were measured on day 2 and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan and Meier survival analysis. The mean parasitemias (asexual) on day 0 were 6,147 parasites/μl of blood in the Riberalta population, 4,251 in Guayaramerín and 5,214 in Yacuiba. The average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817, and 815 ng/ml, respectively. No treatment failures were observed in Yacuiba, whereas in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia. Resistance of Plasmodium vivax to chloroquine was not demonstrated in three regions of Bolivia.

  19. Evolução temporal da resistência in vitro do Plasmodium falciparum às drogas antimaláricas em duas áreas da amazônia brasileira com distintas características sócio-econômicas e geográficas

    Directory of Open Access Journals (Sweden)

    Álvaro Augusto Couto

    1995-12-01

    Full Text Available Avaliou-se a evolução temporal da resistência in vitro do Plasmodium falciparum às drogas cloroquina, amodiaquina, quinino e mefloquina em duas áreas com distintas características sócio-econômicas e geográficas: Lourenço, no Estado do Amapá e Paragominas no Estado do Pará. A primeira caracteriza-se por ser uma área de garimpos a céu aberto e a segunda uma área de colonização, pecuária e extrativismo de madeiras. O estudo revela alta prevalência de resistência à cloroquina nas duas áreas (79,8% em Lourenço e 68,4% em Paragominas, enquanto que para amodiaquina e quinino observamos uma certa flutuação nas respostas para essas drogas, dependendo do período em que foi avaliada, fá para mefloquina, não foram obsewadas cepas resistentes, mas uma perda da sensibilidade ao longo do período estudado.We evaluated the temporal progression of in vitro P. falciparum resistance to chloroquine, amodiaquine, quinine and mefloquine in two areas with distinct socioeconomical and geographical characteristics: Lourenço, in Amapá state and Paragominas, in Pará state. The former region is essentially an "open" gold mining camp, whereas the latter is one currently undergoing a colonization settlement process, in addition to expanding economical activities which mainly include cattle raising and wood exploitation. Our results show high resistance rates to chloroquine in the two study areas: 79.8% and 68.4% in Lourenço and Paragominas, respectively. Variations in the response of P. falciparum to both amodiaquine and quinine were recorded throughout the study period. On the other hand, no mefloquine P. falciparum resistant strains could be identified, despite the tact we had noted a decrease in sensitivity to this antimalarial drug throughout the study period.

  20. Assessment of the therapeutic efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal: an observational cohort study

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    Vaughan-Williams Charles H

    2012-12-01

    Full Text Available Abstract Background Recent malaria epidemics in KwaZulu-Natal indicate that effective anti-malarial therapy is essential for malaria control. Although artemether-lumefantrine has been used as first-line treatment for uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal since 2001, its efficacy has not been assessed since 2002. The objectives of this study were to quantify the proportion of patients treated for uncomplicated P. falciparum malaria with artemether-lumefantrine who failed treatment after 28 days, and to determine the prevalence of molecular markers associated with artemether-lumefantrine and chloroquine resistance. Methods An observational cohort of 49 symptomatic patients, diagnosed with uncomplicated P. falciparum malaria by rapid diagnostic test, had blood taken for malaria blood films and P. falciparum DNA polymerase chain reaction (PCR. Following diagnosis, patients were treated with artemether-lumefantrine (Coartem® and invited to return to the health facility after 28 days for repeat blood film and PCR. All PCR P. falciparum positive samples were analysed for molecular markers of lumefantrine and chloroquine resistance. Results Of 49 patients recruited on the basis of a positive rapid diagnostic test, only 16 were confirmed to have P. falciparum by PCR. At follow-up, 14 were PCR-negative for malaria, one was lost to follow-up and one blood specimen had insufficient blood for a PCR analysis. All 16 with PCR-confirmed malaria carried a single copy of the multi-drug resistant (mdr1 gene, and the wild type asparagine allele mdr1 codon 86 (mdr1 86N. Ten of the 16 samples carried the wild type haplotype (CVMNK at codons 72-76 of the chloroquine resistance transporter gene (pfcrt; three samples carried the resistant CVIET allele; one carried both the resistant and wild type, and in two samples the allele could not be analysed. Conclusions The absence of mdr1 gene copy number variation detected in this study

  1. Assessment of the therapeutic efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal: an observational cohort study.

    Science.gov (United States)

    Vaughan-Williams, Charles H; Raman, Jaishree; Raswiswi, Eric; Immelman, Etienne; Reichel, Holger; Gate, Kelly; Knight, Steve

    2012-12-28

    Recent malaria epidemics in KwaZulu-Natal indicate that effective anti-malarial therapy is essential for malaria control. Although artemether-lumefantrine has been used as first-line treatment for uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal since 2001, its efficacy has not been assessed since 2002. The objectives of this study were to quantify the proportion of patients treated for uncomplicated P. falciparum malaria with artemether-lumefantrine who failed treatment after 28 days, and to determine the prevalence of molecular markers associated with artemether-lumefantrine and chloroquine resistance. An observational cohort of 49 symptomatic patients, diagnosed with uncomplicated P. falciparum malaria by rapid diagnostic test, had blood taken for malaria blood films and P. falciparum DNA polymerase chain reaction (PCR). Following diagnosis, patients were treated with artemether-lumefantrine (Coartem®) and invited to return to the health facility after 28 days for repeat blood film and PCR. All PCR P. falciparum positive samples were analysed for molecular markers of lumefantrine and chloroquine resistance. Of 49 patients recruited on the basis of a positive rapid diagnostic test, only 16 were confirmed to have P. falciparum by PCR. At follow-up, 14 were PCR-negative for malaria, one was lost to follow-up and one blood specimen had insufficient blood for a PCR analysis. All 16 with PCR-confirmed malaria carried a single copy of the multi-drug resistant (mdr1) gene, and the wild type asparagine allele mdr1 codon 86 (mdr1 86N). Ten of the 16 samples carried the wild type haplotype (CVMNK) at codons 72-76 of the chloroquine resistance transporter gene (pfcrt); three samples carried the resistant CVIET allele; one carried both the resistant and wild type, and in two samples the allele could not be analysed. The absence of mdr1 gene copy number variation detected in this study suggests lumefantrine resistance has yet to emerge in Kwa

  2. Efficacy and Safety of Azithromycin-Chloroquine versus Sulfadoxine-Pyrimethamine for Intermittent Preventive Treatment of Plasmodium falciparum Malaria Infection in Pregnant Women in Africa: An Open-Label, Randomized Trial.

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    Joshua Kimani

    Full Text Available The World Health Organization recommends intermittent preventive treatment in pregnancy (IPTp with sulfadoxine-pyrimethamine (SP in African regions with moderate to high malaria transmission. However, growing resistance to SP threatens the effectiveness of IPTp-SP, and alternative drugs are needed. This study tested the efficacy, tolerability, and safety of a fixed-dose combination azithromycin-chloroquine (AZCQ; 250 mg AZ/155 mg CQ base for IPTp relative to IPTp-SP.A randomized, Phase 3, open-label, multi-center study was conducted in sub-Saharan Africa (Benin, Kenya, Malawi, Tanzania, and Uganda between October 2010 and November 2013. Pregnant women received 3 IPTp courses with AZCQ (each course: 1,000/620 mg AZCQ QD for 3 days or SP (each course 1,500/75 mg SP QD for 1 day at 4- to 8-week intervals during the second and third trimester. Long-lasting insecticide-treated bednets were also provided at enrollment. Study participants were followed up until day 28 post delivery (time window: day 28-42. The primary endpoint was the proportion of participants with sub-optimal pregnancy outcomes (a composite endpoint comprising live-borne neonates with low birth weight [LBW, 28 weeks], abortion [≤28 weeks], lost to follow-up prior to observation of pregnancy outcome, or missing birth weight. The study was terminated early after recruitment of 2,891 of the planned 5,044 participants, due to futility observed in a pre-specified 35% interim analysis. In the final intent-to-treat dataset, 378/1,445 (26.2% participants in the AZCQ and 342/1,445 (23.7% in the SP group had sub-optimal pregnancy outcomes, with an estimated risk ratio (RR of 1.11 (95% CI: 0.97, 1.25; p = 0.12. There was no significant difference in the incidence of LBW between treatment groups (57/1138 [5.0%] in the AZCQ group, 68/1188 [5.7%] in the SP group, RR 0.87 [95% CI: 0.62, 1.23]; p = 0.44. IPTp-AZCQ was less well-tolerated in mothers than IPTp-SP. Occurrences of congenital anomalies

  3. Host candidate gene polymorphisms and clearance of drug-resistant Plasmodium falciparum parasites

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    Rockett Kirk

    2011-08-01

    Full Text Available Abstract Background Resistance to anti-malarial drugs is a widespread problem for control programmes for this devastating disease. Molecular tests are available for many anti-malarial drugs and are useful tools for the surveillance of drug resistance. However, the correlation of treatment outcome and molecular tests with particular parasite markers is not perfect, due in part to individuals who are able to clear genotypically drug-resistant parasites. This study aimed to identify molecular markers in the human genome that correlate with the clearance of malaria parasites after drug treatment, despite the drug resistance profile of the protozoan as predicted by molecular approaches. Methods 3721 samples from five African countries, which were known to contain genotypically drug resistant parasites, were analysed. These parasites were collected from patients who subsequently failed to clear their infection following drug treatment, as expected, but also from patients who successfully cleared their infections with drug-resistant parasites. 67 human polymorphisms (SNPs on 17 chromosomes were analysed using Sequenom's mass spectrometry iPLEX gold platform, to identify regions of the human genome, which contribute to enhanced clearance of drug resistant parasites. Results An analysis of all data from the five countries revealed significant associations between the phenotype of ability to clear drug-resistant Plasmodium falciparum infection and human immune response loci common to all populations. Overall, three SNPs showed a significant association with clearance of drug-resistant parasites with odds ratios of 0.76 for SNP rs2706384 (95% CI 0.71-0.92, P = 0.005, 0.66 for SNP rs1805015 (95% CI 0.45-0.97, P = 0.03, and 0.67 for SNP rs1128127 (95% CI 0.45-0.99, P = 0.05, after adjustment for possible confounding factors. The first two SNPs (rs2706384 and rs1805015 are within loci involved in pro-inflammatory (interferon-gamma and anti-inflammatory (IL-4

  4. Ex vivo piperaquine resistance developed rapidly in Plasmodium falciparum isolates in northern Cambodia compared to Thailand

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    Suwanna Chaorattanakawee

    2016-10-01

    Full Text Available Abstract Background The recent dramatic decline in dihydroartemisinin-piperaquine (DHA-PPQ efficacy in northwestern Cambodia has raised concerns about the rapid spread of piperaquine resistance just as DHA-PPQ is being introduced as first-line therapy in neighbouring countries. Methods Ex vivo parasite susceptibilities were tracked to determine the rate of progression of DHA, PPQ and mefloquine (MQ resistance from sentinel sites on the Thai–Cambodian and Thai–Myanmar borders from 2010 to 2015. Immediate ex vivo (IEV histidine-rich protein 2 (HRP-2 assays were used on fresh patient Plasmodium falciparum isolates to determine drug susceptibility profiles. Results IEV HRP-2 assays detected the precipitous emergence of PPQ resistance in Cambodia beginning in 2013 when 40 % of isolates had an IC90 greater than the upper limit of prior years, and this rate doubled to 80 % by 2015. In contrast, Thai–Myanmar isolates from 2013 to 14 remained PPQ-sensitive, while northeastern Thai isolates appeared to have an intermediate resistance profile. The opposite trend was observed for MQ where Cambodian isolates appeared to have a modest increase in overall sensitivity during the same period, with IC50 declining to median levels comparable to those found in Thailand. A significant association between increased PPQ IC50 and IC90 among Cambodian isolates with DHA-PPQ treatment failure was observed. Nearly all Cambodian and Thai isolates were deemed artemisinin resistant with a >1 % survival rate for DHA in the ring-stage assay (RSA, though there was no correlation among isolates to indicate cross-resistance between PPQ and artemisinins. Conclusions Clinical DHA-PPQ failures appear to be associated with declines in the long-acting partner drug PPQ, though sensitivity appears to remain largely intact for now in western Thailand. Rapid progression of PPQ resistance associated with DHA-PPQ treatment failures in northern Cambodia limits drugs of choice in

  5. Assessing the asymptomatic reservoir and dihydroartemisinin-piperaquine effectiveness in a low transmission setting threatened by artemisinin resistant Plasmodium falciparum.

    Science.gov (United States)

    Falq, Grégoire; Van Den Bergh, Rafael; De Smet, Martin; Etienne, William; Nguon, Chea; Rekol, Huy; Imwong, Mallika; Dondorp, Arjen; Kindermans, Jean-Marie

    2016-09-01

    In Cambodia, elimination of artemisinin resistance through direct elimination of the Plasmodium falciparum parasite may be the only strategy. Prevalence and incidence at district and village levels were assessed in Chey Saen district, Preah Vihear province, North of Cambodia. Molecular and clinical indicators for artemisinin resistance were documented. A cross sectional prevalence survey was conducted at village level in the district of Chey Saen from September to October 2014. Plasmodium spp. was assessed with high volume quantitative real-time polymerase chain reaction (qPCR). Plasmodium falciparum-positive samples were screened for mutations in the k13-propeller domain gene. Treatment effectiveness was established after 28 days (D28) using the same qPCR technique. Data from the provincial surveillance system targeting symptomatic cases, supported by Médecins Sans Frontières (MSF), were used to assess incidence. District P. falciparum prevalence was of 0.74 % [0.41; 1.21]; village prevalence ranged from 0 to 4.6 % [1.4; 10.5]. The annual incidence of P. falciparum was 16.8 cases per 1000 inhabitants in the district; village incidence ranged from 1.3 to 54.9 for 1000 inhabitants. Two geographical clusters with high number of cases were identified by both approaches. The marker for artemisinin resistance was found in six samples out of the 11 tested (55 %). 34.9 % of qPCR blood analysis of symptomatic patients were still positive at D28. The overall low prevalence of P. falciparum was confirmed in Chey Saen district in Cambodia, while there were important variations between villages. Symptomatic cases had a different pattern and were likely acquired outside the villages. It illustrates the importance of prevalence surveys in targeting interventions for elimination. Mutations in the k13-propeller domain gene (C580Y), conferring artemisinin resistance, were highly prevalent in both symptomatic and asymptomatic cases (realizing the absolute figures remain low

  6. Chloroquine is a zinc ionophore.

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    Jing Xue

    Full Text Available Chloroquine is an established antimalarial agent that has been recently tested in clinical trials for its anticancer activity. The favorable effect of chloroquine appears to be due to its ability to sensitize cancerous cells to chemotherapy, radiation therapy, and induce apoptosis. The present study investigated the interaction of zinc ions with chloroquine in a human ovarian cancer cell line (A2780. Chloroquine enhanced zinc uptake by A2780 cells in a concentration-dependent manner, as assayed using a fluorescent zinc probe. This enhancement was attenuated by TPEN, a high affinity metal-binding compound, indicating the specificity of the zinc uptake. Furthermore, addition of copper or iron ions had no effect on chloroquine-induced zinc uptake. Fluorescent microscopic examination of intracellular zinc distribution demonstrated that free zinc ions are more concentrated in the lysosomes after addition of chloroquine, which is consistent with previous reports showing that chloroquine inhibits lysosome function. The combination of chloroquine with zinc enhanced chloroquine's cytotoxicity and induced apoptosis in A2780 cells. Thus chloroquine is a zinc ionophore, a property that may contribute to chloroquine's anticancer activity.

  7. Translocation of sickle cell erythrocyte microRNAs into Plasmodium falciparum inhibits parasite translation and contributes to malaria resistance.

    Science.gov (United States)

    LaMonte, Gregory; Philip, Nisha; Reardon, Joseph; Lacsina, Joshua R; Majoros, William; Chapman, Lesley; Thornburg, Courtney D; Telen, Marilyn J; Ohler, Uwe; Nicchitta, Christopher V; Haystead, Timothy; Chi, Jen-Tsan

    2012-08-16

    Erythrocytes carrying a variant hemoglobin allele (HbS), which causes sickle cell disease and resists infection by the malaria parasite Plasmodium falciparum. The molecular basis of this resistance, which has long been recognized as multifactorial, remains incompletely understood. Here we show that the dysregulated microRNA (miRNA) composition, of either heterozygous HbAS or homozygous HbSS erythrocytes, contributes to resistance against P. falciparum. During the intraerythrocytic life cycle of P. falciparum, a subset of erythrocyte miRNAs translocate into the parasite. Two miRNAs, miR-451 and let-7i, were highly enriched in HbAS and HbSS erythrocytes, and these miRNAs, along with miR-223, negatively regulated parasite growth. Surprisingly, we found that miR-451 and let-7i integrated into essential parasite messenger RNAs and, via impaired ribosomal loading, resulted in translational inhibition. Hence, sickle cell erythrocytes exhibit cell-intrinsic resistance to malaria in part through an atypical miRNA activity, which may represent a unique host defense strategy against complex eukaryotic pathogens.

  8. Optimising strategies for Plasmodium falciparum malaria elimination in Cambodia: primaquine, mass drug administration and artemisinin resistance.

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    Richard J Maude

    Full Text Available BACKGROUND: Malaria elimination requires a variety of approaches individually optimized for different transmission settings. A recent field study in an area of low seasonal transmission in South West Cambodia demonstrated dramatic reductions in malaria parasite prevalence following both mass drug administration (MDA and high treatment coverage of symptomatic patients with artemisinin-piperaquine plus primaquine. This study employed multiple combined strategies and it was unclear what contribution each made to the reductions in malaria. METHOD AND FINDINGS: A mathematical model fitted to the trial results was used to assess the effects of the various components of these interventions, design optimal elimination strategies, and explore their interactions with artemisinin resistance, which has recently been discovered in Western Cambodia. The modelling indicated that most of the initial reduction of P. falciparum malaria resulted from MDA with artemisinin-piperaquine. The subsequent continued decline and near elimination resulted mainly from high coverage with artemisinin-piperaquine treatment. Both these strategies were more effective with the addition of primaquine. MDA with artemisinin combination therapy (ACT increased the proportion of artemisinin resistant infections, although much less than treatment of symptomatic cases with ACT, and this increase was slowed by adding primaquine. Artemisinin resistance reduced the effectiveness of interventions using ACT when the prevalence of resistance was very high. The main results were robust to assumptions about primaquine action, and immunity. CONCLUSIONS: The key messages of these modelling results for policy makers were: high coverage with ACT treatment can produce a long-term reduction in malaria whereas the impact of MDA is generally only short-term; primaquine enhances the effect of ACT in eliminating malaria and reduces the increase in proportion of artemisinin resistant infections; parasite

  9. Site-specific genome editing in Plasmodium falciparum using engineered zinc-finger nucleases.

    Science.gov (United States)

    Straimer, Judith; Lee, Marcus C S; Lee, Andrew H; Zeitler, Bryan; Williams, April E; Pearl, Jocelynn R; Zhang, Lei; Rebar, Edward J; Gregory, Philip D; Llinás, Manuel; Urnov, Fyodor D; Fidock, David A

    2012-10-01

    Malaria afflicts over 200 million people worldwide, and its most lethal etiologic agent, Plasmodium falciparum, is evolving to resist even the latest-generation therapeutics. Efficient tools for genome-directed investigations of P. falciparum-induced pathogenesis, including drug-resistance mechanisms, are clearly required. Here we report rapid and targeted genetic engineering of this parasite using zinc-finger nucleases (ZFNs) that produce a double-strand break in a user-defined locus and trigger homology-directed repair. Targeting an integrated egfp locus, we obtained gene-deletion parasites with unprecedented speed (2 weeks), both with and without direct selection. ZFNs engineered against the parasite gene pfcrt, responsible for escape under chloroquine treatment, rapidly produced parasites that carried either an allelic replacement or a panel of specified point mutations. This method will enable a diverse array of genome-editing approaches to interrogate this human pathogen.

  10. Drug resistant falciparum malaria and the use of artesunate-based combinations : focus on clinical trials sponsored by TDR

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    Walter R.J. Taylor, Jean Rigal & Piero L. Olliaro

    2003-09-01

    Full Text Available Antimalarial drug resistance has now become a serious global challenge and is the principal reasonfor the decline in antimalarial drug efficacy. Malaria endemic countries need inexpensive and efficaciousdrugs. Preserving the life spans of antimalarial drugs is a key part of the strategy for rollingback malaria. Artemisinin-based combinations offer a new and potentially highly effective way tocounter drug resistance. Clinical trials conducted in African children have attested to the good tolerabilityof oral artesunate when combined with standard antimalarial drugs. The cure rates of thedifferent combinations were generally dependent on the degree of resistance to the companiondrug. They were high for amodiaquine-artesunate, variable for sulfadoxine/pyrimethamine-artesunate,and poor for chloroquine-artesunate.

  11. Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania

    OpenAIRE

    Balthazary Sakurani T; Malisa Allen L; Mutayoba Benezeth M; Mbugi Erasto V; Nyambo Thomas B; Mshinda Hassan

    2006-01-01

    Abstract Background Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods The genes for dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) were used as markers, to investigate parasite resistance to SP in 141 children aged less than 5 years. Parasite DNA was extracte...

  12. Tudor domain proteins in protozoan parasites and characterization of Plasmodium falciparum tudor staphylococcal nuclease.

    Science.gov (United States)

    Hossain, Manzar J; Korde, Reshma; Singh, Shivani; Mohmmed, Asif; Dasaradhi, P V N; Chauhan, V S; Malhotra, Pawan

    2008-04-01

    RNA-binding proteins play key roles in post-transcriptional regulation of gene expression. In eukaryotic cells, a multitude of RNA-binding proteins with several RNA-binding domains/motifs have been described. Here, we show the existence of two Tudor domain containing proteins, a survival of motor neuron (SMN)-like protein and a Staphylococcus aureus nuclease homologue referred to as TSN, in Plasmodium and other protozoan parasites. Activity analysis shows that Plasmodium falciparum TSN (PfTSN) possesses nuclease activity and Tudor domain is the RNA-binding domain. A specific inhibitor of micrococcal nucleases, 3',5'-deoxythymidine bisphosphate (pdTp) inhibits the nuclease as well as RNA-binding activities of the protein. PfTSN shows a predominant nuclear localization. Treatment of P. falciparum with pdTp, inhibited in vitro growth of both chloroquine-sensitive and chloroquine-resistant strains of P. falciparum, while a four fold concentration of pdTp did not have any significant effect on the mammalian cell line, Huh-7D12. Altogether, these results suggest that PfTSN is an essential enzyme in the parasite's life cycle.

  13. Effect of Farnesyltransferase Inhibitor R115777 on Mitochondria of Plasmodium falciparum.

    Science.gov (United States)

    Ha, Young Ran; Hwang, Bae-Geun; Hong, Yeonchul; Yang, Hye-Won; Lee, Sang Joon

    2015-08-01

    The parasite Plasmodium falciparum causes severe malaria and is the most dangerous to humans. However, it exhibits resistance to their drugs. Farnesyltransferase has been identified in pathogenic protozoa of the genera Plasmodium and the target of farnesyltransferase includes Ras family. Therefore, the inhibition of farnesyltransferase has been suggested as a new strategy for the treatment of malaria. However, the exact functional mechanism of this agent is still unknown. In addition, the effect of farnesyltransferase inhibitor (FTIs) on mitochondrial level of malaria parasites is not fully understood. In this study, therefore, the effect of a FTI R115777 on the function of mitochondria of P. falciparum was investigated experimentally. As a result, FTI R115777 was found to suppress the infection rate of malaria parasites under in vitro condition. It also reduces the copy number of mtDNA-encoded cytochrome c oxidase III. In addition, the mitochondrial membrane potential (ΔΨm) and the green fluorescence intensity of MitoTracker were decreased by FTI R115777. Chloroquine and atovaquone were measured by the mtDNA copy number as mitochondrial non-specific or specific inhibitor, respectively. Chloroquine did not affect the copy number of mtDNA-encoded cytochrome c oxidase III, while atovaquone induced to change the mtDNA copy number. These results suggest that FTI R115777 has strong influence on the mitochondrial function of P. falciparum. It may have therapeutic potential for malaria by targeting the mitochondria of parasites.

  14. 标准使用碳酸氢盐缓冲液进行恶性疟原虫培养和耐药性实验的研究%STANDARDISATION OF THE BICARBONATE BUFFER FORCULTIVATION OF PLASMODIUM FALCIPARUM AND EVALUATION OF DRUG RESISTANCE

    Institute of Scientific and Technical Information of China (English)

    何深一; 古钦民; 李瑛; 周怀瑜; 丛华; 赵群力

    2002-01-01

    目的变化使用碳酸氢盐缓冲液以探讨药物对恶性疟原虫的不同效果. 方法用[3H]次黄嘌呤摄取法检测抗疟药物效果. 结果不同二氧化碳浓度引起的pH变化对氯喹抑制恶性疟原虫的效果差异显著,而乙胺嘧啶抑制恶性疟原虫的效果,受二氧化碳浓度的影响不大. 结论进行恶性疟原虫培养和耐药性实验时应根据二氧化碳的使用浓度而选择适当的碳酸氢钠浓度.%Objective To investigate the differential effects of drugs on Plasmodium falciparum by changes in using bicarbonate buffer. Methods Effects of antimalarial drugs on parasite growth were assayed by monitoring uptake of [3H]hypoxanthine. Results The inhibitory effect of chloroquine, on P. falciparum (K1 strain) is affected by pH differences caused by various CO2 concentrations in the presence of a constant NaHCO3 concentration. In contrast, inhibition by pyrimethamine on the growth of the K1 strain was unaffected by different CO2 concentrations. Conclusion Conventional medium for P. falciparum culture should be modified with constant NaHCO3 according to the CO2 concentration to evaluate drug resistance of P. falciparum.

  15. Pooled deep sequencing of Plasmodium falciparum isolates: an efficient and scalable tool to quantify prevailing malaria drug-resistance genotypes.

    Science.gov (United States)

    Taylor, Steve M; Parobek, Christian M; Aragam, Nash; Ngasala, Billy E; Mårtensson, Andreas; Meshnick, Steven R; Juliano, Jonathan J

    2013-12-15

    Molecular surveillance for drug-resistant malaria parasites requires reliable, timely, and scalable methods. These data may be efficiently produced by genotyping parasite populations using second-generation sequencing (SGS). We designed and validated a SGS protocol to quantify mutant allele frequencies in the Plasmodium falciparum genes dhfr and dhps in mixed isolates. We applied this new protocol to field isolates from children and compared it to standard genotyping using Sanger sequencing. The SGS protocol accurately quantified dhfr and dhps allele frequencies in a mixture of parasite strains. Using SGS of DNA that was extracted and then pooled from individual isolates, we estimated mutant allele frequencies that were closely correlated to those estimated by Sanger sequencing (correlations, >0.98). The SGS protocol obviated most molecular steps in conventional methods and is cost saving for parasite populations >50. This SGS genotyping method efficiently and reproducibly estimates parasite allele frequencies within populations of P. falciparum for molecular epidemiologic studies.

  16. Chloroquine stimulates glucose uptake and glycogen synthase in muscle cells through activation of Akt.

    Science.gov (United States)

    Halaby, Marie-Jo; Kastein, Brandon K; Yang, Da-Qing

    2013-06-14

    Chloroquine is a pharmaceutical agent that has been widely used to treat patients with malaria. Chloroquine has also been reported to have hypoglycemic effects on humans and animal models of diabetes. Despite many previous studies, the mechanism responsible for its hypoglycemic effect is still unclear. Chloroquine was recently reported to be an activator of ATM, the protein deficient in the Ataxia-telagiectasia (A-T) disease. Since ATM is also known as an insulin responsive protein that mediates Akt activation, we tested the effect of chloroquine on the activity of Akt and its downstream targets. In L6 muscle cells treated with insulin and chloroquine, the phosphorylation of Akt and glucose uptake were dramatically increased compared to cells treated with insulin alone, suggesting that chloroquine is a potent activator of Akt and glucose uptake in these cells. We also found that the reduction of insulin-mediated Akt activity in muscle tissues of insulin resistant rats was partially reversed by chloroquine treatment. Moreover, insulin-mediated phosphorylation of glycogen synthase kinase-3β in L6 cells was greatly enhanced by chloroquine. A substantial decrease in phosphorylation of glycogen synthase was also observed in chloroquine-treated L6 cells, indicating enhanced activity of glycogen synthase. Taken together, our results not only show that chloroquine is a novel activator of Akt that stimulates glucose uptake and glycogen synthase, but also validate chloroquine as a potential therapeutic agent for patients with type 2 diabetes mellitus. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Blockage of spontaneous Ca2+ oscillation causes cell death in intraerythrocitic Plasmodium falciparum.

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    Masahiro Enomoto

    Full Text Available Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Resistance to antimalarial drugs is a challenging problem in malaria control. Clinical malaria is associated with the proliferation and development of Plasmodium parasites in human erythrocytes. Especially, the development into the mature forms (trophozoite and schizont of Plasmodium falciparum (P. falciparum causes severe malaria symptoms due to a distinctive property, sequestration which is not shared by any other human malaria. Ca(2+ is well known to be a highly versatile intracellular messenger that regulates many different cellular processes. Cytosolic Ca(2+ increases evoked by extracellular stimuli are often observed in the form of oscillating Ca(2+ spikes (Ca(2+ oscillation in eukaryotic cells. However, in lower eukaryotic and plant cells the physiological roles and the molecular mechanisms of Ca(2+ oscillation are poorly understood. Here, we showed the observation of the inositol 1,4,5-trisphospate (IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum without any exogenous extracellular stimulation by using live cell fluorescence Ca(2+ imaging. Intraerythrocytic P. falciparum exhibited stage-specific Ca(2+ oscillations in ring form and trophozoite stages which were blocked by IP(3 receptor inhibitor, 2-aminoethyl diphenylborinate (2-APB. Analyses of parasitaemia and parasite size and electron micrograph of 2-APB-treated P. falciparum revealed that 2-APB severely obstructed the intraerythrocytic maturation, resulting in cell death of the parasites. Furthermore, we confirmed the similar lethal effect of 2-APB on the chloroquine-resistant strain of P. falciparum. To our best knowledge, we for the first time showed the existence of the spontaneous Ca(2+ oscillation in Plasmodium species and clearly demonstrated that IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum is critical for the development

  18. Five-year surveillance of molecular markers of Plasmodium falciparum antimalarial drug resistance in Korogwe District, Tanzania: accumulation of the 581G mutation in the em>P. falciparum dihydropteroate synthase gene

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Lusingu, John P; Mmbando, Bruno;

    2009-01-01

    In January 2007, Tanzania replaced sulfadoxine-pyrimethamine (SP) with artemether-lumefantrine for treatment of uncomplicated malaria. This study examined the impact of widespread SP use on molecular markers of Plasmodium falciparum drug resistance in blood samples from persons living in two vill...

  19. Decreased prevalence of Plasmodium falciparum resistance markers to amodiaquine despite its wide scale use as ACT partner drug in Zanzibar

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    Fröberg Gabrielle

    2012-09-01

    Full Text Available Abstract Background Zanzibar has recently undergone a rapid decline in Plasmodium falciparum transmission following combined malaria control interventions with artemisinin-based combination therapy (ACT and integrated vector control. Artesunate-amodiaquine (ASAQ was implemented as first-line treatment for uncomplicated P. falciparum malaria in Zanzibar in 2003. Resistance to amodiaquine has been associated with the single nucleotide polymorphism (SNP alleles pfcrt 76T, pfmdr1 86Y, 184Y and 1246Y. An accumulation of these SNP alleles in the parasite population over time might threaten ASAQ efficacy. The aim of this study was to assess whether prolonged use of ASAQ as first-line anti-malarial treatment selects for P. falciparum SNPs associated with resistance to the ACT partner drug amodiaquine. Methods The individual as well as the combined SNP allele prevalence were compared in pre-treatment blood samples from patients with uncomplicated P. falciparum malaria enrolled in clinical trials conducted just prior to the introduction of ASAQ in 2002–2003 (n = 208 and seven years after wide scale use of ASAQ in 2010 (n = 122. Results There was a statistically significant decrease of pfcrt 76T (96–63%, pfmdr1 86Y (75–52%, 184Y (83–72%, 1246Y (28–16% and the most common haplotypes pfcrt/pfmdr1 TYYD (46–26% and TYYY (17–8%, while an increase of pfcrt/pfmdr1 KNFD (0.4–14% and KNYD (1–12%. Conclusions This is the first observation of a decreased prevalence of pfcrt 76T, pfmdr1 86Y, 184Y and 1246Y in an African setting after several years of extensive ASAQ use as first-line treatment for uncomplicated malaria. This may support sustained efficacy of ASAQ on Zanzibar, although it was unexpected considering that all these SNPs have previously been associated with amodiaquine resistance. The underlying factors of these results are unclear. Genetic dilution by imported P. falciparum parasites from mainland Tanzania, a de-selection by

  20. Comparative efficacy of chloroquine and sulphadoxine - pyrimethamine in pregnant women and children: a meta-analysis

    NARCIS (Netherlands)

    G.C. Kalanda; J. Hill; F.H. Verhoeff; B.J. Brabin

    2006-01-01

    Objective: To compare the efficacy of chloroquine and sulphadoxine-pyremethamine against Plasmodium falciparum infection in pregnant women and in children from the same endemic areas of Africa, with the aim of determining the level of correspondence in efficacy determinations in these two risk group

  1. Selection of drug resistance-mediating Plasmodium falciparum genetic polymorphisms by seasonal malaria chemoprevention in Burkina Faso.

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    Somé, Anyirékun Fabrice; Zongo, Issaka; Compaoré, Yves-Daniel; Sakandé, Souleymane; Nosten, François; Ouédraogo, Jean-Bosco; Rosenthal, Philip J

    2014-07-01

    Seasonal malaria chemoprevention (SMC), with regular use of amodiaquine plus sulfadoxine-pyrimethamine (AQ/SP) during the transmission season, is now a standard malaria control measure in the Sahel subregion of Africa. Another strategy under study is SMC with dihydroartemisinin plus piperaquine (DP). Plasmodium falciparum single nucleotide polymorphisms (SNPs) in P. falciparum crt (pfcrt), pfmdr1, pfdhfr, and pfdhps are associated with decreased response to aminoquinoline and antifolate antimalarials and are selected by use of these drugs. To characterize selection by SMC of key polymorphisms, we assessed 13 SNPs in P. falciparum isolated from children aged 3 to 59 months living in southwestern Burkina Faso and randomized to receive monthly DP or AQ/SP for 3 months in 2009. We compared SNP prevalence before the onset of SMC and 1 month after the third treatment in P. falciparum PCR-positive samples from 120 randomly selected children from each treatment arm and an additional 120 randomly selected children from a control group that did not receive SMC. The prevalence of relevant mutations was increased after SMC with AQ/SP. Significant selection was seen for pfcrt 76T (68.5% to 83.0%, P = 0.04), pfdhfr 59R (54.8% to 83.3%, P = 0.0002), and pfdhfr 108N (55.0% to 87.2%, P = 0.0001), with trends toward selection of pfmdr1 86Y, pfdhfr 51I, and pfdhps 437G. After SMC with DP, only borderline selection of wild-type pfmdr1 D1246 (mutant; 7.7% to 0%, P = 0.05) was seen. In contrast to AQ/SP, SMC with DP did not clearly select for known resistance-mediating polymorphisms. SMC with AQ/SP, but not DP, may hasten the development of resistance to components of this regimen. (This study has been registered at ClinicalTrials.gov under registration no. NCT00941785.).

  2. Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania

    NARCIS (Netherlands)

    Mbugi, E.V.; Mutayoba, B.M.; Malisa, A.L.; Balthazary, S.T.; Nyambo, T.B.; Mshinda, H.

    2006-01-01

    Background - Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods - The genes for

  3. Emerging drug resistance in Plasmodium falciparum: A review of well-characterized drug targets for novel antimalarial chemotherapy

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    Arnish Chakraborty

    2016-07-01

    Full Text Available Malaria is a life-threatening, highly infectious parasitic disease caused by the intracellular, protozoan parasites of Plasmodium species. The most severe form of the disease is caused by Plasmodium falciparum, an Apicomplexa parasite with a remarkable ability to acquire resistance to antimalarial medications. Drug resistant malaria is a serious public health concern in the tropical and sub-tropical nations of the world, rendering conventional antimalarial medication ineffective in several regions. Since an effective malaria vaccine is not yet available to the masses, novel antimalarial drugs need to be developed to control the disease on the face of ever increasing reports of drug resistance. The review acquaints the readers to the current situation of chemotherapy and drug resistance in malaria across the globe, the existing antimalarial medications in use, their mechanism of action and how the malaria parasite evolves resistance to them. The review also focuses on the identification, characterization and validation of a plethora of novel drug targets in Plasmodium falciparum from the oxidoreductase, hydrolase and protein kinase groups of enzymes. The work highlights the importance of these drug targets in Plasmodium biology and shines a spotlight on novel inhibitors which have the potential to be developed as future antimalarial drugs. The review ends with a detailed discussion on the prospects and challenges in antimalarial drug discovery.

  4. Resistência à mefloquina do tipo RIII em crianças com malária falciparum em Manaus, AM, Brasil RIII mefloquine resistance in children with falciparum malaria in Manaus, AM, Brazil

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    Elza Noronha

    2000-04-01

    Full Text Available Relata-se a ocorrência de resistência à mefloquina administrada na dose de 20mg/kg em 51 crianças com malária falciparum atendidas em centro de referência em Manaus, Brasil, no período de outubro a novembro de 1997. Todas as crianças foram avaliadas nos dias 3, 5, 7, 14, 21, 28 e 35 do tratamento, segundo critérios clínico e parasitológico. Foi encontrada uma incidência de resistência RIII de 5,9% (IC 95% variando de 1,5 a 17,2, a razão cura/resistência calculada foi 20:1 e cura/gravidade 62:1. Os dados chamam a atenção para a importância da resistência à mefloquina nesse grupo de crianças.We report the occurrence of resistance to mefloquine 20mg/day in 51 children with falciparum malaria treated, at reference center of Manaus, Brazil, from October to December 1997. All children were evaluated at day 3, 5, 7, 14, 21, 28 and 35 of treatment. Clinical and parasitological cure criteria were adopted. The incidence of RIII mefloquine resistance was 5.9% (IC 95% 1.5-17.2. The cure/resistance proportion was 20:1 and cure/severity was 62:1. These findings suggest the importance of mefloquine resistance within this group of children.

  5. A role for fetal hemoglobin and maternal immune IgG in infant resistance to Plasmodium falciparum malaria.

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    Chanaki Amaratunga

    Full Text Available BACKGROUND: In Africa, infant susceptibility to Plasmodium falciparum malaria increases substantially as fetal hemoglobin (HbF and maternal immune IgG disappear from circulation. During the first few months of life, however, resistance to malaria is evidenced by extremely low parasitemias, the absence of fever, and the almost complete lack of severe disease. This resistance has previously been attributed in part to poor parasite growth in HbF-containing red blood cells (RBCs. A specific role for maternal immune IgG in infant resistance to malaria has been hypothesized but not yet identified. METHODS AND FINDINGS: We found that P. falciparum parasites invade and develop normally in fetal (cord blood, CB RBCs, which contain up to 95% HbF. However, these parasitized CB RBCs are impaired in their binding to human microvascular endothelial cells (MVECs, monocytes, and nonparasitized RBCs--cytoadherence interactions that have been implicated in the development of high parasite densities and the symptoms of malaria. Abnormal display of the parasite's cytoadherence antigen P. falciparum erythrocyte membrane protein-1 (PfEMP-1 on CB RBCs accounts for these findings and is reminiscent of that on HbC and HbS RBCs. IgG purified from the plasma of immune Malian adults almost completely abolishes the adherence of parasitized CB RBCs to MVECs. CONCLUSIONS: Our data suggest a model of malaria protection in which HbF and maternal IgG act cooperatively to impair the cytoadherence of parasitized RBCs in the first few months of life. In highly malarious areas of Africa, an infant's contemporaneous expression of HbC or HbS and development of an immune IgG repertoire may effectively reconstitute the waning protective effects of HbF and maternal immune IgG, thereby extending the malaria resistance of infancy into early childhood.

  6. Chloroquine sensitizes biofilms of Candida albicans to antifungal azoles

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    Ravikumar Bapurao Shinde

    2013-08-01

    Full Text Available Biofilms formed by Candida albicans, a human pathogen, are known to be resistant to different antifungal agents. Novel strategies to combat the biofilm associated Candida infections like multiple drug therapy are being explored. In this study, potential of chloroquine to be a partner drug in combination with four antifungal agents, namely fluconazole, voriconazole, amphotericin B, and caspofungin, was explored against biofilms of C. albicans. Activity of various concentrations of chloroquine in combination with a particular antifungal drug was analyzed in a checkerboard format. Growth of biofilm in presence of drugs was analyzed by XTT-assay, in terms of relative metabolic activity compared to that of drug free control. Results obtained by XTT-metabolic assay were confirmed by scanning electron microscopy. The interactions between chloroquine and four antifungal drugs were determined by calculating fractional inhibitory concentration indices. Azole resistance in biofilms was reverted significantly (p < 0.05 in presence of 250 µg/mL of chloroquine, which resulted in inhibition of biofilms at very low concentrations of antifungal drugs. No significant alteration in the sensitivity of biofilms to caspofungin and amphotericin B was evident in combination with chloroquine. This study for the first time indicates that chloroquine potentiates anti-biofilm activity of fluconazole and voriconazole.

  7. The challenge of artemisinin resistance can only be met by eliminating Plasmodium falciparum malaria across the Greater Mekong subregion.

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    Smith Gueye, Cara; Newby, Gretchen; Hwang, Jimee; Phillips, Allison A; Whittaker, Maxine; MacArthur, John R; Gosling, Roly D; Feachem, Richard G A

    2014-01-01

    Artemisinin-based combinations are currently the most effective anti-malarials and, in addition to vector control, have led to significant declines in malaria morbidity and mortality. However, foci of artemisinin drug resistance have been identified in the Greater Mekong subregion (GMS) of the Asia Pacific, threatening the major gains made in malaria control and potentially creating a parasite pool that is more difficult to treat and eliminate. Efforts are underway to halt the spread of artemisinin resistance, including coordination of activities and funding, and identification of areas of suspected artemisinin resistance, now using a newly identified molecular marker. However, targeting resources to the containment of resistant parasites is likely inefficient and monitoring impact is challenging. A more sustainable solution is the rapid elimination of all Plasmodium falciparum parasites from the GMS. This strategy is more efficient for several reasons. First, a subregional strategy is in line with current commitment to elimination and will build upon the existing national political support for elimination as well as enhancing collaboration among countries. Second, the challenge of human mobility in the GMS is subregional in scope and requires a harmonized elimination strategy. Third, countries will need to improve and intensify malaria operations to reach elimination, and this will be a singular goal across the subregion. Rallying around the goal of P. falciparum elimination will not only utilize existing regional bodies to catalyze political and funding support, but will also leverage the funding already in place to achieve this subregional goal.

  8. A resistência à cloroquina e a busca de antimalariais entre as décadas de 1960 e 1980 Chloroquine resistance and the search for antimalarial drugs from the 1960s to 1980s

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    Ivone Manzali de Sá

    2011-06-01

    Full Text Available Em 1961, a Organização Mundial de Saúde (OMS reconheceu a resistência de cepas de Plasmodium à cloroquina, o que estimulou programas de pesquisa e desenvolvimento de novas drogas sintéticas que pudessem substituí-la no combate à malária. Analiso o processo de pesquisa científica relativo à produção de antimalariais nos contextos nacional e internacional, em especial nos EUA e na China, entre as décadas de 1960 e 1980. Pontos de convergência e distanciamento são marcados pelas dinâmicas próprias de cada país e pelos interesses envolvidos nas relações internacionais, em relação aos quais fica evidente o papel central da OMS.In 1961, the World Health Organization (WHO recognized that strains of Plasmodium are resistant to chloroquine, which consequently stimulated R&D programs aimed at finding new synthetic drugs to replace this substance in the fight against malaria. The article analyzes the process of scientific research into the production of antimalarial drugs from the 1960s to the 1980s in both the Brazilian and international contexts, especially the USA and China. The dynamics specific to each country and the interests tied to questions of international relations engendered points of agreement and of disagreement, with WHO playing a key role.

  9. Molecular diagnosis of resistance to antimalarial drugs during epidemics and in war zones.

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    Djimdé, Abdoulaye A; Dolo, Amagana; Ouattara, Amed; Diakité, Sira; Plowe, Christopher V; Doumbo, Ogobara K

    2004-08-15

    Plasmodium falciparum mutations pfcrt K76T and the dhfr/dhps "quintuple mutant" are molecular markers of resistance to chloroquine and sulfadoxine-pyrimethamine, respectively. During an epidemic of P. falciparum malaria in an area of political unrest in northern Mali, where standard efficacy studies have been impossible, we measured the prevalence of these markers in a cross-sectional survey. In 80% of cases of infection, pfcrt K76T was detected, but none of the cases carried the dhfr/dhps quintuple mutant. On the basis of these results, chloroquine was replaced by sulfadoxine-pyrimethamine in control efforts. This example illustrates how molecular markers for drug resistance can provide timely data that inform malaria-control policy during epidemics and other emergency situations.

  10. Genetic Resistance to Malaria Is Associated With Greater Enhancement of Immunoglobulin (Ig)M Than IgG Responses to a Broad Array of Plasmodium falciparum Antigens

    Science.gov (United States)

    Arama, Charles; Skinner, Jeff; Doumtabe, Didier; Portugal, Silvia; Tran, Tuan M.; Jain, Aarti; Traore, Boubacar; Doumbo, Ogobara K.; Davies, David Huw; Troye-Blomberg, Marita; Dolo, Amagana; Felgner, Philip L.; Crompton, Peter D.

    2015-01-01

    Background. People of the Fulani ethnic group are more resistant to malaria compared with genetically distinct ethnic groups, such as the Dogon people, in West Africa, and studies suggest that this resistance is mediated by enhanced antibody responses to Plasmodium falciparum antigens. However, prior studies measured antibody responses to <0.1% of P falciparum proteins, so whether the Fulani mount an enhanced and broadly reactive immunoglobulin (Ig)M and IgG response to P falciparum remains unknown. In general, little is known about the extent to which host genetics influence the overall antigen specificity of IgM and IgG responses to natural infections. Methods. In a cross-sectional study in Mali, we collected plasma from asymptomatic, age-matched Fulani (n = 24) and Dogon (n = 22) adults with or without concurrent P falciparum infection. We probed plasma against a protein microarray containing 1087 P falciparum antigens and compared IgM and IgG profiles by ethnicity. Results. We found that the breadth and magnitude of P falciparum-specific IgM and IgG responses were significantly higher in the malaria-resistant Fulani versus the malaria-susceptible Dogon, and, unexpectedly, P falciparum-specific IgM responses more strongly distinguished the 2 ethnic groups. Conclusions. These findings point to an underappreciated role for IgM in protection from malaria, and they suggest that host genetics may influence the antigen specificity of IgM and IgG responses to infection. PMID:26361633

  11. Genetic Resistance to Malaria Is Associated With Greater Enhancement of Immunoglobulin (Ig)M Than IgG Responses to a Broad Array of Plasmodium falciparum Antigens.

    Science.gov (United States)

    Arama, Charles; Skinner, Jeff; Doumtabe, Didier; Portugal, Silvia; Tran, Tuan M; Jain, Aarti; Traore, Boubacar; Doumbo, Ogobara K; Davies, David Huw; Troye-Blomberg, Marita; Dolo, Amagana; Felgner, Philip L; Crompton, Peter D

    2015-09-01

    Background.  People of the Fulani ethnic group are more resistant to malaria compared with genetically distinct ethnic groups, such as the Dogon people, in West Africa, and studies suggest that this resistance is mediated by enhanced antibody responses to Plasmodium falciparum antigens. However, prior studies measured antibody responses to Dogon (n = 22) adults with or without concurrent P falciparum infection. We probed plasma against a protein microarray containing 1087 P falciparum antigens and compared IgM and IgG profiles by ethnicity. Results.  We found that the breadth and magnitude of P falciparum-specific IgM and IgG responses were significantly higher in the malaria-resistant Fulani versus the malaria-susceptible Dogon, and, unexpectedly, P falciparum-specific IgM responses more strongly distinguished the 2 ethnic groups. Conclusions.  These findings point to an underappreciated role for IgM in protection from malaria, and they suggest that host genetics may influence the antigen specificity of IgM and IgG responses to infection.

  12. Treatment of severe falciparum malaria: quinine versus artesunate

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    Dipesh Patel

    2013-02-01

    Full Text Available Background: Malaria is the most important disease of human being. More than 40% of the world’s population is considered to be at risk of exposure of this disease. Malaria infection has been increasing over recent years due to combination of factors including increasing resistance of malarial parasite. Most of the strains of P. falciparum are now resistance to conventional drugs like chloroquine in many areas. The objective of this study was to compare the efficacy and safety of quinine and artesunate in treatment of P. falciparum malaria. Methods: This is hospital based prospective study, conducted amongst 35 randomly selected patients of severe P. falciparum malaria. Patients with any contraindications of either drug were excluded to avoid bias. Standard statistical tests were applied for qualitative as well as quantitative data. Results: As per the study end point results of difference of mortality in patients receiving either drug was not significant (p > 0.75, but difference in clinical parameters like fever clearance time (p <0.01, parasite clearance time (p < 0.001 and coma resolution time (p < 0.001 were significant among patients receiving artesunate. There were no any significant differences in adverse effects of both the drugs. Mortality was same in both arms taking either drug. Conclusions: Artesunate is as good as quinine in mortality aspect but artesunate is superior in fever clearance time (FCT & parasite clearance time (PCT. Coma resolution time is faster with quinine as compared to artesunate. There are no significant adverse effects of either drug. So artesunate is equivalent or superior for treatment for severe falciparum malaria. [Int J Basic Clin Pharmacol 2013; 2(1.000: 30-36

  13. Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania

    NARCIS (Netherlands)

    Mbugi, E.V.; Mutayoba, B.M.; Malisa, A.L.; Balthazary, S.T.; Nyambo, T.B.; Mshinda, H.

    2006-01-01

    Background - Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods - The genes for dih

  14. Exploring the folate pathway in Plasmodium falciparum.

    Science.gov (United States)

    Hyde, John E

    2005-06-01

    As in centuries past, the main weapon against human malaria infections continues to be intervention with drugs, despite the widespread and increasing frequency of parasite populations that are resistant to one or more of the available compounds. This is a particular problem with the lethal species of parasite, Plasmodium falciparum, which claims some two million lives per year as well as causing enormous social and economic problems. Amongst the antimalarial drugs currently in clinical use, the antifolates have the best defined molecular targets, namely the enzymes dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), which function in the folate metabolic pathway. The products of this pathway, reduced folate cofactors, are essential for DNA synthesis and the metabolism of certain amino acids. Moreover, their formation and interconversions involve a number of other enzymes that have not as yet been exploited as drug targets. Antifolates are of major importance as they currently represent the only inexpensive regime for combating chloroquine-resistant malaria, and are now first-line drugs in a number of African countries. Aspects of our understanding of this pathway and antifolate drug resistance are reviewed here, with a particular emphasis on approaches to analysing the details of, and balance between, folate biosynthesis by the parasite and salvage of pre-formed folate from exogenous sources.

  15. Antimalarial activity of potential inhibitors of Plasmodium falciparum lactate dehydrogenase enzyme selected by docking studies.

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    Julia Penna-Coutinho

    Full Text Available The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docking studies to select potential inhibitors of pLDH, which were then tested for antimalarial activity against P. falciparum in vitro and P. berghei malaria in mice. A virtual screening in DrugBank for analogs of NADH (an essential cofactor to pLDH and computational studies were undertaken, and the potential binding of the selected compounds to the PfLDH active site was analyzed using Molegro Virtual Docker software. Fifty compounds were selected based on their similarity to NADH. The compounds with the best binding energies (itraconazole, atorvastatin and posaconazole were tested against P. falciparum chloroquine-resistant blood parasites. All three compounds proved to be active in two immunoenzymatic assays performed in parallel using monoclonals specific to PfLDH or a histidine rich protein (HRP2. The IC(50 values for each drug in both tests were similar, were lowest for posaconazole (<5 µM and were 40- and 100-fold less active than chloroquine. The compounds reduced P. berghei parasitemia in treated mice, in comparison to untreated controls; itraconazole was the least active compound. The results of these activity trials confirmed that molecular docking studies are an important strategy for discovering new antimalarial drugs. This approach is more practical and less expensive than discovering novel compounds that require studies on human toxicology, since these compounds are already commercially available and thus approved for human use.

  16. Characterization of Plasmodium falciparum genes associated with drug resistance in Hodh Elgharbi, a malaria hotspot near Malian-Mauritanian border.

    Science.gov (United States)

    Ould Ahmedou Salem, Mohamed Salem; Mint Lekweiry, Khadijetou; Bouchiba, Houssem; Pascual, Aurelie; Pradines, Bruno; Ould Mohamed Salem Boukhary, Ali; Briolant, Sébastien; Basco, Leonardo K; Bogreau, Hervé

    2017-04-05

    A malaria hotspot in the southeastern region of Mauritania, near the Malian border, may hamper malaria control strategies. The objectives were to estimate the prevalence of genetic polymorphisms associated with drug resistance in Plasmodium falciparum isolates and establish baseline data. The study was conducted in two malaria-endemic areas in Hodh Elgharbi, situated in the Malian-Mauritanian border area. Blood samples were collected from symptomatic patients. Single nucleotide polymorphisms in Pfcrt, Pfmdr1, Pfdhfr, and Pfdhps were genotyped using PCR-restriction fragment length polymorphism, DNA sequencing and primer extension. The Pfmdr1 gene copy number was determined by real-time PCR. Of 280 P. falciparum-infected patients, 193 (68.9%) carried the Pfcrt 76T mutant allele. The Pfmdr1 86Y and 184F mutations were found in 61 (23.1%) of 264 isolates and 167 (67.6%) of 247 samples that were successfully genotyped, respectively. Pfmdr1 mutant alleles 1034C, 1042D and 1246Y were rarely observed. Of 102 P. falciparum isolates analysed, ten (9.8%) had more than one copy of Pfmdr1 gene. The prevalence of isolates harbouring at least triple mutant Pfdhfr 51I, 59R, 108 N/T was 42% (112/268), of which 42 (37.5%) had an additional Pfdhps 437G mutation. The Pfdhps 540E mutation was observed in four isolates (1.5%), including three associated with Pfdhfr triple mutant. Only two quintuple mutants (Pfdhfr-51I-59R-108N Pfdhps-437G-540E) were observed. The observed mutations in Pfdhfr, Pfdhps, Pfmdr1, and Pfcrt may jeopardize the future of seasonal malaria chemoprevention based on amodiaquine-sulfadoxine-pyrimethamine, intermittent preventive treatment for pregnant women using sulfadoxine-pyrimethamine, and treatment with artesunate-amodiaquine. Complementary studies should be carried out to document the distribution, origin and circulation of P. falciparum populations in this region and more widely in the country to assess the risk of the spread of resistance.

  17. Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax.

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    Eldin Talundzic

    Full Text Available Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species.

  18. Treatment of severe chloroquine poisoning.

    Science.gov (United States)

    Riou, B; Barriot, P; Rimailho, A; Baud, F J

    1988-01-07

    No therapy has been proved to be effective for patients with severe chloroquine poisoning, which is usually fatal. In a retrospective study of 51 cases, we found that ingestion of more than 5 g of chloroquine was an accurate predictor of a fatal outcome, and therefore chose this dose as the criterion for severe chloroquine poisoning. We selected as a control group 11 consecutive patients who had ingested more than 5 g of chloroquine between July 1983 and December 1985. We then undertook a prospective study to determine whether a better outcome could be obtained with immediate mechanical ventilation and the administration of diazepam and epinephrine. Eleven consecutive patients who ingested more than 5 g of chloroquine in 1986 received this combination therapy. Ten of these patients survived, whereas only one control had survived (P = 0.0003). There was no significant difference between the combination-therapy and control groups in age (29 +/- 3 vs. 27 +/- 2 years), amount of chloroquine ingested (7.5 +/- 0.5 vs. 8.5 +/- 0.8 g), systolic arterial pressure (74 +/- 2 vs. 74 +/- 3 mm Hg), or QRS duration (0.14 +/- 0.01 vs. 0.14 +/- 0.01 second). In our combination-therapy group, blood chloroquine levels ranged from 40 to 80 mumol per liter, whereas a literature search showed that no patient in whom blood levels were more than 25 mumol per liter had survived. These preliminary data suggest that combining early mechanical ventilation with the administration of diazepam and epinephrine may be effective in the treatment of severe chloroquine poisoning.

  19. Prevalence of multiple drug-resistant Plasmodium falciparum malaria cases in Northeast India.

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    Sharma, Jitendra; Khan, Siraj Ahmed; Soni, Monika; Dutta, Prafulla

    2017-01-01

    Two numbers of Plasmodium falciparum field isolates from Gossingpara, Runikhata area in Chirang district of Assam had shown multiple mutations in Pfcrt-dhfr-dhps gene (up to seven mutations: One mutation in Pfcrt gene, three mutations in Pfdhfr gene and three mutations in Pfdhps gene). Similarly, two cases in Bat camp, Miao area under Changlang district of Arunachal Pradesh had shown a total of eight mutations, of which one mutation in Pfcrt gene, three mutations in Pfdhfr gene, three mutations in Pfdhps gene and one mutation in PfATPase6 gene. One case in 3 Miles, Miao area of Changlang district has shown mutations in Pfcrt(one mutation), Pfdhfr(four mutations) and Pfdhps(three mutations) gene. These results indicated that there is an existence of multiple mutant P. falciparum malaria cases in northeastern region of India.

  20. In vitro inhibition of Plasmodium falciparum by pyrazofurin, an inhibitor of pyrimidine biosynthesis de novo.

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    Scott, H V; Gero, A M; O'Sullivan, W J

    1986-01-01

    The effect of pyrazofurin, an inhibitor of UMP synthesis, on Plasmodium falciparum growth in vitro has been studied. ID50 values (concentration of compound causing 50% inhibition of [3H]hypoxanthine incorporation) for the FCQ-27, FCI-1 and K-1 (chloroquine-resistant) isolates were 10 +/- 8.7, 6.4 +/- 5.3 and 6.3 +/- 0.5 microM, respectively. Comparative ID50 values for chloroquine were 13.5 +/- 4.2, 22.8 +/- 7.6 and 343 +/- 114 microM, respectively. Over the 48-h intraerythrocytic cycle of tightly synchronized parasites, pyrazofurin both reduced the parasitemia and retarded the maturation of trophozoites and schizonts. Addition of uracil or uridine to the in vitro culture did not decrease the anti-parasitic activity of pyrazofurin. Chloroquine reduced the parasitemia, but did not retard development of the remaining viable parasites. Pyrazofurin (20 microM) caused a 50% inhibition of parasite orotate phosphoribosyltransferase (E.C. 2.4.2.10) and, in the presence of adenosine kinase and ATP, a 73% inhibition of orotidine-5'-phosphate decarboxylase (E.C. 4.1.1.23).

  1. A novel flow cytometric hemozoin detection assay for real-time sensitivity testing of Plasmodium falciparum.

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    Maria Rebelo

    Full Text Available Resistance of Plasmodium falciparum to almost all antimalarial drugs, including the first-line treatment with artemisinins, has been described, representing an obvious threat to malaria control. In vitro antimalarial sensitivity testing is crucial to detect and monitor drug resistance. Current assays have been successfully used to detect drug effects on parasites. However, they have some limitations, such as the use of radioactive or expensive reagents or long incubation times. Here we describe a novel assay to detect antimalarial drug effects, based on flow cytometric detection of hemozoin (Hz, which is rapid and does not require any additional reagents. Hz is an optimal parasite maturation indicator since its amount increases as the parasite matures. Due to its physical property of birefringence, Hz depolarizes light, hence it can be detected using optical methods such as flow cytometry. A common flow cytometer was adapted to detect light depolarization caused by Hz. Synchronized in vitro cultures of P. falciparum were incubated for 48 hours with several antimalarial drugs. Analysis of depolarizing events, corresponding to parasitized red blood cells containing Hz, allowed the detection of parasite maturation. Moreover, chloroquine resistance and the inhibitory effect of all antimalarial drugs tested, except for pyrimethamine, could be determined as early as 18 to 24 hours of incubation. At 24 hours incubation, 50% inhibitory concentrations (IC50 were comparable to previously reported values. These results indicate that the reagent-free, real-time Hz detection assay could become a novel assay for the detection of drug effects on Plasmodium falciparum.

  2. [Erythrocyte polymorphism in Mali: epidemiology and resistance mechanisms against severe Plasmodium falciparum malaria].

    Science.gov (United States)

    Doumbo, Ogobara

    2007-01-01

    Homo sapiens and Plasmodium falciparum have co-evolved since the beginning of agriculture, 10,000 to 20,000 years ago. By domesticating plants and animals, humans linked their destiny to one of the main vectors of malaria, Anopheles gambiae sl complex. The biological interaction between these three species led to exchanges of genes and biochemical processes with significant mutual influence. Humans acquired mutations with selective protective advantages against serious and fatal forms of this hemosporidiosis. This is the case of hemoglobin S, hemoglobin C, hemoglobin E, thalassemias, ovalocytosis and G6PD deficiency, among others. Many epidemiological studies published since 1949 have shown a geographic link between malaria and certain erythrocyte polymorphisms. The link with hemoglobin C was discovered only recently, in 2000, initially in Mali in the Dogon population, then in Burkina Faso. Epidemiological and molecular and cellular biology studies done in Mali and elsewhere showed that the C and S alleles, and G6PD deficiency [A-], conferred significant protection against lethal forms of Plasmodium falciparum malaria. Molecular genetic studies, based on functional genomics, transcriptomics and proteomics, provided possible explanations. Advances in molecular biology and a better understanding of the immune mechanisms underlying this protection will hopefully lead to the development of effective second- and third-generation malaria vaccines. Epidemiological and fundamental research efforts have identified some of the mechanisms by which these erythrocyte polymorphisms protect against the most lethal hematozoan parasite, Plasmodium falciparum.

  3. Rapid increase of Plasmodium falciparum dhfr/dhps resistant haplotypes, after the adoption of sulphadoxine-pyrimethamine as first line treatment in 2002, in southern Mozambique

    DEFF Research Database (Denmark)

    Enosse, Sonia; Magnussen, Pascal; Abacassamo, Fatima

    2008-01-01

    BACKGROUND: In late 2002, the health authorities of Mozambique implemented sulphadoxine-pyrimethamine (SP)/amodiaquine (AQ) as first-line treatment against uncomplicated falciparum malaria. In 2004, this has been altered to SP/artesunate in line with WHO recommendations of using Artemisinin...... investigated the immediate impact of the change to SP on the frequency of SP and CQ resistance-related haplotypes in the Plasmodium falciparum genes Pfdhfr, Pfdhps and Pfcrt before and a year after the introduction of SP. METHODS: Samples were collected during two cross sectional surveys in early 2002 and 2003...

  4. Human IGF1 regulates midgut oxidative stress and epithelial homeostasis to balance lifespan and Plasmodium falciparum resistance in Anopheles stephensi.

    Directory of Open Access Journals (Sweden)

    Anna L Drexler

    2014-06-01

    Full Text Available Insulin and insulin-like growth factor signaling (IIS regulates cell death, repair, autophagy, and renewal in response to stress, damage, and pathogen challenge. Therefore, IIS is fundamental to lifespan and disease resistance. Previously, we showed that insulin-like growth factor 1 (IGF1 within a physiologically relevant range (0.013-0.13 µM in human blood reduced development of the human parasite Plasmodium falciparum in the Indian malaria mosquito Anopheles stephensi. Low IGF1 (0.013 µM induced FOXO and p70S6K activation in the midgut and extended mosquito lifespan, whereas high IGF1 (0.13 µM did not. In this study the physiological effects of low and high IGF1 were examined in detail to infer mechanisms for their dichotomous effects on mosquito resistance and lifespan. Following ingestion, low IGF1 induced phosphorylation of midgut c-Jun-N-terminal kinase (JNK, a critical regulator of epithelial homeostasis, but high IGF1 did not. Low and high IGF1 induced midgut mitochondrial reactive oxygen species (ROS synthesis and nitric oxide (NO synthase gene expression, responses which were necessary and sufficient to mediate IGF1 inhibition of P. falciparum development. However, increased ROS and apoptosis-associated caspase-3 activity returned to baseline levels following low IGF1 treatment, but were sustained with high IGF1 treatment and accompanied by aberrant expression of biomarkers for mitophagy, stem cell division and proliferation. Low IGF1-induced ROS are likely moderated by JNK-induced epithelial cytoprotection as well as p70S6K-mediated growth and inhibition of apoptosis over the lifetime of A. stephensi to facilitate midgut homeostasis and enhanced survivorship. Hence, mitochondrial integrity and homeostasis in the midgut, a key signaling center for IIS, can be targeted to coordinately optimize mosquito fitness and anti-pathogen resistance for improved control strategies for malaria and other vector-borne diseases.

  5. Comparing histopathology of ICR mice infected with chloroquine-sensitive and chloroquine-resistant strains of Plasmodium berghei%伯氏疟原虫氯喹敏感株和抗性株感染ICR鼠病理变化的比较研究

    Institute of Scientific and Technical Information of China (English)

    陈克强; 宋关鸿

    2001-01-01

    目的:研究伯氏疟原虫(Plasmodium berghei)的抗药性与致病力的关系。方法:比较伯氏疟原虫氯喹敏感株(N)和抗性株(RC)感染ICR鼠的肝、脾、脑、心、肺、肾等重要脏器病理组织学的动态变化。结果:N株感染后,小鼠肝、脾有较多的疟色素沉着,肺脏呈郁血性水肿;脑微血管充血和阻塞;各脏器呈急性炎症的病理变化特点。RC株感染后,小鼠肝、脾脏的病理组织学改变与原虫血症的变化有关。肺脏呈间质性肺炎,各脏器呈慢性增生性炎症的病理变化特点。结论:N株致病力较强,感染后引起宿主死亡的主要原因是感染疟原虫的红细胞对脑微血管内皮细胞的粘附,造成微血管阻塞;RC株致病力较弱,宿主的应答反应在感染早期可能是CD4+Th1相关的迟发型超敏炎症反应,而感染后期是CD4+T h2辅助作用下的抗体依赖性的免疫应答,并在疟原虫的最后清除上起着关键性的作用。%Objective: To understand the relationship between chloroquine resistance and the virulence of Plasmodium berghei. Met hods: Dynamic changes of histopathologic features of livers, spleens, brains, hearts, lungs and kidneys of mice infected with the chloroquine-sensitive (N) and the chloroquine-resistant (RC) strains of P. berghei were compared. Results: In mice infected with the N strain, deposition of heavy hemoz oin in livers and spleens, congestive edema in lungs, and congestion and embolis m in the brain capillaries were observed. The histopathologic features revealed ac ute inflammatory reaction. In mice infected with the RC strain, histopathologic variations of livers and spleens were associated with changes of parasitemia. In terstitial pneumonia was displayed in lungs. There were chronic histopathologic changes of the organs in the mice infected with RC strain. Conclusion: The mice infected by the N strain with potent virulence die due to adher ence of

  6. Emergence of sulfadoxine-pyrimethamine resistance in Indian isolates of Plasmodium falciparum in the last two decades.

    Science.gov (United States)

    Kumar, Amit; Moirangthem, Romilla; Gahlawat, Suresh Kumar; Chandra, Jagdish; Gupta, Purva; Valecha, Neena; Anvikar, Anup; Singh, Vineeta

    2015-12-01

    Genotyping the sulfadoxine-pyrimethamine (SP) genes will help in identifying the genes under drug selection and the emergence of resistance in dhfr and dhps genes. India is an important hotspot for studying malaria due to the immense climatic diversity prevalent in the country. The central and eastern parts of the country are most vulnerable sites where malaria cases are reported throughout the year. From different regions of the country 173 field isolates were genotyped at various loci in dhfr and dhps genes collected between 1994 and 2013. This encompasses the period before antimalarial resistance emerged and the period after the use of combination therapy was made mandatory in the country. We observed the rise of resistant SP alleles from very low frequencies (in the year 1994) to steadily rising (in the year 2000) and maintaining this increasing trend subsequently (in the year 2013) as shown by the sequence analysis of dhfr and dhps genes. This study assessed the prevalence of mutations in dhfr and dhps genes associated with SP resistance in samples indicative of increase in resistance levels of Plasmodium falciparum to SP even after the change in malaria treatment policy in the country.

  7. Highly active ozonides selected against drug resistant malaria

    Science.gov (United States)

    Lobo, Lis; de Sousa, Bruno; Cabral, Lília; Cristiano, Maria LS; Nogueira, Fátima

    2016-01-01

    Ever increasing multi-drug resistance by Plasmodium falciparum is creating new challenges in malaria chemotherapy. In the absence of licensed vaccines, treatment and prevention of malaria is heavily dependent on drugs. Potency, range of activity, safety, low cost and ease of administration are crucial issues in the design and formulation of antimalarials. We have tested three synthetic ozonides NAC89, LC50 and LCD67 in vitro and in vivo against multidrug resistant Plasmodium. In vitro, LC50 was at least 10 times more efficient inhibiting P. falciparum multidrug resistant Dd2 strain than chloroquine and mefloquine and as efficient as artemisinin (ART), artesunate and dihydroartemisinin. All three ozonides showed high efficacy in clearing parasitaemia in mice, caused by multi-drug resistant Plasmodium chabaudi strains, by subcutaneous administration, demonstrating high efficacy in vivo against ART and artesunate resistant parasites. PMID:27276364

  8. Highly active ozonides selected against drug resistant malaria

    Directory of Open Access Journals (Sweden)

    Lis Lobo

    2016-01-01

    Full Text Available Ever increasing multi-drug resistance by Plasmodium falciparum is creating new challenges in malaria chemotherapy. In the absence of licensed vaccines, treatment and prevention of malaria is heavily dependent on drugs. Potency, range of activity, safety, low cost and ease of administration are crucial issues in the design and formulation of antimalarials. We have tested three synthetic ozonides NAC89, LC50 and LCD67 in vitro and in vivo against multidrug resistant Plasmodium. In vitro, LC50 was at least 10 times more efficient inhibiting P. falciparum multidrug resistant Dd2 strain than chloroquine and mefloquine and as efficient as artemisinin (ART, artesunate and dihydroartemisinin. All three ozonides showed high efficacy in clearing parasitaemia in mice, caused by multi-drug resistant Plasmodium chabaudi strains, by subcutaneous administration, demonstrating high efficacy in vivo against ART and artesunate resistant parasites.

  9. Malarial parasite diversity in chimpanzees: the value of comparative approaches to ascertain the evolution of Plasmodium falciparum antigens.

    Science.gov (United States)

    Pacheco, M Andreína; Cranfield, Michael; Cameron, Kenneth; Escalante, Ananias A

    2013-09-17

    Plasmodium falciparum shares its most recent common ancestor with parasites found in African apes; these species constitute the so-called Laverania clade. In this investigation, the evolutionary history of Plasmodium lineages found in chimpanzees (Pan troglodytes) was explored. Here, the remainders of 74 blood samples collected as part of the chimpanzees' routine health examinations were studied. For all positive samples with parasite lineages belonging to the Laverania clade, the complete mitochondrial genome (mtDNA), the gene encoding dihydrofolate reductase-thymidylate synthase (dhfr-ts), the chloroquine resistance transporter (Pfcrt), the circumsporozoite protein (csp), merozoite surface protein 2 (msp2), and the DBL-1 domain from var2CSA were amplified, cloned, and sequenced. Other Plasmodium species were included in the mtDNA, dhfr-ts, and csp analyses. Phylogenetic and evolutionary genetic analyses were performed, including molecular clock analyses on the mtDNA. Nine chimpanzees were malaria positive (12.2%); four of those infections were identified as P. falciparum, two as a Plasmodium reichenowi-like parasite or Plasmodium sp., one as Plasmodium gaboni, and two as Plasmodium malariae. All P. falciparum isolates were resistant to chloroquine indicating that the chimpanzees acquired such infections from humans in recent times. Such findings, however, are not sufficient for implicating chimpanzees as an animal reservoir for P. falciparum.Timing estimates support that the Laverania clade has co-existed with hominids for a long-period of time. The proposed species P. gaboni, Plasmodium billbrayi, and Plasmodium billcollinsi are monophyletic groups supporting that they are indeed different species.An expanded CSP phylogeny is presented, including all the Laverania species and other malarial parasites. Contrasting with other Plasmodium, the Laverania csp exhibits great conservation at the central tandem repeat region. Msp2 and var2CSA, however, show extended

  10. Identification and functional validation of the novel antimalarial resistance locus PF10_0355 in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Daria Van Tyne

    2011-04-01

    Full Text Available The Plasmodium falciparum parasite's ability to adapt to environmental pressures, such as the human immune system and antimalarial drugs, makes malaria an enduring burden to public health. Understanding the genetic basis of these adaptations is critical to intervening successfully against malaria. To that end, we created a high-density genotyping array that assays over 17,000 single nucleotide polymorphisms (∼ 1 SNP/kb, and applied it to 57 culture-adapted parasites from three continents. We characterized genome-wide genetic diversity within and between populations and identified numerous loci with signals of natural selection, suggesting their role in recent adaptation. In addition, we performed a genome-wide association study (GWAS, searching for loci correlated with resistance to thirteen antimalarials; we detected both known and novel resistance loci, including a new halofantrine resistance locus, PF10_0355. Through functional testing we demonstrated that PF10_0355 overexpression decreases sensitivity to halofantrine, mefloquine, and lumefantrine, but not to structurally unrelated antimalarials, and that increased gene copy number mediates resistance. Our GWAS and follow-on functional validation demonstrate the potential of genome-wide studies to elucidate functionally important loci in the malaria parasite genome.

  11. Effects of pyrimethamine-sulphadoxine, chloroquine plus chlorpheniramine, and amodiaquine plus pyrimethamine-sulphadoxine on gametocytes during and after treatment of acute, uncomplicated malaria in children

    Directory of Open Access Journals (Sweden)

    A Sowunmi

    2006-12-01

    Full Text Available The effects of pyrimethamine-sulphadoxine (PS, chloroquine plus chlorpheniramine, a H1 receptor antagonist that reverses chloroquine resistance in Plasmodium falciparum in vitro and in vivo (CQCP, and amodiaquine plus pyrimethamine-sulphadoxine (AQPS on gametocyte production were evaluated in 157 children with acute, symptomatic, uncomplicated falciparum malaria who were treated with these drugs. PS was significantly less effective than CQCP or AQPS at clearing asexual parasitaemia or other symptoms of malaria. Gametocyte carriage on days 3, 7, and 14 were significantly higher in those treated with PS. The ratio of the density (per µl blood of peripheral young gametocyte (PYG, that is, < stage III to peripheral mature gametocyte (PMG, that is, stage IV and V, an index of continuing generation of gametocytes, rose to 1 by day 7 of treatment in those treated with PS, but remained consistently below 1 in the other treatment groups. PYG-PMG density ratio increased significantly from day 0-14 in those treated with PS and CQCP (chi2 = 76, P = 0.000001 and chi2 = 42.2, P = 0.00001, respectively but decreased significantly in those treated with AQPS (chi2 = 53.2, P = 0.000001. Both PS-sensitive and -resistant infections generated PYG (18 of 29 vs 13 of 20, chi2 = 0.04, P = 0.93 but PYG was present only in those with resistant response to CQCP. Combination of PS with amodiaquine (AQ, that is, (AQPS resulted in less production of PYG, but in this setting, PYG was not indicative of response to AQPS. These data indicate that PS enhanced production or release of young gametocytes when used alone, but generated less young gametocytes when used in combination with AQ. PYG may be used as an indicator of response to CQCP but not PS or PS-based combination drugs.

  12. Chloroquine psychosis: a chemical psychosis?

    Science.gov (United States)

    Mohan, D; Mohandas, E; Rajat, R

    1981-11-01

    Psychotic states are mimicked by the use of many drugs including amphetamines, cannabis, lysergic acid diethylamide, psilocybin, mescaline, isoniazid, and L-dopa. A paranoid psychotic picture in a clear sensorium is characteristic of amphetamine psychosis. In developing countries, malaria among other diseases is a frequent indicator of chloroquine administration. The present communication reports a series of chloroquine-induced psychosis in a clear sensorium simulating affective illness, such as mania, mixed affective states, or depression. The psychosis disappeared after cessation of the drug, combined with or without the use of low dosage phenothiazines in excited patients. From our cases, two types of presentation of chloroquine psychosis could be seen: (1) psychic with clear sensorium, mood changes, alteration in motor activity, delusions, and hallucinations; and (2) psycho-organic with clouded sensorium, disorientation, and fleeting hallucinations. The precise nature of the mechanism of the psychosis is not clear because of the limited number of reported cases.

  13. Disagreement in genotyping results of drug resistance alleles of the Plasmodium falciparum dihydrofolate reductase (Pfdhfr) gene by allele-specific PCR (ASPCR) assays and Sanger sequencing.

    Science.gov (United States)

    Sharma, Divya; Lather, Manila; Dykes, Cherry L; Dang, Amita S; Adak, Tridibes; Singh, Om P

    2016-01-01

    The rapid spread of antimalarial drug resistance in Plasmodium falciparum over the past few decades has necessitated intensive monitoring of such resistance for an effective malaria control strategy. P. falciparum dihydropteroate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr) genes act as molecular markers for resistance against the antimalarial drugs sulphadoxine and pyrimethamine, respectively. Resistance to pyrimethamine which is used as a partner drug in artemisinin combination therapy (ACT) is associated with several mutations in the Pfdhfr gene, namely A16V, N51I, C59R, S108N/T and I164L. Therefore, routine monitoring of Pfdhfr-drug-resistant alleles in a population may help in effective drug resistance management. Allele-specific PCR (ASPCR) is one of the commonly used methods for molecular genotyping of these alleles. In this study, we genotyped 55 samples of P. falciparum for allele discrimination at four codons of Pfdhfr (N51, C59, S108 and I164) by ASPCR using published methods and by Sanger's DNA sequencing method. We found that the ASPCR identified a significantly higher number of mutant alleles as compared to the DNA sequencing method. Such discrepancies arise due to the non-specificity of some of the allele-specific primer sets and due to the lack of sensitivity of Sanger's DNA sequencing method to detect minor alleles present in multiple clone infections. This study reveals the need of a highly specific and sensitive method for genotyping and detecting minor drug-resistant alleles present in multiple clonal infections.

  14. Plasmodium prevalence and artemisinin-resistant falciparum malaria in Preah Vihear Province, Cambodia: a cross-sectional population-based study.

    Science.gov (United States)

    Bosman, Philippe; Stassijns, Jorgen; Nackers, Fabienne; Canier, Lydie; Kim, Nimol; Khim, Saorin; Alipon, Sweet C; Chuor Char, Meng; Chea, Nguon; Dysoley, Lek; Van den Bergh, Rafael; Etienne, William; De Smet, Martin; Ménard, Didier; Kindermans, Jean-Marie

    2014-10-06

    Intensified efforts are urgently needed to contain and eliminate artemisinin-resistant Plasmodium falciparum in the Greater Mekong subregion. Médecins Sans Frontières plans to support the Ministry of Health in eliminating P. falciparum in an area with artemisinin resistance in the north-east of Cambodia. As a first step, the prevalence of Plasmodium spp. and the presence of mutations associated with artemisinin resistance were evaluated in two districts of Preah Vihear Province. A cross-sectional population-based study using a two-stage cluster sampling was conducted in the rural districts of Chhaeb and Chey Saen, from September to October 2013. In each district, 30 clusters of 10 households were randomly selected. In total, blood samples were collected for 1,275 participants in Chhaeb and 1,224 in Chey Saen. Prevalence of Plasmodium spp. was assessed by PCR on dried blood spots. Plasmodium falciparum positive samples were screened for mutations in the K13-propeller domain gene (PF3D7_1343700). The prevalence of Plasmodium spp. was estimated at 1.49% (95% CI 0.71-3.11%) in Chhaeb and 2.61% (95% CI 1.45-4.66%) in Chey Saen. Twenty-seven samples were positive for P. falciparum, giving a prevalence of 0.16% (95% CI 0.04-0.65) in Chhaeb and 2.04% (95% CI 1.04-3.99%) in Chey Saen. Only 4.0% of the participants testing positive presented with fever or history of fever. K13-propeller domain mutant type alleles (C580Y and Y493H) were found, only in Chey Saen district, in seven out of 11 P. falciparum positive samples with enough genetic material to allow testing. The overall prevalence of P. falciparum was low in both districts but parasites presenting mutations in the K13-propeller domain gene, strongly associated with artemisinin-resistance, are circulating in Chey Saen.The prevalence might be underestimated because of the absentees - mainly forest workers - and the workers of private companies who were not included in the study. These results confirm the need to

  15. Lack of artemisinin resistance in Plasmodium falciparum in northwest Benin after 10 years of use of artemisinin-based combination therapy

    Directory of Open Access Journals (Sweden)

    Ogouyèmi-Hounto Aurore

    2016-01-01

    Full Text Available Aim: In Benin, artemisinin-based combination therapy (ACT has been recommended as the first-line treatment for uncomplicated Plasmodium falciparum malaria since 2004. The emergence in Southeast Asia of parasites that are resistant to artemisinins poses a serious threat to global control of this disease. The presence of artemisinin resistance genotypes in parasite populations in Benin is currently unknown. The present study investigated the prevalence of relevant K13-propeller gene polymorphisms in parasite isolates from the north-western region of Benin. Method: Plasmodium falciparum isolates were collected from children with a confirmed diagnosis of malaria aged 6 months to 5 years in two towns, Cobly and Djougou, in the north-western part of Benin. The study was conducted during the rainy season from July to November 2014 in local health facilities. The K13-propeller gene was amplified in parasite isolates using nested PCR and subsequently sequenced. Results: A total of 108 children were recruited into the study. The efficiency of amplification reactions was 72% (78/108. The propeller domain of the K13 gene was successfully sequenced in 78 P. falciparum isolates; all of them were wild type with no polymorphisms detectable. Conclusion: The absence of mutations in the K13 gene indicates that P. falciparum parasite populations in the study area are still fully susceptible to artemisinins.

  16. A Plasmodium falciparum Homologue of Plasmodium vivax Reticulocyte Binding Protein (PvRBP1) Defines a Trypsin-resistant Erythrocyte Invasion Pathway

    Science.gov (United States)

    Rayner, Julian C.; Vargas-Serrato, Esmeralda; Huber, Curtis S.; Galinski, Mary R.; Barnwell, John W.

    2001-01-01

    Invasion of erythrocytes by Plasmodium merozoites is an intricate process involving multiple receptor-ligand interactions. The glycophorins and an unknown trypsin sensitive factor are all erythrocyte receptors used during invasion by the major human pathogen Plasmodium falciparum. However, only one erythrocyte receptor, Glycophorin A, has a well-established cognate parasite ligand, the merozoite protein erythrocyte binding antigen-175 (EBA-175). The involvement of several other parasite proteins during invasion have been proposed, but no direct evidence links them with a specific invasion pathway. Here we report the identification and characterization of P. falciparum normocyte binding protein 1 (PfNBP1), an ortholog of Plasmodium vivax reticulocyte binding protein-1. PfNBP1 binds to a sialic acid dependent trypsin-resistant receptor on the erythrocyte surface that appears to be distinct from known invasion receptors. Antibodies against PfNBP1 can inhibit invasion of trypsinized erythrocytes and two P. falciparum strains that express truncated PfNBP1 are unable to invade trypsinized erythrocytes. One of these strain, 7G8, also does not invade Glycophorin B–negative erythrocytes. PfNBP1 therefore defines a novel trypsin-resistant invasion pathway and adds a level of complexity to current models for P. falciparum erythrocyte invasion. PMID:11733572

  17. Transgenic Anopheles stephensi coexpressing single-chain antibodies resist Plasmodium falciparum development.

    Science.gov (United States)

    Isaacs, Alison T; Jasinskiene, Nijole; Tretiakov, Mikhail; Thiery, Isabelle; Zettor, Agnès; Bourgouin, Catherine; James, Anthony A

    2012-07-10

    Anopheles stephensi mosquitoes expressing m1C3, m4B7, or m2A10 single-chain antibodies (scFvs) have significantly lower levels of infection compared to controls when challenged with Plasmodium falciparum, a human malaria pathogen. These scFvs are derived from antibodies specific to a parasite chitinase, the 25 kDa protein and the circumsporozoite protein, respectively. Transgenes comprising m2A10 in combination with either m1C3 or m4B7 were inserted into previously-characterized mosquito chromosomal "docking" sites using site-specific recombination. Transgene expression was evaluated at four different genomic locations and a docking site that permitted tissue- and sex-specific expression was researched further. Fitness studies of docking site and dual scFv transgene strains detected only one significant fitness cost: adult docking-site males displayed a late-onset reduction in survival. The m4B7/m2A10 mosquitoes challenged with P. falciparum had few or no sporozoites, the parasite stage infective to humans, in three of four experiments. No sporozoites were detected in m1C3/m2A10 mosquitoes in challenge experiments when both genes were induced at developmentally relevant times. These studies support the conclusion that expression of a single copy of a dual scFv transgene can completely inhibit parasite development without imposing a fitness cost on the mosquito.

  18. High prevalence of mutations in the dihydrofolate reductase gene of Plasmodium falciparum in isolates from Tanzania without evidence of an association to clinical sulfadoxine/pyrimethamine resistance

    DEFF Research Database (Denmark)

    Jelinek, T; Rønn, A M; Curtis, J;

    1997-01-01

    Recently the efficacy of sulfadoxine/pyrimethamine (S/P) in treatment of uncomplicated falciparum malaria in Tanzania has been seriously compromised by the development of resistance. The occurrence of active site mutations in the Plasmodium falciparum gene sequence coding for dihydrofolate...... resistance to the S/P combination. It has been proposed earlier that sulfadoxine could itself act on DHFR, because of a false dihydrofolate produced by drug metabolism through DHPS and dihydrofolate synthase. The results of this treatment study suggest that such a possibility is unlikely....... reductase (DHFR) is known to confer resistance to pyrimethamine. This study investigates the occurrence of these mutations in infected blood samples taken from Tanzanian children before treatment with S/P and their relationship to parasite breakthrough by day 7. The results confirm the occurrence of one...

  19. Absence of the human CYP2C8*3 allele in Ugandan children exposed to Plasmodium falciparum malaria.

    Science.gov (United States)

    Paganotti, Giacomo Maria; Cosentino, Valentina; Russo, Gianluca; Tabacchi, Francesca; Gramolelli, Silvia; Coluzzi, Mario; Romano, Rita

    2014-10-01

    Study of host pharmacogenetics can improve our knowledge of mechanisms of drug resistance selection and spread. This issue has recently been addressed with respect to chloroquine and amodiaquine in malaria endemic areas of West and East Africa. Here we report, from surveys performed in two different areas of Uganda, that the human CYP2C8*3 allele, which had been reported to be strongly associated with parasite drug resistance in Zanzibar, is absent, being a marker of genetic admixture of the Zanzibari population with a Caucasoid component. Moreover, a retrospective analysis of CYP2C8*2 and the Plasmodium falciparum drug resistant pfmdr1 86Y allele does not show any association, which may be related to the high level of drug resistance.

  20. Epidemiology and resistance to chioroquine of Plasmodium falciparum and IPT research prowess.%恶性疟原虫对氯喹抗药性的流行病学及IPT的研究进展

    Institute of Scientific and Technical Information of China (English)

    刘若冰; 吴兰鸥; 杨照青

    2011-01-01

    Chloroquine,first discovered and used as the most effective antimalarial drug,in large-scale treatment for malaria,Hasmodium fcdciparum gradually give rise to resistance to chloroquine and resistant strains of insects spread rapidly around the world. In recent years, studies have shown that chloroquine can be used for periodic preventive treatment of malaria (intermittent preventive treatment,IPT). This article reviews the epidemiology of chloroquine resistance,drug resistance mechanisms and IPT of new progress.%氯喹作为最早发现和使用的最为有效的抗疟药物,在大规模用于疟疾治疗后,恶性疟原虫陆续对它产生抗药性,并且抗性虫株在全球范围迅速播散.近年来的研究显示氯喹可用于疟疾的周期性预防疗法.本文综述了氯喹抗药性流行病学的研究,抗药性产生的机制及周期性预防疗法(Intermittent preventive treatment,IPT)的研究新进展.

  1. Fine-scale genetic characterization of Plasmodium falciparum chromosome 7 encompassing the antigenic var and the drug-resistant pfcrt genes

    Indian Academy of Sciences (India)

    Ruchi Bajaj; Sujata Mohanty; A. P. Dash; Aparup Das

    2008-04-01

    The fact that malaria is still an uncontrolled disease is reflected by the genetic organization of the parasite genome. Efforts to curb malaria should begin with proper understanding of the mechanism by which the parasites evade human immune system and evolve resistance to different antimalarial drugs. We have initiated such a study and presented herewith the results from the in silico understanding of a seventh chromosomal region of the malarial parasite Plasmodium falciparum encompassing the antigenic var genes (coding pfemp1) and the drug-resistant gene pfcrt located at a specified region of the chromosome 7. We found 60 genes of various functions and lengths, majority (61.67%) of them were performing known functions. Almost all the genes have orthologs in other four species of Plasmodium, of which P. chabaudi seems to be the closest to P. falciparum. However, only two genes were found to be paralogous. Interestingly, the drug-resistant gene, pfcrt was found to be surrounded by seven genes coding for several CG proteins out of which six were reported to be responsible for providing drug resistance to P. vivax. The intergenic regions, in this specified region were generally large in size, majority (73%) of them were of more than 500 nucleotide bp length. We also designed primers for amplification of 21 noncoding DNA fragments in the whole region for estimating genetic diversity and inferring the evolutionary history of this region of P. falciparum genome.

  2. Antibodies from malaria-exposed pregnant women recognize trypsin resistant epitopes on the surface of Plasmodium falciparum-infected erythrocytes selected for adhesion to chondroitin sulphate A

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    Staalsoe Trine

    2004-09-01

    Full Text Available Abstract Background The ability of Plasmodium falciparum-infected erythrocytes to adhere to the microvasculature endothelium is thought to play a causal role in malaria pathogenesis. Cytoadhesion to endothelial receptors is generally found to be highly sensitive to trypsinization of the infected erythrocyte surface. However, several studies have found that parasite adhesion to placental receptors can be markedly less sensitive to trypsin. This study investigates whether chondroitin sulphate A (CSA binding parasites express trypsin-resistant variant surface antigens (VSA that bind female-specific antibodies induced as a result of pregnancy associated malaria (PAM. Methods Fluorescence activated cell sorting (FACS was used to measure the levels of adult Scottish and Ghanaian male, and Ghanaian pregnant female plasma immunoglobulin G (IgG that bind to the surface of infected erythrocytes. P. falciparum clone FCR3 cultures were used to assay surface IgG binding before and after selection of the parasite for adhesion to CSA. The effect of proteolytic digestion of parasite erythrocyte surface antigens on surface IgG binding and adhesion to CSA and hyaluronic acid (HA was also studied. Results P. falciparum infected erythrocytes selected for adhesion to CSA were found to express trypsin-resistant VSA that are the target of naturally acquired antibodies from pregnant women living in a malaria endemic region of Ghana. However in vitro adhesion to CSA and HA was relatively trypsin sensitive. An improved labelling technique for the detection of VSA expressed by CSA binding isolates has also been described. Conclusion The VSA expressed by CSA binding P. falciparum isolates are currently considered potential targets for a vaccine against PAM. This study identifies discordance between the trypsin sensitivity of CSA binding and surface recognition of CSA selected parasites by serum IgG from malaria exposed pregnant women. Thus, the complete molecular

  3. Physical factors affecting chloroquine binding to melanin.

    Science.gov (United States)

    Schroeder, R L; Pendleton, P; Gerber, J P

    2015-10-01

    Chloroquine is an antimalarial drug but is also prescribed for conditions such as rheumatoid arthritis. Long-term users risk toxic side effects, including retinopathy, thought to be caused by chloroquine accumulation on ocular melanin. Although the binding potential of chloroquine to melanin has been investigated previously, our study is the first to demonstrate clear links between chloroquine adsorption by melanin and system factors including temperature, pH, melanin type, and particle size. In the current work, two Sepia melanins were compared with bovine eye as a representative mammalian melanin. Increasing the surface anionic character due to a pH change from 4.7 to 7.4 increased each melanin's affinity for chloroquine. Although the chloroquine isotherms exhibited an apparently strong interaction with each melanin, isosteric heat analysis indicated a competitive interaction. Buffer solution cations competed effectively at low surface coverage; chloroquine adsorption occurs via buffer cation displacement and is promoted by temperature-influenced secondary structure swelling.

  4. Blood shizonticidal activities of phenazines and naphthoquinoidal compounds against Plasmodium falciparum in vitro and in mice malaria studies

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    Nicolli Bellotti de Souza

    2014-08-01

    Full Text Available Due to the recent advances of atovaquone, a naphthoquinone, through clinical trials as treatment for malarial infection, 19 quinone derivatives with previously reported structures were also evaluated for blood schizonticide activity against the malaria parasite Plasmodium falciparum. These compounds include 2-hydroxy-3-methylamino naphthoquinones (2-9, lapachol (10, nor-lapachol (11, iso-lapachol (12, phthiocol (13 and phenazines (12-20. Their cytotoxicities were also evaluated against human hepatoma and normal monkey kidney cell lines. Compounds 2 and 5 showed the highest activity against P. falciparum chloroquine-resistant blood-stage parasites (clone W2, indicated by their low inhibitory concentration for 50% (IC50 of parasite growth. The therapeutic potential of the active compounds was evaluated according to the selectivity index, which is a ratio of the cytotoxicity minimum lethal dose which eliminates 50% of cells and the in vitro IC50. Naphthoquinones 2 and 5, with activities similar to the reference antimalarial chloroquine, were also active against malaria in mice and suppressed parasitaemia by more than 60% in contrast to compound 11 which was inactive. Based on their in vitro and in vivo activities, compounds 2 and 5 are considered promising molecules for antimalarial treatment and warrant further study.

  5. Current status of artemisinin-resistant falciparum malaria in South Asia: a randomized controlled artesunate monotherapy trial in Bangladesh.

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    Peter Starzengruber

    Full Text Available OBJECTIVE: Recent reports indicate that first cases of genuine artemisinin resistance have already emerged along the Thai-Cambodian border. The main objective of this trial was to track the potential emergence of artemisinin resistance in Bangladesh, which in terms of drug resistance forms a gateway to the Indian subcontinent. METHODS: We conducted an open-label, randomized, controlled 42-day clinical trial in Southeastern Bangladesh to investigate the potential spread of clinical artemisinin resistance from Southeast Asia. A total of 126 uncomplicated falciparum malaria patients were randomized to one of 3 treatment arms (artesunate monotherapy with 2 or 4 mg/kg/day once daily or quinine plus doxycycline TID for 7 days. Only cases fulfilling a stringent set of criteria were considered as being artemisinin-resistant. FINDINGS: The 28-day and 42-day cure rates in the artesunate monotherapy (2 and 4 mg/kg and quinine/doxycyline arms were 97.8% (95% confidence interval, CI: 87.8-99.8%, 100% (95% CI: 91.1-100%, and 100% (95% CI: 83.4-100%, respectively. One case of re-infection was seen in the artesunate high dose arm, and a single case of recrudescence was observed in the low dose group on day 26. No differences in median parasite and fever clearance times were found between the 2 artesunate arms (29.8 h and 17.9 h vs. 29.5 h and 19.1 h. Not a single case fulfilled our criteria of artemisinin resistance. Parasite clearance times were considerably shorter and ex vivo results indicate significantly higher susceptibility (50% inhibitory concentration for dihydroartemisinin was 1.10 nM; 95% CI: 0.95-1.28 nM to artemisinins as compared to SE-Asia. CONCLUSION: There is currently no indication that artemisinin resistance has reached Bangladesh. However, the fact that resistance has recently been reported from nearby Myanmar indicates an urgent need for close monitoring of artemisinin resistance in the region. TRIAL REGISTRATION: ClinicalTrials.gov NCT

  6. In vitro amodiaquine resistance and its association with mutations in pfcrt and pfmdr1 genes of Plasmodium falciparum isolates from Nigeria.

    Science.gov (United States)

    Folarin, O A; Bustamante, C; Gbotosho, G O; Sowunmi, A; Zalis, M G; Oduola, A M J; Happi, C T

    2011-12-01

    Amodiaquine (AQ) is currently being used as a partner drug in combination with artesunate for treatment of uncomplicated malaria in most endemic countries of Africa. In the absence of molecular markers of artemisinin resistance, molecular markers of resistance to AQ may be useful for monitoring the development and spread of parasites resistance to Artesunate-Amodiaquine combination. This study was designed to assess the potential role of polymorphisms on pfcrt and pfmdr1 genes and parasite in vitro susceptibility for epidemiological surveillance of amodiaquine resistance in Plasmodium falciparum. The modified schizont inhibition assay was used to determine in vitro susceptibility profiles of 98 patients' isolates of P. falciparum to amodiaquine. Polymorphisms on parasites pfcrt and pfmdr1 genes were determined with nested PCR followed by sequencing. The geometric mean (GM) of AQ 50% inhibitory concentration (IC-50) in the 97 P. falciparum isolates was 20.48 nM (95% CI 16.53-25.36 nM). Based on the cut-off value for AQ in vitro susceptibility, 87% (84) of the P. falciparum isolates were sensitive to AQ (GM IC-50=16.32 nM; 95%CI 13.3-20.04 nM) while 13% were resistant to AQ in vitro (GM IC-50=88.73nM; 95%CI 69.67-113.0nM). Molecular analysis showed presence of mutant CVIET pfcrt haplotype, mutant pfmdr1Tyr86 allele and the double mutant CVIET pfcrt haplotype+pfmdr1Tyr86 in 72%, 49% and 35%, respectively. The GM IC-50 of isolates harboring the wild-type pfcrt CVMNK haplotype+pfmdr1Asn86 allele (3.93nM; 95%CI 1.82-8.46 nM) was significantly lower (p=0.001) than those isolates harboring the double mutant pfcrt CVIET haplotype+pfmdr1Tyr86 allele (50.40 nM; 95%CI 40.17-63.24 nM). Results from this study suggest that polymorphisms in pfcrt and pfmdr1 genes are important for AQ resistance and therefore may be useful for epidemiological surveillance of P. falciparum resistance to AQ.

  7. Imputation-based population genetics analysis of Plasmodium falciparum malaria parasites.

    Science.gov (United States)

    Samad, Hanif; Coll, Francesc; Preston, Mark D; Ocholla, Harold; Fairhurst, Rick M; Clark, Taane G

    2015-04-01

    Whole-genome sequencing technologies are being increasingly applied to Plasmodium falciparum clinical isolates to identify genetic determinants of malaria pathogenesis. However, genome-wide discovery methods, such as haplotype scans for signatures of natural selection, are hindered by missing genotypes in sequence data. Poor correlation between single nucleotide polymorphisms (SNPs) in the P. falciparum genome complicates efforts to apply established missing-genotype imputation methods that leverage off patterns of linkage disequilibrium (LD). The accuracy of state-of-the-art, LD-based imputation methods (IMPUTE, Beagle) was assessed by measuring allelic r2 for 459 P. falciparum samples from malaria patients in 4 countries: Thailand, Cambodia, Gambia, and Malawi. In restricting our analysis to 86 k high-quality SNPs across the populations, we found that the complete-case analysis was restricted to 21k SNPs (24.5%), despite no single SNP having more than 10% missing genotypes. The accuracy of Beagle in filling in missing genotypes was consistently high across all populations (allelic r2, 0.87-0.96), but the performance of IMPUTE was mixed (allelic r2, 0.34-0.99) depending on reference haplotypes and population. Positive selection analysis using Beagle-imputed haplotypes identified loci involved in resistance to chloroquine (crt) in Thailand, Cambodia, and Gambia, sulfadoxine-pyrimethamine (dhfr, dhps) in Cambodia, and artemisinin (kelch13) in Cambodia. Tajima's D-based analysis identified genes under balancing selection that encode well-characterized vaccine candidates: apical merozoite antigen 1 (ama1) and merozoite surface protein 1 (msp1). In contrast, the complete-case analysis failed to identify any well-validated drug resistance or candidate vaccine loci, except kelch13. In a setting of low LD and modest levels of missing genotypes, using Beagle to impute P. falciparum genotypes is a viable strategy for conducting accurate large-scale population genetics and

  8. Chloroquine has a cytotoxic effect on Acanthamoeba encystation through modulation of autophagy.

    Science.gov (United States)

    Jha, Bijay Kumar; Jung, Hui-Jung; Seo, Incheol; Kim, Hyun Ah; Suh, Seong-Il; Suh, Min-Ho; Baek, Won-Ki

    2014-10-01

    Encystation of Acanthamoeba castellanii is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of Acanthamoeba. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in A. castellanii. Chloroquine was able to selectively reduce cell survival during the encystation of A. castellanii. However, A. castellanii trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting Acanthamoeba. These results suggest a potential novel therapeutic application of chloroquine as an anti-Acanthamoeba drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against Acanthamoeba infection.

  9. Phase I randomized dose-ascending placebo-controlled trials of ferroquine - a candidate anti-malarial drug - in adults with asymptomatic Plasmodium falciparum infection

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    Ospina Salazar Carmen L

    2011-03-01

    Full Text Available Abstract Background The development and spread of drug resistant Plasmodium falciparum strains is a major concern and novel anti-malarial drugs are, therefore, needed. Ferroquine is a ferrocenic derivative of chloroquine with proven anti-malarial activity against chloroquine-resistant and -sensitive P. falciparum laboratory strains. Methods Adult young male aged 18 to 45 years, asymptomatic carriers of P. falciparum, were included in two-dose escalation, double-blind, randomized, placebo-controlled Phase I trials, a single dose study and a multiple dose study aiming to evaluate oral doses of ferroquine from 400 to 1,600 mg. Results Overall, 54/66 patients (40 and 26 treated in the single and multiple dose studies, respectively experienced at least one adverse event, 15 were under placebo. Adverse events were mainly gastrointestinal symptoms such as abdominal pain (16, diarrhoea (5, nausea (13, and vomiting (9, but also headache (11, and dizziness (5. A few patients had slightly elevated liver parameters (10/66 including two patients under placebo. Moderate changes in QTc and morphological changes in T waves were observed in the course of the study. However, no adverse cardiac effects with clinical relevance were observed. Conclusions These phase I trials showed that clinically, ferroquine was generally well-tolerated up to 1,600 mg as single dose and up to 800 mg as repeated dose in asymptomatic young male with P. falciparum infection. Further clinical development of ferroquine, either alone or in combination with another anti-malarial, is highly warranted and currently underway.

  10. Artemisinin resistance containment project in Thailand. II: responses to mefloquine-artesunate combination therapy among falciparum malaria patients in provinces bordering Cambodia

    Directory of Open Access Journals (Sweden)

    Satimai Wichai

    2012-08-01

    Full Text Available Abstract Background The area along the Thai-Cambodian border is considered an epicenter of anti-malarial drug resistance. Recently, parasite resistance to artemisinin-based therapies has been reported in the area. The artemisinin resistance containment project was initiated in November 2008, with the aim to limit resistant parasites and eliminate malaria in this region. This study describes the response to artemisinin-based therapy among falciparum malaria patients in the area, using data from the malaria surveillance programmed under the containment project. Methods The study was conducted in seven provinces of Thailand along the Thai-Cambodian border. Data of Plasmodium falciparum-positive patients during January 2009 to December 2011 were obtained from the electronic malaria information system (eMIS Web-based reporting system. All P. falciparum cases were followed for 42 days, as the routine case follow-up protocol. The demographic characteristics of the patients were described. Statistical analysis was performed to determine the cure rate of the current standard anti-malarial drug regimen--mefloquine-artesunate combination therapy (MAS. The proportion of patients who remained parasite-positive at each follow-up day was calculated. In addition, factors related to the delayed parasite clearance on day-3 post-treatment, were explored. Results A total of 1,709 P. falciparum-positive cases were reported during the study period. Almost 70% of falciparum cases received MAS therapy (n = 1,174. The majority of cases were males, aged between 31 and 50 years. The overall MAS cure rate was >90% over the three-year period. Almost all patients were able to clear the parasite within 7 to 14 days post-treatment. Approximately 14% of patients undergoing MAS remained parasite-positive on day-3. Delayed parasite clearance was not significantly associated with patient gender, age, or citizenship. However, delayed parasite clearance varied across the

  11. Identification and Characterization of Novel Drug Resistance Loci in Plasmodium falciparum

    OpenAIRE

    Van Tyne, Daria Natalie

    2012-01-01

    Malaria has plagued mankind for millennia. Antimalarial drug use over the last century has generated highly drug-resistant parasites, which amplify the burden of this disease and pose a serious obstacle to control efforts. This dissertation is motivated by the simple fact that malaria parasites have become resistant to nearly every antimalarial drug that has ever been used, yet the precise genetic mechanisms of parasite drug resistance remain largely unknown. Our work pairs genomics-age techn...

  12. Concurrence of Plasmodium falciparum dhfr and crt mutations in northern Ghana

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    Otchwemah Rowland N

    2005-09-01

    Full Text Available Abstract Background Both chloroquine (CQ and sulfadoxine-pyrimethamine (SP are failing drugs in much of sub-Saharan Africa. Previous findings suggest an association between resistance to CQ and to SP in vivo, in vitro, and on the molecular level. Methods In 126 Ghanaian children with uncomplicated malaria, associations between mutations conferring resistance in the Plasmodium falciparum dihydrofolate reductase (dhfr; SP and chloroquine resistance transporter (crt; CQ genes, concentrations of residual antimalarial drugs, and gametocyte carriage were examined. Results Mutant dhfr alleles and the CQ-resistance allele crt T76 were strongly associated with each other. Isolates exhibiting the dhfr triple mutation seven times more likely also contained crt T76 parasites as compared to isolates without the dhfr triple variant (P = 0.0001. Moreover, both, isolates with the dhfr triple mutation (adjusted OR, 3.2 (95%CI, 1.0–10.4 and with crt T76 (adjusted OR, 14.5 (1.4–150.8 were associated with an increased likelihood of pre-treatment gametocytaemia. However, crt T76 did not correlate with gametocytaemia following SP treatment and no selection of crt T76 in SP treatment failure isolates was observed. Conclusion These results confirm an association between CQ and SP resistance markers in isolates from northern Ghana. This could indicate accelerated development of resistance to SP if CQ resistance is already present, or vice versa. Considering the enhanced transmission potential as reflected by the increased proportion of isolates containing gametocytes when resistant parasites are present, co-resistance can be expected to spread in this area. However, the underlying mechanism leading to this constellation remains obscure.

  13. In-Vivo Efficacy of Chloroquine to Clear Asymptomatic Infections in Mozambican Adults: A Randomized, Placebo-controlled Trial with Implications for Elimination Strategies.

    Science.gov (United States)

    Galatas, Beatriz; Nhamussua, Lidia; Candrinho, Baltazar; Mabote, Lurdes; Cisteró, Pau; Gupta, Himanshu; Rabinovich, Regina; Menéndez, Clara; Macete, Eusebio; Saute, Francisco; Mayor, Alfredo; Alonso, Pedro; Bassat, Quique; Aide, Pedro

    2017-05-02

    Recent reports regarding the re-emergence of parasite sensitivity to chloroquine call for a new consideration of this drug as an interesting complementary tool in malaria elimination efforts, given its good safety profile and long half-life. A randomized (2:1), single-blind, placebo-controlled trial was conducted in Manhiça, Mozambique, to assess the in-vivo efficacy of chloroquine to clear plasmodium falciparum (Pf) asymptomatic infections. Primary study endpoint was the rate of adequate and parasitological response (ACPR) to therapy on day 28 (PCR-corrected). Day 0 isolates were analyzed to assess the presence of the PfCRT-76T CQ resistance marker. A total of 52 and 27 male adults were included in the CQ and Placebo group respectively. PCR-corrected ACPR was significantly higher in the CQ arm 89.4% (95%CI 80-98%) compared to the placebo (p < 0.001). CQ cleared 49/50 infections within the first 72 h while placebo cleared 12/26 (LRT p < 0.001). The PfCRT-76T mutation was present only in one out of 108 (0.9%) samples at baseline, well below the 84% prevalence found in 1999 in the same area. This study presents preliminary evidence of a return of chloroquine sensitivity in Mozambican Pf isolates, and calls for its further evaluation in community-based malaria elimination efforts, in combination with other effective anti-malarials. www.clinicalTrials.gov NCT02698748.

  14. In vitro inhibition of Plasmodium falciparum by substances isolated from Amazonian antimalarial plants

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    Valter F de Andrade-Neto

    2007-06-01

    Full Text Available In the present study, a quassinoid, neosergeolide, isolated from the roots and stems of Picrolemma sprucei (Simaroubaceae, the indole alkaloids ellipticine and aspidocarpine, isolated from the bark of Aspidosperma vargasii and A. desmanthum (Apocynaceae, respectively, and 4-nerolidylcatechol, isolated from the roots of Pothomorphe peltata (Piperaceae, all presented significant in vitro inhibition (more active than quinine and chloroquine of the multi-drug resistant K1 strain of Plasmodium falciparum. Neosergeolide presented activity in the nanomolar range. This is the first report on the antimalarial activity of these known, natural compounds. This is also the first report on the isolation of aspidocarpine from A. desmanthum. These compounds are good candidates for pre-clinical tests as novel lead structures with the aim of finding new antimalarial prototypes and lend support to the traditional use of the plants from which these compounds are derived.

  15. Molecular Epidemiology of Plasmodium falciparum Malaria Outbreak, Tumbes, Peru, 2010-2012.

    Science.gov (United States)

    Baldeviano, G Christian; Okoth, Sheila Akinyi; Arrospide, Nancy; Gonzalez, Rommell V; Sánchez, Juan F; Macedo, Silvia; Conde, Silvia; Tapia, L Lorena; Salas, Carola; Gamboa, Dionicia; Herrera, Yeni; Edgel, Kimberly A; Udhayakumar, Venkatachalam; Lescano, Andrés G

    2015-05-01

    During 2010-2012, an outbreak of 210 cases of malaria occurred in Tumbes, in the northern coast of Peru, where no Plasmodium falciparum malaria case had been reported since 2006. To identify the source of the parasite causing this outbreak, we conducted a molecular epidemiology investigation. Microsatellite typing showed an identical genotype in all 54 available isolates. This genotype was also identical to that of parasites isolated in 2010 in the Loreto region of the Peruvian Amazon and closely related to clonet B, a parasite lineage previously reported in the Amazon during 1998-2000. These findings are consistent with travel history of index case-patients. DNA sequencing revealed mutations in the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr1 loci, which are strongly associated with resistance to chloroquine and sulfadoxine/pyrimethamine, and deletion of the Pfhrp2 gene. These results highlight the need for timely molecular epidemiology investigations to trace the parasite source during malaria reintroduction events.

  16. Molecular Epidemiology of Plasmodium falciparum Malaria Outbreak, Tumbes, Peru, 2010–2012

    Science.gov (United States)

    Okoth, Sheila Akinyi; Arrospide, Nancy; Gonzalez, Rommell V.; Sánchez, Juan F.; Macedo, Silvia; Conde, Silvia; Tapia, L. Lorena; Salas, Carola; Gamboa, Dionicia; Herrera, Yeni; Edgel, Kimberly A.; Udhayakumar, Venkatachalam; Lescano, Andrés G.

    2015-01-01

    During 2010–2012, an outbreak of 210 cases of malaria occurred in Tumbes, in the northern coast of Peru, where no Plasmodium falciparum malaria case had been reported since 2006. To identify the source of the parasite causing this outbreak, we conducted a molecular epidemiology investigation. Microsatellite typing showed an identical genotype in all 54 available isolates. This genotype was also identical to that of parasites isolated in 2010 in the Loreto region of the Peruvian Amazon and closely related to clonet B, a parasite lineage previously reported in the Amazon during 1998–2000. These findings are consistent with travel history of index case-patients. DNA sequencing revealed mutations in the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr1 loci, which are strongly associated with resistance to chloroquine and sulfadoxine/pyrimethamine, and deletion of the Pfhrp2 gene. These results highlight the need for timely molecular epidemiology investigations to trace the parasite source during malaria reintroduction events. PMID:25897626

  17. Human IGF1 regulates midgut oxidative stress and epithelial homeostasis to balance lifespan and Plasmodium falciparum resistance in Anopheles stephensi

    National Research Council Canada - National Science Library

    Drexler, Anna L; Pietri, Jose E; Pakpour, Nazzy; Hauck, Eric; Wang, Bo; Glennon, Elizabeth K K; Georgis, Martha; Riehle, Michael A; Luckhart, Shirley

    2014-01-01

    ...) within a physiologically relevant range (0.013-0.13 µM) in human blood reduced development of the human parasite Plasmodium falciparum in the Indian malaria mosquito Anopheles stephensi. Low IGF1 (0.013 µM...

  18. Molecular monitoring of Plasmodium falciparum super-resistance to sulfadoxine-pyrimethamine in Tanzania

    DEFF Research Database (Denmark)

    Kavishe, Reginald A; Kaaya, Robert D; Nag, Sidsel;

    2016-01-01

    and in private drug shops in sub-Saharan Africa. This study reports on the prevalence and distribution of Pfdhps mutations A540E and A581G in Tanzania. When found together, these mutations confer high-level SP resistance (sometimes referred to as 'super-resistance'), which is associated with loss in protective......BACKGROUND: Sulfadoxine-pyrimethamine (SP) is recommended for prophylactic treatment of malaria in pregnancy while artemisinin combination therapy is the recommended first-line anti-malarial treatment. Selection of SP resistance is ongoing since SP is readily available in health facilities...... = 85.3, p resistance. A high prevalence of Pfdhps-581G was observed in Tanga (56.6 %) in northeastern Tanzania and in Kagera (20.4 %) in northwestern Tanzania and the 540-581 EG haplotype was found at 54.5 and 19...

  19. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine and quinine in Guinea-Bissau between 2003 and 2012

    DEFF Research Database (Denmark)

    Jovel, Irina Tatiana; Kofoed, Poul-Erik; Rombo, Lars;

    2015-01-01

    BACKGROUND: Guinea-Bissau, West-Africa introduced artemether-lumefantrine in 2008 but quinine has also been commonly prescribed for treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes...... of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine and quinine are described. METHODS: Pfcrt K76T, pfmdr1 gene copy numbers, N86Y, Y184F and 1034-1246 sequences were determined using PCR-based methods. Blood samples came from virtually all (n=1806) children aged.......001). CONCLUSIONS: Following the discontinuation of an effective chloroquine regimen highly artemether-lumefantrine susceptible P. falciparum (with pfcrt 76T) accumulated possibly due to suboptimal use of quinine and despite a fitness cost linked to 76T....

  20. Surveillance of artemether-lumefantrine associated Plasmodium falciparum multidrug resistance protein-1 gene polymorphisms in Tanzania

    DEFF Research Database (Denmark)

    Kavishe, Reginald A; Paulo, Petro; Kaaya, Robert D

    2014-01-01

    BACKGROUND: Resistance to anti-malarials is a major public health problem worldwide. After deployment of artemisinin-based combination therapy (ACT) there have been reports of reduced sensitivity to ACT by malarial parasites in South-East Asia. In Tanzania, artemether-lumefantrine (ALu) is the re...... pharmacovigilance studies to monitor any delayed parasite clearance by the drug....

  1. Ex vivo susceptibility of Plasmodium falciparum isolates from Dakar, Senegal, to seven standard anti-malarial drugs

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    Pradines Bruno

    2011-10-01

    Full Text Available Abstract Background As a result of widespread chloroquine and sulphadoxine-pyrimethamine resistance, artemisinin-based combination therapy (ACT (which includes artemether-lumefantrine and artesunate-amodiaquine has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Since then, there have been very few reports on the ex vivo susceptibility of Plasmodium falciparum to anti-malarial drugs. To examine whether parasite susceptibility has been affected by the widespread use of ACT, the ex vivo susceptibility of local isolates was assessed at the military hospital of Dakar. Methods The ex vivo susceptibility of 93 P. falciparum isolates from Dakar was successfully determined using the Plasmodium lactate dehydrogenase (pLDH ELISA for the following drugs: chloroquine (CQ, quinine (QN, mefloquine (MQ, monodesethylamodiaquine (MDAQ, lumefantrine (LMF, dihydroartemisinin (DHA and doxycycline (DOX. Results After transformation of the isolate IC50 in ratio of IC50 according to the susceptibility of the 3D7 reference strain (isolate IC50/3D7 IC50, the prevalence of the in vitro resistant isolates with reduced susceptibility was 50% for MQ, 22% for CQ, 12% for DOX, 6% for both QN and MDAQ and 1% for the drugs LMF and DHA. The highest significant positive correlations were shown between responses to CQ and MDAQ (r = 0.569; P r = 0.511; P r = 0.428; P = 0.0001, LMF and MQ (r = 0.413; P = 0.0002, QN and DHA (r = 0.402; P = 0.0003 and QN and MQ (r = 0.421; P = 0.0001. Conclusions The introduction of ACT in 2002 has not induced a decrease in P. falciparum susceptibility to the drugs DHA, MDAQ and LMF, which are common ACT components. However, the prevalence of P. falciparum isolates with reduced susceptibility has increased for both MQ and DOX. Taken together, these data suggest that intensive surveillance of the P. falciparum in vitro susceptibility to anti-malarial drugs in Senegal is required.

  2. Longitudinal in vitro surveillance of Plasmodium falciparum sensitivity to common anti-malarials in Thailand between 1994 and 2010

    Directory of Open Access Journals (Sweden)

    Parker Daniel

    2012-08-01

    Full Text Available Abstract Background Drug and multidrug-resistant Plasmodium falciparum malaria has existed in Thailand for several decades. Furthermore, Thailand serves as a sentinel for drug-resistant malaria within the Greater Mekong sub-region. However, the drug resistance situation is highly dynamic, changing quickly over time. Here parasite in vitro drug sensitivity is reported for artemisinin derivatives, mefloquine, chloroquine and quinine, across Thailand. Methods Blood was drawn from patients infected with P. falciparum in seven sentinel provinces along Thai international borders with Cambodia, Myanmar, Laos, and Malaysia. In vitro parasite sensitivity was tested using the World Health Organization’s microtest (mark III (between 1994 and 2002 and the histidine-rich protein-2 (HRP2-based enzyme-linked immunosorbent assay (in 2010. Following World Health Organization protocol, at least 30 isolates were collected for each province and year represented in this study. Where possible, t-tests were used to test for significant differences. Results There appears to be little variation across study sites with regard to parasite sensitivity to chloroquine. Quinine resistance appears to have been rising prior to 1997, but has subsequently decreased. Mefloquine sensitivity appears high across the provinces, especially along the north-western border with Myanmar and the eastern border with Cambodia. Finally, the data suggest that parasite sensitivity to artemisinin and its derivatives is significantly higher in provinces along the north-western border with Myanmar. Conclusions Parasite sensitivity to anti-malarials in Thailand is highly variable over time and largely mirrors official drug use policy. The findings with regard to reduced sensitivity to artemisinin derivatives are supported by recent reports of reduced parasite clearance associated with artemisinin. This trend is alarming since artemisinin is considered the last defence against malaria. Continued

  3. Pfatp6 molecular profile of Plasmodium falciparum isolates in the western Brazilian Amazon

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    Brasil Larissa W

    2012-04-01

    Full Text Available Abstract Background Anti-malarial drug resistance has emerged as one of the biggest challenges confronting the worldwide effort to control malaria. The appearance of chloroquine and multi-drug resistance had devastating effects on therapeutic efficacy of former first-line agents. Artemisinin has proven to be an excellent therapeutic alternative to fill the void in chemotherapeutic options left by resistance mechanisms. At the time of introduction, no resistance to artemisinins had been recorded, and artemisinins demonstrated excellent parasite reduction rates. In an attempt to protect artemisinin efficacy, the World Health Organization (WHO made artemisinin-based combination therapy (ACT its official first-line treatment recommendation for uncomplicated Plasmodium falciparum in 2006. In Brazil, artemether/lumefantrine became the Brazilian Malaria Control Programme's official treatment recommendation in 2007. The sarco/endoplasmic reticulum Ca2+ - ATPase ortholog of P. falciparum (pfatp6 has been suggested as one of the targets of artemisinins. Consequently, pfatp6 gene polymorphisms are being investigated as markers of artemisinin resistance elsewhere. The goal of this work was to describe the molecular profile of pfatp6 in P. falciparum isolates from different localities in the Amazonas State. Methods DNA polymorphisms of the pfatp6 gene in 80 P. falciparum isolates from 11 municipalities of the Amazonas State (Western Brazilian Amazon, before and after the introduction of ACT in the Brazilian anti-malarial guidelines, were analysed by automatic sequencing. Mutations in the pfatp6 gene were searched using Mutation Surveyor v3.25 software. Results The P. falciparum pfatp6 gene presented polymorphisms at codons 37, 630 and 898. The R37K mutation was found in 16% of the samples, A630S in 32% and I898I in 52%. No S769N mutation, however, was detected in the analysed samples. Conclusion Despite the small number of samples, data presented here

  4. Molecular monitoring of Plasmodium falciparum super-resistance to sulfadoxine-pyrimethamine in Tanzania

    DEFF Research Database (Denmark)

    Kavishe, Reginald A; Kaaya, Robert D; Nag, Sidsel

    2016-01-01

    and in private drug shops in sub-Saharan Africa. This study reports on the prevalence and distribution of Pfdhps mutations A540E and A581G in Tanzania. When found together, these mutations confer high-level SP resistance (sometimes referred to as 'super-resistance'), which is associated with loss in protective...... efficacy of SP-IPTp. METHODS: DNA samples were extracted from malaria-positive blood samples on filter paper, used malaria rapid diagnostic test strips and whole blood collected from eight sites in seven administrative regions of Tanzania. PCR-RFLP and SSOP-ELISA techniques were used to genotype the A540E...... = 85.3, p Tanzania and in Kagera (20.4 %) in northwestern Tanzania and the 540-581 EG haplotype was found at 54.5 and 19...

  5. Reconsideration of Anopheles rivulorum as a vector of Plasmodium falciparum in western Kenya: some evidence from biting time, blood preference, sporozoite positive rate, and pyrethroid resistance

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    Kawada Hitoshi

    2012-10-01

    Full Text Available Abstract Background Anopheles gambiae, An. arabiensis, and An. funestus are widespread malaria vectors in Africa. Anopheles rivulorum is the next most widespread species in the An. funestus group. The role of An. rivulorum as a malaria vector has not been fully studied, although it has been found to be a minor or opportunistic transmitter of Plasmodium falciparum. Methods Mosquitoes were collected indoors over a 12-hour period using a light source attached to a rotating bottle collector in order to determine peak activity times and to provide DNA for meal source identification. Gravid female mosquitoes were collected indoors via an aspirator to generate F1 progeny for testing insecticidal susceptibility. Blood meal sources were identified using a multiplexed PCR assay for human and bovine cytochrome-B, and by matching sequences generated with primers targeting vertebrate and mammalian cytochrome-B segments to the Genbank database. Results Anopheles rivulorum fed on human blood in the early evening between 18:00 and 20:00, when insecticide-treated bed nets are not in use, and the presence of Plasmodium falciparum sporozoites in 0.70% of the An. rivulorum individuals tested was demonstrated. Susceptibility to permethrin, deltamethrin, and DDT is higher in An. rivulorum (84.8%, 91.4%, and 100%, respectively than in An. funestus s.s. (36.8%, 36.4%, and 70%, respectively, whereas mortality rates for propoxur and fenitrothion were 100% for both species. Resistance to pyrethroids was very high in An. funestus s.s. and the potential of the development of high resistance was suspected in An. rivulorum. Conclusion Given the tendency for An. rivulorum to be active early in the evening, the presence of P. falciparum in the species, and the potential for the development of pyrethroid resistance, we strongly advocate reconsideration of the latent ability of this species as an epidemiologically important malaria vector.

  6. Plasmodium falciparum isolates from southern Ghana exhibit polymorphisms in the SERCA-type PfATPase6 though sensitive to artesunate in vitro

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    Ofori Michael F

    2011-07-01

    Full Text Available Abstract Background In 2005, Ghana replaced chloroquine with artemisinin-based combination therapy as the first-line treatment for uncomplicated malaria. The aim of this work was to determine for the first time, polymorphisms in the putative pfATPase6 and pftctp, pfmdr1, pfcrt genes in Ghanaian isolates, particularly at a time when there is no report on artemisinin resistance in malaria parasites from Ghana. The sensitivity of parasite isolates to anti-malaria drugs were also evaluated for a possible association with polymorphisms in these genes. Methods The prevalence of point mutations in the above Plasmodium falciparum genes were assessed from filter-paper blood blot samples by DNA sequencing. In vitro drug sensitivity test was carried out on some of the blood samples from volunteers visiting hospitals/clinics in southern Ghana using a modified version of the standard WHO Mark III micro-test. Results All successfully tested parasite isolates were sensitive to artesunate; while 19.4%, 29.0% and 51.6% were resistant to quinine, amodiaquine and chloroquine respectively. The geometric mean of IC50 value for artesunate was 0.73 nM (95% CI, 0.38-1.08, amodiaquine 30.69 nM (95% CI, 14.18-47.20 and chloroquine 58.73 nM (95% CI, 38.08-79.38. Twenty point mutations were observed in pfATPase6 gene, with no L263E and S769N. All mutations found were low in frequency, except D639G which was observed in about half of the isolates but was not associated with artesunate response (p = 0.42. The pftctp gene is highly conserved as no mutation was observed, while CVIET which is chloroquine-resistant genotype at codon 72-76 of the pfcrt gene was identified in about half of the isolates; this was consistent with chloroquine IC50 values (p = 0.001. Mutations were present in pfmdr1 gene but were not associated with artemisinin response (p = 1.00. Conclusion The pfATPase6 gene is highly polymorphic with D639G appearing to be fixed in Ghanaian isolates. These may just

  7. Molecular markers of anti-malarial drug resistance in Lahj Governorate, Yemen: baseline data and implications

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    Chance Michael L

    2011-08-01

    Full Text Available Abstract Background This is an investigation of anti-malarial molecular markers coupled with a therapeutic efficacy test of chloroquine (CQ against falciparum malaria in an area of unstable malaria in Lahj Governorate, Yemen. The study was aimed at assessment of therapeutic response to CQ and elucidation of baseline information on molecular markers for Plasmodium falciparum resistance against CQ and sulphadoxine/pyrimethamine (SP. Methods Between 2002 and 2003 the field test was conducted according to the standard WHO protocol to evaluate the therapeutic efficacy of CQ in 124 patients with falciparum malaria in an endemic area in Lahj Governorate in Yemen. Blood samples collected during this study were analysed for P. falciparum chloroquine resistance transporter gene (pfcrt-76 polymorphisms, mutation pfcrt-S163R and the antifolate resistance-associated mutations dihydrofolate reductase (dhfr-C59R and dihydropteroate synthase (dhps-K540E. Direct DNA sequencing of the pfcrt gene from three representative field samples was carried out after DNA amplification of the 13 exons of the pfcrt gene. Results Treatment failure was detected in 61% of the 122 cases that completed the 14-day follow-up. The prevalence of mutant pfcrt T76 was 98% in 112 amplified pre-treatment samples. The presence of pfcrt T76 was poorly predictive of in vivo CQ resistance (PPV = 61.8%, 95% CI = 52.7-70.9. The prevalence of dhfr Arg-59 mutation in 99 amplified samples was 5%, while the dhps Glu-540 was not detected in any of 119 amplified samples. Sequencing the pfcrt gene confirmed that Yemeni CQ resistant P. falciparum carry the old world (Asian and African CQ resistant haplotype CVIETSESI at positions 72,73,74,75,76,220,271, 326 and 371. Conclusion This is the first study to report baseline information on the characteristics and implications of anti-malarial drug resistance markers in Yemen. It is also the first report of the haplotype associated with CQR P. falciparum

  8. Whole transcriptome expression analysis and comparison of two different strains of Plasmodium falciparum using RNA-Seq

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    Hiasindh Ashmi Antony

    2016-06-01

    Full Text Available The emergence and distribution of drug resistance in malaria are serious public health concerns in tropical and subtropical regions of the world. However, the molecular mechanism of drug resistance remains unclear. In the present study, we performed a high-throughput RNA-Seq to identify and characterize the differentially expressed genes between the chloroquine (CQ sensitive (3D7 and resistant (Dd2 strains of Plasmodium falciparum. The parasite cells were cultured in the presence and absence of CQ by in vitro method. Total RNA was isolated from the harvested parasite cells using TRIzol, and RNA-Seq was conducted using an Illumina HiSeq 2500 sequencing platform with paired-end reads and annotated using Tophat. The transcriptome analysis of P. falciparum revealed the expression of ~5000 genes, in which ~60% of the genes have unknown function. Cuffdiff program was used to identify the differentially expressed genes between the CQ-sensitive and resistant strains. Here, we furnish a detailed description of the experimental design, procedure, and analysis of the transcriptome sequencing data, that have been deposited in the National Center for Biotechnology Information (accession nos. PRJNA308455 and GSE77499.

  9. Pyronaridine-artesunate versus chloroquine in patients with acute Plasmodium vivax malaria: a randomized, double-blind, non-inferiority trial.

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    Yi Poravuth

    Full Text Available BACKGROUND: New antimalarials are needed for P. vivax and P. falciparum malaria. This study compared the efficacy and safety of pyronaridine-artesunate with that of chloroquine for the treatment of uncomplicated P. vivax malaria. METHODS AND FINDINGS: This phase III randomized, double-blind, non-inferiority trial included five centers across Cambodia, Thailand, India, and Indonesia. In a double-dummy design, patients (aged >3-≤ 60 years with microscopically confirmed P. vivax mono-infection were randomized (1:1 to receive pyronaridine-artesunate (target dose 7.2:2.4 mg/kg to 13.8:4.6 mg/kg or chloroquine (standard dose once daily for three days. Each treatment group included 228 randomized patients. Outcomes for the primary endpoint, Day-14 cure rate in the per-protocol population, were 99.5%, (217/218; 95%CI 97.5, 100 with pyronaridine-artesunate and 100% (209/209; 95%CI 98.3, 100 with chloroquine. Pyronaridine was non-inferior to chloroquine: treatment difference -0.5% (95%CI -2.6, 1.4, i.e., the lower limit of the 2-sided 95%CI for the treatment difference was greater than -10%. Pyronaridine-artesunate cure rates were non-inferior to chloroquine for Days 21, 28, 35 and 42. Parasite clearance time was shorter with pyronaridine-artesunate (median 23.0 h versus chloroquine (32.0 h; p<0.0001, as was fever clearance time (median 15.9 h and 23.8 h, respectively; p = 0.0017. Kaplan-Meier estimates of post-baseline P. falciparum infection incidence until Day 42 were 2.5% with pyronaridine-artesunate, 6.1% with chloroquine (p = 0.048, log-rank test. Post-baseline P. vivax or P. falciparum infection incidence until Day 42 was 6.8% and 12.4%, respectively (p = 0.022, log rank test. There were no deaths. Adverse events occurred in 92/228 (40.4% patients with pyronaridine-artesunate and 72/228 (31.6% with chloroquine. Mild and transient increases in hepatic enzymes were observed for pyronaridine-artesunate. CONCLUSION: Pyronaridine-artesunate efficacy

  10. Pyronaridine-Artesunate versus Chloroquine in Patients with Acute Plasmodium vivax Malaria: A Randomized, Double-Blind, Non-Inferiority Trial

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    Poravuth, Yi; Socheat, Duong; Rueangweerayut, Ronnatrai; Uthaisin, Chirapong; Pyae Phyo, Aung; Valecha, Neena; Rao, B. H. Krishnamoorthy; Tjitra, Emiliana; Purnama, Asep; Borghini-Fuhrer, Isabelle; Duparc, Stephan; Shin, Chang-Sik; Fleckenstein, Lawrence

    2011-01-01

    Background New antimalarials are needed for P. vivax and P. falciparum malaria. This study compared the efficacy and safety of pyronaridine-artesunate with that of chloroquine for the treatment of uncomplicated P. vivax malaria. Methods and Findings This phase III randomized, double-blind, non-inferiority trial included five centers across Cambodia, Thailand, India, and Indonesia. In a double-dummy design, patients (aged >3–≤60 years) with microscopically confirmed P. vivax mono-infection were randomized (1∶1) to receive pyronaridine-artesunate (target dose 7.2∶2.4 mg/kg to 13.8∶4.6 mg/kg) or chloroquine (standard dose) once daily for three days. Each treatment group included 228 randomized patients. Outcomes for the primary endpoint, Day-14 cure rate in the per-protocol population, were 99.5%, (217/218; 95%CI 97.5, 100) with pyronaridine-artesunate and 100% (209/209; 95%CI 98.3, 100) with chloroquine. Pyronaridine was non-inferior to chloroquine: treatment difference −0.5% (95%CI −2.6, 1.4), i.e., the lower limit of the 2-sided 95%CI for the treatment difference was greater than −10%. Pyronaridine-artesunate cure rates were non-inferior to chloroquine for Days 21, 28, 35 and 42. Parasite clearance time was shorter with pyronaridine-artesunate (median 23.0 h) versus chloroquine (32.0 h; pestimates of post-baseline P. falciparum infection incidence until Day 42 were 2.5% with pyronaridine-artesunate, 6.1% with chloroquine (p = 0.048, log-rank test). Post-baseline P. vivax or P. falciparum infection incidence until Day 42 was 6.8% and 12.4%, respectively (p = 0.022, log rank test). There were no deaths. Adverse events occurred in 92/228 (40.4%) patients with pyronaridine-artesunate and 72/228 (31.6%) with chloroquine. Mild and transient increases in hepatic enzymes were observed for pyronaridine-artesunate. Conclusion Pyronaridine-artesunate efficacy in acute uncomplicated P. vivax malaria was at least that of chloroquine. As pyronaridine

  11. Efficacy of chloroquine for the treatment of Plasmodium vivax in the Saharan zone in Mauritania.

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    Ould Ahmedou Salem, Mohamed Salem; Mohamed Lemine, Yeslim Ould; Deida, Jemila Mint; Lemrabott, Mohamed Aly Ould; Ouldabdallahi, Mohamed; Ba, Mamadou Dit Dialaw; Boukhary, Ali Ould Mohamed Salem; Khairy, Mohamed Lemine Ould; Abdel Aziz, Mohamed Boubacar; Ringwald, Pascal; Basco, Leonardo K; Niang, Saidou Doro; Lebatt, Sidi Mohamed

    2015-01-28

    In 2006, the Mauritanian Ministry of Health adopted a new therapeutic strategy based on the systematic use of artemisinin-based combination therapy (ACT), artesunate-amodiaquine and artemether-lumefantrine, for the first- and second-line treatment of uncomplicated malaria, respectively, regardless of Plasmodium spp. In the Saharan zone of the country, recent studies have shown that Plasmodium vivax largely predominates over Plasmodium falciparum. Anti-malarial drug response of P. vivax has not been evaluated in Mauritania. The aim of the present study was to evaluate the clinical efficacy and tolerance of chloroquine to treat P. vivax malaria in Mauritanian patients. Plasmodium vivax-infected patients aged > 6 months old were enrolled in Nouakchott and Atar in September-October 2013. Chloroquine was administered at the standard dose of 25 mg base/kg body weight over three days. Patients were followed until day 28, according to the standard 2009 World Health Organization protocol. A total of 128 patients (67 in Nouakchott and 61 in Atar) were enrolled in the study. Seven patients (5.5%) were either excluded or lost to follow-up. Based on the per protocol analysis, chloroquine efficacy (adequate clinical and parasitological response) was 100%. Treatment was well-tolerated. One patient was excluded on day 1 due to urticaria and treated with artesunate-amodiaquine. Although the current national treatment guideline recommends artesunate-amodiaquine for the first-line treatment of uncomplicated malaria, including P. vivax malaria, chloroquine may still have an important role to play in anti-malarial chemotherapy in Mauritania. Further epidemiological studies are required to map the distribution of P. vivax and P. falciparum in the country.

  12. A Redox-Active Fluorescent pH Indicator for Detecting Plasmodium falciparum Strains with Reduced Responsiveness to Quinoline Antimalarial Drugs.

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    Jida, Mouhamad; Sanchez, Cecilia P; Urgin, Karène; Ehrhardt, Katharina; Mounien, Saravanan; Geyer, Aurelia; Elhabiri, Mourad; Lanzer, Michael; Davioud-Charvet, Elisabeth

    2017-02-10

    Mutational changes in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) have been associated with differential responses to a wide spectrum of biologically active compounds including current and former quinoline and quinoline-like antimalarial drugs. PfCRT confers altered drug responsiveness by acting as a transport system, expelling drugs from the parasite's digestive vacuole where these drugs exert, at least part of, their antiplasmodial activity. To preserve the efficacy of these invaluable drugs, novel functional tools are required for epidemiological surveys of parasite strains carrying mutant PfCRT variants and for drug development programs aimed at inhibiting or circumventing the action of PfCRT. Here we report the synthesis and characterization of a pH-sensitive fluorescent chloroquine analogue consisting of 7-chloro-N-{2-[(propan-2-yl)amino]ethyl}quinolin-4-amine functionalized with the fluorochrome 7-nitrobenzofurazan (NBD) (henceforth termed Fluo-CQ). In the parasite, Fluo-CQ accumulates in the digestive vacuole, giving rise to a strong fluorescence signal but only in parasites carrying the wild type PfCRT. In parasites carrying the mutant PfCRT, Fluo-CQ does not accumulate. The differential handling of the fluorescent probe, combined with live cell imaging, provides a diagnostic tool for quick detection of those P. falciparum strains that carry a PfCRT variant associated with altered responsiveness to quinoline and quinoline-like antimalarial drugs. In contrast to the accumulation studies, chloroquine (CQ)-resistant parasites were observed cross-resistant to Fluo-CQ when the chemical probe was tested in various CQ-sensitive and -resistant parasite strains. NBD derivatives were found to act as redox cyclers of two essential targets, using a coupled assay based on methemoglobin and the NADPH-dependent glutathione reductase (GRs) from P. falciparum. This redox activity is proposed to contribute to the dual action of Fluo-CQ on redox

  13. Drug-resistant genotypes and multi-clonality in Plasmodium falciparum analysed by direct genome sequencing from peripheral blood of malaria patients.

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    Timothy Robinson

    Full Text Available Naturally acquired blood-stage infections of the malaria parasite Plasmodium falciparum typically harbour multiple haploid clones. The apparent number of clones observed in any single infection depends on the diversity of the polymorphic markers used for the analysis, and the relative abundance of rare clones, which frequently fail to be detected among PCR products derived from numerically dominant clones. However, minority clones are of clinical interest as they may harbour genes conferring drug resistance, leading to enhanced survival after treatment and the possibility of subsequent therapeutic failure. We deployed new generation sequencing to derive genome data for five non-propagated parasite isolates taken directly from 4 different patients treated for clinical malaria in a UK hospital. Analysis of depth of coverage and length of sequence intervals between paired reads identified both previously described and novel gene deletions and amplifications. Full-length sequence data was extracted for 6 loci considered to be under selection by antimalarial drugs, and both known and previously unknown amino acid substitutions were identified. Full mitochondrial genomes were extracted from the sequencing data for each isolate, and these are compared against a panel of polymorphic sites derived from published or unpublished but publicly available data. Finally, genome-wide analysis of clone multiplicity was performed, and the number of infecting parasite clones estimated for each isolate. Each patient harboured at least 3 clones of P. falciparum by this analysis, consistent with results obtained with conventional PCR analysis of polymorphic merozoite antigen loci. We conclude that genome sequencing of peripheral blood P. falciparum taken directly from malaria patients provides high quality data useful for drug resistance studies, genomic structural analyses and population genetics, and also robustly represents clonal multiplicity.

  14. Haplotypes associated with resistance to sulfadoxine-pyrimethamine in Plasmodium falciparum in two malaria endemic locations in Colombia.

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    Hernández, Diana Carolina; Guerra, Angela Patricia; Cucunubá, Zulma Milena; Nicholls, Ruben Santiago; Barrera, Sandra Milena

    2013-08-01

    Colombia has four main malaria transmission zones. In vivo efficacy studies carried out in these areas showed big differences in the response of Plasmodium falciparum to treatment with sulphadoxine-pyrimethamine. In addition, there is still insufficient information about the genetics of P. falciparum populations. The objective of this study was to determine the haplotypes in dhfr and dhps genes of P. falciparum circulating in two distinct endemic zones. Samples from patients with non-complicated P. falciparum malaria were collected: 135 from Tumaco and 206 from Tierralta. Alleles 108 and 51 of the dhfr gene, and 437 and 540 of the dhps gene were analyzed by PCR/enzymatic restriction, while alleles 59 and 164 (dhfr), and 581(dhps) by PCR/dot blot/hybridization. Five different haplotypes were found, of which the triple mutant 51I/C59/108N/I164/437G/K540/A581 was the most frequent (54.6%). In Tumaco, the parasites with wild haplotype predominated, while mutant parasites predominated in Tierralta. Another interesting finding is the presence of the C59R mutation in the dhfr gene in two samples, a mutation rarely found in South America. These data provide information about parasite population genetics and highlight the importance of starting a long term molecular surveillance program.

  15. Efficacy of dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum and Plasmodium vivax in Cambodia, 2008 to 2010.

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    Leang, Rithea; Barrette, Amy; Bouth, Denis Mey; Menard, Didier; Abdur, Rashid; Duong, Socheat; Ringwald, Pascal

    2013-02-01

    We describe here the results of antimalarial therapeutic efficacy studies conducted in Cambodia from 2008 to 2010. A total of 15 studies in four sentinel sites were conducted using dihydroartemisinin-piperaquine (DP) for the treatment of Plasmodium falciparum infection and chloroquine (CQ) and DP for the treatment of P. vivax infection. All studies were performed according to the standard World Health Organization protocol for the assessment of antimalarial treatment efficacy. Among the studies of DP for the treatment of P. falciparum, an increase in treatment failure was observed in the western provinces. In 2010, the PCR-corrected treatment failure rates for DP on day 42 were 25% (95% confidence interval [CI] = 10 to 51%) in Pailin and 10.7% (95% CI = 4 to 23%) in Pursat, while the therapeutic efficacy of DP remained high (100%) in Ratanakiri and Preah Vihear provinces, located in northern and eastern Cambodia. For the studies of P. vivax, the day 28 uncorrected treatment failure rate among patients treated with CQ ranged from 4.4 to 17.4%; DP remained 100% effective in all sites. Further study is required to investigate suspected P. falciparum resistance to piperaquine in western Cambodia; the results of in vitro and molecular studies were not found to support the therapeutic efficacy findings. The emergence of artemisinin resistance in this region has likely put additional pressure on piperaquine. Although DP appears to be an appropriate new first-line treatment for P. vivax in Cambodia, alternative treatments are urgently needed for P. falciparum-infected patients in western Cambodia.

  16. Plasmodium falciparum metacaspase PfMCA-1 triggers a z-VAD-fmk inhibitable protease to promote cell death.

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    Benoît Meslin

    Full Text Available Activation of proteolytic cell death pathways may circumvent drug resistance in deadly protozoan parasites such as Plasmodium falciparum and Leishmania. To this end, it is important to define the cell death pathway(s in parasites and thus characterize proteases such as metacaspases (MCA, which have been reported to induce cell death in plants and Leishmania parasites. We, therefore, investigated whether the cell death function of MCA is conserved in different protozoan parasite species such as Plasmodium falciparum and Leishmania major, focusing on the substrate specificity and functional role in cell survival as compared to Saccharomyces cerevisae. Our results show that, similarly to Leishmania, Plasmodium MCA exhibits a calcium-dependent, arginine-specific protease activity and its expression in yeast induced growth inhibition as well as an 82% increase in cell death under oxidative stress, a situation encountered by parasites during the host or when exposed to drugs such as artemisins. Furthermore, we show that MCA cell death pathways in both Plasmodium and Leishmania, involve a z-VAD-fmk inhibitable protease. Our data provide evidence that MCA from both Leishmania and Plasmodium falciparum is able to induce cell death in stress conditions, where it specifically activates a downstream enzyme as part of a cell death pathway. This enzymatic activity is also induced by the antimalarial drug chloroquine in erythrocytic stages of Plasmodium falciparum. Interestingly, we found that blocking parasite cell death influences their drug sensitivity, a result which could be used to create therapeutic strategies that by-pass drug resistance mechanisms by acting directly on the innate pathways of protozoan cell death.

  17. Ex vivo susceptibility of Plasmodium falciparum to antimalarial drugs in western, northern, and eastern Cambodia, 2011-2012: association with molecular markers.

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    Lim, Pharath; Dek, Dalin; Try, Vorleak; Eastman, Richard T; Chy, Sophy; Sreng, Sokunthea; Suon, Seila; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Ashley, Elizabeth A; Miotto, Olivo; Dondorp, Arjen M; White, Nicholas J; Su, Xin-zhuan; Char, Meng Chuor; Anderson, Jennifer M; Amaratunga, Chanaki; Menard, Didier; Fairhurst, Rick M

    2013-11-01

    In 2008, dihydroartemisinin (DHA)-piperaquine (PPQ) became the first-line treatment for uncomplicated Plasmodium falciparum malaria in western Cambodia. Recent reports of increased treatment failure rates after DHA-PPQ therapy in this region suggest that parasite resistance to DHA, PPQ, or both is now adversely affecting treatment. While artemisinin (ART) resistance is established in western Cambodia, there is no evidence of PPQ resistance. To monitor for resistance to PPQ and other antimalarials, we measured drug susceptibilities for parasites collected in 2011 and 2012 from Pursat, Preah Vihear, and Ratanakiri, in western, northern, and eastern Cambodia, respectively. Using a SYBR green I fluorescence assay, we calculated the ex vivo 50% inhibitory concentrations (IC50s) of 310 parasites to six antimalarials: chloroquine (CQ), mefloquine (MQ), quinine (QN), PPQ, artesunate (ATS), and DHA. Geometric mean IC50s (GMIC50s) for all drugs (except PPQ) were significantly higher in Pursat and Preah Vihear than in Ratanakiri (P ≤ 0.001). An increased copy number of P. falciparum mdr1 (pfmdr1), an MQ resistance marker, was more prevalent in Pursat and Preah Vihear than in Ratanakiri and was associated with higher GMIC50s for MQ, QN, ATS, and DHA. An increased copy number of a chromosome 5 region (X5r), a candidate PPQ resistance marker, was detected in Pursat but was not associated with reduced susceptibility to PPQ. The ex vivo IC50 and pfmdr1 copy number are important tools in the surveillance of multidrug-resistant (MDR) parasites in Cambodia. While MDR P. falciparum is prevalent in western and northern Cambodia, there is no evidence for PPQ resistance, suggesting that DHA-PPQ treatment failures result mainly from ART resistance.

  18. Novel phenotypic assays for the detection of artemisinin-resistant Plasmodium falciparum malaria in Cambodia: in-vitro and ex-vivo drug-response studies.

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    Witkowski, Benoit; Amaratunga, Chanaki; Khim, Nimol; Sreng, Sokunthea; Chim, Pheaktra; Kim, Saorin; Lim, Pharath; Mao, Sivanna; Sopha, Chantha; Sam, Baramey; Anderson, Jennifer M; Duong, Socheat; Chuor, Char Meng; Taylor, Walter R J; Suon, Seila; Mercereau-Puijalon, Odile; Fairhurst, Rick M; Menard, Didier

    2013-12-01

    Artemisinin resistance in Plasmodium falciparum lengthens parasite clearance half-life during artemisinin monotherapy or artemisinin-based combination therapy. Absence of in-vitro and ex-vivo correlates of artemisinin resistance hinders study of this phenotype. We aimed to assess whether an in-vitro ring-stage survival assay (RSA) can identify culture-adapted P falciparum isolates from patients with slow-clearing or fast-clearing infections, to investigate the stage-dependent susceptibility of parasites to dihydroartemisinin in the in-vitro RSA, and to assess whether an ex-vivo RSA can identify artemisinin-resistant P falciparum infections. We culture-adapted parasites from patients with long and short parasite clearance half-lives from a study done in Pursat, Cambodia, in 2010 (registered with ClinicalTrials.gov, number NCT00341003) and used novel in-vitro survival assays to explore the stage-dependent susceptibility of slow-clearing and fast-clearing parasites to dihydroartemisinin. In 2012, we implemented the RSA in prospective parasite clearance studies in Pursat, Preah Vihear, and Ratanakiri, Cambodia (NCT01736319), to measure the ex-vivo responses of parasites from patients with malaria. Continuous variables were compared with the Mann-Whitney U test. Correlations were analysed with the Spearman correlation test. In-vitro survival rates of culture-adapted parasites from 13 slow-clearing and 13 fast-clearing infections differed significantly when assays were done on 0-3 h ring-stage parasites (10·88% vs 0·23%; p=0·007). Ex-vivo survival rates significantly correlated with in-vivo parasite clearance half-lives (n=30, r=0·74, 95% CI 0·50-0·87; p<0·0001). The in-vitro RSA of 0-3 h ring-stage parasites provides a platform for the molecular characterisation of artemisinin resistance. The ex-vivo RSA can be easily implemented where surveillance for artemisinin resistance is needed. Institut Pasteur du Cambodge and the Intramural Research Program, NIAID, NIH

  19. Lessons learnt from 20 years surveillance of malaria drug resistance prior to the policy change in Burkina Faso.

    Science.gov (United States)

    Tinto, Halidou; Valea, Innocent; Ouédraogo, Jean-Bosco; Guiguemdé, Tinga Robert

    2016-01-01

    The history of drug resistance to the previous antimalarial drugs, and the potential for resistance to evolve to Artemisinin-based combination therapies, demonstrates the necessity to set-up a good surveillance system in order to provide early warning of the development of resistance. Here we report a review summarizing the history of the surveillance of drug resistance that led to the policy change in Burkina Faso. The first Plasmodium falciparum Chloroquine-Resistance strain identified in Burkina Faso was detected by an in vitro test carried out in Koudougou in 1983. Nevertheless, no further cases were reported until 1987, suggesting that resistant strains had been circulating at a low prevalence before the beginning of the systematic surveillance system from 1984. We observed a marked increase of Chloroquine-Resistance in 2002-2003 probably due to the length of follow-up as the follow-up duration was 7 or 14 days before 2002 and 28 days from 2002 onwards. Therefore, pre-2002 studies have probably under-estimated the real prevalence of Chloroquine-Resistance by not detecting the late recrudescence. With a rate of 8.2% treatment failure reported in 2003, Sulfadoxine-Pyrimethamine was still efficacious for the treatment of uncomplicated malaria in Burkina Faso but this rate might rapidly increase as the result of its spreading from neighboring countries and due to its current use for both the Intermittent Preventive Treatment in pregnant women and Seasonal Malaria Chemoprophylaxis. The current strategy for the surveillance of the Artemisinin-based combination treatments resistance should build on lessons learnt under the previous period of 20 years surveillance of Chloroquine and Sulfadoxine-Pyrimethamine resistance (1994-2004). The most important aspect being to extend the number of sentinel sites so that data would be less patchy and could help understanding the dynamic of the resistance.

  20. Plasmodium falciparum merozoite surface protein 1 - Glycosylation and localization to low-density, detergent-resistant membranes in the parasitized erythrocyte

    DEFF Research Database (Denmark)

    Hoessli, D.C.; Poincelet, M.; Gupta, Ramneek;

    2003-01-01

    In addition to the major carbohydrate moieties of the glycosylphosphatidylinositol (GPI) anchor, we report that Plasmodium falciparum merozoite surface protein 1 (MSP-1) bears O-GlcNAc modifications predominantly in beta-anomeric configuration, in both the C- and N-terminal portions of the protein....... Subcellular fractionation of parasitized erythrocytes in the late trophozoite/schizont stage reveals that GPI-anchored C-terminal fragments of MSP-1 are recovered in Triton X-100 resistant, low-density membrane fractions. Our results suggest that O -GlcNAc-modified MSP-1 N-terminal fragments tend to localize...... within the parasitophorous vacuolar membrane while GPI-anchored MSP-1 C-terminal fragments associate with low-density, Triton X-100 resistant membrane domains (rafts), redistribute in the parasitized erythrocyte and are eventually shed as membrane vesicles that also contain the endogenous, GPI-linked CD...

  1. The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin

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    Barik Sailen

    2003-09-01

    Full Text Available Abstract Background The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA, is a specific inhibitor of heat shock protein 90 (Hsp90 and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. Results We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively and on all erythrocytic stages of the parasite. Conclusions Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug.

  2. Malaria resistance genes are associated with the levels of IgG subclasses directed against Plasmodium falciparum blood-stage antigens in Burkina Faso

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    Afridi Sarwat

    2012-09-01

    Full Text Available Abstract Background HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms have been associated with malaria resistance in humans, whereas cytophilic immunoglobulin G (IgG antibodies are thought to play a critical role in immune protection against asexual blood stages of the parasite. Furthermore, HBB, IL4, TNF, and FCGR2A have been associated with both malaria resistance and IgG levels. This suggests that some malaria resistance genes influence the levels of IgG subclass antibodies. Methods In this study, the effect of HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms on the levels of IgG responses against Plasmodium falciparum blood-stage extract was investigated in 220 individuals living in Burkina Faso. The Pearson’s correlation coefficient among IgG subclasses was determined. A family-based approach was used to assess the association of polymorphisms with anti-P. falciparum IgG, IgG1, IgG2, IgG3 and IgG4 levels. Results After applying a multiple test correction, several polymorphisms were associated with IgG subclass or IgG levels. There was an association of i haemoglobin C with IgG levels; ii the FcγRIIa H/R131 with IgG2 and IgG3 levels; iii TNF-863 with IgG3 levels; iv TNF-857 with IgG levels; and, v TNF1304 with IgG3, IgG4, and IgG levels. Conclusion Taken together, the results support the hypothesis that some polymorphisms affect malaria resistance through their effect on the acquired immune response, and pave the way towards further comprehension of genetic control of an individual’s humoral response against malaria.

  3. Molecular surveillance for drug-resistant Plasmodium falciparum in clinical and subclinical populations from three border regions of Burma/Myanmar: cross-sectional data and a systematic review of resistance studies

    Science.gov (United States)

    2012-01-01

    Background Confirmation of artemisinin-delayed parasite clearance in Plasmodium falciparum along the Thai-Myanmar border has inspired a global response to contain and monitor drug resistance to avert the disastrous consequences of a potential spread to Africa. However, resistance data from Myanmar are sparse, particularly from high-risk areas where limited health services and decades of displacement create conditions for resistance to spread. Subclinical infections may represent an important reservoir for resistance genes that confer a fitness disadvantage relative to wild-type alleles. This study estimates the prevalence of resistance genotypes in three previously unstudied remote populations in Myanmar and tests the a priori hypothesis that resistance gene prevalence would be higher among isolates collected from subclinical infections than isolates collected from febrile clinical patients. A systematic review of resistance studies is provided for context. Methods Community health workers in Karen and Kachin States and an area spanning the Indo-Myanmar border collected dried blood spots from 988 febrile clinical patients and 4,591 villagers with subclinical infection participating in routine prevalence surveys. Samples positive for P. falciparum 18 s ribosomal RNA by real-time PCR were genotyped for P. falciparum multidrug resistance protein (pfmdr1) copy number and the pfcrt K76T polymorphism using multiplex real-time PCR. Results Pfmdr1 copy number increase and the pfcrt K76 polymorphism were determined for 173 and 269 isolates, respectively. Mean pfmdr1 copy number was 1.2 (range: 0.7 to 3.7). Pfmdr1 copy number increase was present in 17.5%, 9.6% and 11.1% of isolates from Karen and Kachin States and the Indo-Myanmar border, respectively. Pfmdr1 amplification was more prevalent in subclinical isolates (20.3%) than clinical isolates (6.4%, odds ratio 3.7, 95% confidence interval 1.1 - 12.5). Pfcrt K76T prevalence ranged from 90-100%. Conclusions Community

  4. Chloroquine use improves dengue-related symptoms

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    Marcos Carvalho Borges

    2013-08-01

    Full Text Available Dengue is the most important arboviral disease in the world. As chloroquine, an antimalarial agent, has shown some antiviral effects, this study evaluated its effect in patients with dengue. A randomised, double-blind study was performed by administering chloroquine or placebo for three days to 129 patients with dengue-related symptoms. Of these patients, 37 were confirmed as having dengue and completed the study; in total, 19 dengue patients received chloroquine and 18 received placebo. There was no significant difference in the duration of the disease or the degree and days of fever. However, 12 patients (63% with confirmed dengue reported a substantial decrease in pain intensity and a great improvement in their ability to perform daily activities (p = 0.0004 while on the medication and the symptoms returned immediately after these patients stopped taking the medication. The same effect was not observed in patients with diseases other than dengue. Therefore, this study shows that patients with dengue treated with chloroquine had an improvement in their quality of life and were able to resume their daily activities. However, as chloroquine did not alter the duration of the disease or the intensity and days of fever, further studies are necessary to confirm the clinical effects and to assess the side effects of chloroquine in dengue patients.

  5. Brazilian Plasmodium falciparum isolates: investigation of candidate polymorphisms for artemisinin resistance before introduction of artemisinin-based combination therapy

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    Rosenthal Philip J

    2010-12-01

    Full Text Available Abstract Background This study was performed to better understand the genetic diversity of known polymorphisms in pfatpase6 and pfmdr1 genes before the introduction of ACT in Brazil, in order to get a genotypic snapshot of Plasmodium falciparum parasites that may be used as baseline reference for future studies. Methods Parasites from P. falciparum samples collected in 2002, 2004 and 2006-2007 were genotyped using PCR and DNA sequencing at codons 86, 130, 184, 1034, 1042, 1109 and 1246 for pfmdr1 gene, and 243, 263, 402, 431, 623, 630, 639, 683, 716, 776, 769 and 771 for pfatpase6 gene. Results A pfmdr1 haplotype NEF/CDVY was found in 97% of the samples. In the case of pfatpase6, four haplotypes, wild-type (37%, 630 S (35%, 402 V (5% and double-mutant 630 S + 402 V (23%, were detected. Conclusion Although some polymorphism in pfmdr1 and pfatpase6 were verified, no reported haplotypes in both genes that may mediate altered response to ACT was detected before the introduction of this therapy in Brazil. Thus, the haplotypes herein described can be very useful as a baseline reference of P. falciparum populations without ACT drug pressure.

  6. Antibodies from malaria-exposed pregnant women recognize trypsin resistant epitopes on the surface of Plasmodium falciparum-infected erythrocytes selected for adhesion to chondroitin sulphate A

    DEFF Research Database (Denmark)

    Sharling, Lisa; Enevold, Anders; Sowa, Kordai M P;

    2004-01-01

    BACKGROUND: The ability of Plasmodium falciparum-infected erythrocytes to adhere to the microvasculature endothelium is thought to play a causal role in malaria pathogenesis. Cytoadhesion to endothelial receptors is generally found to be highly sensitive to trypsinization of the infected erythroc......BACKGROUND: The ability of Plasmodium falciparum-infected erythrocytes to adhere to the microvasculature endothelium is thought to play a causal role in malaria pathogenesis. Cytoadhesion to endothelial receptors is generally found to be highly sensitive to trypsinization of the infected...... erythrocyte surface. However, several studies have found that parasite adhesion to placental receptors can be markedly less sensitive to trypsin. This study investigates whether chondroitin sulphate A (CSA) binding parasites express trypsin-resistant variant surface antigens (VSA) that bind female......-specific antibodies induced as a result of pregnancy associated malaria (PAM). METHODS: Fluorescence activated cell sorting (FACS) was used to measure the levels of adult Scottish and Ghanaian male, and Ghanaian pregnant female plasma immunoglobulin G (IgG) that bind to the surface of infected erythrocytes. P...

  7. Antimalarial activity of Mannich bases derived from 4-(7'-bromo-1',5'-naphthyridin-4'-ylamino)phenol and 4-(7'-trifluoromethylquinolin-4'-ylamino)phenol against Plasmodium falciparum in vitro.

    Science.gov (United States)

    Scott, H V; Tan, W L; Barlin, G B

    1987-04-01

    Mono- and di-Mannich bases derived from 4-(7'-bromo-1',5'-naphthyridin-4'-ylamino)phenol and 4-(7'-trifluoromethylquinolin-4'-ylamino)phenol were assayed for antimalarial activity (using an in vitro radioisotopic technique) against two isolates of Plasmodium falciparum. Many from these two series of compounds had an IC50 value (concentration of compound causing 50% inhibition of 3H-hypoxanthine incorporation) comparable to or better than those of mefloquine and amodiaquine, for both a chloroquine-sensitive isolate (FCQ-27) and the chloroquine-resistant isolate (K1). At least one compound, 2,6-bis (piperidin-1''-ylmethyl)-4-(7'-trifluoromethylquinolin -4'-ylamino)phenol (TN112), showed significant superior activity to the three antimalarials chloroquine, mefloquine and amodiaquine against both isolates. (Statistically superior activity compared to these three antimalarials was found for TN112, except that against the K1 isolate its activity was just outside the range of significance relative to mefloquine.) Some of the 7-bromo-1,5-naphthyridine Mannich bases were appreciably less toxic in mice than amodiaquine.

  8. In vitro resistance selections for Plasmodium falciparum dihydroorotate dehydrogenase inhibitors give mutants with multiple point mutations in the drug-binding site and altered growth.

    Science.gov (United States)

    Ross, Leila S; Gamo, Francisco Javier; Lafuente-Monasterio, Maria José; Singh, Onkar M P; Rowland, Paul; Wiegand, Roger C; Wirth, Dyann F

    2014-06-27

    Malaria is a preventable and treatable disease; yet half of the world's population lives at risk of infection, and an estimated 660,000 people die of malaria-related causes every year. Rising drug resistance threatens to make malaria untreatable, necessitating both the discovery of new antimalarial agents and the development of strategies to identify and suppress the emergence and spread of drug resistance. We focused on in-development dihydroorotate dehydrogenase (DHODH) inhibitors. Characterizing resistance pathways for antimalarial agents not yet in clinical use will increase our understanding of the potential for resistance. We identified resistance mechanisms of Plasmodium falciparum (Pf) DHODH inhibitors via in vitro resistance selections. We found 11 point mutations in the PfDHODH target. Target gene amplification and unknown mechanisms also contributed to resistance, albeit to a lesser extent. These mutant parasites were often hypersensitive to other PfDHODH inhibitors, which immediately suggested a novel combination therapy approach to preventing resistance. Indeed, a combination of wild-type and mutant-type selective inhibitors led to resistance far less often than either drug alone. The effects of point mutations in PfDHODH were corroborated with purified recombinant wild-type and mutant-type PfDHODH proteins, which showed the same trends in drug response as the cognate cell lines. Comparative growth assays demonstrated that two mutant parasites grew less robustly than their wild-type parent, and the purified protein of those mutants showed a decrease in catalytic efficiency, thereby suggesting a reason for the diminished growth rate. Co-crystallography of PfDHODH with three inhibitors suggested that hydrophobic interactions are important for drug binding and selectivity.

  9. Nonlinear mixed-effects modelling of in vitro drug susceptibility and molecular correlates of multidrug resistant Plasmodium falciparum.

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    Julie A Simpson

    Full Text Available The analysis of in vitro anti-malarial drug susceptibility testing is vulnerable to the effects of different statistical approaches and selection biases. These confounding factors were assessed with respect to pfmdr1 gene mutation and amplification in 490 clinical isolates. Two statistical approaches for estimating the drug concentration associated with 50% effect (EC50 were compared: the commonly used standard two-stage (STS method, and nonlinear mixed-effects modelling. The in vitro concentration-effect relationships for, chloroquine, mefloquine, lumefantrine and artesunate, were derived from clinical isolates obtained from patients on the western border of Thailand. All isolates were genotyped for polymorphisms in the pfmdr1 gene. The EC50 estimates were similar for the two statistical approaches but 15-28% of isolates in the STS method had a high coefficient of variation (>15% for individual estimates of EC50 and these isolates had EC50 values that were 32 to 66% higher than isolates derived with more precision. In total 41% (202/490 of isolates had amplification of pfmdr1 and single nucleotide polymorphisms were found in 50 (10%. Pfmdr1 amplification was associated with an increase in EC50 for mefloquine (139% relative increase in EC50 for 2 copies, 188% for 3+ copies, lumefantrine (82% and 75% for 2 and 3+ copies respectively and artesunate (63% and 127% for 2 and 3+ copies respectively. In contrast pfmdr1 mutation at codons 86 or 1042 were associated with an increase in chloroquine EC50 (44-48%. Sample size calculations showed that to demonstrate an EC50 shift of 50% or more with 80% power if the prevalence was 10% would require 430 isolates and 245 isolates if the prevalence was 20%. In conclusion, although nonlinear mixed-effects modelling did not demonstrate any major advantage for determining estimates of anti-malarial drug susceptibility, the method includes all isolates, thereby, potentially improving confirmation of candidate

  10. Safety, efficacy and population pharmacokinetics of fixed-dose combination of artesunate-mefloquine in the treatment of acute uncomplicated Plasmodium falciparum malaria in India.

    Science.gov (United States)

    Valecha, Neena; Srivastava, Bina; Dubhashi, N G; Rao, B H Krishnamoorthy; Kumar, Ashwani; Ghosh, S K; Singh, Jai Prakash Narayan; Kiechel, J R; Sharma, Bhawna; Jullien, V; Dash, A P; Taylor, W R J; Anvikar, Anupkumar R

    2013-12-01

    India has switched over to artemisinin-based combination therapy (ACT) for the treatment of acute uncomplicated Plasmodium falciparum malaria and the ACT used in the national programme is artesunate + sulphadoxine-pyrimethamine. Since the efficacy of ACT is dependent also on the partner drug, there is a need to evaluate and deploy multiple ACTs. This multicentre, single-arm, open-label clinical trial was carried out to assess the efficacy, safety and population pharmacokinetics of a fixed dose combination (FDC) artesunate mefloquine (ASMQ) in P. falciparum infected, Indian adults at Panjim, Goa, and Mangalore, Karnataka between December 2007 and November 2008. A total of 77 patients (males 74) were screened and enrolled: 42 at Goa and 35 at Mangalore with a median age of 25 yr (range 18-55 yr). One patient failed in treatment on D53, a PCR proven new infection, seven developed recurrent vivax parasitaemia and 11 did not have a parasitological endpoint. By per protocol analysis, the D63 cure rate was 58/59 (98.3; 95% C.I. 90.9-99.9%), and 58/58, with PCR correction. ASMQ was well-tolerated and no serious adverse events were reported. The study showed that the ASMQ FDC was efficacious and well-tolerated for the treatment of acute, uncomplicated P. falciparum malaria in highly endemic, chloroquine resistant areas of Goa and Mangalore. It is a viable option for India.

  11. Effect of Crocus sativus Stigma (saffron alone or in combination with chloroquine on chloroquine sensitive strain of Plasmodium berghei in mice

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    Pestechian Nader

    2015-10-01

    Full Text Available Introduction: In malaria treatment protocols, treatment failure or drug resistance of synthesized drugs like alkaloids related to quinine, and aminoquinolines are the main problems now. Therefore, discovering efficient drugs or combination therapy of blood schizonticidal drugs with different mechanisms or different targets in the parasite is a crucial effort to solve this problem. In this study, the effectiveness of Crocus sativus Stigma (saffron individually and in combination with chloroquine, was considered against chloroquine–sensitive strain of Plasmodium berghei.Methods: At the first stage, using 4 day suppressive Peter’s test in mice, ED50 and survival times of saffron methanol extract, and its aqueous and ethyl acetate fractions and chloroquine on P. berghei were calculated. Then, based on the toxicity and survival time results, combination therapy was conducted with the best saffron fraction and chloroquine against the parasite.Results: The saffron extract, aqueous and ethyl acetate fractions resulted in suppression of parasitemia with ED50 values of 587.0 ± 78.7, 323.7 ± 37.2, and 508.7 ± 35.6 mg/kg, respectively. Combination of ethyl acetate fraction with chloroquine, potentiated the antimalarial property and the survived percent of the treated mice on days 7, 14, and 28 significantly more than chloroquine or ethyl acetate fraction alone.Conclusion: Saffron and its fractions individually can be effective in reducing the parasitemia in mice. The outcome of combination of ethyl acetate fraction with chloroquine on the mice showed synergistic effect on the chloroquine–sensitive strain of parasite.

  12. Antimalarial efficacy of Albizia lebbeck (Leguminosae against Plasmodium falciparum in vitro & P. berghei in vivo

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    Shagun Kalia

    2015-01-01

    Full Text Available Background & objectives: Albizia lebbeck Benth. (Leguminosae has long been used in Indian traditional medicine. The current study was designed to test antimalarial activity of ethanolic bark extract of A. lebbeck (EBEAL. Methods: EBEAL was prepared by soxhlet extraction and subjected to phytochemical analysis. The extract was evaluated for its in vitro antimalarial activity against Plasmodium falciparum chloroquine (CQ sensitive (MRC2 and CQ resistant (RKL9 strains. Cytotoxicity (CC 50 of extract against HeLa cells was evaluated. Median lethal dose (LD 50 was determined to assess safety of EBEAL in BALB/c mice. Schizonticidal (100-1000 mg/kg and preventive (100-750 mg/kg activities of EBEAL were evaluated against P. berghei. Curative activity (100-750 mg/kg of extract was also evaluated. Results: Phytochemical screening revealed presence of alkaloids, flavonoids, phenols, saponins, terpenes and phytosterols. The extract exhibited IC 50 of 8.2 µg/ml (MRC2 and 5.1 µg/ml (RKL9. CC 50 of extract on HeLa cell line was calculated to be >1000 µg/ml. EBEAL showed selectivity indices (SI of >121.9 and >196.07 against MRC2 and RKL9 strains of P. falciparum, respectively. LD 50 of EBEAL was observed to be >5 g/kg. Dose-dependent chemosuppression was observed with significant ( p100 mg/kg. Significant (P<0.001 curative and repository activities were exhibited by 750 mg/kg concentration of extract on D7. Interpretation & conclusions: The present investigation reports antiplasmodial efficacy of EBEAL in vitro against P. falciparum as evident by high SI values. ED 50 of <100 mg/kg against P. berghei categorizes EBEAL as active antimalarial. Further studies need to be done to exploit its antiplasmodial activity further.

  13. Submicroscopic gametocytes and the transmission of antifolate-resistant Plasmodium falciparum in Western Kenya

    DEFF Research Database (Denmark)

    Oesterholt, Mayke J A M; Alifrangis, Michael; Sutherland, Colin J

    2009-01-01

    . In the present study, we determine the association between parasite mutations, submicroscopic P. falciparum gametocytemia and malaria transmission to mosquitoes. METHODOLOGY/PRINCIPAL FINDINGS: Samples from children treated with SP alone or in combination with artesunate (AS) or amodiaquine were genotyped...... expressed mutations at all three dhfr codons prior to treatment. The presence of all three mutations was not related to higher Pfs25 QT-NASBA gametocyte prevalence or density during follow-up, compared to double mutant infections. The proportion of infected mosquitoes or oocyst burden was also not related...

  14. Monitoring PfMDR1 transport in Plasmodium falciparum.

    Science.gov (United States)

    Reiling, Sarah J; Rohrbach, Petra

    2015-07-15

    The Plasmodium falciparum multidrug resistance 1 transporter, PfMDR1, contains five amino acid polymorphisms that are suggested to be involved in altered drug transport from the parasite's cytosol into the digestive vacuole (DV). Transport of a substrate into another intracellular compartment influences drug availability at its site of action, therefore making the parasite more susceptible or resistant to a drug. Fluo-4 is a known fluorescent substrate that can be used as a molecular tool to investigate transport dynamics of PfMDR1 in many parasite strains. Six P. falciparum strains with varying PfMDR1 mutations were loaded with Fluo-4 AM. Accumulation of the fluorophore in the DV was measured using confocal microscopy. The role of a key amino acid mutation was verified using selected parasite clones with point mutations at PfMDR1 amino acid position 1042. Equal expression of PfMDR1 was confirmed by Western blot. Fluo-4 was transported by PfMDR1 into the DV of most drug-sensitive and -resistant parasites. Asparagine at PfMDR1 amino acid position 1042 was crucial for Fluo-4 transport, while the N1042D substitution abolished Fluo-4 transport. Competition studies of Fluo-4 with chloroquine, quinine and mefloquine were performed on parasites harbouring asparagine at position 1042. A distinct Fluo-4 transport inhibition pattern for each tested anti-malarial drug was observed in parasite strains of different genetic background. This study demonstrates that Fluo-4 can be used to investigate PfMDR1 transport dynamics in both drug-sensitive and -resistant parasites. Furthermore, direct evidence of altered Fluo-4 transport in PfMDR1 is linked to a single amino acid mutation in the substrate binding pocket. This system offers a great tool to investigate the role of substrate transport by PfMDR1 and the mutations necessary to support transport, which would lead to new insights for the development of novel anti-malarial drugs.

  15. Artesunate-amodiaquine fixed dose combination for the treatment of Plasmodium falciparum malaria in India

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    Anvikar Anupkumar R

    2012-03-01

    Full Text Available Abstract Background Artemisinin-based combination therapy (ACT has been recommended for the treatment of falciparum malaria by the World Health Organization. Though India has already switched to ACT for treating falciparum malaria, there is need to have multiple options of alternative forms of ACT. A randomized trial was conducted to assess the safety and efficacy of the fixed dose combination of artesunate-amodiaquine (ASAQ and amodiaquine (AQ for the treatment of uncomplicated falciparum malaria for the first time in India. The study sites are located in malaria-endemic, chloroquine-resistant areas. Methods This was an open label, randomized trial conducted at two sites in India from January 2007 to January 2008. Patients between six months and 60 years of age having Plasmodium falciparum mono-infection were randomly allocated to ASAQ and AQ arms. The primary endpoint was 28-day PCR-corrected parasitological cure rate. Results Three hundred patients were enrolled at two participating centres, Ranchi, Jharkhand and Rourkela, Odisha. Two patients in AQ arm had early treatment failure while there was no early treatment failure in ASAQ arm. Late treatment failures were seen in 13 and 12 patients in ASAQ and AQ arms, respectively. The PCR-corrected cure rates in intent-to-treat population were 97.51% (94.6-99.1% in ASAQ and 88.65% (81.3-93.9% in AQ arms. In per-protocol population, they were 97.47% (94.2-99.2% and 88.30% (80-94% in ASAQ and AQ arms respectively. Seven serious adverse events (SAEs were reported in five patients, of which two were reported as related to the treatment. All SAEs resolved without sequel. Conclusion The fixed dose combination of ASAQ was found to be efficacious and safe treatment for P. falciparum malaria. Amodiaquine also showed acceptable efficacy, making it a suitable partner of artesunate. The combination could prove to be a viable option in case India opts for fixed dose combination ACT. Clinical trial registry

  16. Comparative study of efficacy of artesunate plus cotrimoxazole and artesunate plus chloroquine in the treatment of malaria in Nigerian children: a preliminary report

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    F.A. Fehintola, S.T. Balogun

    2010-09-01

    Full Text Available Background & objectives: The study was undertaken to evaluate the efficacy of cotrimoxazole plusartesunate and to compare the efficacy of this combination with that of artesunate plus chloroquinein the treatment of acute uncomplicated falciparum malaria in children.Methods: Children aged between 0.5 and 12 yr with clinical and parasitological evidence ofPlasmodium falciparum malaria were randomized to receive either artesunate plus cotrimoxazoleor artesunate plus chloroquine. They were followed-up with clinical and parasitological assessmentfor a period of 14 days.Results: In all, 57 out of 81 (31 in the artesunate plus cotrimoxazole group and 26 in artesunateplus chloroquine group completed the study as per protocol and were evaluated. Pre-treatmentclinical and parasitological parameters were similar in the two treatment groups. The time to clearfever and other symptoms were similar in the two groups 1.0 + 0 vs 1.14 + 0.38 (p > 0.05.Parasite clearance times were also similar; 1.65 + 0.49 days vs 1.58 + 0.67 days respectively forartesunate plus cotrimoxazole and artesunate plus chloroquine (p > 0.05. The cure rates on Day14 were 100% for both artesunate plus cotrimoxazole and artesunate plus chloroquine groups.Both drug combinations were well-tolerated in the small population of children.Conclusion: These results indicate that artesunate plus cotrimoxazole has similar efficacy toartesunate plus chloroquine in the treatment of acute uncomplicated P. falciparum malaria inchildren resident in an endemic area of south-west Nigeria.

  17. Pyronaridine-Artesunate versus Chloroquine in Patients with Acute Plasmodium vivax Malaria: A Randomized, Double-Blind, Non-Inferiority Trial

    OpenAIRE

    Yi Poravuth; Duong Socheat; Ronnatrai Rueangweerayut; Chirapong Uthaisin; Aung Pyae Phyo; Neena Valecha; B. H. Krishnamoorthy Rao; Emiliana Tjitra; Asep Purnama; Isabelle Borghini-Fuhrer; Stephan Duparc; Chang-Sik Shin; Lawrence Fleckenstein

    2011-01-01

    BACKGROUND: New antimalarials are needed for P. vivax and P. falciparum malaria. This study compared the efficacy and safety of pyronaridine-artesunate with that of chloroquine for the treatment of uncomplicated P. vivax malaria. METHODS AND FINDINGS: This phase III randomized, double-blind, non-inferiority trial included five centers across Cambodia, Thailand, India, and Indonesia. In a double-dummy design, patients (aged >3-≤ 60 years) with microscopically confirmed P. vivax mono-infection ...

  18. Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

    Directory of Open Access Journals (Sweden)

    Stephen GS Vreden

    2013-12-01

    Full Text Available The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31% still had parasitaemia on day 3 compared to one (2% out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.

  19. Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether.

    Science.gov (United States)

    Vreden, Stephen G S; Jitan, Jeetendra K; Bansie, Rakesh D; Adhin, Malti R

    2013-12-01

    The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.

  20. 氯喹衍生物CQ11逆转乳腺癌多药耐药细胞株MCF/DOX对多柔比星的耐药性%Reversal of CQ11, a chloroquine derivative,on multidrug resistance in doxorubicin-resistant breast cancer cell line MCF/DOX

    Institute of Scientific and Technical Information of China (English)

    Dalong Wu; Shirong Ma; Fengying Sui; Chengwen Zhang; Lixin Yin; Huanzhang Lu

    2008-01-01

    Objective: To investigate the reversal effect of CQ11, a chloroquine derivative, on multidrug resistance (MDR) in doxorubicin (DOX)-resistant human breast carcinoma cell line MCF/DOX. Methods: Cells of a human breast cancer cell line, MCF, and its DOX-resistant variant, MCF/DOX, were cultivated with DOX and/or CQ11. The cytotoxicity of drugs in vitro was assayed by MTT method. The accumulation of DOX in these cells was detected by fluorescence spectrophotometer. Results: MCF/DOX cells were 119 times more resistant to DOX in comparison with MCF cells. After simultaneous treatment with CQ11 at the concentrations of 1.0, 2.5 and 5.0 μmol/L, the IC50 of DOX for MCF/DOX cells decreased from 3.1±0.47 μmol/L to 0.58 ±0.032, 0.19±0.012 and 0.081±0.015 μmol/L, respectively, thus, increasing the DOX sensitivity by 5.3-fold (P<0.01), 16- fold (P < 0.01) and 38-fold (P < 0.01), respectively. In the accumulation assay of DOX, simultaneous incubation of MCF/DOX cells with CQ11 significantly increased the DOX accumulation in MCF/DOX cells. No such results were found in parental MCF cells. Conclusion: CQ11 had strong MDR reversal effect by enhancing intracellular DOX accumulation in MCF/DOX cells, indicating that CQ11 may be a promising MDR chemosensitivity.

  1. Efficacy and tolerability of four antimalarial combinations in the treatment of uncomplicated Plasmodium falciparum malaria in Senegal

    Directory of Open Access Journals (Sweden)

    Faye Oumar

    2007-06-01

    Full Text Available Abstract Background In view of the high level of chloroquine resistance in many countries, WHO has recommended the use of combination therapy with artemisinin derivatives in the treatment of uncomplicated malaria due to Plasmodium falciparum. Four antimalarial drug combinations, artesunate plus amodiaquine (Arsucam®, artesunate plus mefloquine (Artequin®, artemether plus lumefantrine (Coartem®; four doses and six doses, and amodiaquine plus sulphadoxine-pyrimethamine, were studied in five health districts in Senegal. Methods This is a descriptive, analytical, open, randomized study to evaluate the efficacy and tolerability of these four antimalarial combinations in the treatment of uncomplicated falciparum malaria using the 2002 WHO protocol. Results All drug combinations demonstrated good efficacy. On day 28, all combinations resulted in an excellent clinical and parasitological response rate of 100% after correction for PCR results, except for the four-dose artemether-lumefantrine regimen (96.4%. Follow-up of approximately 10% of each treatment group on day 42 demonstrated an efficacy of 100%. The combinations were well tolerated clinically and biologically. No unexpected side-effect was observed and all side-effects disappeared at the end of treatment. No serious side-effect requiring premature termination of treatment was observed. Conclusion The four combinations are effective and well-tolerated.

  2. Effect of chloroquine on human lymphocyte proliferation

    DEFF Research Database (Denmark)

    Bygbjerg, Ib Christian; Flachs, H

    1986-01-01

    the response to pokeweed mitogen. The response to concanavalin A and to various antigens was suppressed, especially the response to large particulate antigens. Oral intake of 300 mg of chloroquine base/week did not affect the lymphocyte proliferative responses. 600 mg of base/week decreased the response...

  3. Resistência "in vivo" do Plasmodium falciparum às 4-amino - quinoleínas e à associação sulfadoxina-pirimetamina: I - estudo de Porto Velho, Rondônia, 1983

    Directory of Open Access Journals (Sweden)

    Santiago Reyes

    1985-09-01

    Full Text Available Através da prova de 7 dias foi estudado o grau de resistência do Plasmodium falciparum à cloroquina, amodiaquina e sulfadoxina-pirimetamina em Porto Velho, Estado de Rondônia, Brasil. Não se observaram diferenças significativas nas médias de parasitas nos dias de seguimento e nas proporções de resistência entre os três medicamentos testados, fazendo com que os autores recomendem a manutenção das 4-aminoquinoleínas como drogas a serem usadas atualmente em infecções não graves por P. falciparum na área de Porto Velho.

  4. 恶性疟原虫药物抗性相关分子标记研究进展%Progress in researches on molecular markers of Plasmodium falciparum drug resistance

    Institute of Scientific and Technical Information of China (English)

    张梅花; 陆凤; 曹俊; 高琪

    2015-01-01

    药物治疗是疟疾防治的重要手段,但是却面临着抗疟药抗性的威胁。近年来,随着分子生物学的发展,越来越多的分子标记用于疟原虫抗药性监测。本文就恶性疟原虫常见抗药性相关分子标记的研究进展作一综述。%Effective chemotherapy is the mainstay of malaria control. However it is undergoing the serious threat by resis⁃tance of falciparum malaria to antimalarial drugs. In recent years with the development of molecular biology technology molec⁃ular markers have been widely used to monitor antimalarial drug resistance. This paper reviews the researches on the common molecular markers related to Plasmodium falciparum drug resistance.

  5. Chloroquine interference with hemoglobin endocytic trafficking suppresses adaptive heme and iron homeostasis in macrophages: the paradox of an antimalarial agent.

    Science.gov (United States)

    Schaer, Christian A; Laczko, Endre; Schoedon, Gabriele; Schaer, Dominik J; Vallelian, Florence

    2013-01-01

    The CD163 scavenger receptor pathway for Hb:Hp complexes is an essential mechanism of protection against the toxicity of extracellular hemoglobin (Hb), which can accumulate in the vasculature and within tissues during hemolysis. Chloroquine is a lysosomotropic agent, which has been extensively used as an antimalarial drug in the past, before parasite resistance started to limit its efficacy in most parts of the world. More recent use of chloroquine is related to its immunomodulatory activity in patients with autoimmune diseases, which may also involve hemolytic disease components. In this study we examined the effects of chloroquine on the human Hb clearance pathway. For this purpose we developed a new mass-spectrometry-based method to specifically quantify intracellular Hb peptides within the endosomal-lysosomal compartment by single reaction monitoring (SRM). We found that chloroquine exposure impairs trafficking of Hb:Hp complexes through the endosomal-lysosomal compartment after internalization by CD163. Relative quantification of intracellular Hb peptides by SRM confirmed that chloroquine blocked cellular Hb:Hp catabolism. This effect suppressed the cellular heme-oxygenase-1 (HO-1) response and shifted macrophage iron homeostasis towards inappropriately high expression of the transferrin receptor with concurrent inhibition of ferroportin expression. A functional deficiency of Hb detoxification and heme-iron recycling may therefore be an adverse consequence of chloroquine treatment during hemolysis.

  6. Chloroquine Interference with Hemoglobin Endocytic Trafficking Suppresses Adaptive Heme and Iron Homeostasis in Macrophages: The Paradox of an Antimalarial Agent

    Directory of Open Access Journals (Sweden)

    Christian A. Schaer

    2013-01-01

    Full Text Available The CD163 scavenger receptor pathway for Hb:Hp complexes is an essential mechanism of protection against the toxicity of extracellular hemoglobin (Hb, which can accumulate in the vasculature and within tissues during hemolysis. Chloroquine is a lysosomotropic agent, which has been extensively used as an antimalarial drug in the past, before parasite resistance started to limit its efficacy in most parts of the world. More recent use of chloroquine is related to its immunomodulatory activity in patients with autoimmune diseases, which may also involve hemolytic disease components. In this study we examined the effects of chloroquine on the human Hb clearance pathway. For this purpose we developed a new mass-spectrometry-based method to specifically quantify intracellular Hb peptides within the endosomal-lysosomal compartment by single reaction monitoring (SRM. We found that chloroquine exposure impairs trafficking of Hb:Hp complexes through the endosomal-lysosomal compartment after internalization by CD163. Relative quantification of intracellular Hb peptides by SRM confirmed that chloroquine blocked cellular Hb:Hp catabolism. This effect suppressed the cellular heme-oxygenase-1 (HO-1 response and shifted macrophage iron homeostasis towards inappropriately high expression of the transferrin receptor with concurrent inhibition of ferroportin expression. A functional deficiency of Hb detoxification and heme-iron recycling may therefore be an adverse consequence of chloroquine treatment during hemolysis.

  7. Five-year tracking of Plasmodium falciparum allele frequencies in a holoendemic area with indistinct seasonal transitions

    Directory of Open Access Journals (Sweden)

    Akala HM

    2014-11-01

    Full Text Available Hoseah M Akala, Angela O Achieng, Fredrick L Eyase, Dennis W Juma, Luiser Ingasia, Agnes C Cheruiyot, Charles Okello, Duke Omariba, Eunice A Owiti, Catherine Muriuki, Redemptah Yeda, Ben Andagalu, Jacob D Johnson, Edwin Kamau Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya Background: The renewed malaria eradication efforts require an understanding of the seasonal patterns of frequency of polymorphic variants in order to focus limited funds productively. Although cross-sectional studies in holoendemic areas spanning a single year could be useful in describing parasite genotype status at a given point, such information is inadequate in describing temporal trends in genotype polymorphisms. For Plasmodium falciparum isolates from Kisumu District Hospital, Plasmodium falciparum chloroquine-resistance transporter gene (Pfcrt-K76T and P. falciparum multidrug resistance gene 1 (PfMDR1-N86Y, were analyzed for polymorphisms and parasitemia changes in the 53 months from March 2008 to August 2012. Observations were compared with prevailing climatic factors, including humidity, rainfall, and temperature. Methods: Parasitemia (the percentage of infected red blood cells per total red blood cells was established by microscopy for P. falciparum malaria-positive samples. P. falciparum DNA was extracted from whole blood using a Qiagen DNA Blood Mini Kit. Single nucleotide polymorphism identification at positions Pfcrt-K76T and PfMDR1-N86Y was performed using real-time polymerase chain reaction and/or sequencing. Data on climatic variables were obtained from http://www.tutiempo.net/en/. Results: A total of 895 field isolates from 2008 (n=169, 2009 (n=161, 2010 (n=216, 2011 (n=223, and 2012 (n=126 showed large variations in monthly frequency of PfMDR1-N86Y and Pfcrt-K76T as the mutant genotypes decreased from 68.4%±15% and 38.1%±13% to

  8. Molecular epidemiology of malaria in Cameroon. XXX. sequence analysis of Plasmodium falciparum ATPase 6, dihydrofolate reductase, and dihydropteroate synthase resistance markers in clinical isolates from children treated with an artesunate-sulfadoxine-pyrimethamine combination.

    Science.gov (United States)

    Menemedengue, Virginie; Sahnouni, Khalifa; Basco, Leonardo; Tahar, Rachida

    2011-07-01

    Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes are reliable molecular markers for antifolate resistance. The P. falciparum ATPase 6 (pfatp6) gene has been proposed to be a potential marker for artemisinin resistance. In our previous clinical study, we showed that artesunate-sulfadoxine-pyrimethamine is highly effective against uncomplicated malaria in Yaoundé, Cameroon. In the present study, dhfr, dhps, and pfatp6 mutations in P. falciparum isolates obtained from children treated with artesunate-sulfadoxine-pyrimethamine were determined. All 61 isolates had wild-type Pfatp6 263, 623, and 769 alleles, and 11 (18%) had a single E431K substitution. Three additional mutations, E643Q, E432K, and E641Q, were detected. The results did not indicate any warning signal of serious concern (i.e., no parasites were seen with quintuple dhfr-dhps, DHFR Ile164Leu, or pfatp6 mutations), as confirmed by the high clinical efficacy of artesunate-sulfadoxine-pyrimethamine. Further studies are required to identify a molecular marker that reliably predicts artemisinin resistance.

  9. Efficacy of chloroquine, amodiaquine, sulphadoxine-pyrimethamine and combination therapy with artesunate in Mozambican children with non-complicated malaria

    DEFF Research Database (Denmark)

    Abacassamo, F; Enosse, S; Aponte, J J

    2004-01-01

    This paper reports a two-phase study in Manhiça district, Mozambique: first we assessed the clinical efficacy and parasitological response of Plasmodium falciparum to chloroquine (CQ), sulphadoxine-pyrimethamine (SP) and amodiaquine (AQ), then we tested the safety and efficacy in the treatment of......% to AQ. Co-administration of AQ + SP, AR + SP and AQ + AR was safe and had 100% clinical efficacy at 14-day follow-up. The combination therapies affected rapid fever clearance time and reduced the incidence of gametocytaemia during follow-up....

  10. Factors contributing to delay in parasite clearance in uncomplicated falciparum malaria in children

    Directory of Open Access Journals (Sweden)

    Sijuade Abayomi

    2010-02-01

    Full Text Available Abstract Background Drug resistance in Plasmodium falciparum is common in many endemic and other settings but there is no clear recommendation on when to change therapy when there is delay in parasite clearance after initiation of therapy in African children. Methods The factors contributing to delay in parasite clearance, defined as a clearance time > 2 d, in falciparum malaria were characterized in 2,752 prospectively studied children treated with anti-malarial drugs between 1996 and 2008. Results 1,237 of 2,752 children (45% had delay in parasite clearance. Overall 211 children (17% with delay in clearance subsequently failed therapy and they constituted 72% of those who had drug failure, i.e., 211 of 291 children. The following were independent risk factors for delay in parasite clearance at enrolment: age less than or equal to 2 years (Adjusted odds ratio [AOR] = 2.13, 95% confidence interval [CI]1.44-3.15, P 50,000/ul (AOR = 2.21, 95% CI = 1.77-2.75, P 20000/μl a day after treatment began, were independent risk factors for delay in clearance. Non-artemisinin monotherapies were associated with delay in clearance and treatment failures, and in those treated with chloroquine or amodiaquine, with pfmdr 1/pfcrt mutants. Delay in clearance significantly increased gametocyte carriage (P Conclusion Delay in parasite clearance is multifactorial, is related to drug resistance and treatment failure in uncomplicated malaria and has implications for malaria control efforts in sub-Saharan Africa.

  11. Long term persistence of clonal malaria parasite Plasmodium falciparum lineages in the Colombian Pacific region

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    Echeverry Diego F

    2013-01-01

    Full Text Available Abstract Background Resistance to chloroquine and antifolate drugs has evolved independently in South America, suggesting that genotype - phenotype studies aimed at understanding the genetic basis of resistance to these and other drugs should be conducted in this continent. This research was conducted to better understand the population structure of Colombian Plasmodium falciparum in preparation for such studies. Results A set of 384 SNPs were genotyped in blood spot DNA samples from 447 P. falciparum infected subjects collected over a ten year period from four provinces of the Colombian Pacific coast to evaluate clonality, population structure and linkage disequilibrium (LD. Most infections (81% contained a single predominant clone. These clustered into 136 multilocus genotypes (MLGs, with 32% of MLGs recovered from multiple (2 – 28 independent subjects. We observed extremely low genotypic richness (R = 0.42 and long persistence of MLGs through time (median = 537 days, range = 1 – 2,997 days. There was a high probability (>5% of sampling parasites from the same MLG in different subjects within 28 days, suggesting caution is needed when using genotyping methods to assess treatment success in clinical drug trials. Panmixia was rejected as four well differentiated subpopulations (FST = 0.084 - 0.279 were identified. These occurred sympatrically but varied in frequency within the four provinces. Linkage disequilibrium (LD decayed more rapidly (r2 = 0.17 for markers Conclusions We conclude that Colombian populations have several advantages for association studies, because multiple clone infections are uncommon and LD decays over the scale of one or a few genes. However, the extensive population structure and low genotype richness will need to be accounted for when designing and analyzing association studies.

  12. Structure-Guided Lead Optimization of Triazolopyrimidine-Ring Substituents Identifies Potent Plasmodium falciparum Dihydroorotate Dehydrogenase Inhibitors with Clinical Candidate Potential

    Energy Technology Data Exchange (ETDEWEB)

    Coteron, Jose M.; Marco, Maria; Esquivias, Jorge; Deng, Xiaoyi; White, Karen L.; White, John; Koltun, Maria; El Mazouni, Farah; Kokkonda, Sreekanth; Katneni, Kasiram; Bhamidipati, Ravi; Shackleford, David M.; Angulo-Barturen, Inigo; Ferrer, Santiago B.; Jimenez-Diaz, Maria Belen; Gamo, Francisco-Javier; Goldsmith, Elizabeth J.; Charman, William N.; Bathurst, Ian; Floyd, David; Matthews, David; Burrows, Jeremy N.; Rathod, Pradipsinh K.; Charman, Susan A.; Phillips, Margaret A. (UWASH); (MMV, Switzerland); (GSK); (Monash); (UW); (UTSMC)

    2012-02-27

    Drug therapy is the mainstay of antimalarial therapy, yet current drugs are threatened by the development of resistance. In an effort to identify new potential antimalarials, we have undertaken a lead optimization program around our previously identified triazolopyrimidine-based series of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors. The X-ray structure of PfDHODH was used to inform the medicinal chemistry program allowing the identification of a potent and selective inhibitor (DSM265) that acts through DHODH inhibition to kill both sensitive and drug resistant strains of the parasite. This compound has similar potency to chloroquine in the humanized SCID mouse P. falciparum model, can be synthesized by a simple route, and rodent pharmacokinetic studies demonstrated it has excellent oral bioavailability, a long half-life and low clearance. These studies have identified the first candidate in the triazolopyrimidine series to meet previously established progression criteria for efficacy and ADME properties, justifying further development of this compound toward clinical candidate status.

  13. Anti-folate drug resistance in Africa: meta-analysis of reported dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) mutant genotype frequencies in African Plasmodium falciparum parasite populations.

    Science.gov (United States)

    Sridaran, Sankar; McClintock, Shannon K; Syphard, Luke M; Herman, Karen M; Barnwell, John W; Udhayakumar, Venkatachalam

    2010-08-30

    Mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes of Plasmodium falciparum are associated with resistance to anti-folate drugs, most notably sulphadoxine-pyrimethamine (SP). Molecular studies document the prevalence of these mutations in parasite populations across the African continent. However, there is no systematic review examining the collective epidemiological significance of these studies. This meta-analysis attempts to: 1) summarize genotype frequency data that are critical for molecular surveillance of anti-folate resistance and 2) identify the specific challenges facing the development of future molecular databases. This review consists of 220 studies published prior to 2009 that report the frequency of select dhfr and dhps mutations in 31 African countries. Maps were created to summarize the location and prevalence of the highly resistant dhfr triple mutant (N51I, C59R, S108N) genotype and dhps double mutant (A437G and K540E) genotype in Africa. A hierarchical mixed effects logistic regression was used to examine the influence of various factors on reported mutant genotype frequency. These factors include: year and location of study, age and clinical status of sampled population, and reporting conventions for mixed genotype data. A database consisting of dhfr and dhps mutant genotype frequencies from all African studies that met selection criteria was created for this analysis. The map illustrates particularly high prevalence of both the dhfr triple and dhps double mutant genotypes along the Kenya-Tanzania border and Malawi. The regression model shows a statistically significant increase in the prevalence of both the dhfr triple and dhps double mutant genotypes in Africa. Increasing prevalence of the dhfr triple mutant and dhps double mutant genotypes in Africa are consistent with the loss of efficacy of SP for treatment of clinical malaria in most parts of this continent. Continued assessment of the effectiveness

  14. Anti-folate drug resistance in Africa: meta-analysis of reported dihydrofolate reductase (dhfr and dihydropteroate synthase (dhps mutant genotype frequencies in African Plasmodium falciparum parasite populations

    Directory of Open Access Journals (Sweden)

    Sridaran Sankar

    2010-08-01

    Full Text Available Abstract Background Mutations in the dihydrofolate reductase (dhfr and dihydropteroate synthase (dhps genes of Plasmodium falciparum are associated with resistance to anti-folate drugs, most notably sulphadoxine-pyrimethamine (SP. Molecular studies document the prevalence of these mutations in parasite populations across the African continent. However, there is no systematic review examining the collective epidemiological significance of these studies. This meta-analysis attempts to: 1 summarize genotype frequency data that are critical for molecular surveillance of anti-folate resistance and 2 identify the specific challenges facing the development of future molecular databases. Methods This review consists of 220 studies published prior to 2009 that report the frequency of select dhfr and dhps mutations in 31 African countries. Maps were created to summarize the location and prevalence of the highly resistant dhfr triple mutant (N51I, C59R, S108N genotype and dhps double mutant (A437G and K540E genotype in Africa. A hierarchical mixed effects logistic regression was used to examine the influence of various factors on reported mutant genotype frequency. These factors include: year and location of study, age and clinical status of sampled population, and reporting conventions for mixed genotype data. Results A database consisting of dhfr and dhps mutant genotype frequencies from all African studies that met selection criteria was created for this analysis. The map illustrates particularly high prevalence of both the dhfr triple and dhps double mutant genotypes along the Kenya-Tanzania border and Malawi. The regression model shows a statistically significant increase in the prevalence of both the dhfr triple and dhps double mutant genotypes in Africa. Conclusion Increasing prevalence of the dhfr triple mutant and dhps double mutant genotypes in Africa are consistent with the loss of efficacy of SP for treatment of clinical malaria in most parts

  15. High prevalence of pfdhfr-pfdhps triple mutations associated with anti-malarial drugs resistance in Plasmodium falciparum isolates seven years after the adoption of sulfadoxine-pyrimethamine in combination with artesunate as first-line treatment in Iran.

    Science.gov (United States)

    Rouhani, Maryam; Zakeri, Sedigheh; Pirahmadi, Sakineh; Raeisi, Ahmad; Djadid, Navid Dinparast

    2015-04-01

    The spread of anti-malarial drug resistance will challenge any malaria control and elimination strategies, and routine monitoring of resistance-associated molecular markers of commonly used anti-malarial drugs is very important. Therefore, in the present investigation, the extent of mutations/haplotypes in dhfr and dhps genes of Plasmodium falciparum isolates (n=72) was analyzed seven years after the introduction of sulfadoxine-pyrimethamine (SP) plus artesunate (AS) as first-line anti-malarial treatment in Iran using PCR-RFLP methods. The results showed that the majority of the patients (97.2%) carried both 59R and 108N mutations in pure form with wild-type genotype at positions N51 and I164. Additionally, a significant increase (Pdrug for treatment of falciparum patients in these malaria-endemic areas of Iran. However, no quintuple mutations associated with treatment failure were detected. In conclusion, the present results along with in vivo assays suggest that seven years after the adoption of SP-AS as the first-line treatment in Iran, this drug remains efficacious for treatment of uncomplicated falciparum malaria, as a partner drug with AS in these malaria-endemic areas.

  16. Survival strategies of the malarial parasite Plasmodium falciparum

    OpenAIRE

    Ramya, TNC; Surolia, Namita; Surolia, Avadhesha

    2002-01-01

    Plasmodium falciparum, the protozoan parasite causing falciparum malaria, is undoubtedly highly versatile when it comes to survival and defence strategies. Strategies adopted by the asexual blood stages of Plasmodium range from unique pathways of nutrient uptake to immune evasion strategies and multiple drug resistance. Studying the survival strategies of Plasmodium could help us envisage strategies of tackling one of the worst scourges of mankind.

  17. Biowaiver monographs for immediate release solid oral dosage forms based on biopharmaceutics classification system (BCS) literature data: chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride.

    Science.gov (United States)

    Verbeeck, R K; Junginger, H E; Midha, K K; Shah, V P; Barends, D M

    2005-07-01

    Literature data on the properties of chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride related to the Biopharmaceutics Classification System (BCS) are reviewed. The available information indicates that these chloroquine salts can be classified as highly soluble and highly permeable, i.e., BCS class I. The qualitative composition of immediate release (IR) tablets containing these Active Pharmaceutical Ingredients (APIs) with a Marketing Authorization (MA) in Belgium (BE), Germany (DE), Finland (FI), and The Netherlands (NL) is provided. In view of these MA's and the critical therapeutic indication of chloroquine, it is assumed that the registration authorities had evidence that these formulations are bioequivalent to the innovator. It is concluded that IR tablets formulated with these excipients are candidates for a biowaiver.

  18. [Plasmodium falciparum malaria: epidemiology and clinical features at Tarapoto Hospital].

    Science.gov (United States)

    Calderon, J; Rodriguez, J; Romero, D

    1997-01-01

    A retrospective study was conducted of the clinical records of 41 patients discharged from a hospital in Tarapoto, Peru, between August 1992 and June 1996 following treatment for Plasmodium falciparum malaria. Patients ranged in age from 18 to 65 years; 25 were male. The cases were uniformly distributed throughout the year. The duration of illness averaged 11 days. At admission, 40 patients had fever, 36 had shaking chills, 29 had headache, 21 had nausea and vomiting, 21 had hyporexia, 15 had pallor, and 13 had splenomegaly. 3 of the 16 women were pregnant. 7 patients reported a history of malaria. The admission diagnosis was malaria in 33 cases. 31 patients were treated with chloroquine; 18 were subsequently treated with pyrimethamine-sulfadoxin and 1 received doxycycline. No cases of grave illness or death occurred. The increasing presence of Plasmodium falciparum malaria in the Peruvian lowlands should promote review of the adequacy of control programs.

  19. 恶性疟在抗药性时期%Falciparum Malaria in the Age of Drug Resistance

    Institute of Scientific and Technical Information of China (English)

    G. Deninns Shanks

    2002-01-01

    @@ Ant malarial drug resistance exists when adequate drug blood concentration are to kill a previously susceptible parasite. This occurs by evolutionary selection of spontaneously arising mutant parasites that aredrug insensitive. Drug resistance is often, but not always, due to point mutations that change drug accumulation/effiux in the erythrocyte or reduce affinity for target molecule. Drug resistance can present in several ways to include: failure of treatment to clear parasites in a single patient, increase in malaria prevalence, malaria occurring in areas where it had not been seen recently such as epidemic malaria.

  20. Human IGF1 Regulates Midgut Oxidative Stress and Epithelial Homeostasis to Balance Lifespan and Plasmodium falciparum resistance in Anopheles stephensi: e1004231

    National Research Council Canada - National Science Library

    Anna L Drexler; Jose E Pietri; Nazzy Pakpour; Eric Hauck; Bo Wang; Elizabeth K K Glennon; Martha Georgis; Michael A Riehle; Shirley Luckhart

    2014-01-01

    ...) within a physiologically relevant range (0.013-0.13 µM) in human blood reduced development of the human parasite Plasmodium falciparum in the Indian malaria mosquito Anopheles stephensi. Low IGF1 (0.013 µM...

  1. Molecular epidemiology of drug-resistant malaria in western Kenya highlands

    Directory of Open Access Journals (Sweden)

    Menge David M

    2008-07-01

    Full Text Available Abstract Background Since the late 1980s a series of malaria epidemics has occurred in western Kenya highlands. Among the possible factors that may contribute to the highland malaria epidemics, parasite resistance to antimalarials has not been well investigated. Methods Using parasites from highland and lowland areas of western Kenya, we examined key mutations associated with Plasmodium falciparum resistance to sulfadoxine – pyrimethamine and chloroquine, including dihydrofolate reductase (pfdhfr and dihydropteroate synthetase (pfdhps, chloroquine resistance transporter gene (pfcrt, and multi-drug resistance gene 1 (pfmdr1. Results We found that >70% of samples harbored 76T pfcrt mutations and over 80% of samples harbored quintuple mutations (51I/59R/108N pfdhfr and 437G/540E pfdhps in both highland and lowland samples. Further, we did not detect significant difference in the frequencies of these mutations between symptomatic and asymptomatic malaria volunteers, and between highland and lowland samples. Conclusion These findings suggest that drug resistance of malaria parasites in the highlands could be contributed by the mutations and their high frequencies as found in the lowland. The results are discussed in terms of the role of drug resistance as a driving force for malaria outbreaks in the highlands.

  2. Chloroquine Increases Glucose Uptake via Enhancing GLUT4 Translocation and Fusion with the Plasma Membrane in L6 Cells

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    Qi Zhou

    2016-05-01

    Full Text Available Background/Aims: Chloroquine can induce an increase in the cellular uptake of glucose; however, the underlying mechanism is unclear. Methods: In this study, translocation of GLUT4 and intracellular Ca2+ changes were simultaneously observed by confocal microscope in L6 cells stably over-expressing IRAP-mOrange. The GLUT4 fusion with the plasma membrane (PM was traced using HA-GLUT4-GFP. Glucose uptake was measured using a cell-based glucose uptake assay. GLUT4 protein was detected by Western blotting and mRNA level was detected by RT-PCR. Results: We found that chloroquine induced significant increases in glucose uptake, glucose transporter GLUT4 translocation to the plasma membrane (GTPM, GLUT4 fusion with the PM, and intracellular Ca2+ in L6 muscle cells. Chloroquine-induced increases of GTPM and intracellular Ca2+ were inhibited by Gallein (Gβγ inhibitor and U73122 (PLC inhibitor. However, 2-APB (IP3R blocker only blocked the increase in intracellular Ca2+ but did not inhibit GTPM increase. These results indicate that chloroquine, via the Gβγ-PLC-IP3-IP3R pathway, induces elevation of Ca2+, and this Ca2+ increase does not play a role in chloroqui-ne-evoked GTPM increase. However, GLUT4 fusion with the PM and glucose uptake were significantly inhibited with BAPTA-AM. This suggests that Ca2+ enhances GLUT4 fusion with the PM resulting in glucose uptake increase. Conclusion: Our data indicate that chloroquine via Gβγ-PLC-IP3-IP3R induces Ca2+ elevation, which in turn promotes GLUT4 fusion with the PM. Moreover, chloroquine can enhance GLUT4 trafficking to the PM. These mechanisms eventually result in glucose uptake increase in control and insulin-resistant L6 cells. These findings suggest that chloroquine might be a potential drug for improving insulin tolerance in diabetic patients.

  3. Resistência à sulfadoxina-pirimetamina em Maputo, Moçambique: presença de mutações nos genes dhfr e dhps do Plasmodium falciparum Sulfadoxine-pyrimethamine resistance in Maputo, Mozambique: presence of mutations in the dhfr and dhps genes of Plasmodium falciparum

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    Natércia Emília Pedro Fernandes

    2007-08-01

    Full Text Available Foram analisadas a freqüência e distribuição de mutações nos genes dihidrofolato redutase e dihidropteroato sintetase do Plasmodium falciparum, usando a metodologia de reação em cadeia da polimerase e polimorfismos de hidrólise por enzimas de restrição, em amostras de sangue infectado proveniente de crianças moçambicanas, residentes em Maputo. A análise foi feita antes e 7 dias após o tratamento com sulfadoxina-pirimetamina (S/P. Os resultados mostraram a ocorrência de mutações pontuais nos genes estudados e a presença de combinações de três alelos em dhfr (51Ile, 59Arg e 108Asn e do quintúplo mutante (dhfr 51Ile, 59Arg, 108Asn e dhps 437Gly, 540Glu, ambas situações associadas à falha terapêutica no sétimo dia após tratamento com S/P. Esses achados mostram a importância de se estudar a resistência à S/P em Moçambique, e como os marcadores moleculares de resistência aos antimaláricos podem fornecer dados importantes para a política nacional de controlo da malária.The frequency and distribution of mutations in Plasmodium falciparum, dihydrofolate reductase and dihydropteroate synthase genes were analyzed, using the polymerase chain reaction and restriction fragment length polymorphism methodology, in infected blood samples from Mozambican children living in Maputo, before and seven days after treatment with sulfadoxine/pyrimethamine (S/P. The results showed the occurrence of point mutations in the genes studied and the presence of combinations of three alleles in dhfr (51Ile, 59Arg and 108Asn and "quintuple" mutant (dhfr 51Ile, 59Arg, 108Asn and dhps 437Gly, 540Glu. Both of these situations were associated with seven-day therapeutic failure, following treatment with S/P. These findings show the importance of studying S/P resistance in Mozambique, and how molecular markers for antimalarial resistance can provide important data for national malaria control policy.

  4. Phytochemical isolation of compounds from Sceletium tortuosum and activity testing against Plasmodium falciparum

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    Itumeleng I. Setshedi

    2012-06-01

    Full Text Available Malaria is a major health care problem in tropical regions due to the increasing resistance of Plasmodium falciparum against widely available antimalarial drugs. Traditional societies relied on medicinal plants to treat parasitic infections. As a result, drugs like quinine and artemisinin were isolated from herbs and barks (Varughese et al. 2010. Sceletium tortuosum has been used as medicine for social and spiritual purposes by San hunter gatherers and Khoi pastoralists. Sceletium tortuosum is rich in alkaloids, one of the important classes of natural product producing treatment for parasitic infections (Kayser et al. 2002. Laboratory preparation of extracts of fresh S. tortuosum plant material was conducted mimicking traditional methods of preparation using organic solvents. Mesembrine was isolated from a methanol extract using conventional column chromatography. Sixteen extracts and mesembrine were evaluated for antiplasmodium activity using a plasmodium lactate dehydrogenase culture sensitivity assay with chloroquine as reference drug.Of the sixteen extracts, four showed activity against P. falciparum with IC50 ranging between 1.47 µg/mL and 7.32 µg/mL. Extracts prepared from stored material at -20 °C showed no antiplasmodium activity. The four originally active extracts were re-screened six months later, but the antimalarial activity could not be reproduced. To determine discrepancy in biological results, chemical profiling of the extracts was done using high performance liquid chromatography technique. Differences were observed in the profiles of the active extracts when compared to those of stored plant material.The instability of plant constituents observed could be a result of plant storage suggesting that the plant is best used when fresh.

  5. Open-label trial on efficacy of artemether/lumefantrine against the uncomplicated Plasmodium falciparum malaria in Metema district, Northwestern Ethiopia

    Science.gov (United States)

    Wudneh, Feven; Assefa, Ashenafi; Nega, Desalegn; Mohammed, Hussien; Solomon, Hiwot; Kebede, Tadesse; Woyessa, Adugna; Assefa, Yibeltal; Kebede, Amha; Kassa, Moges

    2016-01-01

    Purpose Following the increased Plasmodium falciparum resistance to chloroquine and sulfadoxine/pyrimethamine, Ethiopia adopted artemether/lumefantrine (AL) as the first-line treatment for uncomplicated P. falciparum in 2004. According to the recommendation of the World Health Organization, this study was carried out for regular monitoring of the efficacy of AL in treating the uncomplicated P. falciparum malaria in Metema district, Gondar Zone, Northwest Ethiopia. Patients and methods This is a one-arm prospective 28-day in vivo therapeutic efficacy study among the uncomplicated P. falciparum malaria patients aged 6 months and older. The study was conducted from October 2014 to January 2015, based on the revised World Health Organization protocol of 2009 for surveillance of antimalarial drug therapeutic efficacy study. Standard six-dose regimen of AL was given twice daily for 3 days, and then the treatment outcomes were assessed on days 0, 1, 2, 3, 7, 14, 21, 28, and any other unscheduled day for emergency cases. Results There were 91 study subjects enrolled in this study, of whom 80 study subjects completed the full follow-up schedules and showed adequate clinical and parasitological responses on day 28, with no major adverse event. Per protocol analysis, the unadjusted cure rate of Coartem® was 98.8% (95% confidence interval: 93.3%–100%) in the study area. Recurrence of one P. falciparum case was detected on day 28, with a late parasitological failure rate of 1.2%. No early treatment failure occurred. Complete parasite and fever clearance was observed on day 3. Gametocyte carriage was 4.4% at enrollment that cleared on day 21. Although the difference is statistically not significant, a slight increase in the level of mean hemoglobin from baseline to day 28 was observed. Conclusion The study showed high efficacy and tolerability of Coartem® against uncomplicated P. falciparum malaria, suggesting the continuation as a first-line drug in the study district

  6. Efficacy of non-artemisinin- and artemisinin-based combination therapies for uncomplicated falciparum malaria in Cameroon

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    Thalabard Jean-Christophe

    2010-02-01

    Full Text Available Abstract Background The use of drug combinations, including non-artemisinin-based and artemisinin-based combination therapy (ACT, is a novel strategy that enhances therapeutic efficacy and delays the emergence of multidrug-resistant Plasmodium falciparum. Its use is strongly recommended in most sub-Saharan African countries, namely Cameroon, where resistance to chloroquine is widespread and antifolate resistance is emerging. Methods Studies were conducted in Cameroonian children with acute uncomplicated P. falciparum malaria according to the standard World Health Organization protocol at four sentinel sites between 2003 and 2007. A total of 1,401 children were enrolled, of whom 1,337 were assigned to randomized studies and 64 were included in a single non-randomized study. The proportions of adequate clinical and parasitological response (PCR-uncorrected on day 14 and PCR-corrected on day 28 were the primary endpoints to evaluate treatment efficacy on day 14 and day 28. The relative effectiveness of drug combinations was compared by a multi-treatment Bayesian random-effect meta-analysis. Findings The results based on the meta-analysis suggested that artesunate-amodiaquine (AS-AQ is as effective as other drugs (artesunate-sulphadoxine-pyrimethamine [AS-SP], artesunate-chlorproguanil-dapsone [AS-CD], artesunate-mefloquine [AS-MQ], dihydroartemisinin-piperaquine [DH-PP], artemether-lumefantrine [AM-LM], amodiaquine, and amodiaquine-sulphadoxine-pyrimethamine [AQ-SP]. AM-LM appeared to be the most effective with no treatment failure due to recrudescence, closely followed by DH-PP. Conclusion Although AM-LM requires six doses, rather than three doses for other artemisinin-based combinations, it has potential advantages over other forms of ACT. Further studies are needed to evaluate the clinical efficacy and tolerance of these combinations in different epidemiological context.

  7. Temporal trends of sulphadoxine-pyrimethamine (SP drug-resistance molecular markers in Plasmodium falciparum parasites from pregnant women in western Kenya

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    Iriemenam Nnaemeka C

    2012-07-01

    Full Text Available Abstract Background Resistance to sulphadoxine-pyrimethamine (SP in Plasmodium falciparum parasites is associated with mutations in the dihydrofolate reductase (dhfr and dihydropteroate synthase (dhps genes and has spread worldwide. SP remains the recommended drug for intermittent preventive treatment for malaria in pregnancy (IPTp and information on population prevalence of the SP resistance molecular markers in pregnant women is limited. Methods Temporal trends of SP resistance molecular markers were investigated in 489 parasite samples collected from pregnant women at delivery from three different observational studies between 1996 and 2009 in Kenya, where SP was adopted for both IPTp and case treatment policies in 1998. Using real-time polymerase chain reaction, pyrosequencing and direct sequencing, 10 single-nucleotide polymorphisms (SNPs of SP resistance molecular markers were assayed. Results The prevalence of quintuple mutant (dhfr N51I/C59R/S108N and dhps A437G/K540E combined genotype increased from 7 % in the first study (1996–2000 to 88 % in the third study (2008–2009. When further stratified by sample collection year and adoption of IPTp policy, the prevalence of the quintuple mutant increased from 2.4 % in 1998 to 44.4 % three years after IPTp policy adoption, seemingly in parallel with the increase in percentage of SP use in pregnancy. However, in the 1996–2000 study, more mutations in the combined dhfr/dhps genotype were associated with SP use during pregnancy only in univariable analysis and no associations were detected in the 2002–2008 and 2008–2009 studies. In addition, in the 2008–2009 study, 5.3 % of the parasite samples carried the dhps triple mutant (A437G/K540E/A581G. There were no differences in the prevalence of SP mutant genotypes between the parasite samples from HIV + and HIV- women over time and between paired peripheral and placental samples. Conclusions There was a significant increase in

  8. Prediction of Plasmodium falciparum resistance to sulfadoxine/pyrimethamine in vivo by mutations in the dihydrofolate reductase and dihydropteroate synthetase genes: a comparative study between sites of differing endemicity

    DEFF Research Database (Denmark)

    Alifrangis, Michael; Enosse, Sonja; Khalil, Insaf F;

    2003-01-01

    Plasmodium falciparum resistance to sulfadoxine/pyrimethamine (S/P) is due to mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhfr) genes. Large-scale screening of the prevalence of these mutations could facilitate the surveillance of the level of S/P resistance...... marker seems debatable. The differences may reflect variation in the duration and magnitude of S/P usage (or other antifolate drugs) between the sites. Thus, triple dhfr mutations may prove suitable only as a general guideline for detecting emerging S/P resistance in areas where S/P has been introduced...... in vivo. The prevalence of mutations in dhfr and dhps in relation to S/P efficacy was studied in four sites of differing endemicity in Sudan, Mozambique, and Tanzania. The sites were organized in order of increasing resistance and a significant increase in the prevalence of triple mutations in codons c51...

  9. Therapeutic efficacy of chloroquine for treatment of Plasmodium vivax malaria cases in Halaba district, South Ethiopia

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    Bacha Ketema

    2011-03-01

    Full Text Available Abstract Background Chloroquine is an anti-malarial drug being used to treat Plasmodium vivax malaria cases in Ethiopia. However, emergence of chloroquine resistant strains of the parasite has challenged the current efficacy of the drug. Therefore, the aim of this study was to assess the effectiveness of chloroquine against P. vivax strains in one of the malaria endemic areas of Ethiopia, namely Halaba district, located in South Nations and Nationalities Peoples Region (SNNPR of South Ethiopia Results Among 87 malaria patients enrolled in the study, only 80 of them completed the 28-days follow-up. Seven of them dropped from the study for different reasons. Among those study participants that completed their follow-up, 69 were classified under the category of adequate clinical and parasitological response (ACPR. However, the remaining 11 cases were considered as under treatment failure mainly due to recurrence of parasitemia on day 7 (four patients, day 14 (six patients, and day 21 (one patient. The age of all cases of treatment failures was found to be less than 20 years. The load of parasitemia of patients with treatment failure on day of admission (4709.4/μl was higher than day of recurrence (372.37/μl. Parasite reduction ratio (PRR of treatment failure cases was 12.6/μl. Conclusion This report revealed the rise in treatment failure (13% [95% CI = 0.074 - 0.217] as compared to earlier reports from Ethiopia. It signals the spreading of chloroquine resistant P. vivax (CRPv strains to malaria endemic areas of Ethiopia. It is recommended that all concerned bodies should act aggressively before further expansion of the current drug resistant malaria.

  10. 21 CFR 522.810 - Embutramide, chloroquine, and lidocaine solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Embutramide, chloroquine, and lidocaine solution. 522.810 Section 522.810 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... ANIMAL DRUGS § 522.810 Embutramide, chloroquine, and lidocaine solution. (a) Specifications....

  11. Randomized trials of artemisinin-piperaquine, dihydroartemisinin-piperaquine phosphate and artemether-lumefantrine for the treatment of multi-drug resistant falciparum malaria in Cambodia-Thailand border area

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    Song Jianping

    2011-08-01

    Full Text Available Abstract Background Drug resistance of falciparum malaria is a global problem. Sulphadoxine/pyrimethamine-resistant and mefloquine-resistant strains of falciparum malaria have spread in Southeast Asia at lightning speed in 1980s-1990s, and the Cambodia-Thailand border is one of the malaria epidemic areas with the most severe forms of multi-drug resistant falciparum malaria. Methods Artemisinin-piperaquine (AP, dihydroartemisinin-piperaquine phosphate (DHP and artemether-lumefantrine (AL were used to treat 110, 55 and 55 uncomplicated malaria patients, respectively. The total dosage for adults is 1,750 mg (four tablets, twice over 24 hours of AP, 2,880 mg (eight tablets, four times over two days of DHP, and 3,360 mg (24 tablets, six times over three days of AL. The 28-day cure rate, parasite clearance time, fever clearance time, and drug tolerance of patients to the three drugs were compared. All of the above methods were consistent with the current national guidelines. Results The mean parasite clearance time was similar in all three groups (66.7 ± 21.9 hrs, 65.6 ± 27.3 hrs, 65.3 ± 22.5 hrs in AP, DHP and AL groups, respectively, and there was no remarkable difference between them; the fever clearance time was also similar (31.6 ± 17.7 hrs, 34.6 ± 21.8 hrs and 36.9 ± 15.4 hrs, respectively. After following up for 28-days, the cure rate was 95.1%(97/102, 98.2%(54/55 and 82.4%(42/51; and the recrudescence cases was 4.9%(5/102, 1.8%(1/55 and 17.6%(9/51, respectively. Therefore, the statistical data showed that 28-day cure rate in AP and DHP groups was superior to AL group obviously. The patients had good tolerance to all the three drugs, and some side effects (anoxia, nausea, vomiting, headache and dizziness could be found in every group and they were self-limited; patients in control groups also had good tolerance to DHP and AL, there was no remarkable difference in the three groups. Conclusions AP, DHP and AL all remained efficacious

  12. Ex Vivo Activity of Endoperoxide Antimalarials, Including Artemisone and Arterolane, against Multidrug-Resistant Plasmodium falciparum Isolates from Cambodia

    Science.gov (United States)

    2014-10-01

    2. Dong Y, Chollet J, Matile H, Charman SA, Chiu FC, Charman WN, Scorneaux B, Urwyler H, Santo Tomas J, Scheurer C, Snyder C, Dorn A, Wang X, Karle JM...Malaria burden and artemisinin resistance in the mobile and migrant population on the Thai-Myanmar border, 1999- 2011: an observational study. PLoS Med. 10...36. Vennerstrom JL, Arbe-Barnes S, Brun R, Charman SA, Chiu FCK, Chollet J, Dong Y, Dorn A, Hunziker D, Matile H, McIntosh K, Padmanilayam M, Santo

  13. Screening for mutations related to atovaquone/proguanil resistance in treatment failures and other imported isolates of Plasmodium falciparum in Europe

    DEFF Research Database (Denmark)

    Wichmann, Ole; Muehlberger, Nikolai; Jelinek, Tomas

    2004-01-01

    BACKGROUND: Two single-point mutations of the Plasmodium falciparum cytochrome b gene (Tyr268Asn and Tyr268Ser) were recently reported in cases of atovaquone/proguanil (Malarone) treatment failure. However, little is known about the prevalence of codon-268 mutations and their quantitative...... association with treatment failure. METHODS: We set out to assess the prevalence of codon-268 mutations in P. falciparum isolates imported into Europe and to quantify their association with atovaquone/proguanil treatment failure. Isolates of P. falciparum collected by the European Network on Imported...... Infectious Disease Surveillance between April 2000 and August 2003 were analyzed for codon-268 mutations, by use of polymerase chain reaction-restriction fragment-length polymorphism. RESULTS: We successfully screened 504 samples for the presence of either Tyr268Ser or Tyr268Asn. One case of Ser268...

  14. Reported side effects to chloroquine, chloroquine plus proguanil, and mefloquine as chemoprophylaxis against malaria in Danish travelers

    DEFF Research Database (Denmark)

    Petersen, E; Ronne, T; Ronn, A

    2000-01-01

    BACKGROUND: The aim of the study was to provide data on the relative frequency of reported symptoms in travelers using chloroquine, chloroquine plus proguanil, and mefloquine. METHOD: The study was an open, nonrandomized study recording self-reported events in travelers recruited consecutively fr...

  15. Prevalence of Plasmodium falciparum resistance markers to sulfadoxine-pyrimethamine among pregnant women receiving intermittent preventive treatment for malaria in Uganda

    DEFF Research Database (Denmark)

    Mbonye, Anthony K; Birungi, Josephine; Yanow, Stephanie K;

    2015-01-01

    there was insufficient statistical power to test whether there was a true rise in the prevalence of this allele. The overall high frequency of Pfdhfr and Pfdhps quintuple mutations throughout pregnancy excluded further analyses of possible associations between certain haplotypes and the risk of lower birth weight...... and anemia. However, women infected with P. falciparum had 1.3-g/dl-lower hemoglobin levels (P = 0.001) and delivered babies with a 400-g-lower birth weight (P = 0.001) compared to nonparasitemic women. Despite this, 44 women who were P. falciparum positive at baseline became negative after one or two doses...

  16. Molecular monitoring of plasmodium falciparum drug susceptibility at the time of the introduction of artemisinin-based combination therapy in Yaoundé, Cameroon: Implications for the future

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    Menard Sandie

    2012-04-01

    Full Text Available Abstract Background Regular monitoring of the levels of anti-malarial resistance of Plasmodium falciparum is an essential policy to adapt therapy and improve malaria control. This monitoring can be facilitated by using molecular tools, which are easier to implement than the classical determination of the resistance phenotype. In Cameroon, chloroquine (CQ, previously the first-line therapy for uncomplicated malaria was officially withdrawn in 2002 and replaced initially by amodiaquine (AQ monotherapy. Then, artemisinin-based combination therapy (ACT, notably artesunate-amodiaquine (AS-AQ or artemether-lumefantrine (AL, was gradually introduced in 2004. This situation raised the question of the evolution of P. falciparum resistance molecular markers in Yaoundé, a highly urbanized Cameroonian city. Methods The genotype of pfcrt 72 and 76 and pfmdr1 86 alleles and pfmdr1 copy number were determined using real-time PCR in 447 P. falciparum samples collected between 2005 and 2009. Results This study showed a high prevalence of parasites with mutant pfcrt 76 (83% and pfmdr1 86 (93% codons. On the contrary, no mutations in the pfcrt 72 codon and no samples with duplication of the pfmdr1 gene were observed. Conclusion The high prevalence of mutant pfcrt 76T and pfmdr1 86Y alleles might be due to the choice of alternative drugs (AQ and AS-AQ known to select such genotypes. Mutant pfcrt 72 codon was not detected despite the prolonged use of AQ either as monotherapy or combined with artesunate. The absence of pfmdr1 multicopies suggests that AL would still remain efficient. The limited use of mefloquine or the predominance of mutant pfmdr1 86Y codon could explain the lack of pfmdr1 amplification. Indeed, this mutant codon is rarely associated with duplication of pfmdr1 gene. In Cameroon, the changes of therapeutic strategies and the simultaneous use of several formulations of ACT or other anti-malarials that are not officially recommended result in a

  17. Therapeutic Assessment of Chloroquine-Primaquine Combined Regimen in Adult Cohort of Plasmodium vivax Malaria from Primary Care Centres in Southwestern India

    Science.gov (United States)

    Saravu, Kavitha; Kumar, Rishikesh; Ashok, Herikudru; Kundapura, Premananda; Kamath, Veena; Kamath, Asha; Mukhopadhyay, Chiranjay

    2016-01-01

    Background Several reports of chloroquine treatment failure and resistance in Plasmodium vivax malaria from Southeast Asian countries have been published. Present study was undertaken to assess the efficacy of chloroquine-primaquine (CQ-PQ) combined regimen for the treatment of P. vivax malaria patients who were catered by the selected primary health centres (PHCs) of Udupi taluk, Udupi district, Karnataka, India. Method Five PHCs were selected within Udupi taluk based on probability proportional to size. In-vivo therapeutic efficacy assessment of CQ (1500 mg over three days) plus PQ (210 mg over 14 days) regimen was carried out in accordance with the World Health Organization’s protocol of 28 days follow-up among microscopically diagnosed monoinfection P. vivax cohort. Results In total, 161 participants were recruited in the study of which, 155 (96.3%) participants completed till day 28 follow-up, fully complied with the treatment regimen and showed adequate clinical and parasitological response. Loss to follow up was noted with 5 (3.1%) participants and non-compliance with treatment regimen occurred with one participant (0.6%). Glucose-6-phosphate dehydrogenase deficiency (G6PDd, <30% of normal mean activity) was noted among 5 (3.1%) participants and one of them did develop PQ induced dark-brown urination which subsided after PQ discontinuation. G6PDd patients were treated with PQ 45 mg/week for eight weeks while PQ was discontinued in one case with G6PD 1.4 U/g Hb due to complaint of reddish-brown coloured urine by 48 hours of PQ initiation. Nested polymerase chain reaction test revealed 45 (28%) cases as mixed (vivax and falciparum) malaria. Conclusions The CQ-PQ combined regimen remains outstandingly effective to treat uncomplicated P. vivax malaria in Udupi taluk and thus it should continue as first line regimen. For all P. vivax cases, G6PD screening before PQ administration must be mandatory and made available in all PHCs. PMID:27315280

  18. Therapeutic Assessment of Chloroquine-Primaquine Combined Regimen in Adult Cohort of Plasmodium vivax Malaria from Primary Care Centres in Southwestern India.

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    Kavitha Saravu

    Full Text Available Several reports of chloroquine treatment failure and resistance in Plasmodium vivax malaria from Southeast Asian countries have been published. Present study was undertaken to assess the efficacy of chloroquine-primaquine (CQ-PQ combined regimen for the treatment of P. vivax malaria patients who were catered by the selected primary health centres (PHCs of Udupi taluk, Udupi district, Karnataka, India.Five PHCs were selected within Udupi taluk based on probability proportional to size. In-vivo therapeutic efficacy assessment of CQ (1500 mg over three days plus PQ (210 mg over 14 days regimen was carried out in accordance with the World Health Organization's protocol of 28 days follow-up among microscopically diagnosed monoinfection P. vivax cohort.In total, 161 participants were recruited in the study of which, 155 (96.3% participants completed till day 28 follow-up, fully complied with the treatment regimen and showed adequate clinical and parasitological response. Loss to follow up was noted with 5 (3.1% participants and non-compliance with treatment regimen occurred with one participant (0.6%. Glucose-6-phosphate dehydrogenase deficiency (G6PDd, <30% of normal mean activity was noted among 5 (3.1% participants and one of them did develop PQ induced dark-brown urination which subsided after PQ discontinuation. G6PDd patients were treated with PQ 45 mg/week for eight weeks while PQ was discontinued in one case with G6PD 1.4 U/g Hb due to complaint of reddish-brown coloured urine by 48 hours of PQ initiation. Nested polymerase chain reaction test revealed 45 (28% cases as mixed (vivax and falciparum malaria.The CQ-PQ combined regimen remains outstandingly effective to treat uncomplicated P. vivax malaria in Udupi taluk and thus it should continue as first line regimen. For all P. vivax cases, G6PD screening before PQ administration must be mandatory and made available in all PHCs.

  19. [Plasmodium falciparum and Salmonella Typhi co-infection: a case report].

    Science.gov (United States)

    Sümer, Sua; Ural, Gaye; Ural, Onur

    2014-01-01

    Malaria and salmonella infections are endemic especially in developing countries, however malaria and salmonella co-infection is a rare entity with high mortality. The basic mechanism in developing salmonella co-infection is the impaired mobilization of granulocytes through heme and heme oxygenase which are released from haemoglobin due to the breakdown of erythrocytes during malaria infection. Thus, a malaria infected person becomes more susceptible to develop infection with Salmonella spp. In this report a case with Plasmodium falciparum and Salmonella Typhi co-infection was presented. A 23-year-old male patient was admitted to hospital with the complaints of diarrhea, nausea, vomiting, abdominal pain, fatigue and fever. Laboratory findings yielded decreased number of platelets and increased ALT, AST and CRP levels. Since he had a history of working in Pakistan, malaria infection was considered in differential diagnosis, and the diagnosis was confirmed by the detection of P.falciparum trophozoites in the thick and thin blood smears. As he came from a region with chloroquine-resistant Plasmodium, quinine (3 x 650 mg) and doxycycline (2 x 100 mg/day) were started for the treatment. No erythrocytes, parasite eggs or fungal elements were seen at the stool microscopy of the patient who had diarrhoea during admission. No pathogenic microorganism growth was detected in his stool culture. The patient's blood cultures were also taken in febrile periods starting from the time of his hospitalization. A bacterial growth was observed in his blood cultures, and the isolate was identified as S. Typhi. Thus, the patient was diagnosed with P.falciparum and Salmonella Typhi coinfection. Ceftriaxone (1 x 2 g/day, 14 days) was added to the therapy according to the results of antibiotic susceptibility test. With the combined therapy (quinine, doxycycline, ceftriaxone) the fever was taken under control, his general condition improved and laboratory findings turned to normal values

  20. Chloroquine Inhibits Ca2+ Signaling in Murine CD4+ Thymocytes

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    Jin-Chao Xu

    2015-04-01

    Full Text Available Background/Aims: Bitter-tasting chloroquine can suppress T cell activation by inhibiting Ca2+ signaling. However, the mechanism of inhibition remains largely unclear. Methods: In this study, CD4+ T cells were isolated from the thymus, and the calcium content of CD4+ thymocytes was measured using fura-2 AM and a TILL imaging system. Pyrazole-3 (Pyr3, thapsigargin (TG, and caffeine were used to assess the effects of chloroquine on the intracellular Ca2+ content of CD4+ T cells. Results: In murine CD4+ thymocytes, chloroquine decreased the TG-triggered intracellular Ca2+ increase in a dose-dependent manner. In the absence of chloroquine under Ca2+-free conditions (0 mM Ca2+ and 0.5 mM EGTA, TG induced a transient Ca2+ increase. After restoration of the extracellular Ca2+ concentration to 2 mM, a dramatic Ca2+ increase occurred. This elevation was completely blocked by chloroquine and was markedly inhibited by Pyr3, a selective antagonist of transient receptor potential C3 (TRPC3 channel and stromal interaction molecule (STIM/Orai channel. Furthermore, the TG-induced transient Ca2+ increase under Ca2+-free conditions was eliminated in the presence of chloroquine. Chloroquine also blocked the dialyzed inositol-1,4,5-trisphosphate (IP3-induced intracellular Ca2+ increase. However, chloroquine was not able to decrease the caffeine-induced Ca2+ increase. Conclusion: These data indicate that chloroquine inhibits the elevation of intracellular Ca2+ in thymic CD4+ T cells by inhibiting IP3 receptor-mediated Ca2+ release from intracellular stores and TRPC3 channel-mediated and/or STIM/Orai channel-mediated Ca2+ influx.

  1. Artemether resistance in vitro is linked to mutations in PfATP6 that also interact with mutations in PfMDR1 in travellers returning with Plasmodium falciparum infections.

    KAUST Repository

    Pillai, Dylan R

    2012-04-27

    BACKGROUND: Monitoring resistance phenotypes for Plasmodium falciparum, using in vitro growth assays, and relating findings to parasite genotype has proved particularly challenging for the study of resistance to artemisinins. METHODS: Plasmodium falciparum isolates cultured from 28 returning travellers diagnosed with malaria were assessed for sensitivity to artemisinin, artemether, dihydroartemisinin and artesunate and findings related to mutations in pfatp6 and pfmdr1. RESULTS: Resistance to artemether in vitro was significantly associated with a pfatp6 haplotype encoding two amino acid substitutions (pfatp6 A623E and S769N; (mean IC50 (95% CI) values of 8.2 (5.7 - 10.7) for A623/S769 versus 623E/769 N 13.5 (9.8 - 17.3) nM with a mean increase of 65%; p = 0.012). Increased copy number of pfmdr1 was not itself associated with increased IC50 values for artemether, but when interactions between the pfatp6 haplotype and increased copy number of pfmdr1 were examined together, a highly significant association was noted with IC50 values for artemether (mean IC50 (95% CI) values of 8.7 (5.9 - 11.6) versus 16.3 (10.7 - 21.8) nM with a mean increase of 87%; p = 0.0068). Previously described SNPs in pfmdr1 are also associated with differences in sensitivity to some artemisinins. CONCLUSIONS: These findings were further explored in molecular modelling experiments that suggest mutations in pfatp6 are unlikely to affect differential binding of artemisinins at their proposed site, whereas there may be differences in such binding associated with mutations in pfmdr1. Implications for a hypothesis that artemisinin resistance may be exacerbated by interactions between PfATP6 and PfMDR1 and for epidemiological studies to monitor emerging resistance are discussed.

  2. In vitro antimalarial activity of medicinal plant extracts against Plasmodium falciparum.

    Science.gov (United States)

    Bagavan, Asokan; Rahuman, Abdul Abdul; Kaushik, Naveen Kumar; Sahal, Dinkar

    2011-01-01

    Malaria is a major global public health problem, and the alarming spread of drug resistance and limited number of effective drugs now available underline how important it is to discover new antimalarial compounds. In the present study, ten plants were extracted with ethyl acetate and methanol and tested for their antimalarial activity against chloroquine (CQ)-sensitive (3D7) and CQ-resistant (Dd2 and INDO) strains of Plasmodium falciparum in culture using the fluorescence-based SYBR Green assay. Plant extracts showed moderate to good antiparasitic effects. Promising antiplasmodial activity was found in the extracts from two plants, Phyllanthus emblica leaf 50% inhibitory concentration (IC₅₀) 3D7: 7.25 μg/mL (ethyl acetate extract), 3.125 μg/mL (methanol extract), and Syzygium aromaticum flower bud, IC₅₀ 3D7:13 μg/mL, (ethyl acetate extract) and 6.25 μg/mL (methanol extract). Moderate activity (30-75 μg/mL) was found in the ethyl acetate and methanol extracts of Abrus precatorius (seed) and Gloriosa superba (leaf); leaf ethyl acetate extracts of Annona squamosa and flower of Musa paradisiaca. The above mentioned plant extracts were also found to be active against CQ-resistant strains (Dd2 and INDO). Cytotoxicity study with P. emblica leaf and S. aromaticum flower bud, extracts showed good therapeutic indices. These results demonstrate that leaf ethyl acetate and methanol extracts of P. emblica and flower bud extract of S. aromaticum may serve as antimalarial agents even in their crude form. The isolation of compounds from P. emblica and S. aromaticum seems to be of special interest for further antimalarial studies.

  3. Comparative study of chloroquine and quinine on malaria rodents and their effects on the mouse testis

    Institute of Scientific and Technical Information of China (English)

    Esmail Abolghasemi; Seyed Hassan Moosa-Kazemi; Maryam Davoudi; Ahmad Reisi; Mohammad Taghi Satvat

    2012-01-01

    Objective: To evaluate the effects of quinine and chloroquine against male mice infected withPlasmodium berghei and their adverse effects on the mice testes. Methods: In this study, 48 adult male mice, (20-25 g), aged 8 to 12 weeks were divided into four groups. This study was carried out from December 2009 until May 2010 in the School of Public Health, Tehran University of Medical Sciences. Results: The results showed that 58.33% of mice treated with chloroquine were completely recovered. Parasitemia was 4% on day 8 when compared to that on day 0, whereas it was 9% on day 9. There was no orchitis found in this group. The mortality of mice after exposing to quinine on day 5 was 8.3%, whereas from day 10 to day 14 it was 91.7%. We found 75% orchitis occurred in quinine treated group. There was a significant difference between quinine and chloroquine effects on the parasite and also mice testes (P<0.05). Conclusions: In this study, It can be concluded that male mice have full resistance to the quinine. Quinine does not only make male mice recover completely, but also cause inflammation on mice testicles tissue.

  4. In vitro antiplasmodial activity of bacterium RJAUTHB 14 associated with marine sponge Haliclona Grant against Plasmodium falciparum.

    Science.gov (United States)

    Jacob Inbaneson, Samuel; Ravikumar, Sundaram

    2012-06-01

    Malaria is the most important parasitic disease, leading to annual death of about one million people, and the Plasmodium falciparum develops resistance to well-established antimalarial drugs. The newest antiplasmodial drug from a marine microorganism helps in addressing this problem. In the present study, Haliclona Grant were collected and subjected for enumeration and isolation of associated bacteria. The count of bacterial isolates was maximum in November 2007 (18 × 10(4) colony-forming units (CFU) g(-1), and the average count was maximum during the monsoon season (117 × 10(3) CFU g(-1)). Thirty-three morphologically different bacterial isolates were isolated from Haliclona Grant, and the extracellular ethyl acetate extracts were screened for antiplasmodial activity against P. falciparum. The antiplasmodial activity of bacterium RJAUTHB 14 (11.98 μg[Symbol: see text]ml(-1)) is highly comparable with the positive control chloroquine (IC(50) 19.59 μg[Symbol: see text]ml(-1)), but the other 21 bacterial extracts showed an IC(50) value of more than 100 μg[Symbol: see text]ml(-1). Statistical analysis reveals that significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the ethyl acetate extract of bacterial isolates after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of reducing sugars and alkaloids in the ethyl acetate extracts of bacterium RJAUTHB 14. The 16S rRNA gene partial sequence of bacterium RJAUTHB 14 is deposited in NCBI (GenBank accession no. GU269569). It is concluded from the present study that the ethyl acetate extracts of bacterium RJAUTHB 14 possess lead compounds for the development of antiplasmodial drugs.

  5. Identifying New Chemical Entities that Treat and Prevent Relapsing Vivax and Drug-Resistant Falciparum Malaria in U.S. Military Personnel

    Science.gov (United States)

    2016-10-01

    Southeast Asia, Africa, the Middle East, the Pacific, and both Central and South America . The project combines expertise from the Walter Reed Army...falciparum, P. cynomolgi, asexual blood stages, liver stages, high-throughput screen, drug assays, cell culture , transfection, green fluorescent...by the end of 2016. Active compounds have also been screened against P. berghei liver stages cultured in vitro, using a parasite line expressing

  6. Compliance with a three-day course of artesunate-mefloquine combination and baseline anti-malarial treatment in an area of Thailand with highly multidrug resistant falciparum malaria

    Directory of Open Access Journals (Sweden)

    Na-Bangchang Kesara

    2010-02-01

    and primaquine levels were observed in 24 and 16% of the patients. Conclusion The current first-line treatment and a three-day combination regimen of artesunate-mefloquine provides excellent patient compliance with good efficacy and tolerability in the treatment of highly multidrug resistance falciparum malaria. Previous treatment with mefloquine and primaquine were common in this area.

  7. The Lipid Moiety of Haemozoin (Malaria Pigment and P. falciparum Parasitised Red Blood Cells Bind Synthetic and Native Endothelin-1

    Directory of Open Access Journals (Sweden)

    Nicoletta Basilico

    2010-01-01

    Full Text Available Endothelin1 (ET-1 is a 21-amino acid peptide produced by the vascular endothelium under hypoxia, that acts locally as regulator of vascular tone and inflammation. The role of ET-1 in Plasmodium falciparum malaria is unknown, although tissue hypoxia is frequent as a result of the cytoadherence of parasitized red blood cell (pRBC to the microvasculature. Here, we show that both synthetic and endothelial-derived ET-1 are removed by parasitized RBC (D10 and W2 strains, chloroquine sensitive, and resistant, resp. and native haemozoin (HZ, malaria pigment, but not by normal RBC, delipidized HZ, or synthetic beta-haematin (BH. The effect is dose dependent, selective for ET-1, but not for its precursor, big ET-1, and not due to the proteolysis of ET-1. The results indicate that ET-1 binds to the lipids moiety of HZ and membranes of infected RBCs. These findings may help understanding the consequences of parasite sequestration in severe malaria.

  8. A database of antimalarial drug resistance

    Directory of Open Access Journals (Sweden)

    Ringwald Pascal

    2006-06-01

    Full Text Available Abstract A large investment is required to develop, license and deploy a new antimalarial drug. Too often, that investment has been rapidly devalued by the selection of parasite populations resistant to the drug action. To understand the mechanisms of selection, detailed information on the patterns of drug use in a variety of environments, and the geographic and temporal patterns of resistance is needed. Currently, there is no publically-accessible central database that contains information on the levels of resistance to antimalaria drugs. This paper outlines the resources that are available and the steps that might be taken to create a dynamic, open access database that would include current and historical data on clinical efficacy, in vitro responses and molecular markers related to drug resistance in Plasmodium falciparum and Plasmodium vivax. The goal is to include historical and current data on resistance to commonly used drugs, like chloroquine and sulfadoxine-pyrimethamine, and on the many combinations that are now being tested in different settings. The database will be accessible to all on the Web. The information in such a database will inform optimal utilization of current drugs and sustain the longest possible therapeutic life of newly introduced drugs and combinations. The database will protect the valuable investment represented by the development and deployment of novel therapies for malaria.

  9. Chloroquine is grossly overdosed and overused but well tolerated in Guinea-Bissau

    DEFF Research Database (Denmark)

    Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia;

    2009-01-01

    -Bissau are taken or whether they cause adverse effects. We aimed to determine the dosage of chloroquine commonly prescribed, the doses commonly taken and if there were concentration dependent adverse events in routine practice. Chloroquine prescriptions by 8 physicians and chloroquine intake by 102 children were...... recorded. Chloroquine intake and adverse events were assessed by questioning. Chloroquine concentrations were measured in whole blood. The median total chloroquine dose prescribed and that reportedly taken was 81 and 77 mgkg(-1) respectively. The total dose was usually split into 2-3 daily doses of 6...... in the blood at the time of diagnosis and treatment. No severe adverse events were reported. No adverse events were associated with higher chloroquine concentrations. High doses of chloroquine are commonly taken and well tolerated in Guinea-Bissau. Malaria diagnostics are poor and chloroquine is commonly...

  10. Mutations in the Plasmodium falciparum cytochrome b gene are associated with delayed parasite recrudescence in malaria patients treated with atovaquone-proguanil

    Directory of Open Access Journals (Sweden)

    Fivelman Quinton L

    2008-11-01

    Full Text Available Abstract Background Fixed-dose combination antimalarial drugs have played an increasingly important role in the treatment and chemoprophylaxis of falciparum malaria since the worldwide failure of monotherapy with chloroquine. Atovaquone-proguanil is one such combination drug used both for prophylaxis in travellers, and for treatment of acute malaria cases in European hospitals and clinics. Methods A series of eight atovaquone-proguanil treatment failures and two prophylaxis breakthroughs from four UK hospitals from 2004–2008 were analysed for evidence of mutations in the pfcyt-b gene, previously found to be associated with failure of the atovaquone component. Results Parasites carrying pfcyt-b mutations were found in five falciparum malaria patients with recrudescent parasitaemia occurring weeks after apparently successful treatment of a primary infection with atovaquone-proguanil. Four of these cases carried parasites with the Tyr268Cys mutation in pfcyt-b, previously reported in two French patients with malaria. In contrast, mutations in pfcyt-b were not found in three patients treated with atovaquone-proguanil who exhibited delayed clearance of the primary infection, nor in two returning travellers with malaria who had used the combination for prophylaxis. Using current and previously published data, mean time to recrudescence of parasites carrying pfcytb codon 268 mutations was estimated as 28.0 days after treatment (95% C.I. 23.0 – 33.0 days, whereas treatment failures without codon 268 mutations received rescue treatment an average of 4.71 days after initial AP treatment (95% C.I. 1.76 – 7.67 days. Conclusion Genetically-determined parasite resistance to atovaquone is associated with delayed recrudescence of resistant parasites three weeks or more after initial clearance of parasitaemia by atovaquone/proguanil therapy. The 268-Cys allele of pfcyt-b may have been overlooked in previous studies of atovaquone-proguanil treatment failure

  11. Chloroquine mediated modulation of Anopheles gambiae gene expression.

    Directory of Open Access Journals (Sweden)

    Patrícia Abrantes

    Full Text Available BACKGROUND: Plasmodium development in the mosquito is crucial for malaria transmission and depends on the parasite's interaction with a variety of cell types and specific mosquito factors that have both positive and negative effects on infection. Whereas the defensive response of the mosquito contributes to a decrease in parasite numbers during these stages, some components of the blood meal are known to favor infection, potentiating the risk of increased transmission. The presence of the antimalarial drug chloroquine in the mosquito's blood meal has been associated with an increase in Plasmodium infectivity for the mosquito, which is possibly caused by chloroquine interfering with the capacity of the mosquito to defend against the infection. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we report a detailed survey of the Anopheles gambiae genes that are differentially regulated by the presence of chloroquine in the blood meal, using an A. gambiae cDNA microarray. The effect of chloroquine on transcript abundance was evaluated separately for non-infected and Plasmodium berghei-infected mosquitoes. Chloroquine was found to affect the abundance of transcripts that encode proteins involved in a variety of processes, including immunity, apoptosis, cytoskeleton and the response to oxidative stress. This pattern of differential gene expression may explain the weakened mosquito defense response which accounts for the increased infectivity observed in chloroquine-treated mosquitoes. CONCLUSIONS/SIGNIFICANCE: The results of the present study suggest that chloroquine can interfere with several putative mosquito mechanisms of defense against Plasmodium at the level of gene expression and highlight the need for a better understanding of the impacts of antimalarial agents on parasite transmission.

  12. Resistência in vivo do Plasmodium falciparum às 4-aminoquinoleínas e à associação sulfadoxina-pirimetamina: II - estudo de imperatriz, Maranhão, 1983-1984

    Directory of Open Access Journals (Sweden)

    Afonso Dinis Costa Passos

    1987-06-01

    Full Text Available Através da prova de 7 dias foram estudadas as respostas terapêuticas de 96 pacientes com malária falciparum não grave atendidos pela SUCAM em Imperatriz, Maranhão. Esses pacientes foram distribuídos aleatoriamente em três grupos de estudo, tendo o primeiro recebido cloroquina, o segundo amodiaquina e o terceiro a associação sulfadoxina-pirimetamina. Mesmo sem evidenciar significância estatística ao nível de 5% de probabilidade, as diferenças observadas nas respostas as 3 drogas apontam para a associação sulfadoxina-pirimetamina como a que produziu melhores resultados terapêuticos. Recomenda-se a monitorização contínua da resistência nas áreas malarígenas criticas.

  13. Artesunate-induced hemoglobinuria in falciparum malaria

    Directory of Open Access Journals (Sweden)

    Avik Karak

    2016-01-01

    Full Text Available A 26-year-old male got admitted with fever of 103°F with chills and rigor for 6 days. He was diagnosed with Plasmodium falciparum infection by peripheral blood smear examination, later confirmed by polymerase chain reaction analysis. Blood smear showed 2% parasitemia. As the patient was hypotensive, intravenous artesunate was started. Two days later, he reported passing "Coca-Cola"-colored urine. Examination revealed tachycardia, anemia, and mild icterus. Serum free hemoglobin and lactate dehydrogenase was elevated whereas haptoglobin was very low. Urine showed the presence of hemoglobin without red blood cells. Glucose-6-phosphate dehydrogenase assay was normal. Chloroquine, primaquine, and quinine levels in blood were undetectable. There was no evidence of any coinfection. Artesunate was stopped suspecting a causal relationship. Intravenous quinine was started. The urine showed progressive clearance over 3 days, and the patient recovered. The strong temporal association of initiating artesunate and occurrence of hemoglobinuria suggested the possible etiological implication which is not documented before.

  14. Heterologous Protection against Malaria after Immunization with Plasmodium falciparum Sporozoites.

    Directory of Open Access Journals (Sweden)

    Remko Schats

    Full Text Available Sterile protection in >90% of volunteers against homologous Plasmodium falciparum infection has been achieved only using the controlled human malaria infection (CHMI model. This efficient model involves whole parasite immunizations under chloroquine prophylaxis (CPS-immunization, requiring only 30-45 mosquitoes bites infected with P. falciparum-sporozoites. Given the large diversity of P. falciparum parasites, it is essential to assess protection against heterologous parasite strains.In an open-label follow-up study, 16 volunteers previously CPS-immunized and challenged with P. falciparum NF54 (West-Africa in a dose de-escalation and challenge trial were re-challenged with clone NF135.C10 (Cambodia at 14 months after the last immunization (NCT01660854.Two out of thirteen NF54 protected volunteers previously fully protected against NF54 were also fully protected against NF135.C10, while 11/13 showed a delayed patency (median prepatent period of 10.5 days (range 9.0-15.5 versus 8.5 days in 5 malaria-naïve controls (p = 0.0005. Analysis of patency by qPCR indicated a 91 to >99% estimated reduction of liver parasite load in 7/11 partially protected subjects. Three volunteers previously not protected against NF54, were also not protected against NF135.C10.This study shows that CPS-immunization can induce heterologous protection for a period of more than one year, which is a further impetus for clinical development of whole parasite vaccines.Clinicaltrials.gov NCT01660854.

  15. Exploring the folate pathway in Plasmodium falciparum

    OpenAIRE

    Hyde, John E.

    2005-01-01

    As in centuries past, the main weapon against human malaria infections continues to be intervention with drugs, despite the widespread and increasing frequency of parasite populations that are resistant to one or more of the available compounds. This is a particular problem with the lethal species of parasite, Plasmodium falciparum, which claims some two million lives per year as well as causing enormous social and economic problems. Amongst the antimalarial drugs currently in clinical use, t...

  16. Effect of chloroquine on the urinary excretion of ciprofloxacin.

    Science.gov (United States)

    Ilo, Cajetan E; Ezejiofor, Ndidi A; Agbakoba, Nneka; Brown, Sinye A; Maduagwuna, Chinonye A; Agbasi, Patrick U; Orisakwe, Orish E; Orisakweph, Orish E

    2008-01-01

    Ciprofloxacin is an inexpensive antibacterial, whereas chloroquine is an inexpensive antimalarial. The coadministration of chloroquine and ciprofloxacin is easily encountered because both drugs are commonly prescribed to patients in the tropics. Five healthy male volunteers aged 19 to 31 years who were not taking any of the prescribed medications and who had no sensitivity to either ciprofloxacin or chloroquine each received 500 mg ciprofloxacin orally with 250 mL of water, and after a 2-week washout period, 500 mg ciprofloxacin plus 600 mg chloroquine was administered orally with 250 mL of water after providing informed consent. A urine sample (7 mL) was collected just before taking the drug at 8:00 AM representing 0 hour and continued afterward at 1, 2, 4, 8, 12, and 24 hours the next day. The samples were stored at -20 degrees C until analyzed. The minimum inhibitory concentrations by diffusion through agar technique were used for the assay of urine ciprofloxacin. The rate of ciprofloxacin excretion and cumulative urine ciprofloxacin were significantly increased. The coadministration of chloroquine increased the cumulative urinary concentration and excretion rate of ciprofloxacin.

  17. Multifocal Electroretinography after High Dose Chloroquine Therapy for Malaria

    Directory of Open Access Journals (Sweden)

    Aline Correa de Carvalho

    2013-01-01

    Full Text Available Purpose: To investigate changes in multifocal electroretinography (mfERG parameters associated with high dose chloroquine therapy for treatment of malaria in the Amazonia region of Brazil. Methods: Forty-eight subjects who had received chloroquine treatment for single or multiple malaria infections with a cumulative dose ranging from 1,050 to 27,000mg were included. The control group consisted of 37 healthy aged-matched subjects. Data was collected on amplitude and implicit time of the N1, P1 and N2 waves in the central macular hexagon (R1 and in five concentric rings at different retinal eccentricities (R2-R6. Results: No significant difference was observed in any mfERG parameter between chloroquine treated patients and control subjects. A comparison with previous data obtained from patients with rheumatologic disorders in the same region of Brazil who had received larger cumulative doses of chloroquine and had displayed mfERG changes, indicated that retinal toxicity seems to be dependent on cumulative dose. Conclusion: Lack of mfERG changes in the current study suggests that intensive high dose chloroquine therapy for treatment of malaria is not associated with retinal toxicity.

  18. Clinical trials of chemotherapy for falciparum malaria.

    Science.gov (United States)

    Winstanley, P; Olliaro, P

    1998-02-01

    Plasmodium falciparum remains one of the World's most prevalent and devastating pathogens. Mainly for economic reasons, the parasite's ability to develop resistance to drugs has not been matched by the rate at which new compounds are developed. Even so, there are new drugs (or new combinations of old drugs) currently under investigation, or in the process of development (at the moment): Pyronaridine, a well-tolerated, synthetic drug that may have utility for multi-resistant falciparum malaria in many parts of the world; however,problems remain over the formulation of this drug (which is a major determinant of its bioavailability) and its eventual cost. Chlorproguanil-dapsone (lap dap) is being studied as a possible low-cost'successor' to pyrimethamine-sulfadoxine; the utility of chlorproguanil-dapsone as 'salvage' therapy for clinical cases of pyrimethamine-sulfadoxine failure has yet to be tested in clinical trials. Atovaquone-proguanil (malarone) has utility against multi-resistant parasites; however, it is likely to be expensive (but is currently being provided free-of-charge in certain areas of Africa). Artemether-benflumetol (coartemether) combines the advantages of artemether (a rapid reduction in parasite load) with a second drug that reduces the risk of recrudescence; the cost of this combination is unclear. Rectal artesunate is being studied as an intervention to reduce the proportion of children with falciparum malaria who deteriorate to severe disease; the formulation is appropriate for use in rural health centres.

  19. Synthesis of novel triazole-linked mefloquine derivatives: biological evaluation against Plasmodium falciparum.

    Science.gov (United States)

    Hamann, Anton R; de Kock, Carmen; Smith, Peter J; van Otterlo, Willem A L; Blackie, Margaret A L

    2014-12-01

    Using 2,8-bis(trifluoromethyl)quinoline, the pharmacophore of mefloquine, as scaffold, eleven novel triazole-linked compounds have been synthesised by the application of CuAAC chemistry. The in vitro biological activity of the compounds on the Plasmodium falciparum chloroquine-sensitive strain NF54 was then determined. The compounds all showed IC50s in the lower μM range with (1R,3S,5R)-N-{[1-(2,8-bis(trifluoromethyl)quinoline-4-yl)-1H-1,2,3-triazol-4-yl]methyl}adamantan-2-amine (29) exhibiting the best activity of 1.00 μM.

  20. Genetic loci associated with delayed clearance of Plasmodium falciparum following artemisinin treatment in Southeast Asia

    Science.gov (United States)

    2013-01-02

    Genetic loci associated with delayed clearance of Plasmodium falciparum following artemisinin treatment in Southeast Asia Shannon Takala-Harrisona...resistant Plasmodium falcipa- rum malaria in western Cambodia could threaten prospects for malaria elimination. Identification of the genetic basis of...molecular markers Artemisinin-based combination therapies (ACTs) are the lead-ing treatment for Plasmodium falciparum malaria (1), and their use with

  1. Possible treatment failure of artemether-lumefantrine in an Italian traveler with uncomplicated falciparum malaria.

    Directory of Open Access Journals (Sweden)

    Ernestina Carla Repetto

    2011-10-01

    Full Text Available Artemisinin-combination therapies (ACTs are recommended for the treatment of uncomplicated malaria in endemic areas with multidrug resistant Plasmodium falciparum. We report a case of possible artemether-lumefantrine failure in an Italian traveler with uncomplicated P. falciparum malaria imported from Democratic Republic of Congo.

  2. Possible clinical failure of artemether-lumefantrine in an italian traveler with uncomplicated falciparum malaria.

    Science.gov (United States)

    Repetto, Ernestina C; Traverso, Antonio; Giacomazzi, Claudio G

    2011-01-01

    Artemisinin-combination therapies (ACTs) are recommended for the treatment of uncomplicated malaria in endemic areas with multidrug resistant Plasmodium falciparum. We report a case of possible artemether-lumefantrine clinical failure in an Italian traveler with uncomplicated P. falciparum malaria imported from Democratic Republic of Congo.

  3. Genetics of refractoriness to Plasmodium falciparum in the mosquito Anopheles stephensi

    NARCIS (Netherlands)

    Feldmann, A.M.; Gemert, Geert-Jan van; Vegte-Bolmer, Marga G. van de; Jansen, Ritsert C.

    1998-01-01

    We previously selected a line of the malaria vector mosquito Anopheles stephensi refractory (resistant) to the human malaria parasite Plasmodium falciparum, using in vitro infections with P. falciparum gametocytes. This report presents data on the genetic background of refractoriness. The results of

  4. Possible Clinical Failure of Artemether-Lumefantrine in an Italian Traveler with Uncomplicated Falciparum Malaria.

    Science.gov (United States)

    Repetto, Ernestina C.; Traverso, Antonio; Giacomazzi, Claudio G.

    2011-01-01

    Artemisinin-combination therapies (ACTs) are recommended for the treatment of uncomplicated malaria in endemic areas with multidrug resistant Plasmodium falciparum. We report a case of possible artemether-lumefantrine clinical failure in an Italian traveler with uncomplicated P. falciparum malaria imported from Democratic Republic of Congo. PMID:22084655

  5. In vivo confocal microscopy in chloroquine-induced keratopathy

    Directory of Open Access Journals (Sweden)

    Iacopo Paladini

    2013-01-01

    Full Text Available In vivo confocal microscopy is becoming a mandatory examination to study corneal abnormalities such as drug deposits in systemic disease. A female diagnosed with fibromyalgia on systemic chloroquine for 9 months presented for an ophthalmic examination. Confocal microscopy was performed using the Confoscan 4 (Nidek Co. Ltd., Gamagori, Japan and multiple highly reflective deposits in the epithelial basal cells were found, that were consistent with choloquine. Deposits were also present in the wing cell layer. In the anterior stroma these deposits were rare. Atypically shaped and branched nerves were also present in the anterior stroma. Corneal deposits of chloroquine can be evaluated by confocal microscopy. Confocal microscopy provides information on corneal metabolism and physiology. Chloroquine keratopathy can affect the anterior stroma in addition to the epithelium.

  6. Seizures following chloroquine treatment of type II lepra reaction: a case report.

    Science.gov (United States)

    Ebenso, B E

    1998-06-01

    A case of tonic-clonic seizures following chloroquine treatment for leprosy reactions in a Nigerian male is reported. Seizures were controlled with phenytoin sodium capsules. A casual relationship between the seizures and chloroquine is suggested. There have been no previous reports of this adverse reaction in leprosy patients receiving chloroquine for treatment of reactions. The author recommends that chloroquine be used with caution especially in patients with seizures.

  7. Declining trend of Plasmodium falciparum dihydrofolate reductase (dhfr and dihydropteroate synthase (dhps mutant alleles after the withdrawal of Sulfadoxine-Pyrimethamine in North Western Ethiopia.

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    Sofonias K Tessema

    Full Text Available Antimalarial drug resistance is one of the major challenges in global efforts of malaria control and elimination. In 1998, chloroquine was abandoned and replaced with sulfadoxine/pyrimethamine, which in turn was replaced with artemether/lumefantrine for the treatment of uncomplicated falciparum malaria in 2004. Sulfadoxine/pyrimethamine resistance is associated with mutations in dihydrofolate reductase (Pfdhfr and dihydropteroate synthase (Pfdhps genes. The prevalence of mutation in Pfdhfr and Pfdhps genes were evaluated and compared for a total of 159 isolates collected in two different time points, 2005 and 2007/08, from Pawe hospital, in North Western Ethiopia. The frequency of triple Pfdhfr mutation decreased significantly from 50.8% (32/63 to 15.9% (10/63 (P<0.001, while Pfdhps double mutation remained high and changed only marginally from 69.2% (45/65 to 55.4% (40/65 (P = 0.08. The combined Pfdhfr/Pfdhps quintuple mutation, which is strongly associated with sulfadoxine/pyrimethamine resistance, was significantly decreased from 40.7% (24/59 to 13.6% (8/59 (P<0.0001. On the whole, significant decline in mutant alleles and re-emergence of wild type alleles were observed. The change in the frequency is explained by the reduction of residual drug-resistant parasites caused by the strong drug pressure imposed when sulfadoxine/pyrimethamine was the first-line drug, followed by lower fitness of these resistant parasites in the absence of drug pressure. Despite the decrease in the frequency of mutant alleles, higher percentages of mutation remain prevalent in the study area in 2007/08 in both Pfdhfr and Pfdhps genes. Therefore, further multi-centered studies in different parts of the country will be required to assess the re-emergence of sulfadoxine/pyrimethamine sensitive parasites and to monitor and prevent the establishment of multi drug resistant parasites in this region.

  8. An investigation into the suitability of amidat