WorldWideScience

Sample records for previous epidemic strains

  1. Phylogeography and Molecular Epidemiology of an Epidemic Strain of Dengue Virus Type 1 in Sri Lanka

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    Ocwieja, Karen E.; Fernando, Anira N.; Sherrill-Mix, Scott; Sundararaman, Sesh A.; Tennekoon, Rashika N.; Tippalagama, Rashmi; Krishnananthasivam, Shivankari; Premawansa, Gayani; Premawansa, Sunil; De Silva, Aruna Dharshan

    2014-01-01

    In 2009, a severe epidemic of dengue disease occurred in Sri Lanka, with higher mortality and morbidity than any previously recorded epidemic in the country. It corresponded to a shift to dengue virus 1 as the major disease-causing serotype in Sri Lanka. Dengue disease reached epidemic levels in the next 3 years. We report phylogenetic evidence that the 2009 epidemic DENV-1 strain continued to circulate within the population and caused severe disease in the epidemic of 2012. Bayesian phylogeographic analyses suggest that the 2009 Sri Lankan epidemic DENV-1 strain may have traveled directly or indirectly from Thailand through China to Sri Lanka, and after spreading within the Sri Lankan population, it traveled to Pakistan and Singapore. Our findings delineate the dissemination route of a virulent DENV-1 strain in Asia. Understanding such routes will be of particular importance to global control efforts. PMID:24799375

  2. Variations in SXT elements in epidemic Vibrio cholerae O1 El Tor strains in China.

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    Wang, Ruibai; Yu, Dong; Yue, Junjie; Kan, Biao

    2016-03-09

    Vibrio cholerae O1 El Tor biotype strains are responsible for three multiyear epidemics of cholera in China during the seventh ongoing pandemic. The presence of the integrative conjugative element SXT is strongly correlated with resistance to nalidixic acid, tetracycline, and trimethoprim-sulfamethoxazole in these strains. Here, we sequenced the conserved genes of the SXT element, including eex, setR, and int, from 59 V. cholerae O1 El Tor strains and extracted and assembled the intact SXT sequences from the 11 genome sequenced strains. These elements had characteristics distinct from those of previously reported integrative conjugative elements (ICEs). They could be clearly divided into two types based on the clustering of conserved genes and gene structures of the elements, showing their possibly independent derivation and evolution. These two types were present before and after 2005, respectively, demonstrating the type substitution that occurred in 2005. Four to six antibiotic-resistant genes were found on the SXT elements, including genes resistant to tetracycline, trimethoprim-sulfamethoxazole, and multiple drugs. In summary, our findings demonstrated the roles of the SXT element in the emergence of multidrug resistance in epidemic O1 El Tor V. cholerae strains in China.

  3. Characterisation of MRSA from Malta and the description of a Maltese epidemic MRSA strain.

    LENUS (Irish Health Repository)

    Scicluna, E A

    2010-02-01

    Malta has one of the highest prevalence rates of methicillin-resistant Staphylococcus aureus (MRSA) in Europe. However, only limited typing data are currently available. In order to address this situation, 45 MRSA isolates from the Mater Dei Hospital in Msida, Malta, were characterised using DNA microarrays. The most common strain was ST22-MRSA-IV (UK-EMRSA-15, 30 isolates). Sporadic strains included ST36-MRSA-II (UK-EMRSA-16, two isolates), PVL-positive ST80-MRSA-IV (European Clone, one isolate), ST228-MRSA-I (Italian Clone\\/South German Epidemic Strain, one isolate) and ST239-MRSA-III (Vienna\\/Hungarian\\/Brazilian Epidemic Strain, one isolate). Ten MRSA isolates belonged to a clonal complex (CC) 5\\/ST149, spa type t002 strain. This strain harboured an SCCmec IV element (mecA, delta mecR, ugpQ, dcs, ccrA2 and ccrB2), as well as novel alleles of ccrA\\/B and the fusidic acid resistance element Q6GD50 (previously described in the sequenced strain MSSA476, BX571857.1:SAS0043). It also carried the gene for enterotoxin A (sea) and the egc enterotoxin locus, as well as (in nine out of ten isolates) genes encoding the toxic shock syndrome toxin (tst1) and enterotoxins C and L (sec, sel). While the presence of the other MRSA strains suggests foreign importation due to travel between Malta and other European countries, the CC5\\/t002 strain appears, so far, to be restricted to Malta.

  4. Virulence variation among epidemic and non-epidemic strains of Saint Louis encephalitis virus circulating in Argentina

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    María Elisa Rivarola

    2014-04-01

    Full Text Available Saint Louis encephalitis virus caused an outbreak of febrile illness and encephalitis cases in Córdoba, Argentina, in 2005. During this outbreak, the strain CbaAr-4005 was isolated from Culex quinquefasciatus mosquitoes. We hypothesised that this epidemic variant would be more virulent in a mouse model than two other non-epidemic strains (78V-6507 and CorAn-9275 isolated under different epidemiological conditions. To test this hypothesis, we performed a biological characterisation in a murine model, including mortality, morbidity and infection percentages and lethal infection indices using the three strains. Mice were separated into age groups (7, 10 and 21-day-old mice and analysed after infection. The strain CbaAr-4005 was the most infective and lethal of the three variants, whereas the other two strains exhibited a decreasing mortality percentage with increasing animal age. The strain CbaAr-4005 produced the highest morbidity percentages and no significant differences among age groups were observed. The epidemic strain caused signs of illness in all inoculated animals and showed narrower ranges from the onset of symptoms than the other strains. CbaAr-4005 was the most virulent for Swiss albino mice. Our results highlight the importance of performing biological characterisations of arbovirus strains likely to be responsible for emerging or reemerging human diseases.

  5. Mycobacterium tuberculosis Strains Potentially Involved in the TB Epidemic in Sweden a Century Ago

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    Groenheit, Ramona; Ghebremichael, Solomon; Pennhag, Alexandra; Jonsson, Jerker; Hoffner, Sven; Couvin, David; Koivula, Tuija; Rastogi, Nalin; Källenius, Gunilla

    2012-01-01

    A hundred years ago the prevalence of tuberculosis (TB) in Sweden was one of the highest in the world. In this study we conducted a population-based search for distinct strains of Mycobacterium tuberculosis complex isolated from patients born in Sweden before 1945. Many of these isolates represent the M. tuberculosis complex population that fueled the TB epidemic in Sweden during the first half of the 20th century. Methods Genetic relationships between strains that caused the epidemic and present day strains were studied by spoligotyping and restriction fragment length polymorphism. Results The majority of the isolates from the elderly population were evolutionary recent Principal Genetic Group (PGG)2/3 strains (363/409 or 88.8%), and only a low proportion were ancient PGG1 strains (24/409 or 5.9%). Twenty-two were undefined. The isolates demonstrated a population where the Euro-American superlineage dominated; in particular with Haarlem (41.1%) and T (37.7%) spoligotypes and only 21.2% belonged to other spoligotype families. Isolates from the elderly population clustered much less frequently than did isolates from a young control group population. Conclusions A closely knit pool of PGG2/3 strains restricted to Sweden and its immediate neighbours appears to have played a role in the epidemic, while PGG1 strains are usually linked to migrants in todaýs Sweden. Further studies of these outbreak strains may give indications of why the epidemic waned. PMID:23056484

  6. Mycobacterium tuberculosis strains potentially involved in the TB epidemic in Sweden a century ago.

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    Ramona Groenheit

    Full Text Available UNLABELLED: A hundred years ago the prevalence of tuberculosis (TB in Sweden was one of the highest in the world. In this study we conducted a population-based search for distinct strains of Mycobacterium tuberculosis complex isolated from patients born in Sweden before 1945. Many of these isolates represent the M. tuberculosis complex population that fueled the TB epidemic in Sweden during the first half of the 20(th century. METHODS: Genetic relationships between strains that caused the epidemic and present day strains were studied by spoligotyping and restriction fragment length polymorphism. RESULTS: The majority of the isolates from the elderly population were evolutionary recent Principal Genetic Group (PGG2/3 strains (363/409 or 88.8%, and only a low proportion were ancient PGG1 strains (24/409 or 5.9%. Twenty-two were undefined. The isolates demonstrated a population where the Euro-American superlineage dominated; in particular with Haarlem (41.1% and T (37.7% spoligotypes and only 21.2% belonged to other spoligotype families. Isolates from the elderly population clustered much less frequently than did isolates from a young control group population. CONCLUSIONS: A closely knit pool of PGG2/3 strains restricted to Sweden and its immediate neighbours appears to have played a role in the epidemic, while PGG1 strains are usually linked to migrants in todaýs Sweden. Further studies of these outbreak strains may give indications of why the epidemic waned.

  7. The finch epidemic strain of Trichomonas gallinae is predominant in British non-passerines.

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    Chi, Jean F; Lawson, Becki; Durrant, Chris; Beckmann, Katie; John, Shinto; Alrefaei, Abdulwahed F; Kirkbride, Kim; Bell, Diana J; Cunningham, Andrew A; Tyler, Kevin M

    2013-09-01

    Avian trichomonosis, caused by the flagellated protozoan Trichomonas gallinae, is a recently emerged infectious disease of British passerines. The aetiological agent, a clonal epidemic strain of the parasite, has caused unprecedented finch mortality and population-level declines in Britain and has since spread to continental Europe. To better understand the potential origin of this epidemic and to further investigate its host range, T. gallinae DNA extracts were collected from parasite culture and tissue samples from a range of avian species in Britain. Sequence typing at the ITS1/5.8S rRNA/ITS2 region resolved three distinct ITS region types circulating in free-ranging British birds. Subtyping by sequence analyses at the Fe-hydrogenase gene demonstrated further strain variation within these ITS region types. The UK finch epidemic strain was preponderant amongst columbids sampled, however, wide strain diversity was encountered in isolates from a relatively small number of pigeons, suggesting further strains present in columbid populations across the UK are yet to be identified. Fe-hydrogenase gene sequence data in isolates from birds of prey with disease were predominantly identical to the UK finch epidemic strain, demonstrating its presence as a virulent strain in UK birds of prey since at least 2009.

  8. Genetic Characterization of Northwestern Colombian Chikungunya Virus Strains from the 2014–2015 Epidemic

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    Rodas, Juan D.; Kautz, Tiffany; Camacho, Erwin; Paternina, Luis; Guzmán, Hilda; Díaz, Francisco J.; Blanco, Pedro; Tesh, Robert; Weaver, Scott C.

    2016-01-01

    Chikungunya fever, an acute and often chronic arthralgic disease caused by the mosquito-borne alphavirus, chikungunya virus (CHIKV), spread into the Americas in late 2013. Since then it has caused epidemics in nearly all New World countries, the second largest being Colombia with over 450,000 suspected cases beginning in September, 2014, and focused in Bolivar Department in the north. We examined 32 human sera from suspected cases, including diverse age groups and both genders, and sequenced the CHIKV envelope glycoprotein genes, known determinants of vector host range. As expected for Asian lineage CHIKV strains, these isolates lacked known Aedes albopictus–adaptive mutations. All the Colombian strains were closely related to those from the Virgin Islands, Saint Lucia, Mexico, Puerto Rico, and Brazil, consistent with a single, point-source introduction from the southeast Asia/Pacific region. Two substitutions in the E2 and E1 envelope glycoprotein genes were found in the Colombian strains, especially E1-K211E involving a residue shown previously to affect epistatically the penetrance of the E1-A226V A. albopictus–adaptive substitution. We also identified two amino acid substitutions unique to all American CHIKV sequences: E2-V368A and 6K-L20M. Only one codon, 6K-47, had a high nonsynonymous substitution rate suggesting positive selection. PMID:27430542

  9. An improved technique for isolation of environmental Vibrio cholerae with epidemic potential: monitoring the emergence of a multiple-antibiotic-resistant epidemic strain in Bangladesh.

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    Faruque, Shah M; Islam, M Johirul; Ahmad, Qazi Shafi; Biswas, Kuntal; Faruque, A S G; Nair, G Balakrish; Sack, R Bradley; Sack, David A; Mekalanos, John J

    2006-04-01

    Predicting cholera epidemics through monitoring the environment for the presence of pathogenic Vibrio cholerae is complicated by the presence in water of a large number of mostly nonpathogenic V. cholerae strains. V. cholerae strains causing recent cholera epidemics in Bangladesh carry the sulfamethoxazole-trimethoprim (SXT) element, which encodes resistance to several antibiotics. Here, we show that the use of a culture medium containing streptomycin, sulfamethoxazole, and trimethoprim (the antibiotic selection technique [AST]) can significantly enhance the isolation of environmental V. cholerae O1 with epidemic potential (Pantibiotic-resistant strain of V. cholerae in Bangladesh. The results of this study support the hypothesis that pre-epidemic amplification of pathogenic V. cholerae occurs in the human host and leads to the start of an epidemic cycle dominated by a single clone of V. cholerae that spreads rapidly through environmental waters.

  10. Exploring Genomic, Geographic and Virulence Interactions among Epidemic and Non-Epidemic St. Louis Encephalitis Virus (Flavivirus Strains.

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    Luis A Diaz

    Full Text Available St. Louis encephalitis virus (SLEV is a re-emerging arbovirus in South America. In 2005, an encephalitis outbreak caused by SLEV was reported in Argentina. The reason for the outbreak remains unknown, but may have been related to virological factors, changes in vectors populations, avian amplifying hosts, and/or environmental conditions. The main goal of this study was to characterize the complete genome of epidemic and non-epidemic SLEV strains from Argentina. Seventeen amino acid changes were detected; ten were non-conservative and located in proteins E, NS1, NS3 and NS5. Phylogenetic analysis showed two major clades based on geography: the North America and northern Central America (NAnCA clade and the South America and southern Central America (SAsCA clade. Interestingly, the presence of SAsCA genotype V SLEV strains in the NAnCA clade was reported in California, Florida and Texas, overlapping with known bird migration flyways. This work represents the first step in understanding the molecular mechanisms underlying virulence and biological variation among SLEV strains.

  11. Characteristics of epidemic and sporadic strains of Acinetobacter baumannii isolated in Abu Dhabi hospitals.

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    Sonnevend, Agnes; Ghazawi, Akela; Al Munthari, Noura; Pitout, Martin; Hamadeh, Mohammad Baraa; Hashmey, Rayhan; Girgis, Safinaz Khaleel; Sheikh, Farrukh Amin; Al Haj, Mohamed; Nagelkerke, Nico; Pál, Tibor

    2013-04-01

    We compared the antibiotic susceptibility, clonal lineages and resistance genes of singleton Acinetobacter baumannii strains to those of isolates representing repeatedly encountered molecular types in five Abu Dhabi hospitals. One hundred and ten clinically relevant, non-repeat strains were typed by blaOXA-51-like allele sequencing and by PFGE, and selected isolates also by MLST. Resistance was assessed by MIC determinations and by disc diffusion. Genotyping was carried out by PCR, targeting 28 genes. The 80 epidemic strains belonged to worldwide lineages 1, 2 and 7, representing 11 pulsotypes and 9 genotypes, while the 30 sporadic isolates exhibited a high level of genetic variability and, with the exception of a small subgroup, were not associated with any recognized epidemic lineages. All epidemic subtypes carried the ISAba1-linked blaOXA-23 gene, and harboured the int, the blaPER and the armA genes significantly more frequently than their sporadic counterparts. They were all multi-drug resistant, including non-susceptibility to carbepenems, and were often extensively drug resistant, a phenomenon rarely seen among sporadic strains. Epidemic strains represented 78.8 % of intensive care unit isolates, causing more respiratory infections, while sporadic strains were more frequently isolated from wound and soft tissue infections. The study showed that among strains collected at the same time and from the same region, the very heterogeneous, sensitive sporadic strains, with the exception of a few non-susceptible singleton isolates, clearly differed from the highly resistant epidemic ones, which belonged to multiple pulsotypes and genotypes clustered into three worldwide clonal lineages carrying blaOXA-64, blaOXA-66 and blaOXA-69, respectively.

  12. Characterization and Proposed Nomenclature of Epidemic Strains of MRSA in Canada

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    AE Simor

    1999-01-01

    Full Text Available The incidence of methicillin-resistant Staphylococcus aureus (MRSA has been increasing in many Canadian hospitals over the past few years. Some strains may be considered ‘epidemic’, in that they are clinically or epidemiologically significant, and have been identified in patients from multiple hospitals and geographic regions across the country. This paper describes phenotypic and genotypic characteristics of four epidemic MRSA strains in Canada and proposes standardized nomenclature.

  13. Differential infection properties of three inducible prophages from an epidemic strain of Pseudomonas aeruginosa

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    James Chloe E

    2012-09-01

    Full Text Available Abstract Background Pseudomonas aeruginosa is the most common bacterial pathogen infecting the lungs of patients with cystic fibrosis (CF. The Liverpool Epidemic Strain (LES is transmissible, capable of superseding other P. aeruginosa populations and is associated with increased morbidity. Previously, multiple inducible prophages have been found to coexist in the LES chromosome and to constitute a major component of the accessory genome not found in other sequenced P. aerugionosa strains. LES phages confer a competitive advantage in a rat model of chronic lung infection and may, therefore underpin LES prevalence. Here the infective properties of three LES phages were characterised. Results This study focuses on three of the five active prophages (LESφ2, LESφ3 and LESφ4 that are members of the Siphoviridae. All were induced from LESB58 by norfloxacin. Lytic production of LESφ2 was considerably higher than that of LESφ3 and LESφ4. Each phage was capable of both lytic and lysogenic infection of the susceptible P. aeruginosa host, PAO1, producing phage-specific plaque morphologies. In the PAO1 host background, the LESφ2 prophage conferred immunity against LESφ3 infection and reduced susceptibility to LESφ4 infection. Each prophage was less stable in the PAO1 chromosome with substantially higher rates of spontaneous phage production than when residing in the native LESB58 host. We show that LES phages are capable of horizontal gene transfer by infecting P. aeruginosa strains from different sources and that type IV pili are required for infection by all three phages. Conclusions Multiple inducible prophages with diverse infection properties have been maintained in the LES genome. Our data suggest that LESφ2 is more sensitive to induction into the lytic cycle or has a more efficient replicative cycle than the other LES phages.

  14. Molecular characterization and phylogenetic analysis of porcine epidemic diarrhea virus (PEDV) field strains in south China.

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    Li, Zhi-Li; Zhu, Ling; Ma, Jing-Yun; Zhou, Qing-Feng; Song, Yan-Hua; Sun, Bao-Li; Chen, Rui-Ai; Xie, Qing-Mei; Bee, Ying-Zuo

    2012-08-01

    A total of 127 porcine samples were collected from 48 farms in six provinces in south China. The positive rate of porcine epidemic diarrhea virus (PEDV) was 43.0 % (55/127), and the co-infection rate of PEDV and transmissible gastroenteritis virus (TGEV) was 12.0 % (15/127). The partial S gene and complete M gene were amplified from PEDV-positive strains by RT-PCR, cloned, sequenced and compared with each other, as well as with the reference strains in GenBank. Sequence homology results of the partial S gene and complete M gene showed that all south China field PEDV strains had nucleotide (deduced amino acid) sequence identities of 86.7-98.7 % (83.2-99.3 %) and 96.1-100 % (95.0-100%), respectively, with the foreign reference strains reported in GenBank. Phylogenetic analysis of the partial S gene showed that all the south China PEDV strains and two Thailand strains (08UB01 and 08RB07) belong to the same group and differ genetically from European strains and early domestic strains. Phylogenetic analysis of the complete M gene showed that all south China PEDV strains have a close relationship with most of the strains in Korea and Thailand, but differ genetically from the vaccine strain (CV777).

  15. Virulence traits associated with Burkholderia cenocepacia ST856 epidemic strain isolated from cystic fibrosis patients

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    Milka Malešević

    2017-06-01

    Full Text Available Abstract Background Burkholderia cenocepacia is considered one of the most problematic cystic fibrosis (CF pathogens. Colonization prevalence in the Serbian CF population is high and virtually exclusively limited to a single highly transmissible clone of B. cenocepacia ST856 which is positive for both the B. cepacia epidemic strain marker (BCESM and cable pilin, and is closely related to the epidemic strain CZ1 (ST32. Methods Biofilm formation for 182 isolates, and adhesion to components of the host extracellular matrix, proteolytic activity, mucoidy and motility of selected ST856 representatives, as well as B. cenocepacia ST858 and ST859, and B. stabilis ST857, novel STs isolated from Serbian CF patients, were investigated in this study. The presence of the cepI, cepR, fliG, llpE, wbiI, and bcscV genes was analyzed. Results Biofilm-formation ability of analyzed strains was poor under standard laboratory conditions, but changed in stress conditions (cold stress and conditions that mimic CF milieu (increased CO2. All strains expressed ability to bind to collagen and fibronectin albeit with different intensity. Representatives of ST856 exhibited gelatinase activity. ST858, ST859 and 9/11 of ST856 genotypes were positive for swimming and twitching motility whereas ST857 was non-motile. Mucoidy was demonstrated in all ST856 genotypes, ST857 was semi-mucoid, and ST858 and ST859 were non-mucoid. Molecular analysis for major virulence factors revealed that ST856 and ST857 carried the six analyzed genes, while ST858 and ST859 were negative for the llpE gene. Conclusion Variations in virulence phenotypes in different genotypes of epidemic B. cenocepacia ST856 clone, in vitro, could be a consequence of diversification driven by pathoadaptation. Diversity of epidemic clone genotypes virulence, could be challenging for accurate diagnosis and treatment, as well as for infection control.

  16. Bactericidal Efficacy of Allium sativum (garlic) Against Multidrug Resistant Vibrio cholerae O1 Epidemic Strains

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    Pramod Kumar; Jayprakash Yadav; Meenu Jain; Preeti Yadav; A.K. Goel; Pramod Kumar Yadava

    2016-01-01

    In recent years, emerging trend of antibiotic resistance in Vibrio cholerae associated with cholera epidemics is a matter of serious concern for the management of the disease. Indiscriminate use of antibiotics generally results in selection of antibiotic resistant strains. Introduction of newer antibiotics is a challenging task for the researchers as bacteria soon attain resistance. Therefore, identifying natural compounds of medicinal importance for control of cholera would be the best alter...

  17. The core proteome and pan proteome of Salmonella Paratyphi A epidemic strains.

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    Li Zhang

    Full Text Available Comparative proteomics of the multiple strains within the same species can reveal the genetic variation and relationships among strains without the need to assess the genomic data. Similar to comparative genomics, core proteome and pan proteome can also be obtained within multiple strains under the same culture conditions. In this study we present the core proteome and pan proteome of four epidemic Salmonella Paratyphi A strains cultured under laboratory culture conditions. The proteomic information was obtained using a Two-dimensional gel electrophoresis (2-DE technique. The expression profiles of these strains were conservative, similar to the monomorphic genome of S. Paratyphi A. Few strain-specific proteins were found in these strains. Interestingly, non-core proteins were found in similar categories as core proteins. However, significant fluctuations in the abundance of some core proteins were also observed, suggesting that there is elaborate regulation of core proteins in the different strains even when they are cultured in the same environment. Therefore, core proteome and pan proteome analysis of the multiple strains can demonstrate the core pathways of metabolism of the species under specific culture conditions, and further the specific responses and adaptations of the strains to the growth environment.

  18. Radioimmunoassay determination of antigenic concordance among hemagglutinins of vaccine and epidemic influenza virus strains

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    Blokha, V.V.; Yamnikova, S.S.; Karpovich, L.G.; Yakhno, M.A.; Zakstel' skaya, L.Ya.

    Radioimmunoassay studies were conducted on the antigenic concordance of hemagglutinin of influenza A H3N2 viruses, to determine the suitability of vaccine strains in engendering immunity against viruses circulating in nature. Specifically, the inhibition studies involved the hemagglutinins of the A/Victoria/35/72 vaccine strain, the proposed vaccine strain A/Khabarovsk/15/76, and the RK-5 recombinant strains, containing antigenic determinants of viruses isolated in the 1972-1976 epidemic period (A/Victoria/3/75, A/Leningrad/173/75, A/Victoria/112/76). The results showed that A/Victoria/35/72 is becoming less important as a vaccine, but that RK-5 and A/Khabarovsk/15/76 can provide significant immunity with respect to influenza viruses circulating in 1975-1976. These observations point to the usefulness of radioimmunoassay in assessing the suitability of influenza A viruses for vaccine production. 12 references, 2 figures.

  19. A diagnostic PCR assay for the detection of an Australian epidemic strain of Pseudomonas aeruginosa

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    Murphy Anna

    2010-07-01

    Full Text Available Abstract Background Chronic lung infection with the bacterium Pseudomonas aeruginosa is one of the hallmarks of cystic fibrosis (CF and is associated with worsening lung function, increased hospitalisation and reduced life expectancy. A virulent clonal strain of P. aeruginosa (Australian epidemic strain I; AES-I has been found to be widespread in CF patients in eastern Australia. Methods Suppression subtractive hybridization (SSH was employed to identify genetic sequences that are present in the AES-I strain but absent from the sequenced reference strain PAO1. We used PCR to evaluate the distribution of several of the AES-I loci amongst a collection of 188 P. aeruginosa isolates which was comprised of 35 AES-I isolates (as determined by PFGE, 78 non-AES-I CF isolates including other epidemic CF strains as well as 69 P. aeruginosa isolates from other clinical and environmental sources. Results We have identified a unique AES-I genetic locus that is present in all 35 AES-I isolates tested and not present in any of the other 153 P. aeruginosa strains examined. We have used this unique AES-I locus to develop a diagnostic PCR and a real-time PCR assay to detect the presence of P. aeruginosa and AES-I in patient sputum samples. Conclusions We have developed diagnostic PCR assays that are 100% sensitive and 100% specific for the P. aeruginosa strain AES-I. We have also shown that Whatman FTA® Elute cards may be used with PCR-based assays to rapidly detect the presence of P. aeruginosa strains in CF sputum.

  20. Antigenic relationships among porcine epidemic diarrhea virus and transmissible gastroenteritis virus strains.

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    Lin, Chun-Ming; Gao, Xiang; Oka, Tomoichiro; Vlasova, Anastasia N; Esseili, Malak A; Wang, Qiuhong; Saif, Linda J

    2015-03-01

    Porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) are economically important swine enteropathogenic coronaviruses. These two viruses belong to two distinct species of the Alphacoronavirus genus within Coronaviridae and induce similar clinical signs and pathological lesions in newborn piglets, but they are presumed to be antigenically distinct. In the present study, two-way antigenic cross-reactivity examinations between the prototype PEDV CV777 strain, three distinct U.S. PEDV strains (the original highly virulent PC22A, S indel Iowa106, and S 197del PC177), and two representative U.S. TGEV strains (Miller and Purdue) were conducted by cell culture immunofluorescent (CCIF) and viral neutralization (VN) assays. None of the pig TGEV antisera neutralized PEDV and vice versa. One-way cross-reactions were observed by CCIF between TGEV Miller hyperimmune pig antisera and all PEDV strains. Enzyme-linked immunosorbent assays, immunoblotting using monoclonal antibodies and Escherichia coli-expressed recombinant PEDV and TGEV nucleocapsid (N) proteins, and sequence analysis suggested at least one epitope on the N-terminal region of PEDV/TGEV N protein that contributed to this cross-reactivity. Biologically, PEDV strain CV777 induced greater cell fusion in Vero cells than did U.S. PEDV strains. Consistent with the reported genetic differences, the results of CCIF and VN assays also revealed higher antigenic variation between PEDV CV777 and U.S. strains. Evidence of antigenic cross-reactivity between porcine enteric coronaviruses, PEDV and TGEV, in CCIF assays supports the idea that these two species are evolutionarily related, but they are distinct species defined by VN assays. Identification of PEDV- or TGEV-specific antigenic regions allows the development of more specific immunoassays for each virus. Antigenic and biologic variations between the prototype and current PEDV strains could explain, at least partially, the recurrence of PEDV

  1. Whole-genome pyrosequencing of an epidemic multidrug-resistant Acinetobacter baumannii strain belonging to the European clone II group

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    Iacono, M.; Villa, L.; Fortini, D.

    2008-01-01

    The whole-genome sequence of an epidemic, multidrug-resistant Acinetobacter baumannii strain (strain ACICU) belonging to the European clone II group and carrying the plasmid-mediated bla(OXA-58) carbapenem resistance gene was determined. The A. baumannii ACICU genome was compared with the genomes...

  2. A laminar flow model of aerosol survival of epidemic and non-epidemic strains of Pseudomonas aeruginosa isolated from people with cystic fibrosis

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    Denton Miles

    2008-06-01

    Full Text Available Abstract Background Cystic fibrosis (CF is an inherited multi-system disorder characterised by chronic airway infection with pathogens such as Pseudomonas aeruginosa. Acquisition of P. aeruginosa by patients with CF is usually from the environment, but recent studies have demonstrated patient to patient transmission of certain epidemic strains, possibly via an airborne route. This study was designed to examine the survival of P. aeruginosa within artificially generated aerosols. Results Survival was effected by the solution used for aerosol generation. Within the aerosols it was adversely affected by an increase in air temperature. Both epidemic and non-epidemic strains of P. aeruginosa were able to survive within the aerosols, but strains expressing a mucoid phenotype had a survival advantage. Conclusion This would suggest that segregating individuals free of P. aeruginosa from those with chronic P. aeruginosa infection who are more likely to be infected with mucoid strains may help reduce the risk of cross-infection. Environmental factors also appear to influence bacterial survival. Warming and drying the air within clinical areas and avoidance of humidification devices may also be beneficial in reducing the risk of cross-infection.

  3. Global stability analysis of two-strain epidemic model with bilinear and non-monotone incidence rates

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    Baba, Isa Abdullahi; Hincal, Evren

    2017-05-01

    In this article we studied an epidemic model consisting of two strains with different types of incidence rates; bilinear and non-monotone. The model consists of four equilibrium points: disease-free equilibrium, endemic with respect to strain 1, endemic with respect to strain 2, and endemic with respect to both strains. The global stability analysis of the equilibrium points was carried out through the use of Lyapunov functions. Two basic reproduction ratios R 1 0 and R 2 0 are found, and we have shown that if both are less than one, the disease dies out, and if both are greater than one epidemic occurs. Furthermore, epidemics occur with respect to any strain with a basic reproduction ratio greater than one and disease dies out with respect to any strain with a basic reproduction ratio less than one. It was also shown that any strain with highest basic reproduction ratio will automatically outperform the other strain, thereby eliminating it. Numerical simulations were carried out to support the analytic result and to show the effect of the parameter k in the non-monotone incidence rate, which describes the psychological effect of general public towards infection.

  4. A clonal strain of Trichomonas gallinae is the aetiologic agent of an emerging avian epidemic disease.

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    Lawson, Becki; Cunningham, Andrew A; Chantrey, Julian; Hughes, Laura A; John, Shinto K; Bunbury, Nancy; Bell, Diana J; Tyler, Kevin M

    2011-10-01

    Trichomonas gallinae is a protozoan parasite that is well characterised as a cause of trichomonosis in columbid and raptor species world-wide. The parasite emerged as a novel infection of British passerines in 2005, leading to epidemic mortality associated with significant declines of breeding populations of greenfinches (Carduelis chloris) and chaffinches (Fringilla coelebs). We characterised the extent of T. gallinae genotypic heterogeneity within the affected wild British avifauna by analysing individual isolates from 17 of the species affected. To do so, we employed improved platform-based multilocus typing tools as well as the hydrogenosomal Fe-hydrogenase gene as a single marker locus for fine-typing. We found no evidence of heterogeneity amongst the parasites infecting British passerines, indicating that a clonal strain of T. gallinae is the causative agent of this emerging infectious disease. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Genotype distribution of norovirus around the emergence of Sydney_2012 and the antigenic drift of contemporary GII.4 epidemic strains.

    Science.gov (United States)

    Zhang, Jun; Shen, Zhen; Zhu, Zhaoqin; Zhang, Wanju; Chen, Huifen; Qian, Fangxing; Chen, Haili; Wang, Gang; Wang, Moying; Hu, Yunwen; Yuan, Zhenghong

    2015-11-01

    The pattern of epochal evolution of NoV is ongoing, while novel GII.4 variants emerge and cause new pandemics. Since, the emergence in March 2012, Sydney_2012 had replaced GII.4-2009 as the primary NoV strain in most countries in the northern hemisphere by November 2012. To determine the genotype distribution around the emergence of Sydney_2012 and to investigate the underlying evolution mechanisms of the contemporary GII.4 strains. From January 2012 to December 2013, molecular epidemiology of norovirus in 846 adults (≥16 years) in Shanghai were conducted. The VP1 proteins of the contemporary GII.4 strains (Den_Haag_2006b, New_Orleans_2009 and Sydney_2012) were expressed in vitro and purified. Receptor binding patterns of these three epidemic strains were determined through histo-blood group antigen (HBGA) binding assays. Convalescent serum from patients infected with GII.4 epidemic strains were employed to investigate the role of antigenic drift in the persistence of GII.4 epidemic strains through receptor-binding blockade assays. Epidemiological studies revealed that Sydeny_2012 has completely replaced Den_Haag_2006b and New_Orleans_2009 and has been the dominant circulating strain in Shanghai since its emergence in October 2012. Interestingly, Den_Haag_2006b and New_Orleans_2009 have been co-circulating in Shanghai before the emergence of Sydeny_2012. The contemporary GII.4 epidemic norovirus strains displayed commonly high tropism to the histo-blood group antigen receptors, whereas Sydeny_2012 was antigenically different from Den_Haag_2006b and New_Orleans_2009. Antigenic drift, rather than receptor switch, played a key role in the emergence and spreading of Sydney_2012. The contemporary GII.4 strains were evolving via epochal evolution without altered ligand binding profiles. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Genomic Motifs as a Novel Indicator of the Relationship between Strains Isolated from the Epidemic of Porcine Epidemic Diarrhea in 2013-2014.

    Science.gov (United States)

    Yamamoto, Takehisa; Suzuki, Tohru; Ohashi, Seiichi; Miyazaki, Ayako; Tsutsui, Toshiyuki

    2016-01-01

    Porcine epidemic diarrhea virus (PEDV) is a positive-sense RNA virus that causes infectious gastroenteritis in pigs. Following a PED outbreak that occurred in China in 2010, the disease was identified for the first time in the United States in April 2013, and was reported in many other countries worldwide from 2013 to 2014. As a novel approach to elucidate the epidemiological relationship between PEDV strains, we explored their genome sequences to identify the motifs that were shared within related strains. Of PED outbreaks reported in many countries during 2013-2014, 119 PEDV strains in Japan, USA, Canada, Mexico, Germany, and Korea were selected and used in this study. We developed a motif mining program, which aimed to identify a specific region of the genome that was exclusively shared by a group of PEDV strains. Eight motifs were identified (M1-M8) and they were observed in 41, 9, 18, 6, 10, 14, 2, and 2 strains, respectively. Motifs M1-M6 were shared by strains from more than two countries, and seemed to originate from one PEDV strain, Indiana12.83/USA/2013, among the 119 strains studied. BLAST search for motifs M1-M6 revealed that M3-M5 were almost identical to the strain ZMDZY identified in 2011 in China, while M1 and M2 were similar to other Chinese strains isolated in 2011-2012. Consequently, the PED outbreaks in these six countries may be closely related, and multiple transmissions of PEDV strains between these countries may have occurred during 2013-2014. Although tools such as phylogenetic tree analysis with whole genome sequences are increasingly applied to reveal the connection between isolates, its interpretation is sometimes inconclusive. Application of motifs as a tool to examine the whole genome sequences of causative agents will be more objective and will be an explicit indicator of their relationship.

  7. Genomic Motifs as a Novel Indicator of the Relationship between Strains Isolated from the Epidemic of Porcine Epidemic Diarrhea in 2013-2014.

    Directory of Open Access Journals (Sweden)

    Takehisa Yamamoto

    Full Text Available Porcine epidemic diarrhea virus (PEDV is a positive-sense RNA virus that causes infectious gastroenteritis in pigs. Following a PED outbreak that occurred in China in 2010, the disease was identified for the first time in the United States in April 2013, and was reported in many other countries worldwide from 2013 to 2014. As a novel approach to elucidate the epidemiological relationship between PEDV strains, we explored their genome sequences to identify the motifs that were shared within related strains. Of PED outbreaks reported in many countries during 2013-2014, 119 PEDV strains in Japan, USA, Canada, Mexico, Germany, and Korea were selected and used in this study. We developed a motif mining program, which aimed to identify a specific region of the genome that was exclusively shared by a group of PEDV strains. Eight motifs were identified (M1-M8 and they were observed in 41, 9, 18, 6, 10, 14, 2, and 2 strains, respectively. Motifs M1-M6 were shared by strains from more than two countries, and seemed to originate from one PEDV strain, Indiana12.83/USA/2013, among the 119 strains studied. BLAST search for motifs M1-M6 revealed that M3-M5 were almost identical to the strain ZMDZY identified in 2011 in China, while M1 and M2 were similar to other Chinese strains isolated in 2011-2012. Consequently, the PED outbreaks in these six countries may be closely related, and multiple transmissions of PEDV strains between these countries may have occurred during 2013-2014. Although tools such as phylogenetic tree analysis with whole genome sequences are increasingly applied to reveal the connection between isolates, its interpretation is sometimes inconclusive. Application of motifs as a tool to examine the whole genome sequences of causative agents will be more objective and will be an explicit indicator of their relationship.

  8. Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic.

    NARCIS (Netherlands)

    Garza, D.R.; Thompson, C.C.; Loureiro, E.C.; Dutilh, B.E.; Inada, D.T.; Junior, E.C.; Cardoso, J.F.; Nunes, M.R.; Lima, C.P. de; Silvestre, R.V.; Nunes, K.N.; Santos, E.C.; Edwards, R.A.; Vicente, A.C.; Sa Morais, L.L. de

    2012-01-01

    The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic

  9. Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic.

    Directory of Open Access Journals (Sweden)

    Daniel Rios Garza

    Full Text Available The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic characteristics and the determinants of this altered sucrose fermenting phenotype, the genome of the strain IEC224 was sequenced. This paper reports a broad genomic study of this strain, showing its correlation with the major epidemic lineage. The potentially mobile genomic regions are shown to possess GC content deviation, and harbor the main V. cholera virulence genes. A novel bioinformatic approach was applied in order to identify the putative functions of hypothetical proteins, and was compared with the automatic annotation by RAST. The genome of a large bacteriophage was found to be integrated to the IEC224's alanine aminopeptidase gene. The presence of this phage is shown to be a common characteristic of the El Tor strains from the Latin American epidemic, as well as its putative ancestor from Angola. The defective sucrose fermenting phenotype is shown to be due to a single nucleotide insertion in the V. cholerae sucrose-specific transportation gene. This frame-shift mutation truncated a membrane protein, altering its structural pore-like conformation. Further, the identification of a common bacteriophage reinforces both the monophyletic and African-Origin hypotheses for the main causative agent of the 1991 Latin America cholera epidemics.

  10. [Molecular characterization and phylogenetic analysis of porcine epidemic diarrhea virus field strains in central China during 2010-2012 outbreaks].

    Science.gov (United States)

    Zheng, Feng-Mei; Huo, Jin-Yao; Zhao, Jun; Chang, Hong-Tao; Wang, Xiao-Meng; Chen, Lu; Wang, Chuan-Qing

    2013-03-01

    Since late 2010, porcine epidemic diarrhea virus (PEDV) has been re-emerging in central China. To explore the possible reason of the PEDV outbreaks, twelve PEDV field strains were isolated from different swine breeding farms in central China during 2010-2012, and molecular diversity, phylogenetic relationships of these strains with other PEDV reference strains were investigated. Sequence analysis of S, M and ORE3 genes revealed that the central China PEDV isolates had several specific nucleotides and amino acids which were different from PEDV reference strains. In addition, the entire S genes of eleven central China PEDV isolates were found to be nine nucleotides longer in length than CV777 and large number of amino acid variations was accumulated in the N-terminal region of S gene. Phylogenetic analysis showed that the central China PEDV isolates had close relationship with Korea strains (2007-2009), Thailand strains (2007-2008), Vietnam strains (2009-2010), Japan strains (2010), and other prevailing strains from other parts of China (2010-2012). However, they differed genetically from European strains (CV777, Brl/87), China strains (2003-2007) and the vaccine strains (CV777) used in China. These results imply that a rapid variation and evolution of central China PEDV strains has occurred in recent years, and a more efficient vaccine strain should be selected to prevent and control outbreaks of PEDV in China.

  11. Evidence of circulation of an epidemic strain of Pasteurella multocida in Jiangsu, China by multi-locus sequence typing (MLST).

    Science.gov (United States)

    Wang, Yanhong; Zhu, Jie; Lu, Chengping; Wu, Bai; Liu, Dandan; Hang, Wei; Liu, Huimou; Liu, Xiufan

    2013-12-01

    Pasteurella multocida, the causative agent of fowl cholera, is a serious threat to poultry farming. In this study, we isolated and identified 40 P. multocida strains in fowl cholera outbreaks in Jiangsu province, China. The identified P. multocida was further characterized using multi-locus sequence typing (MLST). All of the 40 P. multocida strains studied are genetically identical and belong to the ST129 sequence type based on seven MLST loci. Our study provides evidence of a circulating epidemic strain of P. multocida in Jiangsu, China. Copyright © 2013. Published by Elsevier B.V.

  12. Analysis of the epidemiological dynamics during the 1982-1983 epidemic of foot-and-mouth disease in Denmark based on molecular high-resolution strain identification

    DEFF Research Database (Denmark)

    Christensen, Laurids Siig; Normann, Preben; Thykier-Nielsen, Søren

    2005-01-01

    An epidemic of foot-and-mouth disease (FMD) causing a total of 23 cases in 1982-1983, primarily on the island of Funen, Denmark, was subjected to molecular epidemiological investigations. In an attempt to exploit the quasi-species nature of foot-and-mouth disease virus strains for molecular high......-resolution strain identification in order to analyse the dynamics of this epidemic, full-length VP1 coding regions were sequenced for 17 isolates collected at different farms during the epidemic. The sequence information together with epidemiological information gathered during the epidemic suggests...

  13. Class 1 Integron-Borne, Multiple-Antibiotic Resistance Encoded by a 150-Kilobase Conjugative Plasmid in Epidemic Vibrio cholerae O1 Strains Isolated in Guinea-Bissau

    OpenAIRE

    Dalsgaard, Anders; Forslund, Anita; Petersen, Andreas; Brown, Derek J.; Dias, Francisco; Monteiro, Serifo; Mølbak, Kåre; Aaby, Peter; Rodrigues, Amabelia; Sandström, Anita

    2000-01-01

    In the 1996–1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality ...

  14. Phylogenetic Analysis of Enterovirus 71 Strains Isolated during Linked Epidemics in Malaysia, Singapore, and Western Australia

    OpenAIRE

    McMinn, Peter; Lindsay, Katie; Perera, David; Chan, Hung Ming; Chan, Kwai Peng; Cardosa, Mary Jane

    2001-01-01

    Enterovirus 71 (EV71) is a frequent cause of hand, foot, and mouth disease (HFMD) epidemics associated with severe neurological sequelae in a small proportion of cases. There has been a significant increase in EV71 epidemic activity throughout the Asia-Pacific region since 1997. Recent HFMD epidemics in this region have been associated with a severe form of brainstem encephalitis associated with pulmonary edema and high case fatality rates. In this study, we show that four genetic lineages of...

  15. Genome sequence of a Lancefield group C Streptococcus zooepidemicus strain causing epidemic nephritis: new information about an old disease.

    Directory of Open Access Journals (Sweden)

    Stephen B Beres

    Full Text Available Outbreaks of disease attributable to human error or natural causes can provide unique opportunities to gain new information about host-pathogen interactions and new leads for pathogenesis research. Poststreptococcal glomerulonephritis (PSGN, a sequela of infection with pathogenic streptococci, is a common cause of preventable kidney disease worldwide. Although PSGN usually occurs after infection with group A streptococci, organisms of Lancefield group C and G also can be responsible. Despite decades of study, the molecular pathogenesis of PSGN is poorly understood. As a first step toward gaining new information about PSGN pathogenesis, we sequenced the genome of Streptococcus equi subsp. zooepidemicus strain MGCS10565, a group C organism that caused a very large and unusually severe epidemic of nephritis in Brazil. The genome is a circular chromosome of 2,024,171 bp. The genome shares extensive gene content, including many virulence factors, with genetically related group A streptococci, but unexpectedly lacks prophages. The genome contains many apparently foreign genes interspersed around the chromosome, consistent with the presence of a full array of genes required for natural competence. An inordinately large family of genes encodes secreted extracellular collagen-like proteins with multiple integrin-binding motifs. The absence of a gene related to speB rules out the long-held belief that streptococcal pyrogenic exotoxin B or antibodies reacting with it singularly cause PSGN. Many proteins previously implicated in GAS PSGN, such as streptokinase, are either highly divergent in strain MGCS10565 or are not more closely related between these species than to orthologs present in other streptococci that do not commonly cause PSGN. Our analysis provides a comparative genomics framework for renewed appraisal of molecular events underlying APSGN pathogenesis.

  16. Genome sequence of a Lancefield group C Streptococcus zooepidemicus strain causing epidemic nephritis: new information about an old disease.

    Science.gov (United States)

    Beres, Stephen B; Sesso, Ricardo; Pinto, Sergio Wyton L; Hoe, Nancy P; Porcella, Stephen F; Deleo, Frank R; Musser, James M

    2008-08-21

    Outbreaks of disease attributable to human error or natural causes can provide unique opportunities to gain new information about host-pathogen interactions and new leads for pathogenesis research. Poststreptococcal glomerulonephritis (PSGN), a sequela of infection with pathogenic streptococci, is a common cause of preventable kidney disease worldwide. Although PSGN usually occurs after infection with group A streptococci, organisms of Lancefield group C and G also can be responsible. Despite decades of study, the molecular pathogenesis of PSGN is poorly understood. As a first step toward gaining new information about PSGN pathogenesis, we sequenced the genome of Streptococcus equi subsp. zooepidemicus strain MGCS10565, a group C organism that caused a very large and unusually severe epidemic of nephritis in Brazil. The genome is a circular chromosome of 2,024,171 bp. The genome shares extensive gene content, including many virulence factors, with genetically related group A streptococci, but unexpectedly lacks prophages. The genome contains many apparently foreign genes interspersed around the chromosome, consistent with the presence of a full array of genes required for natural competence. An inordinately large family of genes encodes secreted extracellular collagen-like proteins with multiple integrin-binding motifs. The absence of a gene related to speB rules out the long-held belief that streptococcal pyrogenic exotoxin B or antibodies reacting with it singularly cause PSGN. Many proteins previously implicated in GAS PSGN, such as streptokinase, are either highly divergent in strain MGCS10565 or are not more closely related between these species than to orthologs present in other streptococci that do not commonly cause PSGN. Our analysis provides a comparative genomics framework for renewed appraisal of molecular events underlying APSGN pathogenesis.

  17. Genome-wide molecular dissection of serotype M3 group A Streptococcus strains causing two epidemics of invasive infections.

    Science.gov (United States)

    Beres, Stephen B; Sylva, Gail L; Sturdevant, Daniel E; Granville, Chanel N; Liu, Mengyao; Ricklefs, Stacy M; Whitney, Adeline R; Parkins, Larye D; Hoe, Nancy P; Adams, Gerald J; Low, Donald E; DeLeo, Frank R; McGeer, Allison; Musser, James M

    2004-08-10

    Molecular factors that contribute to the emergence of new virulent bacterial subclones and epidemics are poorly understood. We hypothesized that analysis of a population-based strain sample of serotype M3 group A Streptococcus (GAS) recovered from patients with invasive infection by using genome-wide investigative methods would provide new insight into this fundamental infectious disease problem. Serotype M3 GAS strains (n = 255) cultured from patients in Ontario, Canada, over 11 years and representing two distinct infection peaks were studied. Genetic diversity was indexed by pulsed-field gel electrophoresis, DNA-DNA microarray, whole-genome PCR scanning, prophage genotyping, targeted gene sequencing, and single-nucleotide polymorphism genotyping. All variation in gene content was attributable to acquisition or loss of prophages, a molecular process that generated unique combinations of proven or putative virulence genes. Distinct serotype M3 genotypes experienced rapid population expansion and caused infections that differed significantly in character and severity. Molecular genetic analysis, combined with immunologic studies, implicated a 4-aa duplication in the extreme N terminus of M protein as a factor contributing to an epidemic wave of serotype M3 invasive infections. This finding has implications for GAS vaccine research. Genome-wide analysis of population-based strain samples cultured from clinically well defined patients is crucial for understanding the molecular events underlying bacterial epidemics.

  18. Rate of torque and electromyographic development during anticipated eccentric contraction is lower in previously strained hamstrings.

    Science.gov (United States)

    Opar, David A; Williams, Morgan D; Timmins, Ryan G; Dear, Nuala M; Shield, Anthony J

    2013-01-01

    The effect of prior strain injury on myoelectrical activity of the hamstrings during tasks requiring high rates of torque development has received little attention. To determine if recreational athletes with a history of unilateral hamstring strain injury will exhibit lower levels of myoelectrical activity during eccentric contraction, rate of torque development (RTD), and impulse (IMP) at 30, 50, and 100 milliseconds after the onset of myoelectrical activity or torque development in the previously injured limb compared with the uninjured limb. Case control study; Level of evidence, 3. Twenty-six recreational athletes were recruited. Of these, 13 athletes had a history of unilateral hamstring strain injury (all confined to biceps femoris long head), and 13 had no history of hamstring strain injury. Following familiarization, all athletes undertook isokinetic dynamometry testing and surface electromyography (integrated EMG; iEMG) assessment of the biceps femoris long head and medial hamstrings during eccentric contractions at -60 and -180 deg·s(-1). In the injured limb of the injured group, compared with the contralateral uninjured limb, RTD and IMP was lower during -60 deg·s(-1) eccentric contractions at 50 milliseconds (RTD: injured limb, 312.27 ± 191.78 N·m·s(-1) vs uninjured limb, 518.54 ± 172.81 N·m·s(-1), P = .008; IMP: injured limb, 0.73 ± 0.30 N·m·s vs uninjured limb, 0.97 ± 0.23 N·m·s, P = .005) and 100 milliseconds (RTD: injured limb, 280.03 ± 131.42 N·m·s(-1) vs uninjured limb, 460.54 ± 152.94 N·m·s(-1), P = .001; IMP: injured limb, 2.15 ± 0.89 N·m·s vs uninjured limb, 3.07 ± 0.63 N·m·s, P contraction. Biceps femoris long head muscle activation was lower at 100 milliseconds at both contraction speeds (-60 deg·s(-1), normalized iEMG activity [×1000]: injured limb, 26.25 ± 10.11 vs uninjured limb, 33.57 ± 8.29, P = .009; -180 deg·s(-1), normalized iEMG activity [×1000]: injured limb, 31.16 ± 10.01 vs uninjured limb, 39.64

  19. [Antibiotic resistance and molecular characterization of Vibrio cholera strains isolated from an outbreak of cholera epidemic in Jiangsu province].

    Science.gov (United States)

    Dong, Chen; Zhang, Xuefeng; Bao, Changjun; Zhu, Yefei; Zhuang, Ling; Tan, Zhongming; Qian, Huimin; Tang, Fenyang

    2015-02-01

    To assess the antibiotic resistance and molecular characterization of cholera strains and to provide basis for clinical treatment and prevention of cholera. 4 stains isolated from an outbreak of cholera epidemic in Huai'an City in Jiangsu province in September 2010 were characterized using antibiotic susceptibility, biotype analysis, virluence genes detection, ctxB gene sequencing, and PFGE analysis. The 4 strains were all resistant to sulphamethoxazole/trimethoprim, erythromycin, streptomycin. High drug susceptibility of the samples was found to 6 kinds of antibiotics such as amikacin, norfloxacin, ciprofloxacin, gentamicin, chloramphenicol, ampicillin. The isolates expressed phenotypic traits of both serogroup O1 ogawa and El Tor and carried 9 kinds of virulence genes, ctxA, ace, zot, toxR, tcpI, ompU, rtxC, tcpA, and hlyA gene. They were also identified as harboring the classical ctxB genotype based on amino acid residue substitutions. The PFGE profiles of NotI showed a single banding pattern, while SfiI's was 2 banding patterns. The bacterium type of Vibrio cholerae causing the epidemic outbreak of cholera belonged to the atypical EL Tor variant which was also identified as toxicogenic strain. The mapping of the strains prompted that there should be the common contamination source. Drug sensitivity test can guide the clinical drug use, in order to reduce the emergence of resistant strains.

  20. Meningococcal factor H binding proteins in epidemic strains from Africa: implications for vaccine development.

    Directory of Open Access Journals (Sweden)

    Rolando Pajon

    2011-09-01

    Full Text Available Factor H binding protein (fHbp is an important antigen for vaccines against meningococcal serogroup B disease. The protein binds human factor H (fH, which enables the bacteria to resist serum bactericidal activity. Little is known about the vaccine-potential of fHbp for control of meningococcal epidemics in Africa, which typically are caused by non-group B strains.We investigated genes encoding fHbp in 106 serogroup A, W-135 and X case isolates from 17 African countries. We determined complement-mediated bactericidal activity of antisera from mice immunized with recombinant fHbp vaccines, or a prototype native outer membrane vesicle (NOMV vaccine from a serogroup B mutant strain with over-expressed fHbp. Eighty-six of the isolates (81% had one of four prevalent fHbp sequence variants, ID 4/5 (serogroup A isolates, 9 (W-135, or 74 (X in variant group 1, or ID 22/23 (W-135 in variant group 2. More than one-third of serogroup A isolates and two-thirds of W-135 isolates tested had low fHbp expression while all X isolates tested had intermediate or high expression. Antisera to the recombinant fHbp vaccines were generally bactericidal only against isolates with fHbp sequence variants that closely matched the respective vaccine ID. Low fHbp expression also contributed to resistance to anti-fHbp bactericidal activity. In contrast to the recombinant vaccines, the NOMV fHbp ID 1 vaccine elicited broad anti-fHbp bactericidal activity, and the antibodies had greater ability to inhibit binding of fH to fHbp than antibodies elicited by the control recombinant fHbp ID 1 vaccine.NOMV vaccines from mutants with increased fHbp expression elicit an antibody repertoire with greater bactericidal activity than recombinant fHbp vaccines. NOMV vaccines are promising for prevention of meningococcal disease in Africa and could be used to supplement coverage conferred by a serogroup A polysaccharide-protein conjugate vaccine recently introduced in some sub

  1. Analysis of the CRISPR-Cas system in bacteriophages active on epidemic strains of Vibrio cholerae in Bangladesh.

    Science.gov (United States)

    Naser, Iftekhar Bin; Hoque, M Mozammel; Nahid, M Ausrafuggaman; Tareq, Tokee M; Rocky, M Kamruzzaman; Faruque, Shah M

    2017-11-01

    CRISPR-Cas (clustered regularly interspersed short palindromic repeats-CRISPR-associated proteins) are microbial nuclease systems involved in defense against phages. Bacteria also resist phages by hosting phage-inducible chromosomal islands (PICI) which prevent phage reproduction. Vibrio cholerae which causes cholera epidemics, interacts with numerous phages in the environment and in cholera patients. Although CRISPR-Cas systems are usually carried by bacteria and archea, recently V. cholerae specific ICP1 phages were found to host a CRISPR-Cas system that inactivates PICI-like elements (PLE) in V. cholerae. We analyzed a collection of phages and V. cholerae isolated during seasonal cholera epidemics in Bangladesh, to study the distribution, and recent evolution of the phage-encoded CRISPR-Cas system. Five distinct but related phages carrying the CRISPR-Cas system, and possible CRISPR-Cas negative progenitor phages were identified. Furthermore, CRISPR arrays in the phages were found to have evolved by acquisition of new spacers targeting diverse regions of PLEs carried by the V. cholerae strains, enabling the phages to efficiently grow on PLE positive strains. Our results demonstrate a continuing arms-race involving genetic determinants of phage-resistance in V. cholerae, and the phage-encoded CRISPR-Cas system in the co-evolution of V. cholerae and its phages, presumably fostered by their enhanced interactions during seasonal epidemics of cholera.

  2. Experimental Infection of Young Pigs with an Early European Strain of Porcine Epidemic Diarrhoea Virus and a Recent US Strain

    DEFF Research Database (Denmark)

    Lohse, Louise; Krog, Jesper Schak; Strandbygaard, Bertel

    2017-01-01

    Outbreaks of porcine epidemic diarrhoea (PED) were reported across Europe during the 1980s and 1990s, but only sporadic outbreaks occurred in recent years. PED virus (PEDV) spread for the first time into the USA in 2013 and has caused severe economic losses. Retrospectively, it was found that two...

  3. Phenotypic, Genotypic, and Antibiotic Sensitivity Patterns of Strains Isolated from the Cholera Epidemic in Zimbabwe

    NARCIS (Netherlands)

    Islam, Mohammad S.; Mahmud, Zahid H.; Ansaruzzaman, Mohammad; Faruque, Shah M.; Talukder, Kaisar A.; Qadri, Firdausi; Alam, Munirul; Islam, Shafiqul; Bardhan, Pradip K.; Mazumder, Ramendra N.; Khan, Azharul I.; Ahmed, Sirajuddin; Iqbal, Anwarul; Chitsatso, Owen; Mudzori, James; Patel, Sheetal; Midzi, Stanley M.; Charimari, Lincoln; Endtz, Hubert P.; Cravioto, Alejandro

    This paper details the phenotypic, genotypic, and antibiotic sensitivity patterns of 88 Vibrio cholerae strains from Zimbabwe. Of the 88 strains, 83 were classified as "altered El Tor" and 5 as "hybrid El Tor" strains. All of the strains were susceptible to tetracycline, doxycycline, ciprofloxacin,

  4. Cell culture isolation and sequence analysis of genetically diverse US porcine epidemic diarrhea virus strains including a novel strain with a large deletion in the spike gene.

    Science.gov (United States)

    Oka, Tomoichiro; Saif, Linda J; Marthaler, Douglas; Esseili, Malak A; Meulia, Tea; Lin, Chun-Ming; Vlasova, Anastasia N; Jung, Kwonil; Zhang, Yan; Wang, Qiuhong

    2014-10-10

    The highly contagious and deadly porcine epidemic diarrhea virus (PEDV) first appeared in the US in April 2013. Since then the virus has spread rapidly nationwide and to Canada and Mexico causing high mortality among nursing piglets and significant economic losses. Currently there are no efficacious preventive measures or therapeutic tools to control PEDV in the US. The isolation of PEDV in cell culture is the first step toward the development of an attenuated vaccine, to study the biology of PEDV and to develop in vitro PEDV immunoassays, inactivation assays and screen for PEDV antivirals. In this study, nine of 88 US PEDV strains were isolated successfully on Vero cells with supplemental trypsin and subjected to genomic sequence analysis. They differed genetically mainly in the N-terminal S protein region as follows: (1) strains (n=7) similar to the highly virulent US PEDV strains; (2) one similar to the reportedly US S INDEL PEDV strain; and (3) one novel strain most closely related to highly virulent US PEDV strains, but with a large (197aa) deletion in the S protein. Representative strains of these three genetic groups were passaged serially and grew to titers of ∼5-6log10 plaque forming units/mL. To our knowledge, this is the first report of the isolation in cell culture of an S INDEL PEDV strain and a PEDV strain with a large (197aa) deletion in the S protein. We also designed primer sets to detect these genetically diverse US PEDV strains. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Identification of resistance and virulence factors in an epidemic Enterobacter hormaechei outbreak strain

    NARCIS (Netherlands)

    Paauw, A.; Caspers, M.P.M.; Leverstein-van Hall, M.A.; Schuren, F.H.J.; Montijn, R.C.; Verhoef, J.; Fluit, A.C.

    2009-01-01

    Bacterial strains differ in their ability to cause hospital outbreaks. Using comparative genomic hybridization, Enterobacter cloacae complex isolates were studied to identify genetic markers specific for Enterobacter cloacae complex outbreak strains. No outbreak-specific genes were found that were

  6. Zika virus infection in Vietnam: current epidemic, strain origin, spreading risk, and perspective.

    Science.gov (United States)

    Chu, Dinh-Toi; Ngoc, Vo Truong Nhu; Tao, Yang

    2017-11-01

    Zika virus infection and its associated microcephaly have being receiving global concern. This infection has spread widely since the first outbreak was recorded in Africa in 1952. Now, it has been reported in over 70 countries on five continents including Africa, North and South America, Asia, and Europe. Vietnam is one of the most recent countries which had cases of Zika virus infection at the end of 2016. This country has also reported the first case of a microcephaly-born baby which was probably linked to Zika virus infection. However, information on the Zika virus epidemic in Vietnam is still limited. This brief report intends to update the current Zika virus epidemic, and to discuss challenges and perspectives in controlling this infection in Vietnam.

  7. Two different dengue virus strains in the Japanese epidemics of 2014.

    Science.gov (United States)

    Nakayama, Eri; Kotaki, Akira; Tajima, Shigeru; Kawada, Miki; Miura, Kuniharu; Gemma, Aki; Adachi, Takuya; Sekizuka, Tsuyoshi; Kato, Kengo; Yamashita, Akifumi; Moi, Meng Ling; Ikeda, Makiko; Yagasaki, Kazumi; Shibasaki, Kenichi; Saijo, Masayuki; Kuroda, Makoto; Takasaki, Tomohiko

    2016-10-01

    In late August 2014, dengue cases were reported in Japan, and a total of 162 cases were confirmed. In the present study, the envelope (E) gene sequences of 12 specimens from the dengue patients were determined. A dengue virus serotype 1 (DENV1) strain (D1/Hu/Shizuoka/NIID181/2014), which was clearly different from the first reported strain (D1/Hu/Saitama/NIID100/2014), was identified, although the other 11 specimens showed the same nucleotide sequences as D1/Hu/Saitama/NIID100/2014. The E gene sequences of two different strains were compared with those of nine DENV1 strains of imported cases in Japan in 2014. Phylogenetic analysis based on the E gene sequences showed that the D1/Hu/Saitama/NIID100/2014 strain was closely related to a strain isolated from an imported case from Singapore. Although no strain closely related to D1/Hu/Shizuoka/NIID181/2014 was found in these imported strains, the strain was closely related to isolates in Thailand and Taiwan in 2009. These data indicate that the dengue cases in Japan were caused by two different dengue virus strains that entered Japan through different means.

  8. Global analysis of multi-strains SIS, SIR and MSIR epidemic models

    OpenAIRE

    Bichara , Derdei; Iggidr , Abderrahman; Sallet , Gauthier

    2014-01-01

    International audience; We consider SIS, SIR and MSIR models with standard mass action and varying population, with $n$ different pathogen strains of an infectious disease. We also consider the same models with vertical transmission. We prove that under generic conditions a competitive exclusion principle holds. To each strain a basic reproduction ratio can be associated. It corresponds to the case where only this strain exists. The basic reproduction ratio of the complete system is the maxim...

  9. Increased survival and proliferation of the epidemic strain Mycobacterium abscessus subsp. massiliense CRM0019 in alveolar epithelial cells.

    Science.gov (United States)

    Ribeiro, Giovanni Monteiro; Matsumoto, Cristianne Kayoko; Real, Fernando; Teixeira, Daniela; Duarte, Rafael Silva; Mortara, Renato Arruda; Leão, Sylvia Cardoso; de Souza Carvalho-Wodarz, Cristiane

    2017-09-13

    Outbreaks of infections caused by rapidly growing mycobacteria have been reported worldwide generally associated with medical procedures. Mycobacterium abscessus subsp. massiliense CRM0019 was obtained during an epidemic of postsurgical infections and was characterized by increased persistence in vivo. To better understand the successful survival strategies of this microorganism, we evaluated its infectivity and proliferation in macrophages (RAW and BMDM) and alveolar epithelial cells (A549). For that, we assessed the following parameters, for both M. abscessus CRM0019 as well as the reference strain M. abscessus ATCC 19977: internalization, intracellular survival for up 3 days, competence to subvert lysosome fusion and the intracellular survival after cell reinfection. CRM0019 and ATCC 19977 strains showed the same internalization rate (approximately 30% after 6 h infection), in both A549 and RAW cells. However, colony forming units data showed that CRM0019 survived better in A549 cells than the ATCC 19977 strain. Phagosomal characteristics of CRM0019 showed the bacteria inside tight phagosomes in A549 cells, contrasting to the loosely phagosomal membrane in macrophages. This observation holds for the ATCC 19977 strain in both cell types. The competence to subvert lysosome fusion was assessed by acidification and acquisition of lysosomal protein. For M. abscessus strains the phagosomes were acidified in all cell lines; nevertheless, the acquisition of lysosomal protein was reduced by CRM0019 compared to the ATCC 19977 strain, in A549 cells. Conversely, in macrophages, both M. abscessus strains were located in mature phagosomes, however without bacterial death. Once recovered from macrophages M. abscessus could establish a new intracellular infection. Nevertheless, only CRM0019 showed a higher growth rate in A549, increasing nearly 10-fold after 48 and 72 h. M. abscessus CRM0019 creates a protective and replicative niche in alveolar epithelial cells mainly by

  10. Identification and Comparison of Receptor Binding Characteristics of the Spike Protein of Two Porcine Epidemic Diarrhea Virus Strains

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    Feng Deng

    2016-02-01

    Full Text Available Porcine epidemic diarrhea virus (PEDV, a member of Alphacoronavirus, has caused huge economic losses for the global pork industry recently. The spike (S protein mediates PEDV entry into host cells. Herein, we investigated the interactions between the S protein and its receptor porcine aminopeptidase N (pAPN or co-receptor sugars. The C-terminal domain (CTD of the S1 domain is bound to pAPN. The prototype strain demonstrated similar receptor-binding activity compared with the variant field isolate. Three loops at the tips of the β-barrel domains did not play crucial roles in the PEDV S-pAPN association, indicating that PEDV conforms to a different receptor recognition model compared with transmissible gastroenteritis virus (TGEV, porcine respiratory CoV (PRCV, and human coronavirus NL63 (HCoV-NL63. The N-terminal domain (NTD of the PEDV S1 domain could bind sugar, a possible co-receptor for PEDV. The prototype strain exhibited weaker sugar-binding activity compared with the variant field isolate. Strategies targeting the receptor binding domain (RBD may be helpful for developing vaccines or antiviral drugs for PEDV. Understanding the differences in receptor binding between the prototype and the variant strains may provide insight into PEDV pathogenesis.

  11. Homogentisate 1-2-Dioxygenase Downregulation in the Chronic Persistence of Pseudomonas aeruginosa Australian Epidemic Strain-1 in the CF Lung.

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    Christopher J Harmer

    Full Text Available Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01 cause persistent chronic infection in cystic fibrosis (CF patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic and artificial sputum medium (mainly hypoxic. Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R against its chronic isogen (AES-1M, isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was homogentisate-1-2-dioxygenase (hmgA; an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p<0.0001, sustained even with no detectable bacteria. PA14ΔhmgA did not show increased TNF-α. This study suggests that hmgA may have a role in P. aeruginosa persistence in chronic infection and the results provide a starting point for clarifying the role of hmgA in chronic AES-1.

  12. Full-length genome sequences of porcine epidemic diarrhoea virus strain CV777; Use of NGS to analyse genomic and sub-genomic RNAs

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Bruun; Boniotti, Maria Beatrice; Papetti, Alice

    2018-01-01

    Porcine epidemic diarrhoea virus, strain CV777, was initially characterized in 1978 as the causative agent of a disease first identified in the UK in 1971. This coronavirus has been widely distributed among laboratories and has been passaged both within pigs and in cell culture. To determine...

  13. Survival of epidemic strains of nosocomial- and community-acquired methicillin-resistant Staphylococcus aureus on coins.

    Science.gov (United States)

    Tolba, Ola; Loughrey, Anne; Goldsmith, Colin E; Millar, B Cherie; Rooney, Paul J; Moore, John E

    2007-06-01

    The aim of this study was to examine the survival dynamics of several epidemic nosocomial and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains on copper alloy coins. Six different phage types of nosocomial MRSA (Irish 1, Irish 2, EMRSA 15, EMRSA 16, distinct type, and untypeable), as well as community-acquired MRSA, were examined in this study. Two isolates of each type were studied, resulting in a total of 14 organisms being examined. Cells were harvested from overnight cultures of Columbia blood agar (Oxoid) supplemented with 5% (wt/vol) defibrinated blood to make a 0.5 McFarland inoculum standard. An inoculum of each MRSA isolate in 5-microl volume was added to washed, dried, and presterilized 1-penny copper-plated steel coins, equating to log(10) 5 colony-forming units (cfu) and allowed to dry naturally at ambient temperatures in the dark. Recovery experiments were unable to isolate any of the inoculated organisms 4 hours postinoculation. To ascertain whether this was a toxic effect from the copper alloy of the coins or a physical desiccation effect, experiments were repeated on glass and plastic, and similar results were demonstrated. The effect of soil was investigated by repeating the experiment with (60)Co irradiated pus and sterile blood, and we were able to demonstrate the survival of all organisms after at least 2 weeks storage in the dark at ambient temperature, during which the quantitative counts were reduced by approximately 1-log unit and 2-log units for blood and pus, respectively. This study demonstrates that all epidemic nosocomial- and community-acquired MRSA do not survive when no organic protection is offered but survive well when soil (pus and blood) is present, thus offering protection from drying. This study indicates that contaminated coins may serve as potential vehicles for MRSA.

  14. Comparative genomics of isolates of a Pseudomonas aeruginosa epidemic strain associated with chronic lung infections of cystic fibrosis patients.

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    Julie Jeukens

    Full Text Available Pseudomonas aeruginosa is the main cause of fatal chronic lung infections among individuals suffering from cystic fibrosis (CF. During the past 15 years, particularly aggressive strains transmitted among CF patients have been identified, initially in Europe and more recently in Canada. The aim of this study was to generate high-quality genome sequences for 7 isolates of the Liverpool epidemic strain (LES from the United Kingdom and Canada representing different virulence characteristics in order to: (1 associate comparative genomics results with virulence factor variability and (2 identify genomic and/or phenotypic divergence between the two geographical locations. We performed phenotypic characterization of pyoverdine, pyocyanin, motility, biofilm formation, and proteolytic activity. We also assessed the degree of virulence using the Dictyostelium discoideum amoeba model. Comparative genomics analysis revealed at least one large deletion (40-50 kb in 6 out of the 7 isolates compared to the reference genome of LESB58. These deletions correspond to prophages, which are known to increase the competitiveness of LESB58 in chronic lung infection. We also identified 308 non-synonymous polymorphisms, of which 28 were associated with virulence determinants and 52 with regulatory proteins. At the phenotypic level, isolates showed extensive variability in production of pyocyanin, pyoverdine, proteases and biofilm as well as in swimming motility, while being predominantly avirulent in the amoeba model. Isolates from the two continents were phylogenetically and phenotypically undistinguishable. Most regulatory mutations were isolate-specific and 29% of them were predicted to have high functional impact. Therefore, polymorphism in regulatory genes is likely to be an important basis for phenotypic diversity among LES isolates, which in turn might contribute to this strain's adaptability to varying conditions in the CF lung.

  15. Class 1 Integron-Borne, Multiple-Antibiotic Resistance Encoded by a 150-Kilobase Conjugative Plasmid in Epidemic Vibrio cholerae O1 Strains Isolated in Guinea-Bissau

    Science.gov (United States)

    Dalsgaard, Anders; Forslund, Anita; Petersen, Andreas; Brown, Derek J.; Dias, Francisco; Monteiro, Serifo; Mølbak, Kåre; Aaby, Peter; Rodrigues, Amabelia; Sandström, Anita

    2000-01-01

    In the 1996–1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality rate from 1.0% before the emergence of the multiple-drug-resistant strain to 5.3% after the emergence of the strain. Our study shows that the strain contained a 150-kb conjugative multiple-antibiotic resistance plasmid with class 1 integron-borne gene cassettes encoding resistance to trimethoprim (dhfrXII) and aminoglycosides [ant(3")-1a]). The finding of transferable resistance to almost all of the antibiotics commonly used to treat cholera is of great public health concern. Studies should be carried out to determine to what extent the strain or its resistance genes have been spread to other areas where cholera is endemic. PMID:11015401

  16. Rapid tests for the detection of the Mycobacterium abscessus subsp. bolletii strain responsible for an epidemic of surgical-site infections in Brazil

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    Cristianne Kayoko Matsumoto

    2012-12-01

    Full Text Available A single strain of Mycobacterium abscessus subsp. bolletii, characterised by a particular rpoB sequevar and two highly related pulsed field gel electrophoresis patterns has been responsible for a nationwide outbreak of surgical infections in Brazil since 2004. In this study, we developed molecular tests based on polymerase chain reaction restriction-enzyme analysis (PRA and sequencing for the rapid identification of this strain. Sequences of 15 DNA regions conserved in mycobacteria were retrieved from GenBank or sequenced and analysed in silico. Single nucleotide polymorphisms specific to the epidemic strain and located in enzyme recognition sites were detected in rpoB, the 3' region of the 16S rDNA and gyrB. The three tests that were developed, i.e., PRA-rpoB, PRA-16S and gyrB sequence analysis, showed 100%, 100% and 92.31% sensitivity and 93.06%, 90.28% and 100% specificity, respectively, for the discrimination of the surgical strain from other M. abscessus subsp. bolletii isolates, including 116 isolates from 95 patients, one environmental isolate and two type strains. The results of the three tests were stable, as shown by results obtained for different isolates from the same patient. In conclusion, due to the clinical and epidemiological importance of this strain, these tests could be implemented in reference laboratories for the rapid preliminary diagnosis and epidemiological surveillance of this epidemic strain.

  17. Comparative Genomics of Isolates of a Pseudomonas aeruginosa Epidemic Strain Associated with Chronic Lung Infections of Cystic Fibrosis Patients

    Science.gov (United States)

    Jeukens, Julie; Boyle, Brian; Kukavica-Ibrulj, Irena; Ouellet, Myriam M.; Aaron, Shawn D.; Charette, Steve J.; Fothergill, Joanne L.; Tucker, Nicholas P.; Winstanley, Craig; Levesque, Roger C.

    2014-01-01

    Pseudomonas aeruginosa is the main cause of fatal chronic lung infections among individuals suffering from cystic fibrosis (CF). During the past 15 years, particularly aggressive strains transmitted among CF patients have been identified, initially in Europe and more recently in Canada. The aim of this study was to generate high-quality genome sequences for 7 isolates of the Liverpool epidemic strain (LES) from the United Kingdom and Canada representing different virulence characteristics in order to: (1) associate comparative genomics results with virulence factor variability and (2) identify genomic and/or phenotypic divergence between the two geographical locations. We performed phenotypic characterization of pyoverdine, pyocyanin, motility, biofilm formation, and proteolytic activity. We also assessed the degree of virulence using the Dictyostelium discoideum amoeba model. Comparative genomics analysis revealed at least one large deletion (40–50 kb) in 6 out of the 7 isolates compared to the reference genome of LESB58. These deletions correspond to prophages, which are known to increase the competitiveness of LESB58 in chronic lung infection. We also identified 308 non-synonymous polymorphisms, of which 28 were associated with virulence determinants and 52 with regulatory proteins. At the phenotypic level, isolates showed extensive variability in production of pyocyanin, pyoverdine, proteases and biofilm as well as in swimming motility, while being predominantly avirulent in the amoeba model. Isolates from the two continents were phylogenetically and phenotypically undistinguishable. Most regulatory mutations were isolate-specific and 29% of them were predicted to have high functional impact. Therefore, polymorphism in regulatory genes is likely to be an important basis for phenotypic diversity among LES isolates, which in turn might contribute to this strain’s adaptability to varying conditions in the CF lung. PMID:24505294

  18. New emerging recombinant HIV-1 strains and close transmission linkage of HIV-1 strains in the Chinese MSM population indicate a new epidemic risk.

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    Jianjun Wu

    Full Text Available In recent years, the population of men who have sex with men (MSM have become the most significant increasing group of HIV-1 transmission in China. To identify new recombinant strains and transmission patterns of HIV-1 in Chinese MSM population, a cross-sectional investigation of MSM in Anhui Province (in south-eastern China was performed in 2011. The diagnosed AIDS case rate, CD4 T-cell counts, HIV subtypes, and origin of the recombinant strains were investigated in 138 collected samples. The phylogenetic and bootscan analyses demonstrated that, apart from three previously reported circulating strains (CRF07_BC, CRF01_AE, subtype B, various recombinant strains among subtype B, subtype C, CRF01_AE, and CRF07_BC were simultaneously identified in Chinese MSM for the first time. The introducing time of B subtype in Chinese MSM populations was estimated in 1985, CRF01_AE in 2000, and CRF07_BC in 2003; the latter two account for more than 85% of MSM infections. Notably, in comparison with B subtype infections in Anhui MSM, CRF01_AE, with the highest prevalence rate, may accelerate AIDS progression. Over half of patients (56% infected with new recombinant strains infection are diagnosed as progression into AIDS. Both Bayes and phylogenetic analyses indicated that there was active HIV transmission among MSM nationwide, which may facilitate the transmission of the new 01B recombinant strains in MSM. In conclusion, new recombinant strains and active transmission were identified in the Chinese MSM population, which may lead to a new alarming HIV pandemic in this population due to the increased pathogenesis of the newly emerging strains.

  19. Fluoroquinolone and Macrolide Exposure Predict Clostridium difficile Infection with the Highly Fluoroquinolone- and Macrolide-Resistant Epidemic C. difficile Strain BI/NAP1/027.

    Science.gov (United States)

    Wieczorkiewicz, Jeffrey T; Lopansri, Bert K; Cheknis, Adam; Osmolski, James R; Hecht, David W; Gerding, Dale N; Johnson, Stuart

    2016-01-01

    Antibiotics have been shown to influence the risk of infection with specific Clostridium difficile strains as well as the risk of C. difficile infection (CDI). We performed a retrospective case-control study of patients infected with the epidemic BI/NAP1/027 strain in a U.S. hospital following recognition of increased CDI severity and culture of stools positive by C. difficile toxin immunoassay. Between 2005 and 2007, 72% (103/143) of patients with first-episode CDIs were infected with the BI strain by restriction endonuclease analysis (REA) typing. Most patients received multiple antibiotics within 6 weeks of CDI onset (median of 3 antibiotic classes). By multivariate analysis, fluoroquinolone and macrolide exposure was more frequent among BI cases than among non-BI-infected controls (odds ratio [OR] for fluoroquinolones, 3.2; 95% confidence interval [CI], 1.3 to 7.5; (P Fluoroquinolone use, macrolide use, and C. difficile resistance to these antibiotic classes were associated with infection by the epidemic BI strain of C. difficile in a U.S. hospital during a time when CDI rates were increasing nationally due to the highly fluoroquinolone-resistant BI/NAP1/027 strain. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  20. Resistance to antimicrobial agents of Vibrio cholerae El Tor strains isolated during the fourth cholera epidemic in the United Republic of Tanzania

    Science.gov (United States)

    Towner, K. J.; Pearson, N. J.; Mhalu, F. S.; O'Grady, F.

    1980-01-01

    Isolates of Vibrio cholerae obtained immediately after the outbreak of the fourth recorded epidemic of cholera in the United Republic of Tanzania were sensitive to tetracycline, but after five months of its extensive therapeutic and prophylactic use, 76% of the isolates were observed to be resistant to this and other antimicrobial agents. The appearance of resistance was found to be due to the rapid spread of antibiotic resistance plasmids belonging to the C incompatibility complex. Although most plasmid incompatibility groups have been shown to be unstable in V. cholerae, the strains found in the present epidemic seem to carry a plasmid belonging to one of the few relatively stable groups. These findings emphasize the importance of monitoring any emergence of bacterial resistance that may occur when mass prophylaxis programmes are in operation and also the importance of determining the genetic basis of the resistance mechanism. PMID:6975183

  1. Effect of challenge of pigs previously immunised with inactivated vaccines containing homologous and heterologous Mycoplasma hyopneumoniae strains

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    Villarreal Iris

    2012-01-01

    Full Text Available Abstract Background Mycoplasma hyopneumoniae is the primary cause of enzootic pneumonia in pigs. Although vaccination is an important control tool, the results observed under field conditions are variable. This may be due to antigenic differences between the strains circulating in pig herds and the vaccine strain. This study compared the protective efficacy of four bacterins against challenge infection with a highly virulent field strain of M. hyopneumoniae. Seventy eight, one-week old piglets were randomly assigned to five treatment groups (A, B, C, D, E, 14 piglets each, and a negative control group (F consisting of 8 piglets. All pigs were injected at 1 (D7 and 4 weeks of age (D28, with 2 ml of either a placebo or a bacterin based on selected M. hyopneumoniae strains, namely A (F7.2C, B (F20.1L, C (B2V1W20 1A-F, D (J strain, E (placebo; positive control, F (placebo; negative control. At D56, all pigs except those of group F were challenged intratracheally with 7 ml culture medium containing 107 CCU/ml of M. hyopneumoniae strain F7.2C. All pigs were euthanized and necropsied at D84. The severity of coughing and pneumonia lesions were the main parameters. Immunofluorescence (IF testing, nested PCR testing of bronchoalveolar lavage (BAL fluid and serology for M. hyopneumoniae were also performed. Results The different bacterins only slightly improved clinical symptoms (average 0.38 in vaccinated groups vs. 0.45 in group E and histopathological lung lesions (average 3.20 in vaccinated groups vs. 3.45 in group E, but did not improve macroscopic lung lesions (score 4.30 vs. 4.03 in group E. None of the vaccines was significantly and/or consistently better or worse than the other ones. All bacterins evoked a serological response in the vaccinated animals. All pigs, except those from group F, were positive with nPCR in BAL fluid at D84. Conclusion The bacterins did not induce a clear overall protection against challenge infection, and there were no

  2. Effect of challenge of pigs previously immunised with inactivated vaccines containing homologous and heterologous Mycoplasma hyopneumoniae strains.

    Science.gov (United States)

    Villarreal, Iris; Vranckx, Katleen; Calus, Dries; Pasmans, Frank; Haesebrouck, Freddy; Maes, Dominiek

    2012-01-06

    Mycoplasma hyopneumoniae is the primary cause of enzootic pneumonia in pigs. Although vaccination is an important control tool, the results observed under field conditions are variable. This may be due to antigenic differences between the strains circulating in pig herds and the vaccine strain. This study compared the protective efficacy of four bacterins against challenge infection with a highly virulent field strain of M. hyopneumoniae. Seventy eight, one-week old piglets were randomly assigned to five treatment groups (A, B, C, D, E), 14 piglets each, and a negative control group (F) consisting of 8 piglets. All pigs were injected at 1 (D7) and 4 weeks of age (D28), with 2 ml of either a placebo or a bacterin based on selected M. hyopneumoniae strains, namely A (F7.2C), B (F20.1L), C (B2V1W20 1A-F), D (J strain), E (placebo; positive control), F (placebo; negative control). At D56, all pigs except those of group F were challenged intratracheally with 7 ml culture medium containing 107 CCU/ml of M. hyopneumoniae strain F7.2C. All pigs were euthanized and necropsied at D84. The severity of coughing and pneumonia lesions were the main parameters. Immunofluorescence (IF) testing, nested PCR testing of bronchoalveolar lavage (BAL) fluid and serology for M. hyopneumoniae were also performed. The different bacterins only slightly improved clinical symptoms (average 0.38 in vaccinated groups vs. 0.45 in group E) and histopathological lung lesions (average 3.20 in vaccinated groups vs. 3.45 in group E), but did not improve macroscopic lung lesions (score 4.30 vs. 4.03 in group E). None of the vaccines was significantly and/or consistently better or worse than the other ones. All bacterins evoked a serological response in the vaccinated animals. All pigs, except those from group F, were positive with nPCR in BAL fluid at D84. The bacterins did not induce a clear overall protection against challenge infection, and there were no significant differences in protective

  3. Distribution of sasX, pvl, and qacA/B genes in epidemic methicillin-resistant Staphylococcus aureus strains isolated from East China

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    Kong H

    2018-01-01

    Full Text Available Haishen Kong,1,2 Lingmei Fang,3 Rujin Jiang,4 Jixiang Tong2 1State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; 2Key Laboratory of Clinical In Vitro Diagnostic Techniques of Zhejiang Province, Department of Laboratory Medicine, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; 3Clinical Laboratory, Chunan First People’s Hospital, Zhejiang Province People’s Hospital Chunan Branch, Hangzhou, China; 4Clinical Laboratory, Yuhang Hospital of Traditional Chinese Medicine, Hangzhou, China Background: Methicillin-resistant Staphylococcus aureus (MRSA is a major nosocomial pathogen. Various virulence and antiseptic-resistant factors increase the pathogenicity of MRSA strains and allow for increased infection rates.Purpose: The purpose of this study was to investigate the prevalence and distribution of virulence-associated and antiseptic-resistant genes from epidemic MRSA strains isolated from East China.Methods: A newly designed multiplex PCR assay was used to assess whether the virulence-associated genes sasX and pvl and the chlorhexidine tolerance gene qacA/B were present in 189 clinical isolates of MRSA. Multilocus sequence typing (MLST and Staphylococcal protein A (spa typing of these isolates were also performed. The frequency of these genes in isolates with epidemic sequence types (STs was investigated. Results: Twenty STs and 36 spa types with five epidemic clones (ST5-t311, ST59-t437, ST5-t002, ST239-t030, and ST239-t037 were identified. The prevalence of sasX, pvl, and qacA/B in all isolates was 5.8%, 10.1%, and 20.1%, respectively. The prevalences of these genes in isolates with ST5, ST59, ST239, and other ST genetic backgrounds were all significantly different (P<0.001. Isolates that had the highest frequency of sas

  4. Variability of the protein sequences of lcrV between epidemic and atypical rhamnose-positive strains of Yersinia pestis.

    Science.gov (United States)

    Anisimov, Andrey P; Panfertsev, Evgeniy A; Svetoch, Tat'yana E; Dentovskaya, Svetlana V

    2007-01-01

    Sequencing of lcrV genes and comparison of the deduced amino acid sequences from ten Y. pestis strains belonging mostly to the group of atypical rhamnose-positive isolates (non-pestis subspecies or pestoides group) showed that the LcrV proteins analyzed could be classified into five sequence types. This classification was based on major amino acid polymorphisms among LcrV proteins in the four "hot points" of the protein sequences. Some additional minor polymorphisms were found throughout these sequence types. The "hot points" corresponded to amino acids 18 (Lys --> Asn), 72 (Lys --> Arg), 273 (Cys --> Ser), and 324-326 (Ser-Gly-Lys --> Arg) in the LcrV sequence of the reference Y. pestis strain CO92. One possible explanation for polymorphism in amino acid sequences of LcrV among different strains is that strain-specific variation resulted from adaptation of the plague pathogen to different rodent and lagomorph hosts.

  5. The HIV-1 epidemic in Bolivia is dominated by subtype B and CRF12_BF "family" strains

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    Guimarães Monick L

    2012-01-01

    Full Text Available Abstract Background Molecular epidemiological studies of HIV-1 in South America have revealed the occurrence of subtypes B, F1 and BF1 recombinants. Even so, little information concerning the HIV-1 molecular epidemiology in Bolivia is available. In this study we performed phylogenetic analyses from samples collected in Bolivia at two different points in time over a 10 year span. We analyzed these samples to estimate the trends in the HIV subtype and recombinant forms over time. Materials and methods Fifty one HIV-1 positive samples were collected in Bolivia over two distinct periods (1996 and 2005. These samples were genetically characterized based on partial pol protease/reverse transcriptase (pr/rt and env regions. Alignment and neighbor-joining (NJ phylogenetic analyses were established from partial env (n = 37 and all pol sequences using Mega 4. The remaining 14 env sequences from 1996 were previously characterized based on HMA-env (Heteroduplex mobility assay. The Simplot v.3.5.1 program was used to verify intragenic recombination, and SplitsTree 4.0 was employed to confirm the phylogenetic relationship of the BF1 recombinant samples. Results Phylogenetic analysis of both env and pol regions confirmed the predominance of "pure" subtype B (72.5% samples circulating in Bolivia and revealed a high prevalence of BF1 genotypes (27.5%. Eleven out of 14 BF1 recombinants displayed a mosaic structure identical or similar to that described for the CRF12_BF variant, one sample was classified as CRF17_BF, and two others were F1pol/Benv. No "pure" HIV-1 subtype F1 or B" variant of subtype B was detected in the present study. Of note, samples characterized as CRF12_BF-related were depicted only in 2005. Conclusion HIV-1 genetic diversity in Bolivia is mostly driven by subtype B followed by BF1 recombinant strains from the CRF12_BF "family". No significant temporal changes were detected between the mid-1990s and the mid-2000s for subtype B (76.2% vs 70

  6. The HIV-1 epidemic in Bolivia is dominated by subtype B and CRF12_BF "family" strains.

    Science.gov (United States)

    Guimarães, Monick L; Velarde-Dunois, Ketty G; Segurondo, David; Morgado, Mariza G

    2012-01-16

    Molecular epidemiological studies of HIV-1 in South America have revealed the occurrence of subtypes B, F1 and BF1 recombinants. Even so, little information concerning the HIV-1 molecular epidemiology in Bolivia is available. In this study we performed phylogenetic analyses from samples collected in Bolivia at two different points in time over a 10 year span. We analyzed these samples to estimate the trends in the HIV subtype and recombinant forms over time. Fifty one HIV-1 positive samples were collected in Bolivia over two distinct periods (1996 and 2005). These samples were genetically characterized based on partial pol protease/reverse transcriptase (pr/rt) and env regions. Alignment and neighbor-joining (NJ) phylogenetic analyses were established from partial env (n = 37) and all pol sequences using Mega 4. The remaining 14 env sequences from 1996 were previously characterized based on HMA-env (Heteroduplex mobility assay). The Simplot v.3.5.1 program was used to verify intragenic recombination, and SplitsTree 4.0 was employed to confirm the phylogenetic relationship of the BF1 recombinant samples. Phylogenetic analysis of both env and pol regions confirmed the predominance of "pure" subtype B (72.5%) samples circulating in Bolivia and revealed a high prevalence of BF1 genotypes (27.5%). Eleven out of 14 BF1 recombinants displayed a mosaic structure identical or similar to that described for the CRF12_BF variant, one sample was classified as CRF17_BF, and two others were F1pol/Benv. No "pure" HIV-1 subtype F1 or B" variant of subtype B was detected in the present study. Of note, samples characterized as CRF12_BF-related were depicted only in 2005. HIV-1 genetic diversity in Bolivia is mostly driven by subtype B followed by BF1 recombinant strains from the CRF12_BF "family". No significant temporal changes were detected between the mid-1990s and the mid-2000s for subtype B (76.2% vs 70.0%) or BF1 recombinant (23.8% vs 30.0%) samples from Bolivia.

  7. Simulation suggests that rapid activation of social distancing can arrest epidemic development due to a novel strain of influenza

    Directory of Open Access Journals (Sweden)

    Kelly Heath

    2009-04-01

    Full Text Available Abstract Background Social distancing interventions such as school closure and prohibition of public gatherings are present in pandemic influenza preparedness plans. Predicting the effectiveness of intervention strategies in a pandemic is difficult. In the absence of other evidence, computer simulation can be used to help policy makers plan for a potential future influenza pandemic. We conducted simulations of a small community to determine the magnitude and timing of activation that would be necessary for social distancing interventions to arrest a future pandemic. Methods We used a detailed, individual-based model of a real community with a population of approximately 30,000. We simulated the effect of four social distancing interventions: school closure, increased isolation of symptomatic individuals in their household, workplace nonattendance, and reduction of contact in the wider community. We simulated each of the intervention measures in isolation and in several combinations; and examined the effect of delays in the activation of interventions on the final and daily attack rates. Results For an epidemic with an R0 value of 1.5, a combination of all four social distancing measures could reduce the final attack rate from 33% to below 10% if introduced within 6 weeks from the introduction of the first case. In contrast, for an R0 of 2.5 these measures must be introduced within 2 weeks of the first case to achieve a similar reduction; delays of 2, 3 and 4 weeks resulted in final attack rates of 7%, 21% and 45% respectively. For an R0 of 3.5 the combination of all four measures could reduce the final attack rate from 73% to 16%, but only if introduced without delay; delays of 1, 2 or 3 weeks resulted in final attack rates of 19%, 35% or 63% respectively. For the higher R0 values no single measure has a significant impact on attack rates. Conclusion Our results suggest a critical role of social distancing in the potential control of a future

  8. Genetic diversity of Mycobacterium tuberculosis from Pará, Brazil, reveals a higher frequency of ancestral strains than previously reported in South America.

    Science.gov (United States)

    Conceição, Emilyn Costa; Rastogi, Nalin; Couvin, David; Lopes, Maria Luíza; Furlaneto, Ismari Perini; Gomes, Harrison Magdinier; Vasconcellos, Sidra Ezídio Gonçalves; Suffys, Philip Noel; Schneider, Maria Paula Cruz; de Sousa, Maísa Silva; Sola, Christophe; de Paula Souza E Guimarães, Ricardo José; Duarte, Rafael Silva; Batista Lima, Karla Valéria

    2017-12-01

    There is only scarce information available on genotypic diversity of the Mycobacterium tuberculosis complex (MTBC) clinical isolates circulating in the Northern part of Brazil, a relatively neglected region regarding research on tuberculosis. We therefore characterized 980 MTBC clinical isolates from the state of Pará, by spoligotyping and data was compared with patterns from around the world, besides analyzing drug susceptibility, and collecting sociodemographic data. We also performed 24 loci MIRU-VNTR typing to evaluate phylogenetic inferences among the East-African-Indian (EAI) lineage strains. The Geographic Information System analyses were performed to generate a descriptive visualization of MTBC strain distribution in the region. A total of 249 different spoligopatterns primarily belonging to evolutionary recent Euro-American lineages, as well as Central-Asian, Manu and ancestral EAI lineages, were identified, in addition to strains with reportedly unknown lineage signatures. The most frequent lineages were Latin American Mediterranean, T and Haarlem. Interestingly, EAI lineage strains were found in a significantly higher proportion in comparison with previous studies from South America. Regarding EAI lineage, the absence of spacers 4-9 and 23-24 co-related to 24 loci MIRU-VNTRs may suggest a close evolutionary relationship between such strains in Pará and those prevalent in Mozambique, which might have contributed to the genetic diversity of MTBC strains in this region. Copyright © 2017. Published by Elsevier B.V.

  9. Detection of the European epidemic strain of Trichomonas gallinae in finches, but not other non-columbiformes, in the absence of macroscopic disease.

    Science.gov (United States)

    Zu Ermgassen, Erasmus K H J; Durrant, Chris; John, Shinto; Gardiner, Roxanne; Alrefaei, Abdulwahed F; Cunningham, Andrew A; Lawson, Becki

    2016-09-01

    Finch trichomonosis is an emerging infectious disease affecting European passerines caused by a clonal strain of Trichomonas gallinae. Migrating chaffinches (Fringilla coelebs) were proposed as the likely vector of parasite spread from Great Britain to Fennoscandia. To test for such parasite carriage, we screened samples of oesophagus/crop from 275 Apodiform, Passeriform and Piciform birds (40 species) which had no macroscopic evidence of trichomonosis (i.e. necrotic ingluvitis). These birds were found dead following the emergence of trichomonosis in Great Britain, 2009-2012, and were examined post-mortem. Polymerase chain reactions were used to detect (ITS1/5·8S rRNA/ITS2 region and single subunit rRNA gene) and to subtype (Fe-hydrogenase gene) T. gallinae. Trichomonas gallinae was detected in six finches [three chaffinches, two greenfinches (Chloris chloris) and a bullfinch (Pyrrhula pyrrhula)]. Sequence data had 100% identity to the European finch epidemic A1 strain for each species. While these results are consistent with finches being vectors of T. gallinae, alternative explanations include the presence of incubating or resolved T. gallinae infections. The inclusion of histopathological examination would help elucidate the significance of T. gallinae infection in the absence of macroscopic lesions.

  10. Trichomonosis outbreak in a flock of canaries (Serinus canaria f. domestica) caused by a finch epidemic strain of Trichomonas gallinae.

    Science.gov (United States)

    Zadravec, Marko; Slavec, Brigita; Krapež, Uroš; Gombač, Mitja; Švara, Tanja; Poljšak-Prijatelj, Mateja; Gruntar, Igor; Račnik, Joško

    2017-05-30

    In the present paper, an outbreak of trichomonosis in a flock of 15 breeding pairs of canaries is described. Trichomonosis was diagnosed on characteristic clinical signs, microscopic examination of crop/esophageal swabs, gross pathology and histopathology. Trichomonads were successfully grown in culture media and were characterized by multi-locus sequence typing. The three genomic loci ITS1-5.8S-ITS2, 18S rRNA and Fe-hydrogenase were analyzed. Molecular characterization confirmed the finch trichomonosis strain, identical to the strain that caused emerging disease in free-living passerine birds in Europe. Flock treatment with metronidazole (200mg/L) in drinking water for 5days was partially effective. After individual treatment with oral application of metronidazole (20mg/kg SID) for 5days no further clinical signs were observed in the flock over next 30 months. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Failure to demonstrate experimental vertical transmission of the epidemic strain of Chikungunya virus in Aedes albopictus from La Réunion Island, Indian Ocean

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    Marie Vazeille

    2009-07-01

    Full Text Available Aedes albopictus was responsible for transmission in the first outbreak of chikungunya (CHIK on La Réunion Island, Indian Ocean, in 2005-2006. The magnitude of the outbreak on this island, which had been free of arboviral diseases for over 30 years, as well as the efficiency of Ae. albopictus as the main vector, raises questions about the maintenance of the CHIK virus (CHIKV through vertical transmission mechanisms. Few specimens collected from the field as larvae were found to be infected. In this study, Ae. albopictus originating from La Réunion were orally infected with a blood-meal containing 10(8 pfu/mL of the CHIKV epidemic strain (CHIKV 06.21. Eggs from the first and second gonotrophic cycles were collected and raised to the adult stage. The infectious status of the progeny was checked (i by immunofluorescence on head squashes of individual mosquitoes to detect the presence of viral particles or (ii by quantitative RT-PCR on mosquito pools to detect viral RNA. We analysed a total of 1,675 specimens from the first gonotrophic cycle and 1,709 from the second gonotrophic cycle without detecting any viral particles or viral RNA. These laboratory results are compared to field records.

  12. Epidemic typhus.

    Science.gov (United States)

    Bechah, Yassina; Capo, Christian; Mege, Jean-Louis; Raoult, Didier

    2008-07-01

    Epidemic typhus is transmitted to human beings by the body louse Pediculus humanus corporis. The disease is still considered a major threat by public-health authorities, despite the efficacy of antibiotics, because poor sanitary conditions are conducive to louse proliferation. Until recently, Rickettsia prowazekii, the causal agent, was thought to be confined to human beings and their body lice. Since 1975, R prowazekii infection in human beings has been related to contact with the flying squirrel Glaucomys volans in the USA. Moreover, Brill-Zinsser disease, a relapsed form of epidemic typhus that appears as sporadic cases many years after the initial infection, is unrelated to louse infestation. Stress or a waning immune system are likely to reactivate this earlier persistent infection, which could be the source of new epidemics when conditions facilitate louse infestation. Finally, R prowazekii is a potential category B bioterrorism agent, because it is stable in dried louse faeces and can be transmitted through aerosols. An increased understanding of the pathogenesis of epidemic typhus may be useful for protection against this bacterial threat.

  13. Identification of a previously undetected metabolic defect in the Complex II Caenorhabditis elegans mev-1 mutant strain using respiratory control analysis.

    Science.gov (United States)

    Fong, Sheng; Ng, Li Fang; Ng, Li Theng; Moore, Philip K; Halliwell, Barry; Gruber, Jan

    2017-04-01

    Hypometabolism may play an important role in the pathogenesis of ageing and ageing-related diseases. The nematode Caenorhabditis elegans offers the opportunity to study "living mitochondria" in a small (~1 mm) animal replete with a highly stereotypical, yet complex, anatomy and physiology. Basal oxygen consumption rate is often employed as a proxy for energy metabolism in this context. This parameter is traditionally measured using single-chamber Clark electrodes without the addition of metabolic modulators. Recently, multi-well oxygen electrodes, facilitating addition of metabolic modulators and hence study of respiratory control during different mitochondrial respiration states, have been developed. However, only limited official protocols exist for C. elegans, and key limitations of these techniques are therefore unclear. Following modification and testing of some of the existing protocols, we used these methods to explore mitochondrial bioenergetics in live nematodes of an electron transfer chain Complex II mutant strain, mev-1, and identified a previously undetected metabolic defect. We find that mev-1 mutants cannot respond adequately to increased energy demands, suggesting that oxidative phosphorylation is more severely impaired in these animals than has previously been appreciated.

  14. Diagnostic evaluation of assays for detection of antibodies against porcine epidemic diarrhea virus (PEDV) in pigs exposed to different PEDV strains

    DEFF Research Database (Denmark)

    Gerber, Priscilla F.; Lelli, Davide; Zhang, Jianqiang

    2016-01-01

    Porcine epidemic diarrhea virus (PEDV) has caused economic losses in the Americas, Asia and Europe in recent years. Reliable serological assays are essential for epidemiological studies and vaccine evaluation. The objective of this study was to compare the ability of five enzyme-linked immunosorb......Porcine epidemic diarrhea virus (PEDV) has caused economic losses in the Americas, Asia and Europe in recent years. Reliable serological assays are essential for epidemiological studies and vaccine evaluation. The objective of this study was to compare the ability of five enzyme...

  15. The complete genome of a new marine Thaumarchaea strain contains evidence of previous virus infection and a possible defense mechanism from infection

    Science.gov (United States)

    Ahlgren, N.; Parada, A. E.; Fuhrman, J. A.

    2016-02-01

    While marine viruses have been isolated from several marine bacterial phyla, no reported viruses have been isolated from mesophilic marine archaea. There is growing evidence for viruses that infect marine Thaumarchaea, an abundant phylum of mesophilic archaea that are important in C and N cycles in the ocean. We have recently sequenced the complete genome of new Thaumarchaeota strain, SPOT01, that contains evidence of viral infection. Two independent virus finding programs, VirSorter and phiSpy, indicate the genome contains a 20 kb region that is likely viral in origin. Manual inspection of this region, including comparison to known viral proteins, also supports that this region contains viral genes. It is unclear if this region is a viable prophage or the remnants of a previous lytic infection. Next to this region are genes for a newly recognized form of DNA modification, phosphorothioation (PT), and an adjacent operon that likely encodes a restriction endonuclease (RE). PT genes are found in a variety of bacteria and archaea, but this is the first example of PT genes in a marine achaeon. PT and adjacent RE genes in Salmonella enterica have been shown to function as a restriction modification system—non PT-modified DNA is degraded by the PT system RE such that the host is protected from invasion of foreign DNA. The discovery of both PT and adjacent RE genes in SPOT01 is novel among marine microbes, and we hypothesize that they act to restrict infection by degrading non PT-modified viral DNA. Recruitment of metagenomes from a near-shore site off California indicates that the putative virus and PT regions are found in roughly 25% and 2% respectively of Thaumarchaea in the field. Results from PacBio sequencing will be presented on which genomic sites are PT modified. This new genome provides compelling evidence that marine Thaumarchaea are susceptible to viral infection and possess a potential new mechanism for defense from infection.

  16. Molecular characterization of Trichomonas gallinae isolates recovered from the Canadian Maritime provinces' wild avifauna reveals the presence of the genotype responsible for the European finch trichomonosis epidemic and additional strains.

    Science.gov (United States)

    McBurney, Scott; Kelly-Clark, Whitney K; Forzán, María J; Lawson, Becki; Tyler, Kevin M; Greenwood, Spencer J

    2015-07-01

    Finch trichomonosis, caused by Trichomonas gallinae, emerged in the Canadian Maritime provinces in 2007 and has since caused ongoing mortality in regional purple finch (Carpodacus purpureus) and American goldfinch (Carduelis tristis) populations. Trichomonas gallinae was isolated from (1) finches and rock pigeons (Columbia livia) submitted for post-mortem or live-captured at bird feeding sites experiencing trichomonosis mortality; (2) bird seed at these same sites; and (3) rock pigeons live-captured at known roosts or humanely killed. Isolates were characterized using internal transcribed spacer (ITS) region and iron hydrogenase (Fe-hyd) gene sequences. Two distinct ITS types were found. Type A was identical to the UK finch epidemic strain and was isolated from finches and a rock pigeon with trichomonosis; apparently healthy rock pigeons and finches; and bird seed at an outbreak site. Type B was obtained from apparently healthy rock pigeons. Fe-hyd sequencing revealed six distinct subtypes. The predominant subtype in both finches and the rock pigeon with trichomonosis was identical to the UK finch epidemic strain A1. Single nucleotide polymorphisms in Fe-hyd sequences suggest there is fine-scale variation amongst isolates and that finch trichomonosis emergence in this region may not have been caused by a single spill-over event.

  17. Emergence of the epidemic methicillin-resistant Staphylococcus aureus strain USA300 coincides with horizontal transfer of the arginine catabolic mobile element and speG-mediated adaptations for survival on skin.

    Science.gov (United States)

    Planet, Paul J; LaRussa, Samuel J; Dana, Ali; Smith, Hannah; Xu, Amy; Ryan, Chanelle; Uhlemann, Anne-Catrin; Boundy, Sam; Goldberg, Julia; Narechania, Apurva; Kulkarni, Ritwij; Ratner, Adam J; Geoghegan, Joan A; Kolokotronis, Sergios-Orestis; Prince, Alice

    2013-12-17

    The arginine catabolic mobile element (ACME) is the largest genomic region distinguishing epidemic USA300 strains of methicillin-resistant Staphylococcus aureus (MRSA) from other S. aureus strains. However, the functional relevance of ACME to infection and disease has remained unclear. Using phylogenetic analysis, we have shown that the modular segments of ACME were assembled into a single genetic locus in Staphylococcus epidermidis and then horizontally transferred to the common ancestor of USA300 strains in an extremely recent event. Acquisition of one ACME gene, speG, allowed USA300 strains to withstand levels of polyamines (e.g., spermidine) produced in skin that are toxic to other closely related S. aureus strains. speG-mediated polyamine tolerance also enhanced biofilm formation, adherence to fibrinogen/fibronectin, and resistance to antibiotic and keratinocyte-mediated killing. We suggest that these properties gave USA300 a major selective advantage during skin infection and colonization, contributing to the extraordinary evolutionary success of this clone. Over the past 15 years, methicillin-resistant Staphylococcus aureus (MRSA) has become a major public health problem. It is likely that adaptations in specific MRSA lineages (e.g., USA300) drove the spread of MRSA across the United States and allowed it to replace other, less-virulent S. aureus strains. We suggest that one major factor in the evolutionary success of MRSA may have been the acquisition of a gene (speG) that allows S. aureus to evade the toxicity of polyamines (e.g., spermidine and spermine) that are produced in human skin. Polyamine tolerance likely gave MRSA multiple fitness advantages, including the formation of more-robust biofilms, increased adherence to host tissues, and resistance to antibiotics and killing by human skin cells.

  18. Genetic structure of Neisseria meningitidis serogroup C epidemic strains in South Brazil Estrutura genética de cepas epidêmicas de Neisseria meningitidis sorogrupo C do Sul do Brasil

    Directory of Open Access Journals (Sweden)

    Claudio Tavares Sacchi

    1995-08-01

    Full Text Available In the present study we report the results of an analysis, based on serotyping, multilocus enzyme electrophoresis (MEE, and ribotyping of N. meningitidis serogroup C strains isolated from patients with meningococcal disease (MD in Rio Grande do Sul (RS and Santa Catarina (SC States, Brazil, as the Center of Epidemiology Control of Ministry of Health detected an increasing of MD cases due to this serogroup in the last two years (1992-1993. We have demonstrated that the MD due to N.meningitidis serogroup C strains in RS and SC States occurring in the last 4 years were caused mainly by one clone of strains (ET 40, with isolates indistinguishable by serogroup, serotype, subtype and even by ribotyping. One small number of cases that were not due to an ET 40 strains, represent closely related clones that probably are new lineages generated from the ET 40 clone referred as ET 11A complex. We have also analyzed N.meningitidis serogroup C strains isolated in the greater São Paulo in 1976 as representative of the first post epidemic year in that region. The ribotyping method, as well as MEE, could provide useful information about the clonal characteristics of those isolates and also of strains isolated in south Brazil. The strains from 1976 have more similarity with the actual endemic than epidemic strains, by the ribotyping, sulfonamide sensitivity, and MEE results. In conclusion, serotyping with monoclonal antibodies (C:2b:P1.3, MEE (ET 11 and ET 11A complex, and ribotyping by using ClaI restriction enzyme (Rb2, were useful to characterize these epidemic strains of N.meningitidis related to the increased incidence of MD in different States of south Brazil. It is mostly probable that these N.meningitidis serogroup C strains have poor or no genetic corelation with 1971-1975 epidemic serogroup C strains. The genetic similarity of members of the ET 11 and ET 11A complex were confirmed by the ribotyping method by using three restriction endonucleases

  19. Complete Genome Sequence of a Field Strain of Peste des Petits Ruminants Virus Isolated during 2010-2014 Epidemics in Senegal.

    Science.gov (United States)

    Salami, Habib; Croville, Guillaume; Kwiatek, Olivier; Mariette, Jérôme; Klopp, Christophe; Valière, Sophie; Guérin, Jean-Luc; Lo, Moustapha; Thiongane, Yaya; Albina, Emmanuel; Libeau, Geneviève

    2014-09-18

    Peste des petits ruminants virus (PPRV) infection is expanding and results in regular epizootic activities in Africa, the Middle East, and Asia. Here, we report the complete genome sequence of a field strain of PPRV isolated in Senegal (SnDk11I13) in 2013. Copyright © 2014 Salami et al.

  20. Mismatch between the 1997/1998 influenza vaccine and the major epidemic A (H3N2) virus strain as the cause of an inadequate vaccine-induced antibody response to this strain in the elderly.

    NARCIS (Netherlands)

    J.C. de Jong (Jan); W.E.Ph. Beyer (Walter); A.M. Palache (Abraham); G.F. Rimmelzwaan (Guus); A.D.M.E. Osterhaus (Albert)

    2000-01-01

    textabstractThe success of influenza vaccination depends largely on the antigenic match between the influenza vaccine strains and the virus strains actually circulating during the season. In the past, this match has proved to be satisfactory in most seasons. In the 1997/1998 season, however,

  1. Comparative analysis of the virulence characteristics of epidemic methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from Chinese children: ST59 MRSA highly expresses core gene-encoded toxin.

    Science.gov (United States)

    Li, Shipeng; Sun, Jing; Zhang, Jianzhong; Li, Xiangmei; Tao, Xiaoxia; Wang, Lijuan; Sun, Mingjiao; Liu, Yingchao; Li, Juan; Qiao, Yanhong; Yu, Sangjie; Yao, Kaihu; Yang, Yonghong; Shen, Xuzhuang

    2014-02-01

    This study aims to investigate the prevalence of a novel cell wall-anchored protein gene, sasX, and to obtain information on the genetic basis for the pathogenic potential of the MRSA strains isolated from Chinese children. The molecular and virulence characteristics of the clinical strains were analyzed. Twenty-two sequence types (STs) were obtained, with six epidemic clones ST59, ST239, ST1, ST910, ST88, and ST338 accounting for 35.8, 22, 6.6, 6.6, 5.3, and 4.1% respectively. The expression levels of hla, psmα, and RNAIII were higher in ST59 than in other STs (p MRSA isolates. ST239-MRSA-SCCmecIII-t037 (61.5%) was the predominant sasX-positive MRSA clone. The expressions of PSMα and RNAIII were higher in sasX-positive ST239 isolates than in sasX-negative ST239 ones (p MRSA was higher than that by sasX-negative ST239 MRSA (p = 0.008). This study indicated that ST59 was the predominant clone in the MRSA isolates obtained from Chinese children and might have stronger pathogenic potential. The prevalence of the sasX gene in the MRSA isolates from children was relatively low. Furthermore, the sasX gene might be related to the expressions of PSMα and RNAIII and infection invasiveness. © 2013 APMIS Published by John Wiley & Sons Ltd.

  2. Detection of the European epidemic strain of Trichomonas gallinae in finches, but not other non-columbiformes, in the absence of macroscopic disease

    OpenAIRE

    Zu Ermgassen, E.; Durrant, C.; John, S.; Gardiner, R.; Alrefaei, A. F.; Cunningham, A. A.; Lawson, B.

    2016-01-01

    Finch trichomonosis is an emerging infectious disease affecting European passerines caused by a clonal strain of Trichomonas gallinae. Migrating chaffinches (Fringilla coelebs) were proposed as the likely vector of parasite spread from Great Britain to Fennoscandia. To test for such parasite carriage, we screened samples of oesophagus/crop from 275 Apodiform, Passeriform and Piciform birds (40 species) which had no macroscopic evidence of trichomonosis (i.e. necrotic ingluvitis). These birds ...

  3. The detection and sequencing of a broad-host-range conjugative IncP-1β plasmid in an epidemic strain of Mycobacterium abscessus subsp. bolletii.

    Directory of Open Access Journals (Sweden)

    Sylvia Cardoso Leão

    Full Text Available BACKGROUND: An extended outbreak of mycobacterial surgical infections occurred in Brazil during 2004-2008. Most infections were caused by a single strain of Mycobacterium abscessus subsp. bolletii, which was characterized by a specific rpoB sequevar and two highly similar pulsed-field gel electrophoresis (PFGE patterns differentiated by the presence of a ∼50 kb band. The nature of this band was investigated. METHODOLOGY/PRINCIPAL FINDINGS: Genomic sequencing of the prototype outbreak isolate INCQS 00594 using the SOLiD platform demonstrated the presence of a 56,267-bp [corrected] circular plasmid, designated pMAB01. Identity matrices, genetic distances and phylogeny analyses indicated that pMAB01 belongs to the broad-host-range plasmid subgroup IncP-1β and is highly related to BRA100, pJP4, pAKD33 and pB10. The presence of pMAB01-derived sequences in 41 M. abscessus subsp. bolletii isolates was evaluated using PCR, PFGE and Southern blot hybridization. Sixteen of the 41 isolates showed the presence of the plasmid. The plasmid was visualized as a ∼50-kb band using PFGE and Southern blot hybridization in 12 isolates. The remaining 25 isolates did not exhibit any evidence of this plasmid. The plasmid was successfully transferred to Escherichia coli by conjugation and transformation. Lateral transfer of pMAB01 to the high efficient plasmid transformation strain Mycobacterium smegmatis mc(2155 could not be demonstrated. CONCLUSIONS/SIGNIFICANCE: The occurrence of a broad-host-range IncP-1β plasmid in mycobacteria is reported for the first time. Thus, genetic exchange could result in the emergence of specific strains that might be better adapted to cause human disease.

  4. Modeling Epidemic Network Failures

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Fagertun, Anna Manolova

    2013-01-01

    This paper presents the implementation of a failure propagation model for transport networks when multiple failures occur resulting in an epidemic. We model the Susceptible Infected Disabled (SID) epidemic model and validate it by comparing it to analytical solutions. Furthermore, we evaluate...... to evaluate multiple epidemic scenarios in various network types....

  5. [Epidemic of rubella encephalitis].

    Science.gov (United States)

    Ben Achour, N; Benrhouma, H; Rouissi, A; Touaiti, H; Kraoua, I; Turki, I; Gouider-Khouja, N

    2013-08-01

    Rubella is a mild viral illness in children. Rubella encephalitis is an extremely uncommon complication of rubella affecting unvaccinated children, aged between 5 and 14 years. From May to June 2011, we observed 9 cases of rubella encephalitis diagnosed during an epidemic of rubella. All were previously healthy (8 boys and 1 girl). None of them had received rubella vaccine. The mean age was 11.6 years. The onset of neurological symptoms occurred within 1-5 days after the typical rush and was associated with seizures and altered consciousness in all cases. The presence of serum immunoglobulin M antibody against rubella virus was demonstrated in all patients. EEGs showed slow wave activity in all patients and brain MRI was normal in the 9 cases. Full recovery was obtained in all patients. However, 4 of them required intensive care unit referral. Acute encephalitis is an extremely rare complication of rubella. The main neurological findings are headache, ataxia, and hemiplegia. Epileptic seizure and altered consciousness are rarely observed. Rubella encephalitis is generally self-limiting with about 80% recovery rate with no sequelae. However, severe courses have been reported. These cases illustrated the potential severity of rubella and they should be prevented by encouraging widespread early childhood vaccination. In Tunisia, rubella encephalitis has been reported once previously and vaccination against rubella virus has only recently been included in the national vaccination program, prescribed only for adolescent females. Following this rubella epidemic, vaccination strategies in Tunisia have been revised. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  6. Molecular complexity of successive bacterial epidemics deconvoluted by comparative pathogenomics.

    Science.gov (United States)

    Beres, Stephen B; Carroll, Ronan K; Shea, Patrick R; Sitkiewicz, Izabela; Martinez-Gutierrez, Juan Carlos; Low, Donald E; McGeer, Allison; Willey, Barbara M; Green, Karen; Tyrrell, Gregory J; Goldman, Thomas D; Feldgarden, Michael; Birren, Bruce W; Fofanov, Yuriy; Boos, John; Wheaton, William D; Honisch, Christiane; Musser, James M

    2010-03-02

    Understanding the fine-structure molecular architecture of bacterial epidemics has been a long-sought goal of infectious disease research. We used short-read-length DNA sequencing coupled with mass spectroscopy analysis of SNPs to study the molecular pathogenomics of three successive epidemics of invasive infections involving 344 serotype M3 group A Streptococcus in Ontario, Canada. Sequencing the genome of 95 strains from the three epidemics, coupled with analysis of 280 biallelic SNPs in all 344 strains, revealed an unexpectedly complex population structure composed of a dynamic mixture of distinct clonally related complexes. We discovered that each epidemic is dominated by micro- and macrobursts of multiple emergent clones, some with distinct strain genotype-patient phenotype relationships. On average, strains were differentiated from one another by only 49 SNPs and 11 insertion-deletion events (indels) in the core genome. Ten percent of SNPs are strain specific; that is, each strain has a unique genome sequence. We identified nonrandom temporal-spatial patterns of strain distribution within and between the epidemic peaks. The extensive full-genome data permitted us to identify genes with significantly increased rates of nonsynonymous (amino acid-altering) nucleotide polymorphisms, thereby providing clues about selective forces operative in the host. Comparative expression microarray analysis revealed that closely related strains differentiated by seemingly modest genetic changes can have significantly divergent transcriptomes. We conclude that enhanced understanding of bacterial epidemics requires a deep-sequencing, geographically centric, comparative pathogenomics strategy.

  7. The Epidemic History of HIV-1 CRF07_BC in Hetian Prefecture and the Role of It on HIV Spreading in China.

    Science.gov (United States)

    Wu, Jianjun; Guo, Hongxiong; Zhang, Jing; Liu, Xiaoming; Ayoupu, Aideaierli; Shen, Yuelan; Miao, Lifeng; Tang, Jihai; Lei, Yanhua; Su, Bin

    2017-04-01

    CRF07_BC is one of the most prevalent HIV-1 strains in China, and Xinjiang Uygur Autonomous Region has ever been considered to be a second epidemic center after Yunnan Province in previous studies. Here we use HIV-1 pol gene sequences identified from Hetian Prefecture located in Xinjiang Autonomous Region to reconstruct the epidemic history of HIV CRF07_BC strain circulating in this region. We found that CRF07_BC is the predominant HIV-1 form in Hetian Prefecture, and the estimated tMRCA analysis shows that there is no enough evidence supporting Xinjiang Autonomous Region as a second epidemic center of spreading HIV-1. It may imply that every city may be only a point among the HIV spreading network because of the frequent migration of population in the whole country nowadays.

  8. Phylodynamics of the HIV-1 epidemic in Cuba.

    Science.gov (United States)

    Delatorre, Edson; Bello, Gonzalo

    2013-01-01

    Previous studies have shown that the HIV-1 epidemic in Cuba displayed a complex molecular epidemiologic profile with circulation of several subtypes and circulating recombinant forms (CRF); but the evolutionary and population history of those viral variants remains unknown. HIV-1 pol sequences of the most prevalent Cuban lineages (subtypes B, C and G, CRF18_cpx, CRF19_cpx, and CRFs20/23/24_BG) isolated between 1999 and 2011 were analyzed. Maximum-likelihood analyses revealed multiple introductions of subtype B (n≥66), subtype C (n≥10), subtype G (n≥8) and CRF18_cpx (n≥2) viruses in Cuba. The bulk of HIV-1 infections in this country, however, was caused by dissemination of a few founder strains probably introduced from North America/Europe (clades B(CU-I) and B(CU-II)), east Africa (clade C(CU-I)) and central Africa (clades G(CU), CRF18(CU) and CRF19(CU)), or locally generated (clades CRFs20/23/24_BG). Bayesian-coalescent analyses show that the major HIV-1 founder strains were introduced into Cuba during 1985-1995; whereas the CRFs_BG strains emerged in the second half of the 1990s. Most HIV-1 Cuban clades appear to have experienced an initial period of fast exponential spread during the 1990s and early 2000s, followed by a more recent decline in growth rate. The median initial growth rate of HIV-1 Cuban clades ranged from 0.4 year⁻¹ to 1.6 year⁻¹. Thus, the HIV-1 epidemic in Cuba has been a result of the successful introduction of a few viral strains that began to circulate at a rather late time of the AIDS pandemic, but then were rapidly disseminated through local transmission networks.

  9. Phylodynamics of the HIV-1 epidemic in Cuba.

    Directory of Open Access Journals (Sweden)

    Edson Delatorre

    Full Text Available Previous studies have shown that the HIV-1 epidemic in Cuba displayed a complex molecular epidemiologic profile with circulation of several subtypes and circulating recombinant forms (CRF; but the evolutionary and population history of those viral variants remains unknown. HIV-1 pol sequences of the most prevalent Cuban lineages (subtypes B, C and G, CRF18_cpx, CRF19_cpx, and CRFs20/23/24_BG isolated between 1999 and 2011 were analyzed. Maximum-likelihood analyses revealed multiple introductions of subtype B (n≥66, subtype C (n≥10, subtype G (n≥8 and CRF18_cpx (n≥2 viruses in Cuba. The bulk of HIV-1 infections in this country, however, was caused by dissemination of a few founder strains probably introduced from North America/Europe (clades B(CU-I and B(CU-II, east Africa (clade C(CU-I and central Africa (clades G(CU, CRF18(CU and CRF19(CU, or locally generated (clades CRFs20/23/24_BG. Bayesian-coalescent analyses show that the major HIV-1 founder strains were introduced into Cuba during 1985-1995; whereas the CRFs_BG strains emerged in the second half of the 1990s. Most HIV-1 Cuban clades appear to have experienced an initial period of fast exponential spread during the 1990s and early 2000s, followed by a more recent decline in growth rate. The median initial growth rate of HIV-1 Cuban clades ranged from 0.4 year⁻¹ to 1.6 year⁻¹. Thus, the HIV-1 epidemic in Cuba has been a result of the successful introduction of a few viral strains that began to circulate at a rather late time of the AIDS pandemic, but then were rapidly disseminated through local transmission networks.

  10. Genome Structural Diversity among 31 Bordetella pertussis Isolates from Two Recent U.S. Whooping Cough Statewide Epidemics.

    Science.gov (United States)

    Bowden, Katherine E; Weigand, Michael R; Peng, Yanhui; Cassiday, Pamela K; Sammons, Scott; Knipe, Kristen; Rowe, Lori A; Loparev, Vladimir; Sheth, Mili; Weening, Keeley; Tondella, M Lucia; Williams, Margaret M

    2016-01-01

    During 2010 and 2012, California and Vermont, respectively, experienced statewide epidemics of pertussis with differences seen in the demographic affected, case clinical presentation, and molecular epidemiology of the circulating strains. To overcome limitations of the current molecular typing methods for pertussis, we utilized whole-genome sequencing to gain a broader understanding of how current circulating strains are causing large epidemics. Through the use of combined next-generation sequencing technologies, this study compared de novo, single-contig genome assemblies from 31 out of 33 Bordetella pertussis isolates collected during two separate pertussis statewide epidemics and 2 resequenced vaccine strains. Final genome architecture assemblies were verified with whole-genome optical mapping. Sixteen distinct genome rearrangement profiles were observed in epidemic isolate genomes, all of which were distinct from the genome structures of the two resequenced vaccine strains. These rearrangements appear to be mediated by repetitive sequence elements, such as high-copy-number mobile genetic elements and rRNA operons. Additionally, novel and previously identified single nucleotide polymorphisms were detected in 10 virulence-related genes in the epidemic isolates. Whole-genome variation analysis identified state-specific variants, and coding regions bearing nonsynonymous mutations were classified into functional annotated orthologous groups. Comprehensive studies on whole genomes are needed to understand the resurgence of pertussis and develop novel tools to better characterize the molecular epidemiology of evolving B. pertussis populations. IMPORTANCE Pertussis, or whooping cough, is the most poorly controlled vaccine-preventable bacterial disease in the United States, which has experienced a resurgence for more than a decade. Once viewed as a monomorphic pathogen, B. pertussis strains circulating during epidemics exhibit diversity visible on a genome structural

  11. Understanding the Opioid Epidemic

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search The CDC Opioid Overdose Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Opioid Overdose Opioid Basics Understanding the Epidemic Commonly Used ...

  12. The Epidemiological Study of Coxsackievirus A6 revealing Hand, Foot and Mouth Disease Epidemic patterns in Guangdong, China.

    Science.gov (United States)

    Zeng, Hanri; Lu, Jing; Zheng, Huanying; Yi, Lina; Guo, Xue; Liu, Leng; Rutherford, Shannon; Sun, Limei; Tan, Xiaohua; Li, Hui; Ke, Changwen; Lin, Jinyan

    2015-05-21

    Enterovirus A71 (EVA71) and Coxsackievirus A16 (CVA16) are regarded as the two major causative pathogens in hand, foot and mouth disease (HFMD) epidemics. However, CVA6, previously largely ignored, became the predominant pathogen in China in 2013. In this study, we describe the epidemiological trends of CVA6 during the annual HFMD outbreaks from 2008 to 2013 in Guangdong, China. The study results show that CVA6 has been one of three major causative agents of HFMD epidemics since 2009. The periodic rotation and dominance of the three pathogens, EVA71, CVA16 and CVA6, may have contributed to the continuously increasing HFMD epidemics. Moreover, phylogenetic analysis of the VP1 gene shows that major circulating CVA6 strains collected from 2009 to 2013 are distinct from the earlier strains collected before 2009. In conclusion, the discovery from this research investigating epidemiological trends of CVA6 from 2008 to 2013 explains the possible pattern of the continuous HFMD epidemic in China. The etiological change pattern also highlights the need for improvement for pathogen surveillance and vaccine strategies for HFMD control in China.

  13. Configuring the autism epidemic

    DEFF Research Database (Denmark)

    Seeberg, Jens; Christensen, Fie Lund Lindegaard

    2017-01-01

    is skewed in favour of boys, and girls with autism tend to be diagnosed much later than boys. Building and further developing the notion of ‘configuration’ of epidemics, this article explores the configuration of autism in Denmark, with a particular focus on the health system and social support to families...... with children diagnosed with autism, seen from a parental perspective. The article points to diagnostic dynamics that contribute to explaining why girls with autism are not diagnosed as easily as boys. We unfold these dynamics through the analysis of a case of a Danish family with autism.......Autism has been described as an epidemic, but this claim is contested and may point to an awareness epidemic, i.e. changes in the definition of what autism is and more attention being invested in diagnosis leading to a rise in registered cases. The sex ratio of children diagnosed with autism...

  14. Discrete epidemic models.

    Science.gov (United States)

    Brauer, Fred; Feng, Zhilan; Castillo-Chavez, Carlos

    2010-01-01

    The mathematical theory of single outbreak epidemic models really began with the work of Kermack and Mackendrick about decades ago. This gave a simple answer to the long-standing question of why epidemics woould appear suddenly and then disappear just as suddenly without having infected an entire population. Therefore it seemed natural to expect that theoreticians would immediately proceed to expand this mathematical framework both because the need to handle recurrent single infectious disease outbreaks has always been a priority for public health officials and because theoreticians often try to push the limits of exiting theories. However, the expansion of the theory via the inclusion of refined epidemiological classifications or through the incorporation of categories that are essential for the evaluation of intervention strategies, in the context of ongoing epidemic outbreaks, did not materialize. It was the global threat posed by SARS in that caused theoreticians to expand the Kermack-McKendrick single-outbreak framework. Most recently, efforts to connect theoretical work to data have exploded as attempts to deal with the threat of emergent and re-emergent diseases including the most recent H1N1 influenza pandemic, have marched to the forefront of our global priorities. Since data are collected and/or reported over discrete units of time, developing single outbreak models that fit collected data naturally is relevant. In this note, we introduce a discrete-epidemic framework and highlight, through our analyses, the similarities between single-outbreak comparable classical continuous-time epidemic models and the discrete-time models introduced in this note. The emphasis is on comparisons driven by expressions for the final epidemic size.

  15. The Obesity Epidemic

    Centers for Disease Control (CDC) Podcasts

    2011-07-18

    Learn about obesity and the community initiatives taking place to prevent and reduce this epidemic.  Created: 7/18/2011 by National Center for Chronic Disease Prevention and Health Promotion, Division of Nutrition, Physical Activity and Obesity.   Date Released: 7/18/2011.

  16. Kanpur epidemic: Time course

    Indian Academy of Sciences (India)

    The first peak was related to water contamination which began in December 1990. The second peak was related to failure of municipal authorities to chlorinate water during the 2nd week of February 1991. The epidemic came under control quickly after water contamination was controlled, providing confirmation for role of ...

  17. Hepatitis E epidemics in India

    Indian Academy of Sciences (India)

    The first well recorded epidemic was in 1955-56 here in Delhi with nearly 30000 cases. Large outbreaks occurred in 1978 in Kashmir. My interest in this disease began in 1991 during investigations into a large epidemic of hepatitis E in Kanpur that my mentor, later Prof SR Naik, and I undertook. I will use this epidemic as an ...

  18. Epidemic Clones” of Listeria monocytogenes Are Widespread and Ancient Clonal Groups

    Science.gov (United States)

    Cantinelli, Thomas; Chenal-Francisque, Viviane; Diancourt, Laure; Frezal, Lise; Leclercq, Alexandre; Wirth, Thierry

    2013-01-01

    The food-borne pathogen Listeria monocytogenes is genetically heterogeneous. Although some clonal groups have been implicated in multiple outbreaks, there is currently no consensus on how “epidemic clones” should be defined. The objectives of this work were to compare the patterns of sequence diversity on two sets of genes that have been widely used to define L. monocytogenes clonal groups: multilocus sequence typing (MLST) and multi-virulence-locus sequence typing (MvLST). Further, we evaluated the diversity within clonal groups by pulsed-field gel electrophoresis (PFGE). Based on 125 isolates of diverse temporal, geographical, and source origins, MLST and MvLST genes (i) had similar patterns of sequence polymorphisms, recombination, and selection, (ii) provided concordant phylogenetic clustering, and (iii) had similar discriminatory power, which was not improved when we combined both data sets. Inclusion of representative strains of previous outbreaks demonstrated the correspondence of epidemic clones with previously recognized MLST clonal complexes. PFGE analysis demonstrated heterogeneity within major clones, most of which were isolated decades before their involvement in outbreaks. We conclude that the “epidemic clone” denominations represent a redundant but largely incomplete nomenclature system for MLST-defined clones, which must be regarded as successful genetic groups that are widely distributed across time and space. PMID:24006010

  19. The epidemiology and socio-economic impact of Rift Valley fever epidemics in Tanzania: A review

    Directory of Open Access Journals (Sweden)

    Calvin Sindato

    2012-06-01

    Full Text Available A review was conducted to provide comprehensive update on Rift Valley fever (RVF in Tanzania, with particular attention devoted to trend of occurrence, epidemiological factors, socio-economic impact and measures which were applied to its control. Information presented in this paper was obtained through extensive literature review. Rift Valley fever was documented for the first time in Tanzania in 1977. This was followed by epidemics in 1997 and 2007. Contrary to the latest epidemic in 2007 sporadic cases of RVF during the previous epidemics were confined to mainly livestock and mostly affecting northern parts of Tanzania. The latest disease epidemic expanded to cover wider areas (mostly northern and central zones of the country involving both human and domestic ruminants. During the latest disease outbreak 52.4% (n = 21 of regions in Tanzania mainland were affected and majority (72.7, n = 11 of the regions had concurrent infections in human and animals. Phylogenetic comparison of nucleotide and amimo acid sequences revealed different virus strains between Kenya and Tanzania. Epidemiological factors that were considered responsible for the previous RVF epidemics in Tanzania included farming systems, climatic factors, vector activities and presence of large population of ruminant species, animal movements and food consumption habits. Majority of the RVF positive cases in the latest epidemic were livestock under pastoral and agro-pastoral farming systems. The disease caused serious effects on rural people’s food security and household nutrition and on direct and indirect losses to livestock producers in the country. Psycho-social distress that communities went through was enormous, which involved the thinking about the loss of their family members and/or relatives, their livestock and crop production. Socially, the status of most livestock producers was eroded in their communities. Cessation of lucrative trade in ruminants resulted in serious

  20. (Epidemic of bacillary dysentery)

    Energy Technology Data Exchange (ETDEWEB)

    Auger, P.; Pouliot, B.; De Grace, M.; Milot, C.; Lafortune, M.; Bergeron, Z.

    1981-10-01

    An outbreak of bacillary dysentery in 1978 affecting 928 persons, most of whom were living in the village of St-Jacques, PQ, is described. An epidemiologic study suggested the water supply as the source of the infection, and it was established that the water carried by the municipal aqueduct was contaminated by feces containing the causal agent, Shigella sonnei. This epidemic, the largest mentioned in he Canadian medical literature, demonstrates how contagious this infection is.

  1. Evidence for Increased Aggressiveness in a Recent Widespread Strain of Puccinia striiformis f. sp. tritici Causing Stripe Rust of Wheat

    DEFF Research Database (Denmark)

    Milus, Eugene A; Kristensen, Kristian; Hovmøller, Mogens S

    2009-01-01

    Stripe rust (yellow rust) of wheat, caused by Puccinia striiformis f. sp. tritici, has become more severe in eastern United States, Australia, and elsewhere since 2000. Recent research has shown that this coincided with a global spread of two closely related strains that were similar based...... to the warm temperature regime for all variables. Based on these results and previously published models for stripe rust epidemics, recent severe stripe rust epidemics were most likely enhanced by the pathogen's increased aggressiveness, especially at higher temperature. Furthermore, these results demonstrate...... that wheat rust fungi can adapt to warmer temperatures and cause severe disease in previously unfavorable environments...

  2. Reconstituting the epidemic history of mono lineage of HIV-1 CRF01_AE in Guizhou province, Southern China.

    Science.gov (United States)

    Zeng, Haiyan; Sun, Binlian; Li, Lingnuo; Li, Yanpeng; Liu, Yong; Xiao, Yao; Jiang, Yan; Yang, Rongge

    2014-08-01

    Guizhou province, located between border provinces and Central province of China, plays a crucial role in the transmission of HIV-1, implying it is important to monitor the epidemic of HIV-1 in this region. Available HIV-1 infected patients' plasma (n=78) were collected from Tongren city, Eastern Guizhou. Full-length gag, partial pol and env gene sequences were amplified and analyzed using phylogenetic, recombinant and Bayesian molecular clock approaches. Phylogenetic and recombinant analyses showed that CRF01_AE predominated among injecting drug users and heterosexuals in Tongren city with 85.9% proportion, it was followed by B' (5.1%), CRF07_BC (3.8%), CRF08_BC (3.8%), and B (1.3%). Moreover, 98.5% of CRF01_AE strains belonged to the distinct lineage CRF01_AE-v previously found in Guangxi province. To infer the most probable origin of CRF01_AE-v in Guizhou province, we download all available full length of CRF01_AE gag, pol and env gene region sequences from China in Los Alamos HIV sequence database. Phylodynamic and phylogeographic analyses revealed that the expanding CRF01_AE-v epidemic in Guizhou province was the result of local epidemic driven by multiple independent introductions of CRF01_AE-v strains from Guangxi province in early 2000s. High prevalence of CRF01_AE in Guizhou province may bridge the epidemic to Central China. It provides a new insight for the understanding of HIV-1 epidemic in Guizhou province and makes the evolutionary history of CRF01_AE in China more intact. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. [Determination of hemagglutination inhibiting antibodies against influenza virus A/Port Chalmers/1/73 in samples from the Roman population (1962-1974). Relation of antibody titers to those obtained against previous influenza A strains].

    Science.gov (United States)

    Castagnari, L; Delia, S; Russo, V; Sebastiani, A

    1975-01-01

    The h.i.a. titer has been determined against the strain of the A/Port Chalmers/1/73 influenza virus in 805 serum samples obtained in Rome from as many adults during six distinct periods between spring 1962 and summer-autumn 1974.

  4. The 1974 epidemic of Chikungunya fever in children in Ibadan.

    Science.gov (United States)

    Tomori, O; Fagbami, A; Fabiyi, A

    1975-12-01

    During an epidemic of Chikunguya fever in Ibadan 16 strains of Chikungunya virus were recovered from children reporting sick with fever at the University College Hospital and Oluyoro Catholic Hospital Outpatient Clinic. Twelve strains were obtained from children within the 1-4 year age group, two from 5-10 year group and one each from less than one-year age group, and 10-15 year age group. A retrospective survey for neutralising antibodies to Chikungunya shows a significantly higher proportion of children were positive for Chikungunya N antibodies just after the 1969 epidemic than in 1974 just before the epidemic, with resultant pooling of Chikungunya seronegative children who are susceptible to infection.

  5. HIV-1 epidemic in Warao Amerindians from Venezuela: spatial phylodynamics and epidemiological patterns.

    Science.gov (United States)

    Villalba, Julian A; Bello, Gonzalo; Maes, Mailis; Sulbaran, Yoneira F; Garzaro, Domingo; Loureiro, Carmen L; Rangel, Hector R; de Waard, Jacobus H; Pujol, Flor H

    2013-07-17

    We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities. HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic. HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities. A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.

  6. Nosocomial epidemic of Serratia marcescens septicemia ascribed to contaminated blood transfusion bags

    DEFF Research Database (Denmark)

    Heltberg, Ole; Skov, F; Gerner-Smidt, P

    1993-01-01

    Two cases of transfusion-related Serratia marcescens bacteremia prompted extensive epidemiologic investigations in three independent hospitals. Test tubes and plasma from donors whose blood was drawn into bags from a single production batch were cultured. Analysis of the ribotype of S. marcescens...... was identified. The clinical isolates from three patients, the three units of blood transfused, and the plant-derived strain shared a unique ribotype. The incident is interpreted as a sporadic, bacterial contamination of blood bags with the S. marcescens epidemic strain, occurring during the manufacturing...... or packaging. A similar incident has not previously been reported. Attention is drawn to the possibility of significant contamination during the complex production of multiple-bag blood collection systems. Guidelines for improved registration and handling of transfusion complications in wards are suggested...

  7. Familial epidemic of meningococcal disease.

    Science.gov (United States)

    Smilović, V; Vrbanec-Megla, L; Payerl-Pal, M; Puntarić, D; Baklaić, Z

    1998-03-01

    Two closely related boys from the same house hold (Home 1), aged two and three, were affected with fulminant meningococcal sepsis known as Waterhouse-Friderichsen syndrome. Neisseria meningitidis serogorup B was isolated from their blood and cerebrospinal fluid. The two-year-old boy died one day after the onset of the disease. Epidemiological examination of contacts and pharyngeal swabs were performed in 14 persons from the household, all of them relatives of the affected children, as well as in a number of other contacts. Chemoprophylaxis with cotrimoxazole was simultaneously administered to all contacts. Family histories revealed that two contacts from the household where the patients did not live (Home 2) were inadvertently omitted. Subsequent examinations, following a report of another contagious disease (salmonelosis), revealed that these two persons were Neisseria meningitidis carriers, together with another one in the same household. The carriers most probably caused the infection of a third, five-year-old boy, the deceased boy's brother (Home 1) who also developed fulminant meningococcal sepsis. The failure to take the appropriate prophylaxis led to a prolonged carrier state in the carrier from the second household. Repeated pharyngeal swab sampling revealed two more carriers from both households that had previously been negative. Control of the epidemic was achieved after 5 weeks by repeated and controlled chemoprophylaxis with ciprofloxacin, and by repeated epidemiological examinations, disinfection, and daily health surveillance by the Sanitary Inspectorate. This extremely rare instance of a familial epidemic with three infected persons emphasizes the need for consistent chemoprophylaxis in meningococcal disease contacts.

  8. Nine challenges for deterministic epidemic models

    DEFF Research Database (Denmark)

    Roberts, Mick G; Andreasen, Viggo; Lloyd, Alun

    2015-01-01

    Deterministic models have a long history of being applied to the study of infectious disease epidemiology. We highlight and discuss nine challenges in this area. The first two concern the endemic equilibrium and its stability. We indicate the need for models that describe multi-strain infections......, infections with time-varying infectivity, and those where superinfection is possible. We then consider the need for advances in spatial epidemic models, and draw attention to the lack of models that explore the relationship between communicable and non-communicable diseases. The final two challenges concern...

  9. Porcine Epidemic Diarrhea Virus among Farmed Pigs, Ukraine.

    Science.gov (United States)

    Dastjerdi, Akbar; Carr, John; Ellis, Richard J; Steinbach, Falko; Williamson, Susanna

    2015-12-01

    An outbreak of porcine epidemic diarrhea occurred in the summer of 2014 in Ukraine, severely affecting piglets <10 days of age; the mortality rate approached 100%. Full genome sequencing showed the virus to be closely related to strains reported from North America, showing a sequence identity of up to 99.8%.

  10. PREVIOUS SECOND TRIMESTER ABORTION

    African Journals Online (AJOL)

    PNLC

    PREVIOUS SECOND TRIMESTER ABORTION: A risk factor for third trimester uterine rupture in three ... for accurate diagnosis of uterine rupture. KEY WORDS: Induced second trimester abortion - Previous uterine surgery - Uterine rupture. ..... scarred uterus during second trimester misoprostol- induced labour for a missed ...

  11. Can influenza epidemics be prevented by voluntary vaccination?

    Directory of Open Access Journals (Sweden)

    Raffaele Vardavas

    2007-05-01

    Full Text Available Previous modeling studies have identified the vaccination coverage level necessary for preventing influenza epidemics, but have not shown whether this critical coverage can be reached. Here we use computational modeling to determine, for the first time, whether the critical coverage for influenza can be achieved by voluntary vaccination. We construct a novel individual-level model of human cognition and behavior; individuals are characterized by two biological attributes (memory and adaptability that they use when making vaccination decisions. We couple this model with a population-level model of influenza that includes vaccination dynamics. The coupled models allow individual-level decisions to influence influenza epidemiology and, conversely, influenza epidemiology to influence individual-level decisions. By including the effects of adaptive decision-making within an epidemic model, we can reproduce two essential characteristics of influenza epidemiology: annual variation in epidemic severity and sporadic occurrence of severe epidemics. We suggest that individual-level adaptive decision-making may be an important (previously overlooked causal factor in driving influenza epidemiology. We find that severe epidemics cannot be prevented unless vaccination programs offer incentives. Frequency of severe epidemics could be reduced if programs provide, as an incentive to be vaccinated, several years of free vaccines to individuals who pay for one year of vaccination. Magnitude of epidemic amelioration will be determined by the number of years of free vaccination, an individuals' adaptability in decision-making, and their memory. This type of incentive program could control epidemics if individuals are very adaptable and have long-term memories. However, incentive-based programs that provide free vaccination for families could increase the frequency of severe epidemics. We conclude that incentive-based vaccination programs are necessary to control

  12. Hepatitis E epidemics in India

    Indian Academy of Sciences (India)

    Notes: We compiled this slide in 1992. It shows dates, locations and number of cases for various epidemics reported from different parts of India till that time. The first well recorded epidemic was in 1955-56 here in Delhi with nearly 30000 cases. Large outbreaks occurred in 1978 in Kashmir. My interest in this disease began ...

  13. The epidemic of methylisothiazolinone

    DEFF Research Database (Denmark)

    Schwensen, Jakob F; Uter, Wolfgang; Bruze, Magnus

    2017-01-01

    BACKGROUND: The use of methylisothiazolinone (MI) in cosmetic products has caused an unprecedented epidemic of MI contact allergy. Current data concerning exposures at a European level are required. OBJECTIVES: To describe demographics and MI exposures for European patients with MI contact allergy....... METHODS: Eleven European dermatology departments from eight European countries prospectively collected data between 1 May and 31 October 2015 among consecutive patients who had positive patch test reactions to MI (2000 ppm aq.). RESULTS: A total of 6.0% (205/3434; range 2.6-13.0%) of patients had positive...... patch test reactions to MI. Dermatitis most frequently affected the hands (43.4%), face (32.7%), arms (14.6%), and eyelids (11.7%); 12.7% had widespread dermatitis. For 72.7% (149/205), MI contact allergy was currently relevant mainly because of exposure to cosmetic products (83.2%; 124...

  14. [Hippocrates. Aphorisms and Epidemics III. Two clinical texts].

    Science.gov (United States)

    Frøland, Anders

    2015-01-01

    The two Hippocratic texts, Aphorisms and Epidemics III, have not been translated into Danish previously. The Aphorisms are 412 short, pithy statements, mostly on the prognosis in relation to certain symptoms in the course of the diseases, very often febrile. The Aphorisms begin with the famous words: "Life is short, the Art long, opportunity fleeting, experiment treacherous, judgment difficult." (Transl. W H S Jones [22]). Epidemics III consists of 28 case histories, again mostly of febrile patients, but also of observations on the connection of the seasons with general morbidity and mortality. The author describes an epidemic, which in some respects resembles Thucydides' report on the plague in Athens in 430 BC. It is suggested, that observations as have been recorded in the seven Hippocratic texts on epidemic diseases are the material on which prognostic statements as those collected in the Aphorisms are founded.

  15. Laparoscopy After Previous Laparotomy

    Directory of Open Access Journals (Sweden)

    Zulfo Godinjak

    2006-11-01

    Full Text Available Following the abdominal surgery, extensive adhesions often occur and they can cause difficulties during laparoscopic operations. However, previous laparotomy is not considered to be a contraindication for laparoscopy. The aim of this study is to present that an insertion of Veres needle in the region of umbilicus is a safe method for creating a pneumoperitoneum for laparoscopic operations after previous laparotomy. In the last three years, we have performed 144 laparoscopic operations in patients that previously underwent one or two laparotomies. Pathology of digestive system, genital organs, Cesarean Section or abdominal war injuries were the most common causes of previouslaparotomy. During those operations or during entering into abdominal cavity we have not experienced any complications, while in 7 patients we performed conversion to laparotomy following the diagnostic laparoscopy. In all patients an insertion of Veres needle and trocar insertion in the umbilical region was performed, namely a technique of closed laparoscopy. Not even in one patient adhesions in the region of umbilicus were found, and no abdominal organs were injured.

  16. Mechanistic movement models to understand epidemic spread.

    Science.gov (United States)

    Fofana, Abdou Moutalab; Hurford, Amy

    2017-05-05

    An overlooked aspect of disease ecology is considering how and why animals come into contact with one and other resulting in disease transmission. Mathematical models of disease spread frequently assume mass-action transmission, justified by stating that susceptible and infectious hosts mix readily, and foregoing any detailed description of host movement. Numerous recent studies have recorded, analysed and modelled animal movement. These movement models describe how animals move with respect to resources, conspecifics and previous movement directions and have been used to understand the conditions for the occurrence and the spread of infectious diseases when hosts perform a type of movement. Here, we summarize the effect of the different types of movement on the threshold conditions for disease spread. We identify gaps in the literature and suggest several promising directions for future research. The mechanistic inclusion of movement in epidemic models may be beneficial for the following two reasons. Firstly, the estimation of the transmission coefficient in an epidemic model is possible because animal movement data can be used to estimate the rate of contacts between conspecifics. Secondly, unsuccessful transmission events, where a susceptible host contacts an infectious host but does not become infected can be quantified. Following an outbreak, this enables disease ecologists to identify 'near misses' and to explore possible alternative epidemic outcomes given shifts in ecological or immunological parameters.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Author(s).

  17. Epidemic meningococcal disease: synthesis of a hypothetical immunoepidemiologic model.

    Science.gov (United States)

    Griffiss, J M

    1982-01-01

    A hypothetical model of the epidermic behavior of Neisseria meningitidis, based upon the induction of susceptibility to disseminated disease by circulating IgA, is presented. The model is based on the assumption that epidemic susceptibility is acquired as a result of induction of serum IgA by cross-reacting enteric bacteria, the priming organism. Co-colonization with the appropriate strain of N. meningitidis then may result in disseminated disease. Colonization by either bacterium in the absence of the other results in reinforcement of the commensal relationship. Slow, silent, fecal-oral transmission of the priming organism determines the time/space characteristics of an epidemic; interruption of fecal-oral transmission aborts it. Aerosol transmission of the meningococcus determines the magnitude of an epidemic. Independent, age-related acquisition of both capsular polysaccharide and lipopolysaccharide antibodies provides immunity in the absence of aberrantly high levels of co-specific serum IgA.

  18. Epidemic cholera spreads like wildfire

    Science.gov (United States)

    Roy, Manojit; Zinck, Richard D.; Bouma, Menno J.; Pascual, Mercedes

    2014-01-01

    Cholera is on the rise globally, especially epidemic cholera which is characterized by intermittent and unpredictable outbreaks that punctuate periods of regional disease fade-out. These epidemic dynamics remain however poorly understood. Here we examine records for epidemic cholera over both contemporary and historical timelines, from Africa (1990-2006) and former British India (1882-1939). We find that the frequency distribution of outbreak size is fat-tailed, scaling approximately as a power-law. This pattern which shows strong parallels with wildfires is incompatible with existing cholera models developed for endemic regions, as it implies a fundamental role for stochastic transmission and local depletion of susceptible hosts. Application of a recently developed forest-fire model indicates that epidemic cholera dynamics are located above a critical phase transition and propagate in similar ways to aggressive wildfires. These findings have implications for the effectiveness of control measures and the mechanisms that ultimately limit the size of outbreaks.

  19. Characterization of Neisseria meningitidis Isolates from Recent Outbreaks in Ethiopia and Comparison with Those Recovered during the Epidemic of 1988 to 1989

    Science.gov (United States)

    Norheim, Gunnstein; Rosenqvist, Einar; Aseffa, Abraham; Yassin, Mohammed Ahmed; Mengistu, Getahun; Kassu, Afework; Fikremariam, Dereje; Tamire, Wegene; Høiby, E. Arne; Alebel, Tsegaye; Berhanu, Degu; Merid, Yarid; Harboe, Morten; Caugant, Dominique A.

    2006-01-01

    The objectives of this study were to collect and characterize epidemic meningococcal isolates from Ethiopia from 2002 to 2003 and to compare them to 21 strains recovered during the previous large epidemic of 1988 to 1989. Ninety-five patients in all age groups with clinical signs of meningitis and a turbid cerebrospinal fluid (CSF) sample were included in the study of isolates from 2002 to 2003. Seventy-one patients (74.7%) were confirmed as having Neisseria meningitidis either by culture (n = 40) or by porA PCR (n = 31) of their CSF. The overall case fatality rate (CFR) was 11.6%; the N. meningitidis-specific CFR was 4.2%. All 40 strains were fully susceptible to all antibiotics tested except sulfonamide, were serotyped as A:4/21:P1.20,9, and belonged to sequence type 7 (ST-7). The strains from 1988 to 1989 were also equally susceptible and were characterized as A:4/21:P1.20,9, but they belonged to ST-5. Antigenic characterization of the strains revealed differences in the repertoire of lipooligosaccharides and Opa proteins between the old and the recent strains. PCR analysis of the nine lgt genes revealed the presence of the lgtAHFG genes in both old and recent strains; lgtB was present in only some of the strains, but no correlation with sequence type was observed. Further analysis showed that in addition to their pgm alleles, the Ethiopian ST-5 and ST-7 strains also differed in their tbpB, opa, fetA, and lgtA genes. The occurrence of new antigenic structures in strains sharing the same serogroup, PorA, and PorB may help explain the replacement of ST-5 by ST-7 in the African meningitis belt. PMID:16517868

  20. Association of Drought with Typhus Epidemics in Central Mexico

    Science.gov (United States)

    Acuna-Soto, R.; Stahle, D.; Villanueva Diaz, J.; Therrell, M.

    2007-05-01

    Typhus is an acute infectious disease caused by the bacteria Rickettsia prowazekii, which is transmitted among humans by the body lice (Pediculus humanus corporis). The disease is highly contagious and transmission is favored in populations living in crowded conditions. Under these circumstances, typhus transmission is facilitated by factors that favor the colonization and proliferation of body lice such as absence of personal hygiene and wearing the same clothes for long periods of time. Historically, periods of war and famine were associated with devastating epidemics with high mortality rates in many parts of the world. Central Mexico has a long record of typhus epidemics. In this region, at > 2000 meters above sea level, the disease was endemic and occurred with a seasonal pattern in winter, with occasional large epidemics. Recently, we completed a chronology of epidemics in Mexico. A total of 22 well-defined major typhus epidemics were identified between 1650 and 1920. All of them caused periods of increased mortality that lasted 2 - 4 years (more than one standard deviation from the previous ten year period). The record of typhus epidemics was evaluated against the tree-ring record of Cuauhtmoc La Fragua, Puebla. This chronology, based on Douglas fir, has demonstrated to be a faithful record of precipitation in central Mexico. The results indicate that a statistically significant drought (t test, p war. This indicates that drought alone was capable of inducing the social conditions for increased transmission of typhus in pre-industrial central Mexico.

  1. Characterization of the Epidemic European Fusidic Acid-Resistant Impetigo Clone of Staphylococcus aureus▿

    Science.gov (United States)

    O'Neill, A. J.; Larsen, A. R.; Skov, R.; Henriksen, A. S.; Chopra, I.

    2007-01-01

    Resistance to the antibiotic fusidic acid in European strains of Staphylococcus aureus causing impetigo has increased in recent years. This increase appears to have resulted from clonal expansion of a strain we have designated the epidemic European fusidic acid-resistant impetigo clone (EEFIC), which carries the fusidic acid resistance determinant fusB on its chromosome. To understand better the properties of the EEFIC responsible for its success, we have performed detailed phenotypic and genotypic characterization of this clone. Molecular typing revealed the EEFIC to be ST123, spa type t171, and agr type IV and therefore unrelated to earlier prevalent fusB+ strains found in the United Kingdom. EEFIC strains exhibited resistance to fusidic acid, penicillin, and, in some cases, erythromycin, which are all used in the treatment of impetigo. PCR analysis of the EEFIC and complete DNA sequencing of the 39.3 Kb plasmid it harbors identified genes encoding several toxins previously implicated in impetigo (exfoliative toxins A and B and EDIN-C). The location of fusB was mapped on the chromosome and found to be associated with a novel 16.6-kb genomic island integrated downstream of groEL. Although this element is related to classical staphylococcal pathogenicity islands, it does not encode any known virulence factors and consequently has been designated SaRIfusB (for “S. aureus resistance island carrying fusB”). PMID:17344365

  2. Predicting Subnational Ebola Virus Disease Epidemic Dynamics from Sociodemographic Indicators.

    Directory of Open Access Journals (Sweden)

    Linda Valeri

    Full Text Available The recent Ebola virus disease (EVD outbreak in West Africa has spread wider than any previous human EVD epidemic. While individual-level risk factors that contribute to the spread of EVD have been studied, the population-level attributes of subnational regions associated with outbreak severity have not yet been considered.To investigate the area-level predictors of EVD dynamics, we integrated time series data on cumulative reported cases of EVD from the World Health Organization and covariate data from the Demographic and Health Surveys. We first estimated the early growth rates of epidemics in each second-level administrative district (ADM2 in Guinea, Sierra Leone and Liberia using exponential, logistic and polynomial growth models. We then evaluated how these growth rates, as well as epidemic size within ADM2s, were ecologically associated with several demographic and socio-economic characteristics of the ADM2, using bivariate correlations and multivariable regression models.The polynomial growth model appeared to best fit the ADM2 epidemic curves, displaying the lowest residual standard error. Each outcome was associated with various regional characteristics in bivariate models, however in stepwise multivariable models only mean education levels were consistently associated with a worse local epidemic.By combining two common methods-estimation of epidemic parameters using mathematical models, and estimation of associations using ecological regression models-we identified some factors predicting rapid and severe EVD epidemics in West African subnational regions. While care should be taken interpreting such results as anything more than correlational, we suggest that our approach of using data sources that were publicly available in advance of the epidemic or in real-time provides an analytic framework that may assist countries in understanding the dynamics of future outbreaks as they occur.

  3. A framework to gauge the epidemic potential of plant pathogens in environmental reservoirs: the example of kiwifruit canker.

    Science.gov (United States)

    Bartoli, Claudia; Lamichhane, Jay Ram; Berge, Odile; Guilbaud, Caroline; Varvaro, Leonardo; Balestra, Giorgio M; Vinatzer, Boris A; Morris, Cindy E

    2015-02-01

    New economically important diseases on crops and forest trees emerge recurrently. An understanding of where new pathogenic lines come from and how they evolve is fundamental for the deployment of accurate surveillance methods. We used kiwifruit bacterial canker as a model to assess the importance of potential reservoirs of new pathogenic lineages. The current kiwifruit canker epidemic is at least the fourth outbreak of the disease on kiwifruit caused by Pseudomonas syringae in the mere 50 years in which this crop has been cultivated worldwide, with each outbreak being caused by different genetic lines of the bacterium. Here, we ask whether strains in natural (non-agricultural) environments could cause future epidemics of canker on kiwifruit. To answer this question, we evaluated the pathogenicity, endophytic colonization capacity and competitiveness on kiwifruit of P. syringae strains genetically similar to epidemic strains and originally isolated from aquatic and subalpine habitats. All environmental strains possessing an operon involved in the degradation of aromatic compounds via the catechol pathway grew endophytically and caused symptoms in kiwifruit vascular tissue. Environmental and epidemic strains showed a wide host range, revealing their potential as future pathogens of a variety of hosts. Environmental strains co-existed endophytically with CFBP 7286, an epidemic strain, and shared about 20 virulence genes, but were missing six virulence genes found in all epidemic strains. By identifying the specific gene content in genetic backgrounds similar to known epidemic strains, we developed criteria to assess the epidemic potential and to survey for such strains as a means of forecasting and managing disease emergence. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  4. Florida's tuberculosis epidemic. Public health response.

    Science.gov (United States)

    Witte, J J; Bigler, W J

    1994-03-01

    Florida ranked fourth in the nation with 1,707 tuberculosis cases reported in 1992 for a rate of 12.7 per 100,000 population. Thirteen percent of these patients had AIDS. Recent cases in prisons, shelters, hospitals and schools have stimulated interest and media coverage. Resurgence of strains of multiple-drug resistant tuberculosis is a serious concern. The Florida Department of Health and Rehabilitative Services, in collaboration with allied agencies, has utilized several initiatives in response. The most significant, Tuberculosis Epidemic Containment Plan, details intervention strategies needed to eliminate TB in the state by the year 2010. Successful implementation depends upon local TB prevention and control coalitions that include private and public sector providers.

  5. Epidemic processes in complex networks

    Science.gov (United States)

    Pastor-Satorras, Romualdo; Castellano, Claudio; Van Mieghem, Piet; Vespignani, Alessandro

    2015-07-01

    In recent years the research community has accumulated overwhelming evidence for the emergence of complex and heterogeneous connectivity patterns in a wide range of biological and sociotechnical systems. The complex properties of real-world networks have a profound impact on the behavior of equilibrium and nonequilibrium phenomena occurring in various systems, and the study of epidemic spreading is central to our understanding of the unfolding of dynamical processes in complex networks. The theoretical analysis of epidemic spreading in heterogeneous networks requires the development of novel analytical frameworks, and it has produced results of conceptual and practical relevance. A coherent and comprehensive review of the vast research activity concerning epidemic processes is presented, detailing the successful theoretical approaches as well as making their limits and assumptions clear. Physicists, mathematicians, epidemiologists, computer, and social scientists share a common interest in studying epidemic spreading and rely on similar models for the description of the diffusion of pathogens, knowledge, and innovation. For this reason, while focusing on the main results and the paradigmatic models in infectious disease modeling, the major results concerning generalized social contagion processes are also presented. Finally, the research activity at the forefront in the study of epidemic spreading in coevolving, coupled, and time-varying networks is reported.

  6. Networked SIS Epidemics With Awareness

    KAUST Repository

    Paarporn, Keith

    2017-07-20

    We study a susceptible-infected-susceptible epidemic process over a static contact network where the nodes have partial information about the epidemic state. They react by limiting their interactions with their neighbors when they believe the epidemic is currently prevalent. A node\\'s awareness is weighted by the fraction of infected neighbors in their social network, and a global broadcast of the fraction of infected nodes in the entire network. The dynamics of the benchmark (no awareness) and awareness models are described by discrete-time Markov chains, from which mean-field approximations (MFAs) are derived. The states of the MFA are interpreted as the nodes\\' probabilities of being infected. We show a sufficient condition for the existence of a

  7. Stochastic dynamics of cholera epidemics

    Science.gov (United States)

    Azaele, Sandro; Maritan, Amos; Bertuzzo, Enrico; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2010-05-01

    We describe the predictions of an analytically tractable stochastic model for cholera epidemics following a single initial outbreak. The exact model relies on a set of assumptions that may restrict the generality of the approach and yet provides a realm of powerful tools and results. Without resorting to the depletion of susceptible individuals, as usually assumed in deterministic susceptible-infected-recovered models, we show that a simple stochastic equation for the number of ill individuals provides a mechanism for the decay of the epidemics occurring on the typical time scale of seasonality. The model is shown to provide a reasonably accurate description of the empirical data of the 2000/2001 cholera epidemic which took place in the Kwa Zulu-Natal Province, South Africa, with possibly notable epidemiological implications.

  8. Environmental Factors Influencing Epidemic Cholera

    Science.gov (United States)

    Jutla, Antarpreet; Whitcombe, Elizabeth; Hasan, Nur; Haley, Bradd; Akanda, Ali; Huq, Anwar; Alam, Munir; Sack, R. Bradley; Colwell, Rita

    2013-01-01

    Cholera outbreak following the earthquake of 2010 in Haiti has reaffirmed that the disease is a major public health threat. Vibrio cholerae is autochthonous to aquatic environment, hence, it cannot be eradicated but hydroclimatology-based prediction and prevention is an achievable goal. Using data from the 1800s, we describe uniqueness in seasonality and mechanism of occurrence of cholera in the epidemic regions of Asia and Latin America. Epidemic regions are located near regional rivers and are characterized by sporadic outbreaks, which are likely to be initiated during episodes of prevailing warm air temperature with low river flows, creating favorable environmental conditions for growth of cholera bacteria. Heavy rainfall, through inundation or breakdown of sanitary infrastructure, accelerates interaction between contaminated water and human activities, resulting in an epidemic. This causal mechanism is markedly different from endemic cholera where tidal intrusion of seawater carrying bacteria from estuary to inland regions, results in outbreaks. PMID:23897993

  9. Scaling behavior of threshold epidemics

    Science.gov (United States)

    Ben-Naim, E.; Krapivsky, P. L.

    2012-05-01

    We study the classic Susceptible-Infected-Recovered (SIR) model for the spread of an infectious disease. In this stochastic process, there are two competing mechanism: infection and recovery. Susceptible individuals may contract the disease from infected individuals, while infected ones recover from the disease at a constant rate and are never infected again. Our focus is the behavior at the epidemic threshold where the rates of the infection and recovery processes balance. In the infinite population limit, we establish analytically scaling rules for the time-dependent distribution functions that characterize the sizes of the infected and the recovered sub-populations. Using heuristic arguments, we also obtain scaling laws for the size and duration of the epidemic outbreaks as a function of the total population. We perform numerical simulations to verify the scaling predictions and discuss the consequences of these scaling laws for near-threshold epidemic outbreaks.

  10. OBESITY: OVERVIEW OF AN EPIDEMIC

    OpenAIRE

    Mitchell, Nia; Catenacci, Vicki; Wyatt, Holly R.; Hill, James O.

    2011-01-01

    Despite growing recognition of the problem, the obesity epidemic continues in the U.S., and obesity rates are increasing around the world. The latest estimates are that approximately 34% of adults and 15–20% of children and adolescents in the U.S. are obese. Obesity affects every segment of the U.S. population. Obesity increases the risk of many chronic diseases in children and adults. The epidemic of obesity arose gradually over time, apparently from a small, consistent degree of positive en...

  11. The narcissism epidemic is dead : Long live the narcissism epidemic

    NARCIS (Netherlands)

    Wetzel, Eunike; Brown, Anna; Hill, Patrick; Chung, J.M.H.; Robins, R.W.; Roberts, B.W.

    2017-01-01

    Are recent cohorts of college students more narcissistic than their predecessors? To address debates about the so-called “narcissism epidemic,” we used data from three cohorts of students (N1990s = 1,166; N2000s = 33,647; N2010s = 25,412) to test whether narcissism levels (overall and specific

  12. HIV epidemic in South Africa: A comparison of HIV epidemic ...

    African Journals Online (AJOL)

    2014-08-26

    Aug 26, 2014 ... Method: 'Know your epidemic' synthesis suggests that HIV prevalence is rising in older age groups and falling in younger people. Using secondary data analyses of population-based and antenatal care surveillance (ANC) surveys, we explored trends and patterns in HIV prevalence in KwaZulu-Natal and ...

  13. Analysis of Dengue Serotype 4 in Sri Lanka during the 2012-2013 Dengue Epidemic.

    Science.gov (United States)

    Uehara, Anna; Tissera, Hasitha Aravinda; Bodinayake, Champica K; Amarasinghe, Ananda; Nagahawatte, Ajith; Tillekeratne, L Gayani; Cui, Jie; Reller, Megan E; Palihawadana, Paba; Gunasena, Sunethra; Desilva, Aruna Dharshan; Wilder-Smith, Annelies; Gubler, Duane J; Woods, Christopher W; Sessions, October M

    2017-07-01

    The four serotypes of dengue virus (DENV-1, -2, -3, and -4) have had a rapidly expanding geographic range and are now endemic in over 100 tropical and subtropical countries. Sri Lanka has experienced periodic dengue outbreaks since the 1960s, but since 1989 epidemics have become progressively larger and associated with more severe disease. The dominant virus in the 2012 epidemic was DENV-1, but DENV-4 infections were also commonly observed. DENV-4 transmission was first documented in Sri Lanka when it was isolated from a traveler in 1978, but has been comparatively uncommon since dengue surveillance began in the early 1980s. To better understand the molecular epidemiology of DENV-4 infections in Sri Lanka, we conducted whole-genome sequencing on dengue patient samples from two different geographic locations. Phylogenetic analysis indicates that all sequenced DENV-4 strains belong to genotype 1 and are most closely related to DENV-4 viruses previously found in Sri Lanka and those recently found to be circulating in India and Pakistan.

  14. OmpU as a biomarker for rapid discrimination between toxigenic and epidemic Vibrio cholerae O1/O139 and non-epidemic Vibrio cholerae in a modified MALDI-TOF MS assay.

    Science.gov (United States)

    Paauw, Armand; Trip, Hein; Niemcewicz, Marcin; Sellek, Ricela; Heng, Jonathan Me; Mars-Groenendijk, Roos H; de Jong, Ad L; Majchrzykiewicz-Koehorst, Joanna A; Olsen, Jaran S; Tsivtsivadze, Evgeni

    2014-06-18

    Cholera is an acute diarrheal disease caused by Vibrio cholerae. Outbreaks are caused by a genetically homogenous group of strains from serogroup O1 or O139 that are able to produce the cholera toxin. Rapid detection and identification of these epidemic strains is essential for an effective response to cholera outbreaks. The use of ferulic acid as a matrix in a new MALDI-TOF MS assay increased the measurable mass range of existing MALDI-TOF MS protocols for bacterial identification. The assay enabled rapid discrimination between epidemic V. cholerae O1/O139 strains and other less pathogenic V. cholerae strains. OmpU, an outer membrane protein whose amino acid sequence is highly conserved among epidemic strains of V. cholerae, appeared as a discriminatory marker in the novel MALDI-TOF MS assay. The extended mass range of MALDI-TOF MS measurements obtained by using ferulic acid improved the screening for biomarkers in complex protein mixtures. Differences in the mass of abundant homologous proteins due to variation in amino acid sequences can rapidly be examined in multiple samples. Here, a rapid MALDI-TOF MS assay was developed that could discriminate between epidemic O1/O139 strains and other less pathogenic V. cholerae strains based on differences in mass of the OmpU protein. It appeared that the amino acid sequence of OmpU from epidemic V. cholerae O1/O139 strains is unique and highly conserved.

  15. Mortality Rates during Cholera Epidemic, Haiti, 2010-2011.

    Science.gov (United States)

    Luquero, Francisco J; Rondy, Marc; Boncy, Jacques; Munger, André; Mekaoui, Helmi; Rymshaw, Ellen; Page, Anne-Laure; Toure, Brahima; Degail, Marie Amelie; Nicolas, Sarala; Grandesso, Francesco; Ginsbourger, Maud; Polonsky, Jonathan; Alberti, Kathryn P; Terzian, Mego; Olson, David; Porten, Klaudia; Ciglenecki, Iza

    2016-03-01

    The 2010 cholera epidemic in Haiti was one of the largest cholera epidemics ever recorded. To estimate the magnitude of the death toll during the first wave of the epidemic, we retrospectively conducted surveys at 4 sites in the northern part of Haiti. Overall, 70,903 participants were included; at all sites, the crude mortality rates (19.1-35.4 deaths/1,000 person-years) were higher than the expected baseline mortality rate for Haiti (9 deaths/1,000 person-years). This finding represents an excess of 3,406 deaths (2.9-fold increase) for the 4.4% of the Haiti population covered by these surveys, suggesting a substantially higher cholera mortality rate than previously reported.

  16. Mortality Rates during Cholera Epidemic, Haiti, 2010–2011

    Science.gov (United States)

    Rondy, Marc; Boncy, Jacques; Munger, André; Mekaoui, Helmi; Rymshaw, Ellen; Page, Anne-Laure; Toure, Brahima; Degail, Marie Amelie; Nicolas, Sarala; Grandesso, Francesco; Ginsbourger, Maud; Polonsky, Jonathan; Alberti, Kathryn P.; Terzian, Mego; Olson, David; Porten, Klaudia; Ciglenecki, Iza

    2016-01-01

    The 2010 cholera epidemic in Haiti was one of the largest cholera epidemics ever recorded. To estimate the magnitude of the death toll during the first wave of the epidemic, we retrospectively conducted surveys at 4 sites in the northern part of Haiti. Overall, 70,903 participants were included; at all sites, the crude mortality rates (19.1–35.4 deaths/1,000 person-years) were higher than the expected baseline mortality rate for Haiti (9 deaths/1,000 person-years). This finding represents an excess of 3,406 deaths (2.9-fold increase) for the 4.4% of the Haiti population covered by these surveys, suggesting a substantially higher cholera mortality rate than previously reported. PMID:26886511

  17. Stochastic Processes in Epidemic Theory

    CERN Document Server

    Lefèvre, Claude; Picard, Philippe

    1990-01-01

    This collection of papers gives a representative cross-selectional view of recent developments in the field. After a survey paper by C. Lefèvre, 17 other research papers look at stochastic modeling of epidemics, both from a theoretical and a statistical point of view. Some look more specifically at a particular disease such as AIDS, malaria, schistosomiasis and diabetes.

  18. Epidemic Synchronization in Robotic Swarms

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Nielsen, Jens Frederik Dalsgaard; Ngo, Trung Dung

    2009-01-01

    Clock synchronization in swarms of networked mobile robots is studied in a probabilistic, epidemic framework. In this setting communication and synchonization is considered to be a randomized process, taking place at unplanned instants of geographical rendezvous between robots. In combination...... as an infinite-dimensional optimal controlproblem. Illustrative numerical examples are given and commented....

  19. The First American Cocaine Epidemic.

    Science.gov (United States)

    Courtwright, David T.

    1991-01-01

    Discusses the wave of cocaine abuse that followed the drug's recommendation by the late nineteenth-century medical community as a cure all. Details drug addiction among ethnic and social groups at the turn of the century. Warns that drug epidemics have important social and legal consequences. Suggests legal pressure may alter the form of drug…

  20. Opioids: The Prescription Drug & Heroin Overdose Epidemic

    Science.gov (United States)

    ... About the Epidemic Help, Resources and Information National Opioids Crisis Search Search National Helpline SAMHSA’s National Helpline ... 1-800-662-4357 Visit Helpline Website THE OPIOID EPIDEMIC IN NUMBERS 80% Nearly 80% of heroin ...

  1. The global spread of HIV-1 subtype B epidemic.

    Science.gov (United States)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G; Lepej, Snjezana J; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie-Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne-Mieke; Paraskevis, Dimitrios

    2016-12-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti to United States. However, the pattern of the subsequent spread still remains poorly understood. Here we analyze a large dataset of globally representative HIV-1 subtype B strains to map their spread around the world over the last 50years and describe significant spread patterns. We show that subtype B travelled from North America to Western Europe in different occasions, while Central/Eastern Europe remained isolated for the most part of the early epidemic. Looking with more detail in European countries we see that the United Kingdom, France and Switzerland exchanged viral isolates with non-European countries than with European ones. The observed pattern is likely to mirror geopolitical landmarks in the post-World War II era, namely the rise and the fall of the Iron Curtain and the European colonialism. In conclusion, HIV-1 spread through specific migration routes which are consistent with geopolitical factors that affected human activities during the last 50years, such as migration, tourism and trade. Our findings support the argument that epidemic control policies should be global and incorporate political and socioeconomic factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  2. [Epidemic process of gonorrhea in modern world].

    Science.gov (United States)

    Kostiukova, N N; Bekhalo, V A

    2009-01-01

    Gonorrhea in spite of its fully elucidated etiopathogenesis and available drugs for etiotropic therapy belongs to infections which are not controlled by vaccination due to absence of immunity formation. Analysis of scientific publication, statistical materials and WHO's data showed that epidemic process of gonorrhea infection depends mainly from people's behaviour, first of all, sexual. Modern epidemic process of gonorrhea infection consists from irregular increases and decreases of incidence due to various reasons. Reasons for increases of incidence appear to be simultaneous action of a range of biologic and anthropogenic factors. First reason--rapid increase of resistance of gonococci to widely used antibacterial preparations as well as synergy of pathogenic effects between HIV and gonococci; anthropogenic--wars, increase of high-risk groups due to urbanization, use of oral contraceptives, rise of prostitution, migration, inadequate access to medical care, poverty, intensification of intercourses (including hetero- and homosexual) between people, as well as demographic changes--increase of proportion of young people in population structure. Same but reciprocal factors lead to decrease of morbidity. Of them, the following were considered as most important: mass implementation of new effective antimicrobial drug as well as intensification of sanitary education, availability of early diagnostics and treatment, increase of material and cultural standards of life, decrease in number of persons belonging to high risk groups. Yet, capabilities of modern science expressed only in continuous development of new antibacterial drugs active against circulating population of gonococci, which is resistant to previously used drug.

  3. Influenza in Poland in 2013 and 2013/2014 epidemic season

    Science.gov (United States)

    Kondratiuk, Katarzyna; Czarkowski, Mirosław P; Hallmann-Szelińska, Ewelina; Staszewska, Ewa; Bednarska, Karolina; Cielebąk, Ewa; Brydak, Lidia B

    2016-01-01

    Analysis of epidemiological situation of influenza in Poland in 2013 and 2013/14 epidemic season in reference to previous years and seasons. Analysis was based on: 1) data collected within influenza routine surveillance system in Poland, including data published in annual bulletins “Infectious diseases and poisonings in Poland” as well as unpublished data gathered in the Department of Epidemiology of the NIPH-NIH; 2) data collected within influenza system - Sentinel, and beyond this system, concerning results of virological tests carried out in 2013/14 epidemic season in the Department of Influenza Research, National Influenza Center in the NIPHNIH and/or laboratories of provincial sanitary and epidemiological stations which are gathered in the National Influenza Center. Compared to 2012, the number of influenza and influenza-like cases increased more than twofold in 2013 in Poland. A total of 3 164 405 cases were reported. Incidence was 8 218.7 per 100,000 population (33 733.2 in 0-4 age group). As many as 0.45% of patients were referred to hospitals. According to the data of the Central Statistical Office, 115 deaths due to influenza were notified. Based on the data of the sanitary inspection (incomplete data), the percentage of population vaccinated against influenza was 2.4% (7.7% of persons aged more than 64 years). A total of 2 780 945 cases were registered in 2013/14 epidemic season. Its peak was reported in March 2014. Incidence was 7 224.0 per 100,000 population (35 172.8 in 0-4 age group). Compared to 2012/13 epidemic season, it was lower by 8.0%. Incidence rates ranged from 29 339.6 in pomorskie voivodeship to 1 306.5 in lubuskie voivodeship. Nearly a half of all cases (48.7%) were registered in children and adolescents up to 15 years. As many as 0.34% of patients were referred to hospitals (0.87% of persons aged more than 64 years). From the data of the Central Statistical Office transpires that 8 deaths due to influenza were reported in epidemic

  4. High proportion of intestinal colonization with successful epidemic clones of ESBL-producing Enterobacteriaceae in a neonatal intensive care unit in Ecuador.

    Directory of Open Access Journals (Sweden)

    Viveka Nordberg

    Full Text Available BACKGROUND AND AIMS: Neonatal infections caused by Extended-spectrum beta-lactamase (ESBL-producing bacteria are associated with increased morbidity and mortality. No data are available on neonatal colonization with ESBL-producing bacteria in Ecuador. The aim of this study was to determine the proportion of intestinal colonization with ESBL-producing Enterobacteriaceae, their resistance pattern and risk factors of colonization in a neonatal intensive care unit in Ecuador. METHODS: During a three month period, stool specimens were collected every two weeks from hospitalized neonates. Species identification and susceptibility testing were performed with Vitek2, epidemiologic typing with automated repetitive PCR. Associations between groups were analyzed using the Pearson X (2 test and Fisher exact test. A forward step logistic regression model identified significant predictors for colonization. RESULTS: Fifty-six percent of the neonates were colonized with ESBL-producing Enterobacteriaceae. Length of stay longer than 20 days and enteral feeding with a combination of breastfeeding and formula feeding were significantly associated with ESBL-colonization. The strains found were E. coli (EC, 89% and K. pneumoniae (KP, 11% and epidemiological typing divided these isolates in two major clusters. All EC and KP had bla CTX-M group 1 except for a unique EC isolate that had bla CTX-M group 9. Multi-locus sequence typing performed on the K. pneumoniae strains showed that the strains belonged to ST855 and ST897. The two detected STs belong to two different epidemic clonal complexes (CC, CC11 and CC14, which previously have been associated with dissemination of carbapenemases. None of the E. coli strains belonged to the epidemic ST 131 clone. CONCLUSIONS: More than half of the neonates were colonized with ESBL-producing Enterobacteriaceae where the main risk factor for colonization was length of hospital stay. Two of the isolated clones were epidemic and known

  5. Genomic Dissection of an Icelandic Epidemic of Respiratory Disease in Horses and Associated Zoonotic Cases

    Directory of Open Access Journals (Sweden)

    Sigríður Bjornsdíóttir

    2017-08-01

    Full Text Available Iceland is free of the major infectious diseases of horses. However, in 2010 an epidemic of respiratory disease of unknown cause spread through the country’s native horse population of 77,000. Microbiological investigations ruled out known viral agents but identified the opportunistic pathogen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus in diseased animals. We sequenced the genomes of 257 isolates of S. zooepidemicus to differentiate epidemic from endemic strains. We found that although multiple endemic clones of S. zooepidemicus were present, one particular clone, sequence type 209 (ST209, was likely to have been responsible for the epidemic. Concurrent with the epidemic, ST209 was also recovered from a human case of septicemia, highlighting the pathogenic potential of this strain. Epidemiological investigation revealed that the incursion of this strain into one training yard during February 2010 provided a nidus for the infection of multiple horses that then transmitted the strain to farms throughout Iceland. This study represents the first time that whole-genome sequencing has been used to investigate an epidemic on a national scale to identify the likely causative agent and the link to an associated zoonotic infection. Our data highlight the importance of national biosecurity to protect vulnerable populations of animals and also demonstrate the potential impact of S. zooepidemicus transmission to other animals, including humans.

  6. Epidemic thresholds for bipartite networks

    Science.gov (United States)

    Hernández, D. G.; Risau-Gusman, S.

    2013-11-01

    It is well known that sexually transmitted diseases (STD) spread across a network of human sexual contacts. This network is most often bipartite, as most STD are transmitted between men and women. Even though network models in epidemiology have quite a long history now, there are few general results about bipartite networks. One of them is the simple dependence, predicted using the mean field approximation, between the epidemic threshold and the average and variance of the degree distribution of the network. Here we show that going beyond this approximation can lead to qualitatively different results that are supported by numerical simulations. One of the new features, that can be relevant for applications, is the existence of a critical value for the infectivity of each population, below which no epidemics can arise, regardless of the value of the infectivity of the other population.

  7. Multiple routes transmitted epidemics on multiplex networks

    International Nuclear Information System (INIS)

    Zhao, Dawei; Li, Lixiang; Peng, Haipeng; Luo, Qun; Yang, Yixian

    2014-01-01

    This letter investigates the multiple routes transmitted epidemic process on multiplex networks. We propose detailed theoretical analysis that allows us to accurately calculate the epidemic threshold and outbreak size. It is found that the epidemic can spread across the multiplex network even if all the network layers are well below their respective epidemic thresholds. Strong positive degree–degree correlation of nodes in multiplex network could lead to a much lower epidemic threshold and a relatively smaller outbreak size. However, the average similarity of neighbors from different layers of nodes has no obvious effect on the epidemic threshold and outbreak size. -- Highlights: •We studies multiple routes transmitted epidemic process on multiplex networks. •SIR model and bond percolation theory are used to analyze the epidemic processes. •We derive equations to accurately calculate the epidemic threshold and outbreak size. •ASN has no effect on the epidemic threshold and outbreak size. •Strong positive DDC leads to a lower epidemic threshold and a smaller outbreak size.

  8. Legionella pneumophila pangenome reveals strain-specific virulence factors

    Directory of Open Access Journals (Sweden)

    Peris-Bondia Francesc

    2010-03-01

    Full Text Available Abstract Background Legionella pneumophila subsp. pneumophila is a gram-negative γ-Proteobacterium and the causative agent of Legionnaires' disease, a form of epidemic pneumonia. It has a water-related life cycle. In industrialized cities L. pneumophila is commonly encountered in refrigeration towers and water pipes. Infection is always via infected aerosols to humans. Although many efforts have been made to eradicate Legionella from buildings, it still contaminates the water systems. The town of Alcoy (Valencian Region, Spain has had recurrent outbreaks since 1999. The strain "Alcoy 2300/99" is a particularly persistent and recurrent strain that was isolated during one of the most significant outbreaks between the years 1999-2000. Results We have sequenced the genome of the particularly persistent L. pneumophila strain Alcoy 2300/99 and have compared it with four previously sequenced strains known as Philadelphia (USA, Lens (France, Paris (France and Corby (England. Pangenome analysis facilitated the identification of strain-specific features, as well as some that are shared by two or more strains. We identified: (1 three islands related to anti-drug resistance systems; (2 a system for transport and secretion of heavy metals; (3 three systems related to DNA transfer; (4 two CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats systems, known to provide resistance against phage infections, one similar in the Lens and Alcoy strains, and another specific to the Paris strain; and (5 seven islands of phage-related proteins, five of which seem to be strain-specific and two shared. Conclusions The dispensable genome disclosed by the pangenomic analysis seems to be a reservoir of new traits that have mainly been acquired by horizontal gene transfer and could confer evolutionary advantages over strains lacking them.

  9. A new epidemic model of computer viruses

    Science.gov (United States)

    Yang, Lu-Xing; Yang, Xiaofan

    2014-06-01

    This paper addresses the epidemiological modeling of computer viruses. By incorporating the effect of removable storage media, considering the possibility of connecting infected computers to the Internet, and removing the conservative restriction on the total number of computers connected to the Internet, a new epidemic model is proposed. Unlike most previous models, the proposed model has no virus-free equilibrium and has a unique endemic equilibrium. With the aid of the theory of asymptotically autonomous systems as well as the generalized Poincare-Bendixson theorem, the endemic equilibrium is shown to be globally asymptotically stable. By analyzing the influence of different system parameters on the steady number of infected computers, a collection of policies is recommended to prohibit the virus prevalence.

  10. Epidemic spread on weighted networks.

    Directory of Open Access Journals (Sweden)

    Christel Kamp

    Full Text Available The contact structure between hosts shapes disease spread. Most network-based models used in epidemiology tend to ignore heterogeneity in the weighting of contacts between two individuals. However, this assumption is known to be at odds with the data for many networks (e.g. sexual contact networks and to have a critical influence on epidemics' behavior. One of the reasons why models usually ignore heterogeneity in transmission is that we currently lack tools to analyze weighted networks, such that most studies rely on numerical simulations. Here, we present a novel framework to estimate key epidemiological variables, such as the rate of early epidemic expansion (r0 and the basic reproductive ratio (R0, from joint probability distributions of number of partners (contacts and number of interaction events through which contacts are weighted. These distributions are much easier to infer than the exact shape of the network, which makes the approach widely applicable. The framework also allows for a derivation of the full time course of epidemic prevalence and contact behaviour, which we validate with numerical simulations on networks. Overall, incorporating more realistic contact networks into epidemiological models can improve our understanding of the emergence and spread of infectious diseases.

  11. Understanding the Cholera Epidemic, Haiti

    Science.gov (United States)

    Barrais, Robert; Faucher, Benoît; Haus, Rachel; Piarroux, Martine; Gaudart, Jean; Magloire, Roc; Raoult, Didier

    2011-01-01

    After onset of a cholera epidemic in Haiti in mid-October 2010, a team of researchers from France and Haiti implemented field investigations and built a database of daily cases to facilitate identification of communes most affected. Several models were used to identify spatiotemporal clusters, assess relative risk associated with the epidemic’s spread, and investigate causes of its rapid expansion in Artibonite Department. Spatiotemporal analyses highlighted 5 significant clusters (p<0.001): 1 near Mirebalais (October 16–19) next to a United Nations camp with deficient sanitation, 1 along the Artibonite River (October 20–28), and 3 caused by the centrifugal epidemic spread during November. The regression model indicated that cholera more severely affected communes in the coastal plain (risk ratio 4.91) along the Artibonite River downstream of Mirebalais (risk ratio 4.60). Our findings strongly suggest that contamination of the Artibonite and 1 of its tributaries downstream from a military camp triggered the epidemic. PMID:21762567

  12. Large measles epidemic in the Netherlands, May 2013 to March 2014: changing epidemiology.

    Science.gov (United States)

    Woudenberg, Tom; van Binnendijk, Rob S; Sanders, Elisabeth A M; Wallinga, Jacco; de Melker, Hester E; Ruijs, Wilhelmina L M; Hahné, Susan J M

    2017-01-19

    Since the early 1990s, the Netherlands has experienced several large measles epidemics, in 1992-94, 1999-2000 and in 2013-14. These outbreaks mainly affected orthodox Protestants, a geographically clustered population with overall lower measles-mumps-rubella first dose (MMR-1) vaccination coverage (60%) than the rest of the country (> 95%). In the 2013-14 epidemic described here, which occurred between 27 May 2013 and 12 March 2014, 2,700 cases were reported. Several control measures were implemented including MMR vaccination for 6-14-month-olds and recommendations to reduce the risk in healthcare workers. The vast majority of reported cases were unvaccinated (94%, n = 2,539), mostly for religious reasons (84%, n = 2,135). The median age in the epidemic was 10 years, 4 years older than in the previous epidemic in 1999-2000. A likely explanation is that the inter-epidemic interval before the 2013-2014 epidemic was longer than the interval before the 1999-2000 epidemic. The size of the unvaccinated orthodox Protestant community is insufficient to allow endemic transmission of measles in the Netherlands. However, large epidemics are expected in the future, which is likely to interfere with measles elimination in the Netherlands and elsewhere. This article is copyright of The Authors, 2017.

  13. Modernising epidemic science: enabling patient-centred research during epidemics.

    Science.gov (United States)

    Rojek, Amanda M; Horby, Peter W

    2016-12-19

    Emerging and epidemic infectious disease outbreaks are a significant public health problem and global health security threat. As an outbreak begins, epidemiological investigations and traditional public health responses are generally mounted very quickly. However, patient-centred research is usually not prioritised when planning and enacting the response. Instead, the clinical research response occurs subsequent to and separate from the public health response, and is inadequate for evidence-based decision-making at the bedside or in the offices of public health policymakers. The deficiencies of the clinical research response to severe acute respiratory syndrome, pandemic influenza, Middle East respiratory syndrome coronavirus and Ebola virus demonstrate that current research models do not adequately inform and improve the quality of clinical care or public health response. Three suggestions for improvements are made. First, integrate the data and sample collection needs for clinical and public health decision-making within a unified framework, combined with a risk-based, rather than a discipline-based, approach to ethical review and consent. Second, develop clinical study methods and tools that are specifically designed to meet the epidemiological and contextual challenges of emerging and epidemic infectious diseases. Third, invest in investigator-led clinical research networks that are primed and incentivised to respond to outbreak infections, and which can call on the support and resources of a central centre of excellence. It is crucial that the field of epidemic science matures to place patients at the heart of the response. This can only be achieved when patient-centred research is integrated in the outbreak response from day one and practical steps are taken to reduce the barriers to the generation of reliable and useful evidence.

  14. OmpU as a biomarker for rapid discrimination between toxigenic and epidemic Vibrio cholerae O1/O139 and non-epidemic Vibrio cholerae in a modified MALDI-TOF MS assay

    NARCIS (Netherlands)

    Paauw, A.; Trip, H.; Niemcewicz, M.; Sellek, R.; Heng, J.M.E.; Mars-Groenendijk, R.H.; Jong, A.L. de; Majchrzykiewicz-Koehorst, J.A.; Olsen, J.S.; Tsivtsivadze, E.

    2014-01-01

    Background Cholera is an acute diarrheal disease caused by Vibrio cholerae. Outbreaks are caused by a genetically homogenous group of strains from serogroup O1 or O139 that are able to produce the cholera toxin. Rapid detection and identification of these epidemic strains is essential for an

  15. The impact of multiple information on coupled awareness-epidemic dynamics in multiplex networks

    Science.gov (United States)

    Pan, Yaohui; Yan, Zhijun

    2018-02-01

    Growing interest has emerged in the study of the interplay between awareness and epidemics in multiplex networks. However, previous studies on this issue usually assume that all aware individuals take the same level of precautions, ignoring individual heterogeneity. In this paper, we investigate the coupled awareness-epidemic dynamics in multiplex networks considering individual heterogeneity. Here, the precaution levels are heterogeneous and depend on three types of information: contact information and local and global prevalence information. The results show that contact-based precautions can decrease the epidemic prevalence and augment the epidemic threshold, but prevalence-based precautions, regardless of local or global information, can only decrease the epidemic prevalence. Moreover, unlike previous studies in single-layer networks, we do not find a greater impact of local prevalence information on the epidemic prevalence compared to global prevalence information. In addition, we find that the altruistic behaviors of infected individuals can effectively suppress epidemic spreading, especially when the level of contact-based precaution is high.

  16. SIS Epidemic Propagation on Hypergraphs.

    Science.gov (United States)

    Bodó, Ágnes; Katona, Gyula Y; Simon, Péter L

    2016-04-01

    Mathematical modelling of epidemic propagation on networks is extended to hypergraphs in order to account for both the community structure and the nonlinear dependence of the infection pressure on the number of infected neighbours. The exact master equations of the propagation process are derived for an arbitrary hypergraph given by its incidence matrix. Based on these, moment closure approximation and mean-field models are introduced and compared to individual-based stochastic simulations. The simulation algorithm, developed for networks, is extended to hypergraphs. The effects of hypergraph structure and the model parameters are investigated via individual-based simulation results.

  17. A retrospective study detects a novel variant of porcine epidemic diarrhea virus in England in archived material from the year 2000

    Directory of Open Access Journals (Sweden)

    Falko Steinbach

    2016-10-01

    Full Text Available Outbreaks of porcine epidemic diarrhea (PED were first recorded in England in the 1970s and continued to be confirmed until 2002. Retrospective analysis of archived material from one of the last confirmed cases in England in the year 2000 demonstrates the previous existence of a very diverse PED virus strain. Following the outbreaks of PED in North America in 2013, there has been renewed interest in phylogenetic analysis of sequences from PEDV strains worldwide. There is a gap in the available sequence data between the mid 1980s and the mid 2000s. This work is an example of how this gap can be at least partially filled by the examination of archived material.

  18. Human enterovirus 71 epidemics: what's next?

    Science.gov (United States)

    Yip, Cyril C. Y.; Lau, Susanna K. P.; Woo, Patrick C. Y.; Yuen, Kwok-Yung

    2013-01-01

    Human enterovirus 71 (EV71) epidemics have affected various countries in the past 40 years. EV71 commonly causes hand, foot and mouth disease (HFMD) in children, but can result in neurological and cardiorespiratory complications in severe cases. Genotypic changes of EV71 have been observed in different places over time, with the emergence of novel genotypes or subgenotypes giving rise to serious outbreaks. Since the late 1990s, intra- and inter-typic recombination events in EV71 have been increasingly reported in the Asia-Pacific region. In particular, ‘double-recombinant’ EV71 strains belonging to a novel genotype D have been predominant in mainland China and Hong Kong over the last decade, though co-circulating with a minority of other EV71 subgenotypes and coxsackie A viruses. Continuous surveillance and genome studies are important to detect potential novel mutants or recombinants in the near future. Rapid and sensitive molecular detection of EV71 is of paramount importance in anticipating and combating EV71 outbreaks. PMID:24119538

  19. Contact allergy epidemics and their controls

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Johansen, Jeanne Duus; Menné, Torkil

    2007-01-01

    Contact dermatitis can be severe and lead to sick leave as well as significant healthcare expenses. The aim of this review is to present the published knowledge on 6 historical epidemics of contact allergy to apply this knowledge on the prevention and control of future contact allergy epidemics...... to prevent contact allergy epidemics. It is essential that dermatologist, scientists, administrators, and consumers organize and structure known methods to accelerate the control of emerging contact allergens....

  20. Epidemic Survivability: Characterizing Networks Under Epidemic-like Failure Propagation Scenarios

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

    2013-01-01

    in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur......, such as in other multiple failure scenarios, identifying the level of vulnerability offered by a network is one of the main challenges. In this paper, we present epidemic survivability, a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Moreover......, this metric is able to identify the set of nodes which are more vulnerable under an epidemic attack. In addition, two applications of epidemic survivability are provided. First, we introduce epidemic criticality, a novel robustness metric for epidemic failure scenarios. A case study shows the utility...

  1. Epidemic Survivability: Characterizing Networks Under Epidemic-like Failure Propagation Scenarios

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

    2013-01-01

    Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models in telecommunicat......Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models...... in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur...

  2. Can rewiring strategy control the epidemic spreading?

    Science.gov (United States)

    Dong, Chao; Yin, Qiuju; Liu, Wenyang; Yan, Zhijun; Shi, Tianyu

    2015-11-01

    Relation existed in the social contact network can affect individuals' behaviors greatly. Considering the diversity of relation intimacy among network nodes, an epidemic propagation model is proposed by incorporating the link-breaking threshold, which is normally neglected in the rewiring strategy. The impact of rewiring strategy on the epidemic spreading in the weighted adaptive network is explored. The results show that the rewiring strategy cannot always control the epidemic prevalence, especially when the link-breaking threshold is low. Meanwhile, as well as strong links, weak links also play a significant role on epidemic spreading.

  3. Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control.

    Science.gov (United States)

    Abubakar, Abdinasir; Bwire, Godfrey; Azman, Andrew S; Bouhenia, Malika; Deng, Lul L; Wamala, Joseph F; Rumunu, John; Kagirita, Atek; Rauzier, Jean; Grout, Lise; Martin, Stephen; Orach, Christopher Garimoi; Luquero, Francisco J; Quilici, Marie-Laure

    2018-05-01

    Combining the official cholera line list data and outbreak investigation reports from the ministries of health in Uganda and South Sudan with molecular analysis of Vibrio cholerae strains revealed the interrelatedness of the epidemics in both countries in 2014. These results highlight the need for collaboration to control cross-border outbreaks.

  4. Climate-based models for understanding and forecasting dengue epidemics.

    Directory of Open Access Journals (Sweden)

    Elodie Descloux

    Full Text Available BACKGROUND: Dengue dynamics are driven by complex interactions between human-hosts, mosquito-vectors and viruses that are influenced by environmental and climatic factors. The objectives of this study were to analyze and model the relationships between climate, Aedes aegypti vectors and dengue outbreaks in Noumea (New Caledonia, and to provide an early warning system. METHODOLOGY/PRINCIPAL FINDINGS: Epidemiological and meteorological data were analyzed from 1971 to 2010 in Noumea. Entomological surveillance indices were available from March 2000 to December 2009. During epidemic years, the distribution of dengue cases was highly seasonal. The epidemic peak (March-April lagged the warmest temperature by 1-2 months and was in phase with maximum precipitations, relative humidity and entomological indices. Significant inter-annual correlations were observed between the risk of outbreak and summertime temperature, precipitations or relative humidity but not ENSO. Climate-based multivariate non-linear models were developed to estimate the yearly risk of dengue outbreak in Noumea. The best explicative meteorological variables were the number of days with maximal temperature exceeding 32°C during January-February-March and the number of days with maximal relative humidity exceeding 95% during January. The best predictive variables were the maximal temperature in December and maximal relative humidity during October-November-December of the previous year. For a probability of dengue outbreak above 65% in leave-one-out cross validation, the explicative model predicted 94% of the epidemic years and 79% of the non epidemic years, and the predictive model 79% and 65%, respectively. CONCLUSIONS/SIGNIFICANCE: The epidemic dynamics of dengue in Noumea were essentially driven by climate during the last forty years. Specific conditions based on maximal temperature and relative humidity thresholds were determinant in outbreaks occurrence. Their persistence was

  5. Climate-based models for understanding and forecasting dengue epidemics.

    Science.gov (United States)

    Descloux, Elodie; Mangeas, Morgan; Menkes, Christophe Eugène; Lengaigne, Matthieu; Leroy, Anne; Tehei, Temaui; Guillaumot, Laurent; Teurlai, Magali; Gourinat, Ann-Claire; Benzler, Justus; Pfannstiel, Anne; Grangeon, Jean-Paul; Degallier, Nicolas; De Lamballerie, Xavier

    2012-01-01

    Dengue dynamics are driven by complex interactions between human-hosts, mosquito-vectors and viruses that are influenced by environmental and climatic factors. The objectives of this study were to analyze and model the relationships between climate, Aedes aegypti vectors and dengue outbreaks in Noumea (New Caledonia), and to provide an early warning system. Epidemiological and meteorological data were analyzed from 1971 to 2010 in Noumea. Entomological surveillance indices were available from March 2000 to December 2009. During epidemic years, the distribution of dengue cases was highly seasonal. The epidemic peak (March-April) lagged the warmest temperature by 1-2 months and was in phase with maximum precipitations, relative humidity and entomological indices. Significant inter-annual correlations were observed between the risk of outbreak and summertime temperature, precipitations or relative humidity but not ENSO. Climate-based multivariate non-linear models were developed to estimate the yearly risk of dengue outbreak in Noumea. The best explicative meteorological variables were the number of days with maximal temperature exceeding 32°C during January-February-March and the number of days with maximal relative humidity exceeding 95% during January. The best predictive variables were the maximal temperature in December and maximal relative humidity during October-November-December of the previous year. For a probability of dengue outbreak above 65% in leave-one-out cross validation, the explicative model predicted 94% of the epidemic years and 79% of the non epidemic years, and the predictive model 79% and 65%, respectively. The epidemic dynamics of dengue in Noumea were essentially driven by climate during the last forty years. Specific conditions based on maximal temperature and relative humidity thresholds were determinant in outbreaks occurrence. Their persistence was also crucial. An operational model that will enable health authorities to anticipate the

  6. Epidemic corruption: a bio-economic homology

    OpenAIRE

    Hathroubi, Salem

    2013-01-01

    This paper aims to study corruption as an epidemic phenomenon using the epidemic diffusion model of Kermack and Mc-Kendrick (1927). We seek to determine the dynamics of corruption and its impact on the composition of the population at a given time. We determine a threshold epidemiological corruption based on the approximation of the honest population.

  7. Epidemic Network Failures in Optical Transport Networks

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Katsikas, Dimitrios; Fagertun, Anna Manolova

    2013-01-01

    This paper presents a failure propagation model for transport networks which are affected by epidemic failures. The network is controlled using the GMPLS protocol suite. The Susceptible Infected Disabled (SID) epidemic model is investigated and new signaling functionality of GMPLS to support...

  8. Reemerging threat of epidemic typhus in Algeria.

    Science.gov (United States)

    Mokrani, K; Fournier, P E; Dalichaouche, M; Tebbal, S; Aouati, A; Raoult, D

    2004-08-01

    We report a case of epidemic typhus in a patient from the Batna region of Algeria, who presented with generalized febrile exanthema. The clinical diagnosis was confirmed by serological cross-adsorption followed by Western blotting. Our report emphasizes the threat of epidemic typhus in the highlands of Algeria.

  9. A break in the obesity epidemic?

    DEFF Research Database (Denmark)

    Visscher, T L S; Heitmann, B L; Rissanen, A

    2015-01-01

    epidemic. However, follow-ups of short duration may, in part, explain the apparent break or decrease in the obesity epidemic. On the other hand, a single focus on body mass index (BMI) ⩾25 or ⩾30 kg m(-)(2) is likely to mask a real increase in the obesity epidemic. And, in both children and adults, trends......Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look...... into the literature presented in recent reviews to address the major potential biases and distortions, and to develop insights about how to interpret the presented suggestions for a potential break in the obesity epidemic. Decreasing participation rates, the use of reported rather than measured data and small sample...

  10. Influenza surveillance in Europe: establishing epidemic thresholds by the Moving Epidemic Method

    Science.gov (United States)

    Vega, Tomás; Lozano, Jose Eugenio; Meerhoff, Tamara; Snacken, René; Mott, Joshua; Ortiz de Lejarazu, Raul; Nunes, Baltazar

    2012-01-01

    Please cite this paper as: Vega et al. (2012) Influenza surveillance in Europe: establishing epidemic thresholds by the moving epidemic method. Influenza and Other Respiratory Viruses 7(4), 546–558. Background  Timely influenza surveillance is important to monitor influenza epidemics. Objectives  (i) To calculate the epidemic threshold for influenza‐like illness (ILI) and acute respiratory infections (ARI) in 19 countries, as well as the thresholds for different levels of intensity. (ii) To evaluate the performance of these thresholds. Methods  The moving epidemic method (MEM) has been developed to determine the baseline influenza activity and an epidemic threshold. False alerts, detection lags and timeliness of the detection of epidemics were calculated. The performance was evaluated using a cross‐validation procedure. Results  The overall sensitivity of the MEM threshold was 71·8% and the specificity was 95·5%. The median of the timeliness was 1 week (range: 0–4·5). Conclusions  The method produced a robust and specific signal to detect influenza epidemics. The good balance between the sensitivity and specificity of the epidemic threshold to detect seasonal epidemics and avoid false alerts has advantages for public health purposes. This method may serve as standard to define the start of the annual influenza epidemic in countries in Europe. PMID:22897919

  11. Population-Level Immune-Mediated Adaptation in HIV-1 Polymerase during the North American Epidemic

    Science.gov (United States)

    Kinloch, Natalie N.; MacMillan, Daniel R.; Le, Anh Q.; Cotton, Laura A.; Bangsberg, David R.; Buchbinder, Susan; Carrington, Mary; Fuchs, Jonathan; Harrigan, P. Richard; Koblin, Beryl; Kushel, Margot; Markowitz, Martin; Mayer, Kenneth; Milloy, M. J.; Schechter, Martin T.; Wagner, Theresa; Walker, Bruce D.; Carlson, Jonathan M.; Poon, Art F. Y.

    2015-01-01

    ABSTRACT Human leukocyte antigen (HLA) class I-associated polymorphisms in HIV-1 that persist upon transmission to HLA-mismatched hosts may spread in the population as the epidemic progresses. Transmission of HIV-1 sequences containing such adaptations may undermine cellular immune responses to the incoming virus in future hosts. Building upon previous work, we investigated the extent of HLA-associated polymorphism accumulation in HIV-1 polymerase (Pol) through comparative analysis of linked HIV-1/HLA class I genotypes sampled during historic (1979 to 1989; n = 338) and modern (2001 to 2011; n = 278) eras from across North America (Vancouver, BC, Canada; Boston, MA; New York, NY; and San Francisco, CA). Phylogenies inferred from historic and modern HIV-1 Pol sequences were star-like in shape, with an inferred most recent common ancestor (epidemic founder virus) sequence nearly identical to the modern North American subtype B consensus sequence. Nevertheless, modern HIV-1 Pol sequences exhibited roughly 2-fold-higher patristic (tip-to-tip) genetic distances than historic sequences, with HLA pressures likely driving ongoing diversification. Moreover, the frequencies of published HLA-associated polymorphisms in individuals lacking the selecting HLA class I allele was on average ∼2.5-fold higher in the modern than in the historic era, supporting their spread in circulation, though some remained stable in frequency during this time. Notably, polymorphisms restricted by protective HLA alleles appear to be spreading to a greater relative extent than others, though these increases are generally of modest absolute magnitude. However, despite evidence of polymorphism spread, North American hosts generally remain at relatively low risk of acquiring an HIV-1 polymerase sequence substantially preadapted to their HLA profiles, even in the present era. IMPORTANCE HLA class I-restricted cytotoxic T-lymphocyte (CTL) escape mutations in HIV-1 that persist upon transmission may

  12. Diabetes mellitus: The epidemic of the century

    Science.gov (United States)

    Kharroubi, Akram T; Darwish, Hisham M

    2015-01-01

    The epidemic nature of diabetes mellitus in different regions is reviewed. The Middle East and North Africa region has the highest prevalence of diabetes in adults (10.9%) whereas, the Western Pacific region has the highest number of adults diagnosed with diabetes and has countries with the highest prevalence of diabetes (37.5%). Different classes of diabetes mellitus, type 1, type 2, gestational diabetes and other types of diabetes mellitus are compared in terms of diagnostic criteria, etiology and genetics. The molecular genetics of diabetes received extensive attention in recent years by many prominent investigators and research groups in the biomedical field. A large array of mutations and single nucleotide polymorphisms in genes that play a role in the various steps and pathways involved in glucose metabolism and the development, control and function of pancreatic cells at various levels are reviewed. The major advances in the molecular understanding of diabetes in relation to the different types of diabetes in comparison to the previous understanding in this field are briefly reviewed here. Despite the accumulation of extensive data at the molecular and cellular levels, the mechanism of diabetes development and complications are still not fully understood. Definitely, more extensive research is needed in this field that will eventually reflect on the ultimate objective to improve diagnoses, therapy and minimize the chance of chronic complications development. PMID:26131326

  13. Population structure of Pseudomonas aeruginosa from five Mediterranean countries: evidence for frequent recombination and epidemic occurrence of CC235.

    Directory of Open Access Journals (Sweden)

    Makaoui Maatallah

    Full Text Available Several studies in recent years have provided evidence that Pseudomonas aeruginosa has a non-clonal population structure punctuated by highly successful epidemic clones or clonal complexes. The role of recombination in the diversification of P. aeruginosa clones has been suggested, but not yet demonstrated using multi-locus sequence typing (MLST. Isolates of P. aeruginosa from five Mediterranean countries (n = 141 were subjected to pulsed-field gel electrophoresis (PFGE, serotyping and PCR targeting the virulence genes exoS and exoU. The occurrence of multi-resistance (≥ 3 antipseudomonal drugs was analyzed with disk diffusion according to EUCAST. MLST was performed on a subset of strains (n = 110 most of them had a distinct PFGE variant. MLST data were analyzed with Bionumerics 6.0, using minimal spanning tree (MST as well as eBURST. Measurement of clonality was assessed by the standardized index of association (I(A (S. Evidence of recombination was estimated by ClonalFrame as well as SplitsTree4.0. The MST analysis connected 70 sequence types, among which ST235 was by far the most common. ST235 was very frequently associated with the O11 serotype, and frequently displayed multi-resistance and the virulence genotype exoS⁻/exoU⁺. ClonalFrame linked several groups previously identified by eBURST and MST, and provided insight to the evolutionary events occurring in the population; the recombination/mutation ratio was found to be 8.4. A Neighbor-Net analysis based on the concatenated sequences revealed a complex network, providing evidence of frequent recombination. The index of association when all the strains were considered indicated a freely recombining population. P. aeruginosa isolates from the Mediterranean countries display an epidemic population structure, particularly dominated by ST235-O11, which has earlier also been coupled to the spread of ß-lactamases in many countries.

  14. Implication of lateral genetic transfer in the emergence of Aeromonas hydrophila isolates of epidemic outbreaks in channel catfish.

    Directory of Open Access Journals (Sweden)

    Mohammad J Hossain

    Full Text Available To investigate the molecular basis of the emergence of Aeromonas hydrophila responsible for an epidemic outbreak of motile aeromonad septicemia of catfish in the Southeastern United States, we sequenced 11 A. hydrophila isolates that includes five reference and six recent epidemic isolates. Comparative genomics revealed that recent epidemic A. hydrophila isolates are highly clonal, whereas reference isolates are greatly diverse. We identified 55 epidemic-associated genetic regions with 313 predicted genes that are present in epidemic isolates but absent from reference isolates and 35% of these regions are located within genomic islands, suggesting their acquisition through lateral gene transfer. The epidemic-associated regions encode predicted prophage elements, pathogenicity islands, metabolic islands, fitness islands and genes of unknown functions, and 34 of the genes encoded in these regions were predicted as virulence factors. We found two pilus biogenesis gene clusters encoded within predicted pathogenicity islands. A functional metabolic island that encodes a complete pathway for myo-inositol catabolism was evident by the ability of epidemic A. hydrophila isolates to use myo-inositol as a sole carbon source. Testing of A. hydrophila field isolates found a consistent correlation between myo-inositol utilization as a sole carbon source and the presence of an epidemic-specific genetic marker. All epidemic isolates and one reference isolate shared a novel O-antigen cluster. Altogether we identified four different O-antigen biosynthesis gene clusters within the 11 sequenced A. hydrophila genomes. Our study reveals new insights into the evolutionary changes that have resulted in the emergence of recent epidemic A. hydrophila strains.

  15. Temporal prediction of epidemic patterns in community networks

    International Nuclear Information System (INIS)

    Peng, Xiao-Long; Xu, Xin-Jian; Fu, Xinchu; Small, Michael

    2013-01-01

    Most previous studies of epidemic dynamics on complex networks suppose that the disease will eventually stabilize at either a disease-free state or an endemic one. In reality, however, some epidemics always exhibit sporadic and recurrent behaviour in one region because of the invasion from an endemic population elsewhere. In this paper we address this issue and study a susceptible–infected–susceptible epidemiological model on a network consisting of two communities, where the disease is endemic in one community but alternates between outbreaks and extinctions in the other. We provide a detailed characterization of the temporal dynamics of epidemic patterns in the latter community. In particular, we investigate the time duration of both outbreak and extinction, and the time interval between two consecutive inter-community infections, as well as their frequency distributions. Based on the mean-field theory, we theoretically analyse these three timescales and their dependence on the average node degree of each community, the transmission parameters and the number of inter-community links, which are in good agreement with simulations, except when the probability of overlaps between successive outbreaks is too large. These findings aid us in better understanding the bursty nature of disease spreading in a local community, and thereby suggesting effective time-dependent control strategies. (paper)

  16. Distinguishing epidemic waves from disease spillover in a wildlife population.

    Science.gov (United States)

    Craft, Meggan E; Volz, Erik; Packer, Craig; Meyers, Lauren Ancel

    2009-05-22

    Serengeti lions frequently experience viral outbreaks. In 1994, one-third of Serengeti lions died from canine distemper virus (CDV). Based on the limited epidemiological data available from this period, it has been unclear whether the 1994 outbreak was propagated by lion-to-lion transmission alone or involved multiple introductions from other sympatric carnivore species. More broadly, we do not know whether contacts between lions allow any pathogen with a relatively short infectious period to percolate through the population (i.e. reach epidemic proportions). We built one of the most realistic contact network models for a wildlife population to date, based on detailed behavioural and movement data from a long-term lion study population. The model allowed us to identify previously unrecognized biases in the sparse data from the 1994 outbreak and develop methods for judiciously inferring disease dynamics from typical wildlife samples. Our analysis of the model in light of the 1994 outbreak data strongly suggest that, although lions are sufficiently well connected to sustain epidemics of CDV-like diseases, the 1994 epidemic was fuelled by multiple spillovers from other carnivore species, such as jackals and hyenas.

  17. A Study Of Hospitalised Cases Of Acute Gastroenteritis Admitted In Civil Hospital, Ahmedabad During The Epidemic Of 1988.

    Directory of Open Access Journals (Sweden)

    Kumar P

    1990-01-01

    Full Text Available An epidemic of gastroenteritis occurred between July and November 1988 in Ahmedabad City. The epidemic originated from Saijpur Bocha locality of the city and thereafter several new foci also development. The city has a number of Government and Municipal Corporation run hospitals as well as private treatment centers where these cases were treated. The Corporation also took measures to control this epidemic. The present study analysis the cases of gastroenteritis (2008 and cholera (112 admitted to the Civil Hospital during this period. The cases occurred in all age groups and both sexes. However, when compared with hospital records of previous non- epidemic years, more cases were found in the adult population and the case fatality rate was low during this epidemic. The study details the various control measures taken by the Municipal Corporation.

  18. Modeling Epidemics Spreading on Social Contact Networks.

    Science.gov (United States)

    Zhang, Zhaoyang; Wang, Honggang; Wang, Chonggang; Fang, Hua

    2015-09-01

    Social contact networks and the way people interact with each other are the key factors that impact on epidemics spreading. However, it is challenging to model the behavior of epidemics based on social contact networks due to their high dynamics. Traditional models such as susceptible-infected-recovered (SIR) model ignore the crowding or protection effect and thus has some unrealistic assumption. In this paper, we consider the crowding or protection effect and develop a novel model called improved SIR model. Then, we use both deterministic and stochastic models to characterize the dynamics of epidemics on social contact networks. The results from both simulations and real data set conclude that the epidemics are more likely to outbreak on social contact networks with higher average degree. We also present some potential immunization strategies, such as random set immunization, dominating set immunization, and high degree set immunization to further prove the conclusion.

  19. Can epidemics be non-communicable?

    DEFF Research Database (Denmark)

    Seeberg, Jens; Meinert, Lotte

    2015-01-01

    This article argues that the concept of communicability that is central to the distinction between communicable diseases (CDs) and noncommunicable diseases (NCDs) is poorly conceptualized. The epidemic spread of NCDs such as diabetes, depression, and eating disorders demonstrates...

  20. The hidden epidemic: confronting sexually transmitted diseases

    National Research Council Canada - National Science Library

    Eng, Thomas R; Butler, William T

    .... In addition, STDs increase the risk of HIV transmission. The Hidden Epidemic examines the scope of sexually transmitted infections in the United States and provides a critical assessment of the nation's response to this public health crisis...

  1. Epidemic spreading on weighted complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ye [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Liu, Chuang, E-mail: liuchuang@hznu.edu.cn [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Chu-Xu [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Zi-Ke, E-mail: zhangzike@gmail.com [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China)

    2014-01-31

    Nowadays, the emergence of online services provides various multi-relation information to support the comprehensive understanding of the epidemic spreading process. In this Letter, we consider the edge weights to represent such multi-role relations. In addition, we perform detailed analysis of two representative metrics, outbreak threshold and epidemic prevalence, on SIS and SIR models. Both theoretical and simulation results find good agreements with each other. Furthermore, experiments show that, on fully mixed networks, the weight distribution on edges would not affect the epidemic results once the average weight of whole network is fixed. This work may shed some light on the in-depth understanding of epidemic spreading on multi-relation and weighted networks.

  2. Epidemic spreading on weighted complex networks

    International Nuclear Information System (INIS)

    Sun, Ye; Liu, Chuang; Zhang, Chu-Xu; Zhang, Zi-Ke

    2014-01-01

    Nowadays, the emergence of online services provides various multi-relation information to support the comprehensive understanding of the epidemic spreading process. In this Letter, we consider the edge weights to represent such multi-role relations. In addition, we perform detailed analysis of two representative metrics, outbreak threshold and epidemic prevalence, on SIS and SIR models. Both theoretical and simulation results find good agreements with each other. Furthermore, experiments show that, on fully mixed networks, the weight distribution on edges would not affect the epidemic results once the average weight of whole network is fixed. This work may shed some light on the in-depth understanding of epidemic spreading on multi-relation and weighted networks.

  3. Epidemics and rumours in complex networks

    CERN Document Server

    Draief, Moez

    2009-01-01

    Information propagation through peer-to-peer systems, online social systems, wireless mobile ad hoc networks and other modern structures can be modelled as an epidemic on a network of contacts. Understanding how epidemic processes interact with network topology allows us to predict ultimate course, understand phase transitions and develop strategies to control and optimise dissemination. This book is a concise introduction for applied mathematicians and computer scientists to basic models, analytical tools and mathematical and algorithmic results. Mathematical tools introduced include coupling

  4. Detecting nonlinearity and chaos in epidemic data

    Energy Technology Data Exchange (ETDEWEB)

    Ellner, S.; Gallant, A.R. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Statistics; Theiler, J. [Santa Fe Inst., NM (United States)]|[Los Alamos National Lab., NM (United States)

    1993-08-01

    Historical data on recurrent epidemics have been central to the debate about the prevalence of chaos in biological population dynamics. Schaffer and Kot who first recognized that the abundance and accuracy of disease incidence data opened the door to applying a range of methods for detecting chaos that had been devised in the early 1980`s. Using attractor reconstruction, estimates of dynamical invariants, and comparisons between data and simulation of SEIR models, the ``case for chaos in childhood epidemics`` was made through a series of influential papers beginning in the mid 1980`s. The proposition that the precise timing and magnitude of epidemic outbreaks are deterministic but chaotic is appealing, since it raises the hope of finding determinism and simplicity beneath the apparently stochastic and complicated surface of the data. The initial enthusiasm for methods of detecting chaos in data has been followed by critical re-evaluations of their limitations. Early hopes of a ``one size fits all`` algorithm to diagnose chaos vs. noise in any data set have given way to a recognition that a variety of methods must be used, and interpretation of results must take into account the limitations of each method and the imperfections of the data. Our goals here are to outline some newer methods for detecting nonlinearity and chaos that have a solid statistical basis and are suited to epidemic data, and to begin a re-evaluation of the claims for nonlinear dynamics and chaos in epidemics using these newer methods. We also identify features of epidemic data that create problems for the older, better known methods of detecting chaos. When we ask ``are epidemics nonlinear?``, we are not questioning the existence of global nonlinearities in epidemic dynamics, such as nonlinear transmission rates. Our question is whether the data`s deviations from an annual cyclic trend (which would reflect global nonlinearities) are described by a linear, noise-driven stochastic process.

  5. Phylodynamic analysis of HIV sub-epidemics in Mochudi, Botswana

    Directory of Open Access Journals (Sweden)

    Vlad Novitsky

    2015-12-01

    Real-time HIV genotyping and breaking down local HIV epidemics into phylogenetically distinct sub-epidemics may help to reveal the structure and dynamics of HIV transmission networks in communities, and aid in the design of targeted interventions for members of the acute sub-epidemics that likely fuel local HIV/AIDS epidemics.

  6. Transcriptome Remodeling Contributes to Epidemic Disease Caused by the Human Pathogen Streptococcus pyogenes.

    Science.gov (United States)

    Beres, Stephen B; Kachroo, Priyanka; Nasser, Waleed; Olsen, Randall J; Zhu, Luchang; Flores, Anthony R; de la Riva, Ivan; Paez-Mayorga, Jesus; Jimenez, Francisco E; Cantu, Concepcion; Vuopio, Jaana; Jalava, Jari; Kristinsson, Karl G; Gottfredsson, Magnus; Corander, Jukka; Fittipaldi, Nahuel; Di Luca, Maria Chiara; Petrelli, Dezemona; Vitali, Luca A; Raiford, Annessa; Jenkins, Leslie; Musser, James M

    2016-05-31

    For over a century, a fundamental objective in infection biology research has been to understand the molecular processes contributing to the origin and perpetuation of epidemics. Divergent hypotheses have emerged concerning the extent to which environmental events or pathogen evolution dominates in these processes. Remarkably few studies bear on this important issue. Based on population pathogenomic analysis of 1,200 Streptococcus pyogenes type emm89 infection isolates, we report that a series of horizontal gene transfer events produced a new pathogenic genotype with increased ability to cause infection, leading to an epidemic wave of disease on at least two continents. In the aggregate, these and other genetic changes substantially remodeled the transcriptomes of the evolved progeny, causing extensive differential expression of virulence genes and altered pathogen-host interaction, including enhanced immune evasion. Our findings delineate the precise molecular genetic changes that occurred and enhance our understanding of the evolutionary processes that contribute to the emergence and persistence of epidemically successful pathogen clones. The data have significant implications for understanding bacterial epidemics and for translational research efforts to blunt their detrimental effects. The confluence of studies of molecular events underlying pathogen strain emergence, evolutionary genetic processes mediating altered virulence, and epidemics is in its infancy. Although understanding these events is necessary to develop new or improved strategies to protect health, surprisingly few studies have addressed this issue, in particular, at the comprehensive population genomic level. Herein we establish that substantial remodeling of the transcriptome of the human-specific pathogen Streptococcus pyogenes by horizontal gene flow and other evolutionary genetic changes is a central factor in precipitating and perpetuating epidemic disease. The data unambiguously show that

  7. Measles epidemics of variable lethality in the early 20th century.

    Science.gov (United States)

    Shanks, G Dennis; Hu, Zheng; Waller, Michael; Lee, Seung-eun; Terfa, Daniel; Howard, Alan; van Heyningen, Elizabeth; Brundage, John F

    2014-02-15

    Until the mid-20th century, mortality rates were often very high during measles epidemics, particularly among previously isolated populations (e.g., islanders), refugees/internees who were forcibly crowded into camps, and military recruits. Searching for insights regarding measles mortality rates, we reviewed historical records of measles epidemics on the Polynesian island of Rotuma (in 1911), in Boer War concentration camps (in 1900-1902), and in US Army mobilization camps during the First World War (in 1917-1918). Records classified measles deaths by date and clinical causes; by demographic characteristics, family relationships (for Rotuma islanders and Boer camp internees), and prior residences; and by camp (for Boer internees and US Army recruits). During the Rotuman and Boer War epidemics, measles-related mortality rates were high (up to 40%); however, mortality rates differed more than 10-fold across camps/districts, even though conditions were similar. During measles epidemics, most deaths among camp internees/military recruits were due to secondary bacterial pneumonias; in contrast, most deaths among Rotuman islanders were due to gastrointestinal complications. The clinical expressions, courses, and outcomes of measles during first-contact epidemics differ from those during camp epidemics. The degree of isolation from respiratory pathogens other than measles may significantly determine measles-related mortality risk.

  8. Large-scale application of highly-diluted bacteria for Leptospirosis epidemic control.

    Science.gov (United States)

    Bracho, Gustavo; Varela, Enrique; Fernández, Rolando; Ordaz, Barbara; Marzoa, Natalia; Menéndez, Jorge; García, Luis; Gilling, Esperanza; Leyva, Richard; Rufín, Reynaldo; de la Torre, Rubén; Solis, Rosa L; Batista, Niurka; Borrero, Reinier; Campa, Concepción

    2010-07-01

    Leptospirosis is a zoonotic disease of major importance in the tropics where the incidence peaks in rainy seasons. Natural disasters represent a big challenge to Leptospirosis prevention strategies especially in endemic regions. Vaccination is an effective option but of reduced effectiveness in emergency situations. Homeoprophylactic interventions might help to control epidemics by using highly-diluted pathogens to induce protection in a short time scale. We report the results of a very large-scale homeoprophylaxis (HP) intervention against Leptospirosis in a dangerous epidemic situation in three provinces of Cuba in 2007. Forecast models were used to estimate possible trends of disease incidence. A homeoprophylactic formulation was prepared from dilutions of four circulating strains of Leptospirosis. This formulation was administered orally to 2.3 million persons at high risk in an epidemic in a region affected by natural disasters. The data from surveillance were used to measure the impact of the intervention by comparing with historical trends and non-intervention regions. After the homeoprophylactic intervention a significant decrease of the disease incidence was observed in the intervention regions. No such modifications were observed in non-intervention regions. In the intervention region the incidence of Leptospirosis fell below the historic median. This observation was independent of rainfall. The homeoprophylactic approach was associated with a large reduction of disease incidence and control of the epidemic. The results suggest the use of HP as a feasible tool for epidemic control, further research is warranted. 2010 Elsevier Ltd. All rights reserved.

  9. Deterministic Seirs Epidemic Model for Modeling Vital Dynamics, Vaccinations, and Temporary Immunity

    Directory of Open Access Journals (Sweden)

    Marek B. Trawicki

    2017-01-01

    Full Text Available In this paper, the author proposes a new SEIRS model that generalizes several classical deterministic epidemic models (e.g., SIR and SIS and SEIR and SEIRS involving the relationships between the susceptible S, exposed E, infected I, and recovered R individuals for understanding the proliferation of infectious diseases. As a way to incorporate the most important features of the previous models under the assumption of homogeneous mixing (mass-action principle of the individuals in the population N, the SEIRS model utilizes vital dynamics with unequal birth and death rates, vaccinations for newborns and non-newborns, and temporary immunity. In order to determine the equilibrium points, namely the disease-free and endemic equilibrium points, and study their local stability behaviors, the SEIRS model is rescaled with the total time-varying population and analyzed according to its epidemic condition R0 for two cases of no epidemic (R0 ≤ 1 and epidemic (R0 > 1 using the time-series and phase portraits of the susceptible s, exposed e, infected i, and recovered r individuals. Based on the experimental results using a set of arbitrarily-defined parameters for horizontal transmission of the infectious diseases, the proportional population of the SEIRS model consisted primarily of the recovered r (0.7–0.9 individuals and susceptible s (0.0–0.1 individuals (epidemic and recovered r (0.9 individuals with only a small proportional population for the susceptible s (0.1 individuals (no epidemic. Overall, the initial conditions for the susceptible s, exposed e, infected i, and recovered r individuals reached the corresponding equilibrium point for local stability: no epidemic (DFE X ¯ D F E and epidemic (EE X ¯ E E .

  10. An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa

    Science.gov (United States)

    Grover-Kopec, Emily; Kawano, Mika; Klaver, Robert W.; Blumenthal, Benno; Ceccato, Pietro; Connor, Stephen J.

    2005-01-01

    Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response.Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization.The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI) that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to previous seasons and climatological

  11. An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa

    Directory of Open Access Journals (Sweden)

    Ceccato Pietro

    2005-01-01

    Full Text Available Abstract Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response. Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization. The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to

  12. [Extent and impact of the measles epidemics of 1846 and 1882 in Iceland].

    Science.gov (United States)

    Gunnarsdottir, Sandra; Briem, Haraldur; Gottfredsson, Magnus

    2014-04-01

    Measles have increased in incidence in some parts of the developed world in the past 10-15 years. They can be fatal and lead to severe sequelae.Measles were infrequently introduced to Iceland in the 19th century and consequently, epidemics were few but associated with an extremely high mortality. The availability of 19th century church registries enables studies on the impact of measles on mortality. Historical accounts mention two major measles epidemics, starting mid-year 1846 and 1882. We analysed these two epidemics using contemporary historical sources, mainly original church registries. In the 1846 epidemic the data show a clear increase in mortality in June and reach a peak in July of 741 fatal cases total, a four-fold increase from expected baseline rate. The epidemic subsided in the ensuing five months. A cluster of measles was described in the eastern region of Iceland in 1869 but did not spread further. The epidemic of 1882 reached its peak in July, when 1084 individuals died, a five-fold increase from the expected rate. Excess mortality was highest in N-Isafjardarsysla county, 4,7 %, and none in A-Skaftafellssysla county where the illness was described 13 years previously. The highest numbers of fatal cases in the 1882 epidemic (64,6%) was among 0-4 year old children. The number of fatalities among women of child-bearing age was more than two-fold compared to men; the number of births 7-9 months following the 1882 peak dropped significantly by 50%. This study highlights the consequences of measles following introduction into a largely susceptible population and also documents the importance of herd immunity. Information can be identified on most individual fatalities during the 1846 and 1882 measles epidemics in Iceland.

  13. Increased number of deaths during a chikungunya epidemic in Pernambuco, Brazil.

    Science.gov (United States)

    Brito, Carlos Alexandre Antunes de; Teixeira, Maria Glória

    2017-09-01

    In early 2016, it was suspected that there were more deaths in Pernambuco than in previous years during an epidemic of chikungunya. This study tested whether there was an increased number of deaths and, if so, whether this increase could be related to a chikungunya epidemic. Indeed, there was an increase of 4235 deaths in 2016 compared to the average of the four previous years, and the highest differences were found during the peak period of the epidemic. It was evident that not all of these deaths could be attributed to complications of chikungunya. However, considering the temporal overlap, some of these deaths may have been caused by the aggravation of pre-existing comorbidities or complications caused directly by chikungunya virus infection.

  14. Recent results on the spatiotemporal modelling and comparative analysis of Black Death and bubonic plague epidemics

    Science.gov (United States)

    Christakos, G.; Olea, R.A.; Yu, H.-L.

    2007-01-01

    Background: This work demonstrates the importance of spatiotemporal stochastic modelling in constructing maps of major epidemics from fragmentary information, assessing population impacts, searching for possible etiologies, and performing comparative analysis of epidemics. Methods: Based on the theory previously published by the authors and incorporating new knowledge bases, informative maps of the composite space-time distributions were generated for important characteristics of two major epidemics: Black Death (14th century Western Europe) and bubonic plague (19th-20th century Indian subcontinent). Results: The comparative spatiotemporal analysis of the epidemics led to a number of interesting findings: (1) the two epidemics exhibited certain differences in their spatiotemporal characteristics (correlation structures, trends, occurrence patterns and propagation speeds) that need to be explained by means of an interdisciplinary effort; (2) geographical epidemic indicators confirmed in a rigorous quantitative manner the partial findings of isolated reports and time series that Black Death mortality was two orders of magnitude higher than that of bubonic plague; (3) modern bubonic plague is a rural disease hitting harder the small villages in the countryside whereas Black Death was a devastating epidemic that indiscriminately attacked large urban centres and the countryside, and while the epidemic in India lasted uninterruptedly for five decades, in Western Europe it lasted three and a half years; (4) the epidemics had reverse areal extension features in response to annual seasonal variations. Temperature increase at the end of winter led to an expansion of infected geographical area for Black Death and a reduction for bubonic plague, reaching a climax at the end of spring when the infected area in Western Europe was always larger than in India. Conversely, without exception, the infected area during winter was larger for the Indian bubonic plague; (5) during the

  15. Recent results on the spatiotemporal modelling and comparative analysis of Black Death and bubonic plague epidemics.

    Science.gov (United States)

    Christakos, G; Olea, R A; Yu, H-L

    2007-09-01

    This work demonstrates the importance of spatiotemporal stochastic modelling in constructing maps of major epidemics from fragmentary information, assessing population impacts, searching for possible etiologies, and performing comparative analysis of epidemics. Based on the theory previously published by the authors and incorporating new knowledge bases, informative maps of the composite space-time distributions were generated for important characteristics of two major epidemics: Black Death (14th century Western Europe) and bubonic plague (19th-20th century Indian subcontinent). The comparative spatiotemporal analysis of the epidemics led to a number of interesting findings: (1) the two epidemics exhibited certain differences in their spatiotemporal characteristics (correlation structures, trends, occurrence patterns and propagation speeds) that need to be explained by means of an interdisciplinary effort; (2) geographical epidemic indicators confirmed in a rigorous quantitative manner the partial findings of isolated reports and time series that Black Death mortality was two orders of magnitude higher than that of bubonic plague; (3) modern bubonic plague is a rural disease hitting harder the small villages in the countryside whereas Black Death was a devastating epidemic that indiscriminately attacked large urban centres and the countryside, and while the epidemic in India lasted uninterruptedly for five decades, in Western Europe it lasted three and a half years; (4) the epidemics had reverse areal extension features in response to annual seasonal variations. Temperature increase at the end of winter led to an expansion of infected geographical area for Black Death and a reduction for bubonic plague, reaching a climax at the end of spring when the infected area in Western Europe was always larger than in India. Conversely, without exception, the infected area during winter was larger for the Indian bubonic plague; (5) during the Indian epidemic, the disease

  16. Molecular studies of an impetigo bullosa epidemic in full-term infants.

    Science.gov (United States)

    Jursa-Kulesza, Joanna; Kordek, Agnieszka; Kopron, Katarzyna; Wojciuk, Bartosz; Giedrys-Kalemba, Stefania

    2009-01-01

    Carriers of Staphylococcus aureus strains can be the source of epidemic infection for patients. A molecular epidemiological analysis of an impetigo bullosa outbreak in a neonatal ward was performed in order to determine a potential source of the infection and possible routes of subsequent spreading of the epidemic strain. The genetic relatedness of S. aureus strains isolated from 6 neonates with epidermal lesions and from 21 staff members was verified by the pulsed field gel electrophoresis (PFGE) method. Additionally, detection of eta and etb genes of S. aureus strains using PCR was performed. None of the infected newborns' mothers was a carrier. Seven strains, 6 isolated from the newborns and 1 taken from a midwife, showed the same restriction pattern, i.e. type A. In the other 20 health care workers colonized with S. aureus, 3 genetic types could be distinguished, i.e. B (2), C (7) and D (2), as well as 9 strains with unique PFGE patterns. The eta gene detected in 7 strains belonged to the genetic type A; there was no etb gene in any of the 27 S. aureus isolates. The presence of the same genetic type A of S. aureus in the infected newborns is a factor which indicates that the impetigo bullosa was a hospital infection. A probable source of the infection was a midwife who was colonized with the same S. aureus type. She was present at the birth of the first infected newborn. Today, molecular methods are essential for prompt recognition of an epidemic and implementation of appropriate infection control strategies. Copyright 2009 S. Karger AG, Basel.

  17. Epidemics with Multistrain Interactions: Cross Immunity and Antibody-Dependent Enhancement

    Science.gov (United States)

    Bianco, Simone; Shaw, Leah

    2008-03-01

    Dynamics of epidemic spread is a problem of global interest. In this work we investigate the dynamical properties of a multistrain disease in a population where the strains interact via antibody-dependent enhancement (ADE) and cross immunity. ADE is a property of some multistrain diseases, such as dengue fever and Ebola, in which the antibodies generated by a primary infection with a strain tend to increase the infectiousness of a secondary infection with a different strain. After a primary infection, cross immunity provides temporary reduced susceptibility to the other strains. The presence of chaotic outbreaks and desynchronization between strains has already been observed in a model with no cross immunity if the ADE is sufficiently strong. The addition of weak cross immunity provides a stabilizing effect, while strong cross immunity leads to large amplitude chaotic outbreaks. A stochastic version of the model is also considered.

  18. Genotyping and antibiotic resistance of Acinetobacter baumannii strains isolated from patients hospitalized in teaching hospitals of Shahrekord by Pulsed- Field Gel Electrophorsis

    Directory of Open Access Journals (Sweden)

    A Gholipur

    2017-06-01

    Conclusion: Although variations among strains of Acinetobacter baumannii were observed by using PFGE in Shahrekord, but no epidemic strain was detected among them. In terms of resistance to commonly used antibiotics were also different patterns.

  19. HIV epidemics in Shenzhen and Chongqing, China.

    Directory of Open Access Journals (Sweden)

    Shu Yang

    Full Text Available Men who have sex with men (MSM and heterosexuals are the populations with the fastest growing HIV infection rates in China. We characterize the epidemic growth and age patterns between these two routes from 2004 to 2015 in Chongqing and Shenzhen, China.Data were downloaded from the National HIV/ AIDS Comprehensive Response Information Management System. For the new HIV diagnoses of heterosexuals and MSM in both cities, we estimated the growth rates by fitting different sub-exponential models. Heat maps are used to show their age patterns. We used histograms to compare these patterns by birth cohort.The MSM epidemics grew significantly in both cities. Chongqing experienced quadratic growth in HIV reported cases with an estimated growth rate of 0.086 per week and a "deceleration rate" of 0.673. HIV reported cases of MSM in Shenzhen grew even more drastically with a growth rate of 0.033 per week and "deceleration rate" of 0.794. The new infections are mainly affecting the ages of 18 to 30 in Chongqing and ages of 20 to 35 in Shenzhen. They peaked in early 1990's and mid-1990's birth cohorts in Chongqing and Shenzhen respectively. The HIV epidemic among heterosexuals grew rapidly in both cities. The growth rates were estimated as 0.02 and 0.028 in Chongqing and Shenzhen respectively whereas the "deceleration rates" were 0.878 and 0.790 in these two places. It affected mostly aged 18 to 75 in males and 18 to 65 in females in Chongqing and aged 18 to 45 in males and 18 to 50 in females in Shenzhen in 2015. In Chongqing, the heterosexual female epidemics display two peaks in HIV diagnoses in the birth cohorts of early 1950's and early 1980's, with heterosexual male epidemics peaked in early 1940's and early 1960's. The heterosexual male and female epidemics display higher rates in the birth cohort 1940-1960, than the birth cohort 1960-1990. It peaked in birth cohorts of 1950's and 1980's in Shenzhen.We revealed striking differences in epidemic growth

  20. Epidemic dropsy: A mimic of scleroderma?

    Directory of Open Access Journals (Sweden)

    Anupam Wakhlu

    2017-01-01

    Full Text Available Systemic sclerosis (SSc is an autoimmune connective tissue disease involving the skin and internal organs and characterized pathologically by microvascular damage and increased deposition of connective tissue. Skin changes seen in SSc include edema, inflammation, induration, thickening, and progressive skin fibrosis. Histologically, skin fibrosis, accumulation of compact collagen in the dermis, effacement of rete pegs, infiltration by CD4+ T cells, and skin atrophy are observed. The “toxic oil syndrome” reported from Spain caused an outbreak of a scleroderma-like illness and was caused by ingestion of contaminated rapeseed cooking oil. Epidemic dropsy is caused by ingestion of mustard oil contaminated with the oil of Argemone mexicana. The major alkaloids in Argemone oil are sanguinarine and dihydrosanguinarine. These alkaloids produce widespread capillary dilatation, increased capillary permeability, and endothelial proliferation, akin to the toxic oil syndrome. Cutaneous manifestations include erythematous and tender bilaterally symmetrical pitting edema usually involving lower limbs, skin thickening and tethering, pigmentation, and presence of telangiectasias. The dermatopathology observed in epidemic dropsy includes atrophy and flattening of rete pegs, hypertrophy of and deposition of collagen, vascular dilatation and proliferation, and subcutaneous inflammation and fibrosis. Epidemic dropsy usually presents with subacute multisystem involvement, which may mimic a connective tissue disease. Skin involvement in epidemic dropsy may closely mimic cutaneous manifestations in SSc, both clinically and histologically. Thus, the clinician needs to be aware that epidemic dropsy with cutaneous involvement, especially if encountered sporadically, may be mistakenly diagnosed as scleroderma.

  1. Dimensionality reduction in epidemic spreading models

    Science.gov (United States)

    Frasca, M.; Rizzo, A.; Gallo, L.; Fortuna, L.; Porfiri, M.

    2015-09-01

    Complex dynamical systems often exhibit collective dynamics that are well described by a reduced set of key variables in a low-dimensional space. Such a low-dimensional description offers a privileged perspective to understand the system behavior across temporal and spatial scales. In this work, we propose a data-driven approach to establish low-dimensional representations of large epidemic datasets by using a dimensionality reduction algorithm based on isometric features mapping (ISOMAP). We demonstrate our approach on synthetic data for epidemic spreading in a population of mobile individuals. We find that ISOMAP is successful in embedding high-dimensional data into a low-dimensional manifold, whose topological features are associated with the epidemic outbreak. Across a range of simulation parameters and model instances, we observe that epidemic outbreaks are embedded into a family of closed curves in a three-dimensional space, in which neighboring points pertain to instants that are close in time. The orientation of each curve is unique to a specific outbreak, and the coordinates correlate with the number of infected individuals. A low-dimensional description of epidemic spreading is expected to improve our understanding of the role of individual response on the outbreak dynamics, inform the selection of meaningful global observables, and, possibly, aid in the design of control and quarantine procedures.

  2. Widespread epidemic cholera caused by a restricted subset of Vibrio cholerae clones.

    Science.gov (United States)

    Moore, S; Thomson, N; Mutreja, A; Piarroux, R

    2014-05-01

    Since 1817, seven cholera pandemics have plagued humankind. As the causative agent, Vibrio cholerae, is autochthonous in the aquatic ecosystem and some studies have revealed links between outbreaks and fluctuations in climatic and aquatic conditions, it has been widely assumed that cholera epidemics are triggered by environmental factors that promote the growth of local bacterial reservoirs. However, mounting epidemiological findings and genome sequence analysis of clinical isolates have indicated that epidemics are largely unassociated with most of the V. cholerae strains in aquatic ecosystems. Instead, only a specific subset of V. cholerae El Tor 'types' appears to be responsible for current epidemics. A recent report examining the evolution of a variety of V. cholerae strains indicates that the current pandemic is monophyletic and originated from a single ancestral clone that has spread globally in successive waves. In this review, we examine the clonal nature of the disease, with the example of the recent history of cholera in the Americas. Epidemiological data and genome sequence-based analysis of V. cholerae isolates demonstrate that the cholera epidemics of the 1990s in South America were triggered by the importation of a pathogenic V. cholerae strain that gradually spread throughout the region until local outbreaks ceased in 2001. Latin America remained almost unaffected by the disease until a new toxigenic V. cholerae clone was imported into Haiti in 2010. Overall, cholera appears to be largely caused by a subset of specific V. cholerae clones rather than by the vast diversity of V. cholerae strains in the environment. © 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.

  3. The epidemic of Tuberculosis on vaccinated population

    Science.gov (United States)

    Syahrini, Intan; Sriwahyuni; Halfiani, Vera; Meurah Yuni, Syarifah; Iskandar, Taufiq; Rasudin; Ramli, Marwan

    2017-09-01

    Tuberculosis is an infectious disease which has caused a large number of mortality in Indonesia. This disease is caused by Mycrobacterium tuberculosis. Besides affecting lung, this disease also affects other organs such as lymph gland, intestine, kidneys, uterus, bone, and brain. This article discusses the epidemic of tuberculosis through employing the SEIR model. Here, the population is divided into four compartments which are susceptible, exposed, infected and recovered. The susceptible population is further grouped into two which are vaccinated group and unvaccinated group. The behavior of the epidemic is investigated through analysing the equilibrium of the model. The result shows that administering vaccine to the susceptible population contributes to the reduction of the tuberculosis epidemic rate.

  4. Epidemic Spreading in Unidirectional Mobile Agents

    Science.gov (United States)

    Nagatani, Takashi; Ichinose, Genki; Tainaka, Kei-ichi

    2017-11-01

    We present an epidemic model combined with a traffic cellular automaton. Each agent or individual is either susceptible (S) or infected (I). An agent with a certain density moves to a fixed direction on one-dimensional lattice. Simulations for SIS model show that the epidemic spreads via migration. We find a dynamical phase transition between infectious and non-infectious phases. If the density exceeds the critical limit ρC, the epidemic spreads into the population. The value of ρC decreases along with the recovery rate as predicted by mean-field theory. However, this theory cannot explain the simulation result that a traffic jam strongly affects the phase transition. It is found that the minimum value of ρC corresponds to the critical value of the jamming transition.

  5. Epidemic and Cascading Survivability of Complex Networks

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex...... networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present epidemic survivability ( ES ), a new network measure that describes...... the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose cascading survivability ( CS ), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from ES and CS...

  6. Different Epidemic Models on Complex Networks

    International Nuclear Information System (INIS)

    Zhang Haifeng; Small, Michael; Fu Xinchu

    2009-01-01

    Models for diseases spreading are not just limited to SIS or SIR. For instance, for the spreading of AIDS/HIV, the susceptible individuals can be classified into different cases according to their immunity, and similarly, the infected individuals can be sorted into different classes according to their infectivity. Moreover, some diseases may develop through several stages. Many authors have shown that the individuals' relation can be viewed as a complex network. So in this paper, in order to better explain the dynamical behavior of epidemics, we consider different epidemic models on complex networks, and obtain the epidemic threshold for each case. Finally, we present numerical simulations for each case to verify our results.

  7. GENERAL: Epidemic spreading on networks with vaccination

    Science.gov (United States)

    Shi, Hong-Jing; Duan, Zhi-Sheng; Chen, Guan-Rong; Li, Rong

    2009-08-01

    In this paper, a new susceptible-infected-susceptible (SIS) model on complex networks with imperfect vaccination is proposed. Two types of epidemic spreading patterns (the recovered individuals have or have not immunity) on scale-free networks are discussed. Both theoretical and numerical analyses are presented. The epidemic thresholds related to the vaccination rate, the vaccination-invalid rate and the vaccination success rate on scale-free networks are demonstrated, showing different results from the reported observations. This reveals that whether or not the epidemic can spread over a network under vaccination control is determined not only by the network structure but also by the medicine's effective duration. Moreover, for a given infective rate, the proportion of individuals to vaccinate can be calculated theoretically for the case that the recovered nodes have immunity. Finally, simulated results are presented to show how to control the disease prevalence.

  8. Urgent epidemic control mechanism for aviation networks

    KAUST Repository

    Peng, Chengbin

    2011-01-01

    In the current century, the highly developed transportation system can not only boost the economy, but also greatly accelerate the spreading of epidemics. While some epidemic diseases may infect quite a number of people ahead of our awareness, the health care resources such as vaccines and the medical staff are usually locally or even globally insufficient. In this research, with the network of major aviation routes as an example, we present a method to determine the optimal locations to allocate the medical service in order to minimize the impact of the infectious disease with limited resources. Specifically, we demonstrate that when the medical resources are insufficient, we should concentrate our efforts on the travelers with the objective of effectively controlling the spreading rate of the epidemic diseases. © 2011 Springer-Verlag Berlin Heidelberg.

  9. HIV-1 CRF_BC recombinants infection in China: molecular epidemic and characterizations.

    Science.gov (United States)

    Ouyang, Yabo; Shao, Yiming; Ma, Liying

    2012-03-01

    CRF_BC recombinant strains were first identified in China and are one of the most prevalent and characteristically unique HIV-1 subtypes across China. Here we aim to review the published data about HIV-1 CRF_BC recombinant strains epidemic in China and to characterize the genetics, biology and drug resistance of this virus. This study may help to better understand the current situation of HIV-1 CRF_BC prevalence and facilitate the development of vaccines and more efficient anti-HIV-1 regimens in China.

  10. Emergence and global spread of epidemic healthcare-associated Clostridium difficile

    OpenAIRE

    He, Miao; Miyajima, Fabio; Roberts, Paul; Ellison, Louise; Pickard, Derek J.; Martin, Melissa J.; Connor, Thomas R.; Harris, Simon R.; Fairley, Derek; Bamford, Kathleen B.; D?Arc, Stephanie; Brazier, Jon; Brown, Derek; Coia, John E.; Douce, Gill

    2012-01-01

    Epidemic C. difficile (027/BI/NAP1) has rapidly emerged in the past decade as the leading cause of antibiotic-associated diarrhea worldwide. However, the key events in evolutionary history leading to its emergence and the subsequent patterns of global spread remain unknown. Here, we define the global population structure of C. difficile 027/BI/NAP1 using whole-genome sequencing and phylogenetic analysis. We show that two distinct epidemic lineages, FQR1 and FQR2, not one as previously thought...

  11. Emergence of recombinant forms in geographic regions with co-circulating HIV subtypes in the dynamic HIV-1 epidemic

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ming [Los Alamos National Laboratory; Letiner, Thomas K [Los Alamos National Laboratory; Korber, Bette T [Los Alamos National Laboratory; Foley, Brian [Los Alamos National Laboratory

    2009-01-01

    We have reexamined the subtype designations of {approx}10,000 subtype A, B, C, G, and AG, BC, BF recombinant sequences, and compared the results of the new analysis with their published designations. Intersubtype recombinants dominate HIV epidemics in three different geographical regions. The circulating recombinant from (CRF) CRF02-AG, common in West Central Africa, appears to result from a recombination event that occurred early in the divergence between subtypes A and G, although additional more recent recombination events may have contributed to the breakpoint pattern in this recombinant lineage as well. The Chinese recombinant epidemic strains CRF07 and CRF08, in contrast, result from recent recombinations between more contemporary strains. Nevertheless, CRF07 and CRF08 contributed to many subsequent recombination events. The BF recombinant epidemics in two HIV-1 epicenters in South America are not independent and BF epidemics in South America have an unusually high fraction of unique recombinant forms (URFs) that have each been found only once and carry distinctive breakpoints. Taken together, these analyses reveal a complex and dynamic picture of the current HIV-1 epidemic, and suggest a means of grouping and tracking relationships between viruses through preservation of shared breakpints.

  12. In search for factors that drive hantavirus epidemics.

    Directory of Open Access Journals (Sweden)

    Paul eHeyman

    2012-07-01

    Full Text Available In Europe, hantaviruses (Bunyaviridae are small mammal-associated zoonotic and emerging pathogens that can cause hemorrhagic fever with renal syndrome (HFRS. Puumala virus, the main etiological agent carried by the bank vole Myodes glareolus is responsible for a mild form of HFRS while Dobrava virus induces less frequent but more severe cases of HFRS.Since 2000 in Europe, more than 3000 cases of HFRS have been recorded, in average, each year, which is nearly double compared to the previous decade. In addition to this upside long-term trend, significant oscillations occur. Epidemic years appear, usually every 2-4 years, with an increased incidence, generally in localised hot spots. Moreover, the virus has been identified in new areas in the recent years.A great number of surveys have been carried out in order to assess the prevalence of the infection in the reservoir host and to identify links with different biotic and abiotic factors. The factors that drive the infections are related to the density and diversity of bank vole populations, prevalence of infection in the reservoir host, viral excretion in the environment, survival of the virus outside its host, and human behaviour, which affect the main transmission virus route through inhalation of infected rodent excreta..At the scale of a rodent population, the prevalence of the infection increases with the age of the individuals but also other parameters, such as sex and genetic variability, interfere. The contamination of the environment may be correlated to the number of newly infected rodents, which heavily excrete the virus. The interactions between these different parameters add to the complexity of the situation and explain the absence of reliable tools to predict epidemics. In this review, the factors that drive the epidemics of hantaviruses in Middle Europe are discussed through a panorama of the epidemiological situation in Belgium, France and Germany.

  13. Multiple alignment analysis on phylogenetic tree of the spread of SARS epidemic using distance method

    Science.gov (United States)

    Amiroch, S.; Pradana, M. S.; Irawan, M. I.; Mukhlash, I.

    2017-09-01

    Multiple Alignment (MA) is a particularly important tool for studying the viral genome and determine the evolutionary process of the specific virus. Application of MA in the case of the spread of the Severe acute respiratory syndrome (SARS) epidemic is an interesting thing because this virus epidemic a few years ago spread so quickly that medical attention in many countries. Although there has been a lot of software to process multiple sequences, but the use of pairwise alignment to process MA is very important to consider. In previous research, the alignment between the sequences to process MA algorithm, Super Pairwise Alignment, but in this study used a dynamic programming algorithm Needleman wunchs simulated in Matlab. From the analysis of MA obtained and stable region and unstable which indicates the position where the mutation occurs, the system network topology that produced the phylogenetic tree of the SARS epidemic distance method, and system area networks mutation.

  14. Mitigating the future impact of Cholera Epidemics

    CSIR Research Space (South Africa)

    Woodborne, S

    2008-11-01

    Full Text Available . 2005. Climate Drives the Meningitis Epidemics Onset in West Africa. PLoS Medicine, 2: 0043-0049. TAMPLIN, M.L., GAUZENS, A.L., HUQ,A., SACK, D.A. & COLWELL, R.R. 1990. COLWELL. Attachment of Vibrio cholerae Serogroup 01 to Zooplankton...

  15. Police Brutality--the New Epidemic

    Science.gov (United States)

    Sandoval, Ruben; Martinez, Douglas R.

    1978-01-01

    Recently, incidents of police abuse against Hispanics have increased so rapidly that the phenomenon has been called an epidemic. Of special concern to Hispanic leaders is the lack of Federal intervention in these police brutality cases. A list of 56 documented cases involving police brutality against Hispanics is included. (Author/NQ)

  16. Phylogenetics of the Danish HIV epidemic

    DEFF Research Database (Denmark)

    Audelin, Anne Margrethe; Cowan, Susan A; Obel, Niels

    2013-01-01

    BACKGROUND:: In Denmark 300 new individuals are diagnosed with HIV every year, despite decades of public health campaigns aimed to raise awareness of potential risk behaviour for HIV transmission. It is important to identify the driving forces of the epidemic, to enable more targeted campaigns...

  17. The Prescription Opioid Pain Medication Overdose Epidemic

    Centers for Disease Control (CDC) Podcasts

    2016-04-19

    Overdose related to prescription opioids has become an epidemic. This podcast discusses the risks of this type of drug sometimes used to treat pain, and how to protect yourself. .  Created: 4/19/2016 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 4/19/2016.

  18. Acute haemorrhagic conjunctivitis epidemics and outbreaks of ...

    African Journals Online (AJOL)

    An epidemic of acute conjunctivitis in Dar es Salaam in 2010 demonstrated the importance of a strong infectious diseases epidemiological surveillance network to minimise disease outbreaks. Misunderstanding of the causes and management of diseases explains the repetitive nature of acute haemorrhagic conjunctivitis ...

  19. Epidemic spastic paraparesis in Bandundu (Zaire).

    Science.gov (United States)

    Carton, H; Kayembe, K; Kabeya; Odio; Billiau, A; Maertens, K

    1986-06-01

    Epidemiological findings of twenty sporadic cases of epidemic spastic paraparesis (buka-buka) in three areas of Bandundu (Zaire) are reported. These findings suggest the involvement of an infectious agent and do not support the hypothesis of a dietary cyanide intoxication, which has been advanced to explain the outbreak of a very similar disease (Mantakassa) in Mozambique.

  20. School Violence, the Media's Phanton Epidemic.

    Science.gov (United States)

    Best, Joel

    2002-01-01

    Argues that public perceptions of an epidemic of school violence are media-induced; asserts that violence in schools declined during the 1990s; supports assertion with evidence from the National School Safety Center; states the estimates of bullying in school are exaggerated. (PKP)

  1. Cholera Epidemic Control | Zachariah | Malawi Medical Journal

    African Journals Online (AJOL)

    Malawi Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 13, No 1 (2001) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Cholera Epidemic Control. R Zachariah. Full Text: EMAIL FREE ...

  2. Social epidemics in the aftermath of disasters.

    NARCIS (Netherlands)

    IJzermans, C.J.

    2002-01-01

    Issue/problem: After disasters, terrorist attacks and wars social epidemics of medically unexplained physical symptoms/syndromes (ups) are often seen. In modern times people feel more vulnerable and especially under pressure of those incidents, everyday symptoms are interpreted as disease and

  3. Classification of Epidemic Community-Acquired Methicillin-Resistant Staphylococcus aureus by Anatomical Site of Isolation

    Directory of Open Access Journals (Sweden)

    Jill C. Roberts

    2014-01-01

    Full Text Available Methicillin-resistant Staphylococcus aureus contributes significantly to cost, morbidity, and mortality due to infectious disease. We surveyed community-associated MRSA isolates to determine which strains were present within anatomical sites of interest. The most likely sources of MRSA among anatomic sites swabbed were wounds followed by the nasal cavity. The USA 300 MRSA strain was most commonly isolated among wound infections while nasal swabs largely yielded USA 100 MRSA. The frequency of isolation of USA 100 amongst community-associated strains is clinically significant as this strain is often correlated with invasive disease, exhibits broad antibiotic resistance, and has been considered to be hospital associated. The potential of USA 100 to cause serious disease and the frequency of its isolation suggest an important reservoir for opportunistic infection. These data demonstrate that MRSA epidemic clones are widespread among the community.

  4. Epidemics can be prevented with a Doctor on Call

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Epidemics can be prevented with a Doctor on Call. A potential epidemic of Chicken Pox was halted by a simple email to the right people. Instant response from the Government Doctors.

  5. Burden of transmitted multidrug resistance in epidemics of tuberculosis: a transmission modelling analysis.

    Science.gov (United States)

    Kendall, Emily A; Fofana, Mariam O; Dowdy, David W

    2015-12-01

    Multidrug-resistant (MDR) tuberculosis can be acquired through de-novo mutation during tuberculosis treatment or through transmission from other individuals with active MDR tuberculosis. Understanding the balance between these two mechanisms is essential when allocating resources for MDR tuberculosis. We aimed to create a dynamic transmission model of an MDR tuberculosis epidemic to estimate the contributions of treatment-related acquisition and person-to-person transmission of resistance to incident MDR tuberculosis cases. In this modelling analysis, we constructed a dynamic transmission model of an MDR tuberculosis epidemic, allowing for both treatment-related acquisition and person-to-person transmission of resistance. We used national tuberculosis notification data to inform Bayesian estimates of the proportion of each country's 2013 MDR tuberculosis incidence that resulted from MDR transmission rather than treatment-related MDR acquisition. Global estimates of 3·5% MDR tuberculosis prevalence among new tuberculosis notifications and 20·5% among re-treatment notifications translate into an estimate that resistance transmission rather than acquisition accounts for a median 95·9% (95% uncertainty range [UR] 68·0-99·6) of all incident MDR tuberculosis, and 61·3% (16·5-95·2) of incident MDR tuberculosis in previously treated individuals. The estimated proportion of MDR tuberculosis resulting from transmission varied substantially with different countries' notification data-ranging from 48% (95% UR 30-75) in Bangladesh to 99% (91-100) in Uzbekistan. Estimates were most sensitive to estimates of the transmissibility of MDR strains, the probability of acquiring MDR during tuberculosis treatment, and the responsiveness of MDR tuberculosis to first-line treatment. Notifications of MDR prevalence from most high-burden settings are consistent with most incident MDR tuberculosis resulting from transmission rather than new treatment-related acquisition of resistance

  6. Vibrio cholerae O1 epidemic variants in Angola: a retrospective study between 1992 and 2006.

    Directory of Open Access Journals (Sweden)

    Romy eValia

    2013-11-01

    Full Text Available Cholera is still a major public health concern in many African countries. In Angola, after a decade of absence, cholera reemerged in 1987, spreading throughout the country until 1996, with outbreaks recurring in a seasonal pattern. In 2006 Angola was hit by one of the most severe outbreaks of the last decade, with ca. 240,000 cases reported.We analyzed 21 clinical strains isolated between 1992 and 2006 from several provinces throughout the country: Benguela, Bengo, Luanda, Cuando Cubango and Cabinda. We used two multiplex PCR assays to investigate discriminatory mobile genetic elements (ICEs, VSP-II, GI12, GI14, GI15, K and TLC phages and we compared the profiles obtained with those of different reference V. cholerae O1 variants (prototypical, altered and hybrid, responsible for the ongoing 7th pandemic. We also tested the strains for the presence of specific VSP-II variants and for the presence of a genomic island (WASA-1, correlated with the transmission of seventh pandemic cholera from Africa to South America. Based on the presence/absence of the analyzed genetic elements, five novel profiles were detected in the epidemic strains circulating in the 1990s. The most frequent profiles, F and G, were characterized by the absence of ICEs and the three GIs tested, and the presence of genomic island WASA-1 and the WASA variant of the VSP-II island. Our results identified unexpected variability within the 1990s epidemic, showing different rearrangements in a dynamic part of the genome not present in the prototypical V. cholerae O1 N16961. Moreover the 2006 strains differed from the current pandemic V. cholerae O1 strain. Taken together, our results highlight the role of horizontal gene transfer in diversifying the genetic background of V. cholerae within a single epidemic.

  7. Genetic shifts in methicillin-resistant Staphylococcus aureus epidemic clones and toxin gene profiles in Japan: comparative analysis among pre-epidemic, epidemic and post-epidemic phases.

    Science.gov (United States)

    Osaka, Shunsuke; Okuzumi, Katsuko; Koide, Shota; Tamai, Kiyoko; Sato, Tomoaki; Tanimoto, Koichi; Tomita, Haruyoshi; Suzuki, Masahiro; Nagano, Yukiko; Shibayama, Keigo; Arakawa, Yoshichika; Nagano, Noriyuki

    2018-03-01

    The decline in methicillin-resistant Staphylococcus aureus (MRSA) isolation rates has become a general observation worldwide, including Japan. We hypothesized that some genetic shift in MRSA might cause this phenomenon, and therefore we investigated the genetic profiles among MRSA clinical isolates obtained from three different epidemic phases in Japan. A total of 353 MRSA isolates were selected from 202 medical facilities in 1990 (pre-epidemic phase), 2004 (epidemic phase) and 2016 (post-epidemic phase). Molecular typing was performed by PCR detection of 22 genes using the polymerase chain reaction (PCR)-based ORF typing (POT) system, including an additional eight genes including small genomic islets and seven toxin genes. Isolates with a POT1 of score 93, identified as presumed clonal complex (pCC)5-staphylococcal cassette chromosome mec (SCCmec) type II including ST5-SCCmec type II New York/Japan clone, represented the major epidemic MRSA lineage in 1990 and 2004. In 2016, however, a marked decrease in isolates with a POT1 score of 93, along with changes in the epidemiology of toxin genes carried, was noted, where the carriers of tst genes including the tst-sec combination were markedly reduced, and those possessing the seb gene alone were markedly increased. Rather, isolates with a POT1 score of 106, including pCC1 or pCC8 among the isolates with SCCmec type IV, which often links to community-associated MRSA, were predominant. Interestingly, the pCC1 and pCC8 lineages were related to sea and tst-sec carriage, respectively. Over time, a transition in MRSA genetic profiles from a POT1 score of 93 in 1990 and 2004 to 106 in 2014 was found in Japan.

  8. Emergence and control of epidemic meningococcal meningitis in sub-Saharan Africa.

    Science.gov (United States)

    Mohammed, Idris; Iliyasu, Garba; Habib, Abdulrazaq Garba

    2017-02-01

    For more than a century, meningitis epidemics have regularly recurred across sub-Saharan Africa, involving 19 contiguous countries that constitute a 'meningitis belt' where historically the causative agent has been serogroup A meningococcus. Attempts to control epidemic meningococcal meningitis in Africa by vaccination with meningococcal polysaccharide (PS) vaccines have not been successful. This is largely because PS vaccines are poorly immunogenic in young children, do not induce immunological memory, and have little or no effect on the pharyngeal carriage. Meningococcal PS-protein conjugate vaccines overcome these deficiencies. Conjugate meningococcal vaccine against serotype A (MenAfriVac) was developed between 2001 and 2009 and deployed in 2010. So far, 262 million individuals have been immunized across the meningitis belt. The public health benefits of MenAfriVac have already been demonstrated by a sharp decline in reported cases of meningococcal disease in the countries where it has been introduced. However, serogroup replacement following mass meningitis vaccination has been noted, and in 2015 an epidemic with a novel strain of serogroup C was recorded in Niger and Nigeria for the first time since 1975. This has posed a serious challenge toward elimination of meningococcal meningitis epidemics in the African. For an effective control of meningococcal meningitis in the African meningitis belt, there is a need for an effective surveillance system, provision of rapid antigen detection kits as well as affordable vaccine that provides protection against the main serogroups causing meningitis in the sub-region.

  9. Parameter Scaling for Epidemic Size in a Spatial Epidemic Model with Mobile Individuals.

    Directory of Open Access Journals (Sweden)

    Chiyori T Urabe

    Full Text Available In recent years, serious infectious diseases tend to transcend national borders and widely spread in a global scale. The incidence and prevalence of epidemics are highly influenced not only by pathogen-dependent disease characteristics such as the force of infection, the latent period, and the infectious period, but also by human mobility and contact patterns. However, the effect of heterogeneous mobility of individuals on epidemic outcomes is not fully understood. Here, we aim to elucidate how spatial mobility of individuals contributes to the final epidemic size in a spatial susceptible-exposed-infectious-recovered (SEIR model with mobile individuals in a square lattice. After illustrating the interplay between the mobility parameters and the other parameters on the spatial epidemic spreading, we propose an index as a function of system parameters, which largely governs the final epidemic size. The main contribution of this study is to show that the proposed index is useful for estimating how parameter scaling affects the final epidemic size. To demonstrate the effectiveness of the proposed index, we show that there is a positive correlation between the proposed index computed with the real data of human airline travels and the actual number of positive incident cases of influenza B in the entire world, implying that the growing incidence of influenza B is attributed to increased human mobility.

  10. Outbreak or Epidemic? How Obama's Language Choice Transformed the Ebola Outbreak Into an Epidemic.

    Science.gov (United States)

    Gesser-Edelsburg, Anat; Shir-Raz, Yaffa; Bar-Lev, Oshrat Sassoni; James, James J; Green, Manfred S

    2016-08-01

    Our aim was to examine in what terms leading newspapers' online sites described the current Ebola crisis. We employed a quantitative content analysis of terms attributed to Ebola. We found and analyzed 582 articles published between March 23 and September 30, 2014, on the online websites of 3 newspapers: The New York Times, Daily Mail, and Ynet. Our theoretical framework drew from the fields of health communication and emerging infectious disease communication, including such concepts as framing media literacy, risk signatures, and mental models. We found that outbreak and epidemic were used interchangeably in the articles. From September 16, 2014, onward, epidemic predominated, corresponding to when President Barack Obama explicitly referred to Ebola as an epidemic. Prior to Obama's speech, 86.8% of the articles (323) used the term outbreak and only 8.6% (32) used the term epidemic. Subsequently, both terms were used almost the same amount: 53.8% of the articles (113) used the term outbreak and 53.3% (112) used the term epidemic. Effective communication is crucial during public health emergencies such as Ebola, because language framing affects the decision-making process of social judgments and actions. The choice of one term (outbreak) over another (epidemic) can create different conceptualizations of the disease, thereby influencing the risk signature. (Disaster Med Public Health Preparedness. 2016;10:669-673).

  11. Selective epidemic vaccination under the performant routing algorithms

    Science.gov (United States)

    Bamaarouf, O.; Alweimine, A. Ould Baba; Rachadi, A.; EZ-Zahraouy, H.

    2018-04-01

    Despite the extensive research on traffic dynamics and epidemic spreading, the effect of the routing algorithms strategies on the traffic-driven epidemic spreading has not received an adequate attention. It is well known that more performant routing algorithm strategies are used to overcome the congestion problem. However, our main result shows unexpectedly that these algorithms favor the virus spreading more than the case where the shortest path based algorithm is used. In this work, we studied the virus spreading in a complex network using the efficient path and the global dynamic routing algorithms as compared to shortest path strategy. Some previous studies have tried to modify the routing rules to limit the virus spreading, but at the expense of reducing the traffic transport efficiency. This work proposed a solution to overcome this drawback by using a selective vaccination procedure instead of a random vaccination used often in the literature. We found that the selective vaccination succeeded in eradicating the virus better than a pure random intervention for the performant routing algorithm strategies.

  12. Modeling a SI epidemic with stochastic transmission: hyperbolic incidence rate.

    Science.gov (United States)

    Christen, Alejandra; Maulén-Yañez, M Angélica; González-Olivares, Eduardo; Curé, Michel

    2018-03-01

    In this paper a stochastic susceptible-infectious (SI) epidemic model is analysed, which is based on the model proposed by Roberts and Saha (Appl Math Lett 12: 37-41, 1999), considering a hyperbolic type nonlinear incidence rate. Assuming the proportion of infected population varies with time, our new model is described by an ordinary differential equation, which is analogous to the equation that describes the double Allee effect. The limit of the solution of this equation (deterministic model) is found when time tends to infinity. Then, the asymptotic behaviour of a stochastic fluctuation due to the environmental variation in the coefficient of disease transmission is studied. Thus a stochastic differential equation (SDE) is obtained and the existence of a unique solution is proved. Moreover, the SDE is analysed through the associated Fokker-Planck equation to obtain the invariant measure when the proportion of the infected population reaches steady state. An explicit expression for invariant measure is found and we study some of its properties. The long time behaviour of deterministic and stochastic models are compared by simulations. According to our knowledge this incidence rate has not been previously used for this type of epidemic models.

  13. Transferring the Malaria Epidemic Prediction Model to Users in East ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Transferring the Malaria Epidemic Prediction Model to Users in East Africa. In the highlands of East Africa, epidemic malaria is an emerging climate-related hazard that urgently needs addressing. Malaria incidence increased by 337% during the 1987 epidemic in Rwanda. In Tanzania, Uganda and Kenya, malaria incidence ...

  14. Zika virus epidemic: an update.

    Science.gov (United States)

    Valentine, Gregory; Marquez, Lucila; Pammi, Mohan

    2016-12-01

    Zika Virus (ZIKV), previously the cause of only rare and sporadic human infections, is now considered a Public Health Emergency of International Concern. Over the past two years, ZIKV has become a pandemic encompassing much of the Americas. ZIKV is now proven to cause microcephaly and ophthalmic anomalies in the newborn. Hydrops fetalis, developmental delay, and other anomalies are increasingly being attributed to ZIKV infection in fetuses and neonates. Sequelae of congenital infection and rapid spread of ZIKV throughout the Americas has catapulted Zika virus concerns to the forefront of the medical community. Areas covered: This review seeks to consolidate ZIKV epidemiology, diagnostic testing methods, CDC screening recommendations, and preventive strategies including potential vaccines. Expert commentary: Many unknowns still exist regarding ZIKV infections and its long-term effects in neonates. In addition, further studies need to evaluate if genomic differences that have occurred from the African to the Asian lineage of the virus have led to increased virulence of the virus. The authors believe that all pregnant women with fetuses showing microcephaly and/or intracranial calcifications should be tested for ZIKV infection if they cannot recall their sexual partner travel history. This change from the current CDCs recommendations could increase substantially the number of pregnant women and neonates, screened for ZIKV.

  15. Diphtheria in the Republic of Georgia: Use of Molecular Typing Techniques for Characterization of Corynebacterium diphtheriae Strains

    Science.gov (United States)

    Sulakvelidze, Alexander; Kekelidze, Merab; Gomelauri, Tsaro; Deng, Yingkang; Khetsuriani, Nino; Kobaidze, Ketino; De Zoysa, Aruni; Efstratiou, Androulla; Morris, J. Glenn; Imnadze, Paata

    1999-01-01

    Sixty-six Corynebacterium diphtheriae strains (62 of the gravis biotype and 4 of the mitis biotype) isolated during the Georgian diphtheria epidemic of 1993 to 1998 and 13 non-Georgian C. diphtheriae strains (10 Russian and 3 reference isolates) were characterized by (i) biotyping, (ii) toxigenicity testing with the Elek assay and PCR, (iii) the randomly amplified polymorphic DNA (RAPD) technique, and (iv) pulsed-field gel electrophoresis (PFGE). Fifteen selected strains were ribotyped. Six RAPD types and 15 PFGE patterns were identified among all strains examined, and 12 ribotypes were found among the 15 strains that were ribotyped. The Georgian epidemic apparently was caused by one major clonal group of C. diphtheriae (PFGE type A, ribotype R1), which was identical to the predominant epidemic strain(s) isolated during the concurrent diphtheria epidemic in Russia. A dendrogram based on the PFGE patterns revealed profound differences between the minor (nonpredominant) epidemic strains found in Georgia and Russia. The methodologies for RAPD typing, ribotyping, and PFGE typing of C. diphtheriae strains were improved to enable rapid and convenient molecular typing of the strains. The RAPD technique was adequate for biotype differentiation; however, PFGE and ribotyping were better (and equal to each other) at discriminating between epidemiologically related and unrelated isolates. PMID:10488190

  16. Epidemic dynamics and endemic states in complex networks

    International Nuclear Information System (INIS)

    Pastor-Satorras, Romualdo; Vespignani, Alessandro

    2001-01-01

    We study by analytical methods and large scale simulations a dynamical model for the spreading of epidemics in complex networks. In networks with exponentially bounded connectivity we recover the usual epidemic behavior with a threshold defining a critical point below that the infection prevalence is null. On the contrary, on a wide range of scale-free networks we observe the absence of an epidemic threshold and its associated critical behavior. This implies that scale-free networks are prone to the spreading and the persistence of infections whatever spreading rate the epidemic agents might possess. These results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks

  17. Epidemic Spread of Multidrug-Resistant Tuberculosis in Johannesburg, South Africa

    Science.gov (United States)

    Marais, Ben J.; Mlambo, Charmaine K.; Rastogi, Nalin; Zozio, Thierry; Duse, Adriano G.; Victor, Thomas C.; Marais, Else

    2013-01-01

    Numerous reports have documented isolated transmission events or clonal outbreaks of multidrug-resistant Mycobacterium tuberculosis strains, but knowledge of their epidemic spread remains limited. In this study, we evaluated drug resistance, strain diversity, and clustering rates in patients diagnosed with multidrug-resistant (MDR) tuberculosis (TB) at the National Health Laboratory Service (NHLS) Central TB Laboratory in Johannesburg, South Africa, between March 2004 and December 2007. Phenotypic drug susceptibility testing was done using the indirect proportion method, while each isolate was genotyped using a combination of spoligotyping and 12-MIRU typing (12-locus multiple interspersed repetitive unit typing). Isolates from 434 MDR-TB patients were evaluated, of which 238 (54.8%) were resistant to four first-line drugs (isoniazid, rifampin, ethambutol, and streptomycin). Spoligotyping identified 56 different strains and 28 clusters of variable size (2 to 71 cases per cluster) with a clustering rate of 87.1%. Ten clusters included 337 (77.6%) of all cases, with strains of the Beijing genotype being most prevalent (16.4%). Combined analysis of spoligotyping and 12-MIRU typing increased the discriminatory power (Hunter Gaston discriminatory index [HGDI] = 0.962) and reduced the clustering rate to 66.8%. Resolution of Beijing genotype strains was further enhanced with the 24-MIRU-VNTR (variable-number tandem repeat) typing method by identifying 15 subclusters and 19 unique strains from twelve 12-MIRU clusters. High levels of clustering among a variety of strains suggest a true epidemic spread of MDR-TB in the study setting, emphasizing the urgency of early diagnosis and effective treatment to reduce transmission within this community. PMID:23554196

  18. Epidemic of charcoal burning suicide in Japan.

    Science.gov (United States)

    Yoshioka, Eiji; Hanley, Sharon J B; Kawanishi, Yasuyuki; Saijo, Yasuaki

    2014-01-01

    The charcoal burning suicide epidemics in both Hong Kong and Taiwan have been well documented. However, little is known about the situation in Japan. To examine the impact of charcoal burning suicide on the overall and other method-specific suicide rates between 1998 and 2007 in Japan. Using data obtained from the Vital Statistics of Japan, negative binomial regression analyses were performed to investigate the impact of the charcoal burning method. In males and females aged 15-24 and 25-44 years, the charcoal burning epidemic led to a substantial increase in overall suicides, without a decrease in other methods. In all other age groups, no such trend was observed. In young Japanese, the charcoal burning method may have appealed to individuals who might not have chosen other highly or relatively lethal methods, and consequently led to an increase in overall suicides.

  19. [The depression epidemic does not exist].

    Science.gov (United States)

    van der Feltz-Cornelis, Christina M

    2009-01-01

    There has been much discussion in the media about the question of the existence of a depression epidemic. This leads on to the questions of whether the social and economic approaches are adequate, and what the alternatives are. The concept of the disease 'depression' can be defined using a medical model, or from a patient's or a societal perspective. From a medical perspective, indeed a depression epidemic has ensued from the increased prosperity and the associated decompression of the mortality rate. Society responded with preventative measures and policies aimed at improving functioning in the workplace. However, patients with a major depressive disorder (MDD) who are eligible for treatment are often not motivated to take it up, or are undertreated. Research is necessary in order to explore what patients think about the identification and treatment of depression. The confusion regarding the concept of depression found in the media, needs to be cleared.

  20. Eight challenges for network epidemic models

    Directory of Open Access Journals (Sweden)

    Lorenzo Pellis

    2015-03-01

    Full Text Available Networks offer a fertile framework for studying the spread of infection in human and animal populations. However, owing to the inherent high-dimensionality of networks themselves, modelling transmission through networks is mathematically and computationally challenging. Even the simplest network epidemic models present unanswered questions. Attempts to improve the practical usefulness of network models by including realistic features of contact networks and of host–pathogen biology (e.g. waning immunity have made some progress, but robust analytical results remain scarce. A more general theory is needed to understand the impact of network structure on the dynamics and control of infection. Here we identify a set of challenges that provide scope for active research in the field of network epidemic models.

  1. New Approaches to the Methamphetamine Epidemic

    OpenAIRE

    Zusman, Mara B.

    2004-01-01

    Methamphetamine abuse has become an epidemic in the United States. As methamphetamine becomes increasingly available, more and more people are trying – and becoming addicted to – this potent drug. But although methamphetamine is made using over-the-counter (OTC) drugs containing pseudoephedrine, shifting OTC drugs containing pseudoephedrine to prescription status is not the solution to the methamphetamine crisis. Rather, society must adopt a comprehensive...

  2. Oscillations in epidemic models with spread of awareness.

    Science.gov (United States)

    Just, Winfried; Saldaña, Joan; Xin, Ying

    2018-03-01

    We study ODE models of epidemic spreading with a preventive behavioral response that is triggered by awareness of the infection. Previous studies of such models have mostly focused on the impact of the response on the initial growth of an outbreak and the existence and location of endemic equilibria. Here we study the question whether this type of response is sufficient to prevent future flare-ups from low endemic levels if awareness is assumed to decay over time. In the ODE context, such flare-ups would translate into sustained oscillations with significant amplitudes. Our results show that such oscillations are ruled out in Susceptible-Aware-Infectious-Susceptible models with a single compartment of aware hosts, but can occur if we consider two distinct compartments of aware hosts who differ in their willingness to alert other susceptible hosts.

  3. Epidemic Venezuelan equine encephalitis in La Guajira, Colombia, 1995.

    Science.gov (United States)

    Rivas, F; Diaz, L A; Cardenas, V M; Daza, E; Bruzon, L; Alcala, A; De la Hoz, O; Caceres, F M; Aristizabal, G; Martinez, J W; Revelo, D; De la Hoz, F; Boshell, J; Camacho, T; Calderon, L; Olano, V A; Villarreal, L I; Roselli, D; Alvarez, G; Ludwig, G; Tsai, T

    1997-04-01

    In 1995, the first Venezuelan equine encephalitis (VEE) outbreak in Colombia in 22 years caused an estimated 75,000 human cases, 3000 with neurologic complications and 300 fatal, in La Guajira State. Of the state's estimated 50,000 equines, 8% may have died. An epizootic IC virus, probably introduced from Venezuela, was rapidly amplified among unvaccinated equines. Record high rainfall, producing high densities of vector Aedes taeniorhynchus, led to extensive epidemic transmission (30% attack rate) in the four affected municipalities. Native Wayuu Indians, constituting 24% of the state's population, were at increased risk of infection (risk ratio, 3.3; 95% confidence interval, 2.2-5.3). Epidemiologic studies found no evidence of human-to-human transmission. A higher-than-expected number of abortions during the outbreak confirmed a previously suspected abortifacient role of VEE infection. Pesticide applications and a mass equine vaccination program contributed to preventing the outbreak's spread south of La Guajira.

  4. Connecting the obesity and the narcissism epidemics.

    Science.gov (United States)

    Lemaitre, Bruno

    2016-10-01

    Obesity and metabolic syndromes are major threats to health in both developed and developing countries. This opinion article is a holistic attempt to understand the obesity epidemic, by connecting it to the widespread narcissism in society. The narcissism epidemic refers to an increased prevalence of status-striving individualism and a decreased sense of community, observed in Westerns populations and spreading worldwide. Based on social personality and evolutionary psychology approaches, I speculate that this rise of narcissism underlies a steep social hierarchy resulting in increase of social stress. This social stress markedly affects individuals who are sensitive to social hierarchy dominance due to their personality, yet are relegated at a lower social position. I speculate that over-eating is one major mechanism for coping with this stress, and discuss the possibility that visceral fat may constitute an adaptive behaviour to the lower social hierarchy position, which is perceived as unjust. Connecting the prevalence of obesity to the narcissism epidemic allows for a more thorough examination of factors, which contribute to obesity, which includes early difficult childhood experience, lower rank, and the overall competitive framework of the society. Copyright © 2016 The Author. Published by Elsevier Ltd.. All rights reserved.

  5. Inferring epidemic network topology from surveillance data.

    Directory of Open Access Journals (Sweden)

    Xiang Wan

    Full Text Available The transmission of infectious diseases can be affected by many or even hidden factors, making it difficult to accurately predict when and where outbreaks may emerge. One approach at the moment is to develop and deploy surveillance systems in an effort to detect outbreaks as timely as possible. This enables policy makers to modify and implement strategies for the control of the transmission. The accumulated surveillance data including temporal, spatial, clinical, and demographic information, can provide valuable information with which to infer the underlying epidemic networks. Such networks can be quite informative and insightful as they characterize how infectious diseases transmit from one location to another. The aim of this work is to develop a computational model that allows inferences to be made regarding epidemic network topology in heterogeneous populations. We apply our model on the surveillance data from the 2009 H1N1 pandemic in Hong Kong. The inferred epidemic network displays significant effect on the propagation of infectious diseases.

  6. The glue ear 'epidemic': a historical perspective.

    Science.gov (United States)

    Alderson, David

    2011-12-01

    This paper explores the historical context of the dramatic rise in surgery for glue ear in the mid-20th century, and questions the published assertion that this represented a manufactured 'epidemic'. In examining historical sources, the reader's theoretical viewpoint greatly influences their conclusions: the sustained rise in treatment for glue ear may be seen as the advance of science in a golden age or the resistance of insular professionals to reason in the light of new scientific study methods. Current views on the practice of medicine, consumerism, science and standardisation, rationing and the nature of 'truth' all affect the way that we see this period. Technological advances clearly allowed better diagnosis and more effective treatment, but these did not appear to drive an 'epidemic', rather they were developed to meet the pre-existing challenges of otological practice. The proposition that an 'epidemic' was created does not appear to have any solid grounding. Society's perception of what constitutes disease and what needs treatment may have evolved, but the prevalence of other important diseases changed dramatically over this time period, and a real change in the epidemiology of glue ear cannot be dismissed. In defining the case for and against surgical treatment, a solely positivist, quantitative worldview cannot give us a complete picture of benefit and risk to individuals, families and society at large.

  7. Reactivity of Porcine Epidemic Diarrhea Virus Structural Proteins to Antibodies against Porcine Enteric Coronaviruses: Diagnostic Implications.

    Science.gov (United States)

    Gimenez-Lirola, Luis Gabriel; Zhang, Jianqiang; Carrillo-Avila, Jose Antonio; Chen, Qi; Magtoto, Ronaldo; Poonsuk, Korakrit; Baum, David H; Piñeyro, Pablo; Zimmerman, Jeffrey

    2017-05-01

    The development of porcine epidemic diarrhea virus (PEDV) antibody-based assays is important for detecting infected animals, confirming previous virus exposure, and monitoring sow herd immunity. However, the potential cross-reactivity among porcine coronaviruses is a major concern for the development of pathogen-specific assays. In this study, we used serum samples ( n = 792) from pigs of precisely known infection status and a multiplex fluorescent microbead-based immunoassay and/or enzyme-linked immunoassay platform to characterize the antibody response to PEDV whole-virus (WV) particles and recombinant polypeptides derived from the four PEDV structural proteins, i.e., spike (S), nucleocapsid (N), membrane (M), and envelope (E). Antibody assay cutoff values were selected to provide 100% diagnostic specificity for each target. The earliest IgG antibody response, mainly directed against S1 polypeptides, was observed at days 7 to 10 postinfection. With the exception of nonreactive protein E, we observed similar antibody ontogenies and patterns of seroconversion for S1, N, M, and WV antigens. Recombinant S1 provided the best diagnostic sensitivity, regardless of the PEDV strain, with no cross-reactivity detected against transmissible gastroenteritis virus (TGEV), porcine respiratory coronavirus (PRCV), or porcine deltacoronavirus (PDCoV) pig antisera. The WV particles showed some cross-reactivity to TGEV Miller and TGEV Purdue antisera, while N protein presented some cross-reactivity to TGEV Miller. The M protein was highly cross-reactive to TGEV and PRCV antisera. Differences in the antibody responses to specific PEDV structural proteins have important implications in the development and performance of antibody assays for the diagnosis of PEDV enteric disease. Copyright © 2017 American Society for Microbiology.

  8. Unusual pattern of chikungunya virus epidemic in the Americas, the Panamanian experience

    Science.gov (United States)

    Denis, Bernardino; Barahona de Mosca, Itza; Rodriguez, Dennys; Cedeño, Israel; Arauz, Dimelza; González, Publio; Cerezo, Lizbeth; Moreno, Lourdes; García, Lourdes; Sáenz, Lisseth E.; Atencio, María Aneth; Rojas-Fermin, Eddy; Vizcaino, Fernando; Perez, Nicolas; Moreno, Brechla; López-Vergès, Sandra; Valderrama, Anayansi; Armién, Blas

    2017-01-01

    Background Chikungunya virus (CHIKV) typically causes explosive epidemics of fever, rash and polyarthralgia after its introduction into naïve populations. Since its introduction in Panama in May of 2014, few autochthonous cases have been reported; most of them were found within limited outbreaks in Panama City in 2014 and Puerto Obaldia town, near the Caribbean border with Colombia in 2015. In order to confirm that Panama had few CHIKV cases compared with neighboring countries, we perform an epidemiological analysis of chikungunya cases reported from May 2014 to July 2015. Moreover, to understand this paucity of confirmed CHIKV cases, a vectorial analysis in the counties where these cases were reported was performed. Methods Chikungunya cases were identified at medical centers and notified to health authorities. Sera samples were analyzed at Gorgas Memorial Institute for viral RNA and CHIKV-specific antibody detection. Results A total of 413 suspected cases of CHIKV infections were reported, with incidence rates of 0.5 and 0.7 per 100,000 inhabitants in 2014 and 2015, respectively. During this period, 38.6% of CHIKV cases were autochthonous with rash and polyarthralgia as predominant symptoms. CHIKV and DENV incidence ratios were 1:306 and 1:34, respectively. A phylogenetic analysis of E1/E2 genomic segment indicates that the outbreak strains belong to the Asian genotype and cluster together with CHIKV isolates from other American countries during the same period. Statistical analysis of the National Vector Control program at the district level shows low and medium vector infestation level for most of the counties with CHIKV cases. This index was lower than for neighboring countries. Conclusions Previous training of clinical, laboratory and vector workers allowed a good caption and detection of the chikungunya cases and fast intervention. It is possible that low/medium vector infestation level could explain in part the paucity of chikungunya infections in Panama

  9. Impact of porcine epidemic diarrhea on performance of growing pigs.

    Directory of Open Access Journals (Sweden)

    Julio Alvarez

    Full Text Available The impact of porcine epidemic diarrhea virus (PEDv infection on the US pork industry has mainly been attributed to the mortality that it causes in suckling piglets, and, consequently, much effort has been invested in the quantification of its effect in sow farms. However, no information on the performance of surviving pigs that were exposed to the PEDv as piglets is available. Here, a retrospective cohort study to evaluate the impact of porcine epidemic diarrhea virus (PEDv infection on growing pigs' performance, as indicated by mortality, average daily gain (ADG, average daily feed intake (ADFI, and feed conversion ratio (FCR was performed using production records from weaned pigs in nursery and wean-to-finish sites from sow farms that became PEDv-infected between May 2013 and June 2014. Production records from the first batch of growing pigs weaned in infected flows after the PEDv outbreak ("infected batches" were compared with those from pigs weaned within the previous 14 to 120 days ("control batches". Performance records from infected and control batches, paired by flow, were compared using non-parametric paired tests. Mortality, ADG and FCR were significantly different in PEDv-positive (infected compared with PEDv-negative (control batches, with a mean increase of mortality and FCR of 11% and 0.5, respectively, and a decrease of ADG of 0.16 lb/day. Our results demonstrate a poorer performance of growing pigs weaned after a PEDv outbreak compared with those weaned within the previous 14-120 days, suggesting that in addition to the mortality induced by PEDv in suckling pigs, the disease also impairs the performance of surviving pig. These findings help to quantify the impact of PEDv infection in the US and, ultimately, contribute to efforts to quantify the cost-effectiveness of disease prevention and control measures.

  10. Memory effects on epidemic evolution: The susceptible-infected-recovered epidemic model

    Science.gov (United States)

    Saeedian, M.; Khalighi, M.; Azimi-Tafreshi, N.; Jafari, G. R.; Ausloos, M.

    2017-02-01

    Memory has a great impact on the evolution of every process related to human societies. Among them, the evolution of an epidemic is directly related to the individuals' experiences. Indeed, any real epidemic process is clearly sustained by a non-Markovian dynamics: memory effects play an essential role in the spreading of diseases. Including memory effects in the susceptible-infected-recovered (SIR) epidemic model seems very appropriate for such an investigation. Thus, the memory prone SIR model dynamics is investigated using fractional derivatives. The decay of long-range memory, taken as a power-law function, is directly controlled by the order of the fractional derivatives in the corresponding nonlinear fractional differential evolution equations. Here we assume "fully mixed" approximation and show that the epidemic threshold is shifted to higher values than those for the memoryless system, depending on this memory "length" decay exponent. We also consider the SIR model on structured networks and study the effect of topology on threshold points in a non-Markovian dynamics. Furthermore, the lack of access to the precise information about the initial conditions or the past events plays a very relevant role in the correct estimation or prediction of the epidemic evolution. Such a "constraint" is analyzed and discussed.

  11. Phylogenetic analysis of canine distemper virus in South America clade 1 reveals unique molecular signatures of the local epidemic.

    Science.gov (United States)

    Fischer, Cristine D B; Gräf, Tiago; Ikuta, Nilo; Lehmann, Fernanda K M; Passos, Daniel T; Makiejczuk, Aline; Silveira, Marcos A T; Fonseca, André S K; Canal, Cláudio W; Lunge, Vagner R

    2016-07-01

    Canine distemper virus (CDV) is a highly contagious pathogen for domestic dogs and several wild carnivore species. In Brazil, natural infection of CDV in dogs is very high due to the large non-vaccinated dog population, a scenario that calls for new studies on the molecular epidemiology. This study investigates the phylodynamics and amino-acid signatures of CDV epidemic in South America by analyzing a large dataset compiled from publicly available sequences and also by collecting new samples from Brazil. A population of 175 dogs with canine distemper (CD) signs was sampled, from which 89 were positive for CDV, generating 42 new CDV sequences. Phylogenetic analysis of the new and publicly available sequences revealed that Brazilian sequences mainly clustered in South America 1 (SA1) clade, which has its origin estimated to the late 1980's. The reconstruction of the demographic history in SA1 clade showed an epidemic expanding until the recent years, doubling in size every nine years. SA1 clade epidemic distinguished from the world CDV epidemic by the emergence of the R580Q strain, a very rare and potentially detrimental substitution in the viral genome. The R580Q substitution was estimated to have happened in one single evolutionary step in the epidemic history in SA1 clade, emerging shortly after introduction to the continent. Moreover, a high prevalence (11.9%) of the Y549H mutation was observed among the domestic dogs sampled here. This finding was associated (p<0.05) with outcome-death and higher frequency in mixed-breed dogs, the later being an indicator of a continuous exchange of CDV strains circulating among wild carnivores and domestic dogs. The results reported here highlight the diversity of the worldwide CDV epidemic and reveal local features that can be valuable for combating the disease. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Epidemic optic neuropathy in Cuba. Eye findings.

    Science.gov (United States)

    Sadun, A A; Martone, J F; Muci-Mendoza, R; Reyes, L; DuBois, L; Silva, J C; Roman, G; Caballero, B

    1994-05-01

    To characterize and establish a clinical definition of the optic neuropathy that appeared in epidemic form in Cuba in 1992 and 1993. At the invitation of the Cuban Ministry of Health, Havana, members of ORBIS International and the Pan American Health Organization, assembled teams that traveled to Cuba in May 1993. We were initially briefed by Cuban national experts in the areas of virology, nutrition, toxicology, ophthalmology, neurology, and public health. We then examined 20 patients on our own. Thirteen of these patients underwent a comprehensive neuro-ophthalmologic examination, including neurologic examination, ophthalmologic examination, visual fields, optic nerve function studies, contrast sensitivity studies, and funduscopy. We returned 4 months later to perform an additional 12 comprehensive neuro-ophthalmologic and follow-up examinations. Only seven of the 13 patients who were alleged to have the optic form of the epidemic and who were rigorously and systematically examined on the first visit demonstrated a bilateral optic neuropathy. These seven patients had several features that included decreased visual acuity, poor color vision, central scotomas, decreased contrast sensitivity, saccadic eye movements, and most prominent and distinctive of all, nerve fiber layer wedge defects of the papillomacular bundle. Our clinical definition was then implemented by the Cuban ophthalmologists and epidemiologists. On returning 4 months later, we found that all newly presented patients were correctly diagnosed to have the epidemic disease. With the new case definition and the application of a few simple psychophysical tests, the false-positive rate of diagnosis became much lower. After vitamin therapy, we reexamined the patients seen on our initial visit, and all showed marked improvement. The Cuban epidemic was characterized by an optic neuropathy with features that were similar to those of tobacco/alcohol amblyopia and Leber's optic atrophy. Recent political

  13. [Epidemics and pandemics in general practice. What can we learn from the swine flu (H1N1) and EHEC outbreak?].

    Science.gov (United States)

    Eisele, M; Hansen, H; Wagner, H-O; von Leitner, E; Pohontsch, N; Scherer, M

    2014-06-01

    As primary care givers with a coordinating function, general practitioners (GP) play a key role in dealing with epidemics and pandemics. As of yet, there are no studies in Germany describing the difficulties experienced by GPs in patient care during epidemics/pandemics. This study aimed at identifying the problem areas in GPs' patient care during the H1N1 and EHEC (enterohemorrhagic strain of Escherichia coli) outbreaks. With this information, recommendations for guaranteeing proper patient care during future epidemics/pandemics can be derived. In all, 12 qualitative, semi-structured, open guideline interviews with GPs in Hamburg and Lübeck were conducted, transcribed, and evaluated with qualitative content analysis. Five areas in ambulatory patient care were identified in which changes are needed from the primary care perspective: provision of information for GPs, workload, financing of epidemic-related measures, organization of the practices, care of those taken ill. The workload of GPs in particular can and should be reduced through successful, centralized information distribution during epidemics/pandemics. The GP's function as a coordinator should be supported and consolidated, in order to relieve the in-patient sector in cases of an epidemic/pandemic. Secured financing of epidemic-associated measures can help ensure patient care.

  14. Effects of awareness diffusion and self-initiated awareness behavior on epidemic spreading - An approach based on multiplex networks

    Science.gov (United States)

    Kan, Jia-Qian; Zhang, Hai-Feng

    2017-03-01

    In this paper, we study the interplay between the epidemic spreading and the diffusion of awareness in multiplex networks. In the model, an infectious disease can spread in one network representing the paths of epidemic spreading (contact network), leading to the diffusion of awareness in the other network (information network), and then the diffusion of awareness will cause individuals to take social distances, which in turn affects the epidemic spreading. As for the diffusion of awareness, we assume that, on the one hand, individuals can be informed by other aware neighbors in information network, on the other hand, the susceptible individuals can be self-awareness induced by the infected neighbors in the contact networks (local information) or mass media (global information). Through Markov chain approach and numerical computations, we find that the density of infected individuals and the epidemic threshold can be affected by the structures of the two networks and the effective transmission rate of the awareness. However, we prove that though the introduction of the self-awareness can lower the density of infection, which cannot increase the epidemic threshold no matter of the local information or global information. Our finding is remarkably different to many previous results on single-layer network: local information based behavioral response can alter the epidemic threshold. Furthermore, our results indicate that the nodes with more neighbors (hub nodes) in information networks are easier to be informed, as a result, their risk of infection in contact networks can be effectively reduced.

  15. Molecular characterisation of Sporothrix schenckii isolates from humans and cats involved in the sporotrichosis epidemic in Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Rosani Santos Reis

    2009-08-01

    Full Text Available An epidemic of sporotrichosis, a subcutaneous mycosis caused by the fungus Sporothrix schenckii, is ongoing in Rio de Janeiro, Brazil, in which cases of human infection are related to exposure to cats. In an attempt to demonstrate the zoonotic character of this epidemic using molecular methodology, we characterised by DNA-based typing methods 19 human and 25 animal S. schenckii isolates from the epidemic, as well as two control strains. To analyse the isolates, the random amplified polymorphic DNA (RAPD technique was performed using three different primers, together with DNA fingerprinting using the minisatellite derived from the wild-type phage M13 core-sequence. The analyses generated amplicons with considerable polymorphism. Although isolates exhibited high levels of genetic relatedness, they could be clustered into 5-10 genotypes. The RAPD profiles of epidemic S. schenckii isolates could be distinguished from that of the United States isolate, displaying 20% similarity to each primer and 60% when amplified with the M13 primer. DNA fingerprinting of S. schenckii isolated from the nails (42.8% and the oral cavities (66% of cats were identical to related human samples, suggesting that there is a common infection source for animals and humans in this epidemic. It is clear that cats act as a vehicle for dissemination of S. schenckii.

  16. An epidemic model for the future progression of the current Haiti cholera epidemic

    Science.gov (United States)

    Bertuzzo, E.; Mari, L.; Righetto, L.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2012-04-01

    As a major cholera epidemic progresses in Haiti, and the figures of the infection, up to December 2011, climb to 522,000 cases and 7,000 deaths, the development of general models to track and predict the evolution of the outbreak, so as to guide the allocation of medical supplies and staff, is gaining notable urgency. We propose here a spatially explicit epidemic model that accounts for the dynamics of susceptible and infected individuals as well as the redistribution of Vibrio cholera, the causative agent of the disease, among different human communities. In particular, we model two spreading pathways: the advection of pathogens through hydrologic connections and the dissemination due to human mobility described by means of a gravity-like model. To this end the country has been divided into hydrologic units based on drainage directions derived from a digital terrain model. Moreover the population of each unit has been estimated from census data downscaled to 1 km x 1 km resolution via remotely sensed geomorphological information (LandScan project). The model directly accounts for the role of rainfall patterns in driving the seasonality of cholera outbreaks. The two main outbreaks in fact occurred during the rainy seasons (October and May) when extensive floodings severely worsened the sanitation conditions and, in turn, raised the risk of infection. The model capability to reproduce the spatiotemporal features of the epidemic up to date grants robustness to the foreseen future development. To this end, we generate realistic scenario of future precipitation in order to forecast possible epidemic paths up to the end of the 2013. In this context, the duration of acquired immunity, a hotly debated topic in the scientific community, emerges as a controlling factor for progression of the epidemic in the near future. The framework presented here can straightforwardly be used to evaluate the effectiveness of alternative intervention strategies like mass vaccinations

  17. Defining and detecting malaria epidemics in south-east Iran

    Directory of Open Access Journals (Sweden)

    McKelvie William R

    2012-03-01

    Full Text Available Abstract Background A lack of consensus on how to define malaria epidemics has impeded the evaluation of early detection systems. This study aimed to develop local definitions of malaria epidemics in a known malarious area of Iran, and to use that definition to evaluate the validity of several epidemic alert thresholds. Methods Epidemic definition variables generated from surveillance data were plotted against weekly malaria counts to assess which most accurately labelled aberrations. Various alert thresholds were then generated from weekly counts or log counts. Finally, the best epidemic definition was used to calculate and compare sensitivities, specificities, detection delays, and areas under ROC curves of the alert thresholds. Results The best epidemic definition used a minimum duration of four weeks and week-specific and overall smoothed geometric means plus 1.0 standard deviation. It defined 13 epidemics. A modified C-SUM alert of untransformed weekly counts using a threshold of mean + 0.25 SD had the highest combined sensitivity and specificity. Untransformed C-SUM alerts also had the highest area under the ROC curve. Conclusions Defining local malaria epidemics using objective criteria facilitated the evaluation of alert thresholds. This approach needs further study to refine epidemic definitions and prospectively evaluate epidemic alerts.

  18. Defining and detecting malaria epidemics in south-east Iran.

    Science.gov (United States)

    McKelvie, William R; Haghdoost, Ali Akbar; Raeisi, Ahmad

    2012-03-23

    A lack of consensus on how to define malaria epidemics has impeded the evaluation of early detection systems. This study aimed to develop local definitions of malaria epidemics in a known malarious area of Iran, and to use that definition to evaluate the validity of several epidemic alert thresholds. Epidemic definition variables generated from surveillance data were plotted against weekly malaria counts to assess which most accurately labelled aberrations. Various alert thresholds were then generated from weekly counts or log counts. Finally, the best epidemic definition was used to calculate and compare sensitivities, specificities, detection delays, and areas under ROC curves of the alert thresholds. The best epidemic definition used a minimum duration of four weeks and week-specific and overall smoothed geometric means plus 1.0 standard deviation. It defined 13 epidemics. A modified C-SUM alert of untransformed weekly counts using a threshold of mean+0.25 SD had the highest combined sensitivity and specificity. Untransformed C-SUM alerts also had the highest area under the ROC curve. Defining local malaria epidemics using objective criteria facilitated the evaluation of alert thresholds. This approach needs further study to refine epidemic definitions and prospectively evaluate epidemic alerts.

  19. antimicrobial susceptibility pattern of vibrio cholerae 01 strains

    African Journals Online (AJOL)

    hi-tech

    2000-07-07

    Jul 7, 2000 ... for the rapid rise in antimicrobial resistance have been extensive antimicrobial prophylaxis, unauthorised dispensing and use of these agents in animal husbandry(11,12). In Tanzania, data collected during cholera epidemics in 1990 and 1991 showed that all V. cholerae 01 strains were sensitive to ...

  20. Analysis of an asymmetric two-strain dengue model.

    NARCIS (Netherlands)

    Kooi, B.W.; Aguiar, M.; Stollenwerk, N.

    2014-01-01

    In this paper we analyse a two-strain compartmental dengue fever model that allows us to study the behaviour of a Dengue fever epidemic. Dengue fever is the most common mosquito-borne viral disease of humans that in recent years has become a major international public health concern. The model is an

  1. An outbreak of epidemic keratoconjunctivitis at an outpatient ophthalmology clinic

    Directory of Open Access Journals (Sweden)

    Timothy J Doyle

    2010-12-01

    Full Text Available Epidemic keratoconjunctivitis (EKC is an acute eye infection caused by adenovirus. We investigated an outbreak of EKC at an outpatient ophthalmology practice in the context of a suspected community wide increase in EKC activity. A site visit was made to the facility reporting the outbreak. A line list was created of patients clinically diagnosed with EKC at the practice during the previous 5 months. A questionnaire was faxed to all other licensed ophthalmologists in the county regarding recent EKC activity in their facility. Descriptive data analyses were conducted. The outbreak facility reported 37 patients clinically diagnosed with EKC during the previous 5 months. In addition, the single ophthalmologist at the practice also had symptoms compatible with EKC during the outbreak period. Specimens were collected on 4 patients and all were positive for adenovirus serotype 8. Forty percent of ophthalmologists surveyed in the county saw at least one EKC patient in the previous 3 months, and 20% reported a perceived increase in EKC activity in recent months over normal seasonal patterns. The outbreak at the facility likely began as part of a widespread community increase in EKC that may have been amplified at the facility through nosocomial transmission. Medical providers experiencing increases in EKC activity above seasonally expected norms should contact their public health department for assistance with etiologic diagnoses and outbreak control.

  2. Full-genome dissection of an epidemic of severe invasive disease caused by a hypervirulent, recently emerged clone of group A Streptococcus.

    Science.gov (United States)

    Fittipaldi, Nahuel; Beres, Stephen B; Olsen, Randall J; Kapur, Vivek; Shea, Patrick R; Watkins, M Ebru; Cantu, Concepcion C; Laucirica, Daniel R; Jenkins, Leslie; Flores, Anthony R; Lovgren, Marguerite; Ardanuy, Carmen; Liñares, Josefina; Low, Donald E; Tyrrell, Gregory J; Musser, James M

    2012-04-01

    Group A Streptococcus (GAS) causes an exceptionally broad range of infections in humans, from relatively mild pharyngitis and skin infections to life-threatening necrotizing fasciitis and toxic shock syndrome. An epidemic of severe invasive human infections caused by type emm59 GAS, heretofore an exceedingly rare cause of disease, spread west to east across Canada over a 3-year period (2006 to 2008). By sequencing the genomes of 601 epidemic, historic, and other emm59 organisms, we discovered that a recently emerged, genetically distinct emm59 clone is responsible for the Canadian epidemic. Using near-real-time genome sequencing, we were able to show spread of the Canadian epidemic clone into the United States. The extensive genome data permitted us to identify patterns of geographic dissemination as well as links between emm59 subclonal lineages that cause infections. Mouse and nonhuman primate models of infection demonstrated that the emerged clone is unusually virulent. Transmission of epidemic emm59 strains may have occurred primarily by skin contact, as suggested by an experimental model of skin transmission. In addition, the emm59 strains had a significantly impaired ability to persist in human saliva and to colonize the oropharynx of mice, and seldom caused human pharyngitis. Our study contributes new information to the rapidly emerging field of molecular pathogenomics of bacterial epidemics and illustrates how full-genome data can be used to precisely illuminate the landscape of strain dissemination during a bacterial epidemic. Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  3. Emergence and global spread of epidemic healthcare-associated Clostridium difficile.

    Science.gov (United States)

    He, Miao; Miyajima, Fabio; Roberts, Paul; Ellison, Louise; Pickard, Derek J; Martin, Melissa J; Connor, Thomas R; Harris, Simon R; Fairley, Derek; Bamford, Kathleen B; D'Arc, Stephanie; Brazier, Jon; Brown, Derek; Coia, John E; Douce, Gill; Gerding, Dale; Kim, Hee Jung; Koh, Tse Hsien; Kato, Haru; Senoh, Mitsutoshi; Louie, Tom; Michell, Stephen; Butt, Emma; Peacock, Sharon J; Brown, Nick M; Riley, Tom; Songer, Glen; Wilcox, Mark; Pirmohamed, Munir; Kuijper, Ed; Hawkey, Peter; Wren, Brendan W; Dougan, Gordon; Parkhill, Julian; Lawley, Trevor D

    2013-01-01

    Epidemic C. difficile (027/BI/NAP1) has rapidly emerged in the past decade as the leading cause of antibiotic-associated diarrhea worldwide. However, the key events in evolutionary history leading to its emergence and the subsequent patterns of global spread remain unknown. Here, we define the global population structure of C. difficile 027/BI/NAP1 using whole-genome sequencing and phylogenetic analysis. We show that two distinct epidemic lineages, FQR1 and FQR2, not one as previously thought, emerged in North America within a relatively short period after acquiring the same fluoroquinolone resistance-conferring mutation and a highly related conjugative transposon. The two epidemic lineages showed distinct patterns of global spread, and the FQR2 lineage spread more widely, leading to healthcare-associated outbreaks in the UK, continental Europe and Australia. Our analysis identifies key genetic changes linked to the rapid transcontinental dissemination of epidemic C. difficile 027/BI/NAP1 and highlights the routes by which it spreads through the global healthcare system.

  4. Modeling historical tuberculosis epidemics among Canadian First Nations: effects of malnutrition and genetic variation

    Directory of Open Access Journals (Sweden)

    Sarah F. Ackley

    2015-09-01

    Full Text Available Late 19th century epidemics of tuberculosis (TB in Western Canadian First Nations resulted in peak TB mortality rates more than six times the highest rates recorded in Europe. Using a mathematical modeling approach and historical TB mortality time series, we investigate potential causes of high TB mortality and rapid epidemic decline in First Nations from 1885 to 1940. We explore two potential causes of dramatic epidemic dynamics observed in this setting: first, we explore effects of famine prior to 1900 on both TB and population dynamics. Malnutrition is recognized as an individual-level risk factor for TB progression and mortality; its population-level effects on TB epidemics have not been explored previously. Second, we explore effects of heterogeneity in susceptibility to TB in two ways: modeling heterogeneity in susceptibility to infection, and heterogeneity in risk of developing disease once infected. Our results indicate that models lacking famine-related changes in TB parameters or heterogeneity result in an implausibly poor fit to both the TB mortality time series and census data; the inclusion of these features allows for the characteristic decline and rise in population observed in First Nations during this time period and confers improved fits to TB mortality data.

  5. Forecasting Epidemics Through Nonparametric Estimation of Time-Dependent Transmission Rates Using the SEIR Model.

    Science.gov (United States)

    Smirnova, Alexandra; deCamp, Linda; Chowell, Gerardo

    2017-05-02

    Deterministic and stochastic methods relying on early case incidence data for forecasting epidemic outbreaks have received increasing attention during the last few years. In mathematical terms, epidemic forecasting is an ill-posed problem due to instability of parameter identification and limited available data. While previous studies have largely estimated the time-dependent transmission rate by assuming specific functional forms (e.g., exponential decay) that depend on a few parameters, here we introduce a novel approach for the reconstruction of nonparametric time-dependent transmission rates by projecting onto a finite subspace spanned by Legendre polynomials. This approach enables us to effectively forecast future incidence cases, the clear advantage over recovering the transmission rate at finitely many grid points within the interval where the data are currently available. In our approach, we compare three regularization algorithms: variational (Tikhonov's) regularization, truncated singular value decomposition (TSVD), and modified TSVD in order to determine the stabilizing strategy that is most effective in terms of reliability of forecasting from limited data. We illustrate our methodology using simulated data as well as case incidence data for various epidemics including the 1918 influenza pandemic in San Francisco and the 2014-2015 Ebola epidemic in West Africa.

  6. Deterministic Seirs Epidemic Model for Modeling Vital Dynamics, Vaccinations, and Temporary Immunity

    OpenAIRE

    Marek B. Trawicki

    2017-01-01

    In this paper, the author proposes a new SEIRS model that generalizes several classical deterministic epidemic models (e.g., SIR and SIS and SEIR and SEIRS) involving the relationships between the susceptible S, exposed E, infected I, and recovered R individuals for understanding the proliferation of infectious diseases. As a way to incorporate the most important features of the previous models under the assumption of homogeneous mixing (mass-action principle) of the individuals in the popula...

  7. The Global Epidemic of Childhood Obesity: Poverty, Urbanization, and the Nutrition Transition

    OpenAIRE

    Brody, Jennifer

    2002-01-01

    Childhood obesity is increasing worldwide at rates of epidemic proportion (1, 2). Previously a public health concern of only the modern, industrialized world, this problem now increasingly affects children and adolescents of poor, developing countries. This new and somewhat baffling phenomenon urgently begs the question: How is it that impoverished children around the world become obese? Recent studies suggest that rapid globalization and urbanization account for significant shifts in dietary...

  8. Dynamical interplay between awareness and epidemic spreading in multiplex networks.

    Science.gov (United States)

    Granell, Clara; Gómez, Sergio; Arenas, Alex

    2013-09-20

    We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases.

  9. Strain superlattices in graphene

    Science.gov (United States)

    Zhang, Yingjie; Kim, Youngseok; Lyding, Joseph; Gilbert, Matthew; Mason, Nadya

    Superlattices have been widely explored to tailor the electronic properties of two-dimensional electron systems. Previous approaches to create superlattices have been limited to periodic potential modulations, either in the form of electrostatic gating or moiré heterostructures. Here we present a new strategy to generate superlattices in 2D materials. We deposit these 2D membranes on a periodic array of dielectric nanospheres, and achieve superlattices with periodic strain modulations. We studied the electronic and magneto-transport properties of strained graphene superlattices, and observed salient features of Dirac point cloning and Hofstadter's butterfly. Furthermore, we were able to tune the transport properties by changing the magnitude of strain in the graphene superlattice. This new degree of freedom provides a novel platform both for fundamental studies of 2D electron correlations and for prospective applications in 2D electronic devices. Y.Z. and N.M. acknowledge support from the National Science Foundation under Grant No. ENG-1434147.

  10. [The effects of closure to live poultry markets on Avian influenza A (H7N9) epidemics in China].

    Science.gov (United States)

    Liu, T; Zhu, G H; Zhang, B; Song, T; Kang, M; Lu, J; Zhao, Y Q; Huang, Z; Huang, Y L; Wang, X J; Yang, X Y; Ma, W J

    2017-12-10

    Since March 2013, China had experienced five seasonal epidemics related to Avian influenza A (H7N9). An unprecedented outbreak of H7N9 epidemic started from September 2016, with 730 cases reported till June 30(th) 2017, in mainland China that caused profound influences on both social development and health of the people. As an emerging infectious disease, information on pathogenic characteristics, transmission patterns and other epidemiological features of H7N9 virus somehow remained unclear. Data from previous studies suggested that the live poultry market (LPM) seemed to have served as main places where H7N9 virus got originated, mutated, spread and thus infected the human beings. Hence, closure of LPMs was suggested a major measure to control and prevent H7N9 epidemics in China. However, the effectiveness of different ways of LPM closures on H7N9 epidemics had been controversial. This study systemically summarized the effects of different ways of LPM closures on H7N epidemics from previous studies, aiming to provide references for developing a better program on H7N9 control and prevention in the country.

  11. Heterogeneous Epidemic Model for Assessing Data Dissemination in Opportunistic Networks

    DEFF Research Database (Denmark)

    Rozanova, Liudmila; Alekseev, Vadim; Temerev, Alexander

    2014-01-01

    that amount of data transferred between network nodes possesses a Pareto distribution, implying scale-free properties. In this context, more heterogeneity in susceptibility means the less severe epidemic progression, and, on the contrary, more heterogeneity in infectivity leads to more severe epidemics...... — assuming that the other parameter (either heterogeneity or susceptibility) stays fixed. The results are general enough to be useful for estimating the epidemic progression with no significant acquired immunity — in the cases where Pareto distribution holds....

  12. Susceptibility of Ae. aegypti (Diptera: Culicidae) to infection with epidemic (subtype IC) and enzootic (subtypes ID, IIIC, IIID) Venezuelan equine encephalitis complex alphaviruses.

    Science.gov (United States)

    Ortiz, Diana I; Kang, Wenli; Weaver, Scoti C

    2008-11-01

    To test the hypothesis that enzootic and epidemic Venezuelan equine encephalitis (VEE) complex alphaviruses can infect and be transmitted by Ae. aegypti, we conducted a series of experimental infection studies. One set of experiments tested the susceptibility of geographic strains of Ae. aegypti from Peru and Texas (U.S.A.) for epidemic (subtype IC) and enzootic (subtype ID) strains from Colombia/Venezuela, whereas the second set of experiments tested the susceptibility of Ae. aegypti from Iquitos, Peru, to enzootic VEE complex strains (subtypes ID, IIIC, and IIID) isolated in the same region, at different infectious doses. Experimental infections using artificial bloodmeals suggested that Ae. aegypti mosquitoes, particularly the strain from Iquitos, Peru, is moderately to highly susceptible to all of these VEE complex alphaviruses. The occurrence of enzootic VEE complex viruses circulating endemically in Iquitos suggests the possibility of a dengue-like transmission cycle among humans in tropical cities.

  13. Hurricanes, climate change and the cholera epidemic in Puerto Rico of 1855-1856.

    Science.gov (United States)

    Christenson, Bernard

    2008-01-01

    Hurricanes and global climate changes may affect the environmental factors of cholera dynamics in warm coastal areas, vulnerable to seasonal or sporadic outbreaks. The cholera epidemic of Puerto Rico in 1855-1856 had a profound effect on the Puerto Rican society; but it was not influenced by any climatic events, such as preceding hurricanes or storms based on past documentary sources. Particularly, the environmental non-toxigenic strains of Vibrio Cholerae in Puerto Rican water sources can maintain their pathogenic potential for sporadic or erratic toxigenic cholera outbreaks--if a "perfect storm" ever occurs.

  14. Behavioral synchronization induced by epidemic spread in complex networks

    Science.gov (United States)

    Sun, Mengfeng; Lou, Yijun; Duan, Jinqiao; Fu, Xinchu

    2017-06-01

    During the spread of an epidemic, individuals in realistic networks may exhibit collective behaviors. In order to characterize this kind of phenomenon and explore the correlation between collective behaviors and epidemic spread, in this paper, we construct several mathematical models (including without delay, with a coupling delay, and with double delays) of epidemic synchronization by applying the adaptive feedback motivated by real observations. By using Lyapunov function methods, we obtain the conditions for local and global stability of these epidemic synchronization models. Then, we illustrate that quenched mean-field theory is more accurate than heterogeneous mean-field theory in the prediction of epidemic synchronization. Finally, some numerical simulations are performed to complement our theoretical results, which also reveal some unexpected phenomena, for example, the coupling delay and epidemic delay influence the speed of epidemic synchronization. This work makes further exploration on the relationship between epidemic dynamics and synchronization dynamics, in the hope of being helpful to the study of other dynamical phenomena in the process of epidemic spread.

  15. Epidemics: Lessons from the past and current patterns of response

    Science.gov (United States)

    Martin, Paul

    2008-09-01

    Hippocrates gave the term 'epidemic' its medical meaning. From antiquity to modern times, the meaning of the word epidemic has continued to evolve. Over the centuries, researchers have reached an understanding of the varying aspects of epidemics and have tried to combat them. The role played by travel, trade, and human exchanges in the propagation of epidemic infectious diseases has been understood. In 1948, the World Health Organization was created and given the task of advancing ways of combating epidemics. An early warning system to combat epidemics has been implemented by the WHO. The Global Outbreak Alert and Response Network (GOARN) is collaboration between existing institutions and networks that pool their human and technical resources to fight outbreaks. Avian influenza constitutes currently the most deadly epidemic threat, with fears that it could rapidly reach pandemic proportions and put several thousands of lives in jeopardy. Thanks to the WHO's support, most of the world's countries have mobilised and implemented an 'Action Plan for Pandemic Influenza'. As a result, most outbreaks of the H5N1 avian flu virus have so far been speedily contained. Cases of dengue virus introduction in countries possessing every circumstance required for its epidemic spread provide another example pertinent to the prevention of epidemics caused by vector-borne pathogens.

  16. A field guide to pandemic, epidemic and sporadic clones of methicillin-resistant Staphylococcus aureus.

    LENUS (Irish Health Repository)

    Monecke, Stefan

    2011-04-01

    In recent years, methicillin-resistant Staphylococcus aureus (MRSA) have become a truly global challenge. In addition to the long-known healthcare-associated clones, novel strains have also emerged outside of the hospital settings, in the community as well as in livestock. The emergence and spread of virulent clones expressing Panton-Valentine leukocidin (PVL) is an additional cause for concern. In order to provide an overview of pandemic, epidemic and sporadic strains, more than 3,000 clinical and veterinary isolates of MRSA mainly from Germany, the United Kingdom, Ireland, France, Malta, Abu Dhabi, Hong Kong, Australia, Trinidad & Tobago as well as some reference strains from the United States have been genotyped by DNA microarray analysis. This technique allowed the assignment of the MRSA isolates to 34 distinct lineages which can be clearly defined based on non-mobile genes. The results were in accordance with data from multilocus sequence typing. More than 100 different strains were distinguished based on affiliation to these lineages, SCCmec type and the presence or absence of PVL. These strains are described here mainly with regard to clinically relevant antimicrobial resistance- and virulence-associated markers, but also in relation to epidemiology and geographic distribution. The findings of the study show a high level of biodiversity among MRSA, especially among strains harbouring SCCmec IV and V elements. The data also indicate a high rate of genetic recombination in MRSA involving SCC elements, bacteriophages or other mobile genetic elements and large-scale chromosomal replacements.

  17. A Field Guide to Pandemic, Epidemic and Sporadic Clones of Methicillin-Resistant Staphylococcus aureus

    Science.gov (United States)

    Monecke, Stefan; Coombs, Geoffrey; Shore, Anna C.; Coleman, David C.; Akpaka, Patrick; Borg, Michael; Chow, Henry; Ip, Margaret; Jatzwauk, Lutz; Jonas, Daniel; Kadlec, Kristina; Kearns, Angela; Laurent, Frederic; O'Brien, Frances G.; Pearson, Julie; Ruppelt, Antje; Schwarz, Stefan; Scicluna, Elizabeth; Slickers, Peter; Tan, Hui-Leen; Weber, Stefan; Ehricht, Ralf

    2011-01-01

    In recent years, methicillin-resistant Staphylococcus aureus (MRSA) have become a truly global challenge. In addition to the long-known healthcare-associated clones, novel strains have also emerged outside of the hospital settings, in the community as well as in livestock. The emergence and spread of virulent clones expressing Panton-Valentine leukocidin (PVL) is an additional cause for concern. In order to provide an overview of pandemic, epidemic and sporadic strains, more than 3,000 clinical and veterinary isolates of MRSA mainly from Germany, the United Kingdom, Ireland, France, Malta, Abu Dhabi, Hong Kong, Australia, Trinidad & Tobago as well as some reference strains from the United States have been genotyped by DNA microarray analysis. This technique allowed the assignment of the MRSA isolates to 34 distinct lineages which can be clearly defined based on non-mobile genes. The results were in accordance with data from multilocus sequence typing. More than 100 different strains were distinguished based on affiliation to these lineages, SCCmec type and the presence or absence of PVL. These strains are described here mainly with regard to clinically relevant antimicrobial resistance- and virulence-associated markers, but also in relation to epidemiology and geographic distribution. The findings of the study show a high level of biodiversity among MRSA, especially among strains harbouring SCCmec IV and V elements. The data also indicate a high rate of genetic recombination in MRSA involving SCC elements, bacteriophages or other mobile genetic elements and large-scale chromosomal replacements. PMID:21494333

  18. Evolutionary pathway to increased virulence and epidemic group A Streptococcus disease derived from 3,615 genome sequences.

    Science.gov (United States)

    Nasser, Waleed; Beres, Stephen B; Olsen, Randall J; Dean, Melissa A; Rice, Kelsey A; Long, S Wesley; Kristinsson, Karl G; Gottfredsson, Magnus; Vuopio, Jaana; Raisanen, Kati; Caugant, Dominique A; Steinbakk, Martin; Low, Donald E; McGeer, Allison; Darenberg, Jessica; Henriques-Normark, Birgitta; Van Beneden, Chris A; Hoffmann, Steen; Musser, James M

    2014-04-29

    We sequenced the genomes of 3,615 strains of serotype Emm protein 1 (M1) group A Streptococcus to unravel the nature and timing of molecular events contributing to the emergence, dissemination, and genetic diversification of an unusually virulent clone that now causes epidemic human infections worldwide. We discovered that the contemporary epidemic clone emerged in stepwise fashion from a precursor cell that first contained the phage encoding an extracellular DNase virulence factor (streptococcal DNase D2, SdaD2) and subsequently acquired the phage encoding the SpeA1 variant of the streptococcal pyrogenic exotoxin A superantigen. The SpeA2 toxin variant evolved from SpeA1 by a single-nucleotide change in the M1 progenitor strain before acquisition by horizontal gene transfer of a large chromosomal region encoding secreted toxins NAD(+)-glycohydrolase and streptolysin O. Acquisition of this 36-kb region in the early 1980s into just one cell containing the phage-encoded sdaD2 and speA2 genes was the final major molecular event preceding the emergence and rapid intercontinental spread of the contemporary epidemic clone. Thus, we resolve a decades-old controversy about the type and sequence of genomic alterations that produced this explosive epidemic. Analysis of comprehensive, population-based contemporary invasive strains from seven countries identified strong patterns of temporal population structure. Compared with a preepidemic reference strain, the contemporary clone is significantly more virulent in nonhuman primate models of pharyngitis and necrotizing fasciitis. A key finding is that the molecular evolutionary events transpiring in just one bacterial cell ultimately have produced millions of human infections worldwide.

  19. Resource allocation for epidemic control in metapopulations.

    Directory of Open Access Journals (Sweden)

    Martial L Ndeffo Mbah

    Full Text Available Deployment of limited resources is an issue of major importance for decision-making in crisis events. This is especially true for large-scale outbreaks of infectious diseases. Little is known when it comes to identifying the most efficient way of deploying scarce resources for control when disease outbreaks occur in different but interconnected regions. The policy maker is frequently faced with the challenge of optimizing efficiency (e.g. minimizing the burden of infection while accounting for social equity (e.g. equal opportunity for infected individuals to access treatment. For a large range of diseases described by a simple SIRS model, we consider strategies that should be used to minimize the discounted number of infected individuals during the course of an epidemic. We show that when faced with the dilemma of choosing between socially equitable and purely efficient strategies, the choice of the control strategy should be informed by key measurable epidemiological factors such as the basic reproductive number and the efficiency of the treatment measure. Our model provides new insights for policy makers in the optimal deployment of limited resources for control in the event of epidemic outbreaks at the landscape scale.

  20. The opioid overdose epidemic: opportunities for pharmacists

    Directory of Open Access Journals (Sweden)

    Wu LT

    2017-07-01

    Full Text Available Li-Tzy Wu,1–4 Udi E Ghitza,5 Anne L Burns,6 Paolo Mannelli,1 1Department of Psychiatry and Behavioral Sciences, 2Department of Medicine, 3Duke Clinical Research Institute, Duke University School of Medicine, 4Center for Child and Family Policy, Sanford School of Public Policy, Duke University, Durham, NC, 5Center for Clinical Trials Network, National Institute on Drug Abuse, Bethesda, MD, 6American Pharmacists Association, Washington, DC, USA The USA is experiencing an opioid overdose epidemic. It has been driven largely by prescription opioids and intensified by a surge of illicit opioids (e.g., heroin and fentanyl.1,2 Drug-involved overdose, mainly opioids (e.g., prescription opioids and heroin, is a leading cause of accidental death in the USA. The opioid overdose epidemic has been escalating consistently for over a decade.2 Every day, an estimated 91 Americans die from opioid-related overdose.3 Opioid overdose appears to have disproportionally affected men, adults aged 25–64 years, and non-Hispanic whites.2

  1. Devastating epidemics in recent ages Greek populations.

    Science.gov (United States)

    Kotsiou, Antonia; Michalaki, Vasiliki; Anagnostopoulou, Helen N

    2017-12-01

    In the recent Greek ages the most devastating epidemics were plague, smallpox, leprosy and cholera. In 1816 plague struck the Ionian and Aegean Islands, mainland Greece, Constantinople and Smyrna. The Venetians ruling the Ionian Islands effectively combated plague in contrast to the Ottomans ruling all other regions. In 1922, plague appeared in Patras refugees who were expelled by the Turks from Smyrna and Asia Minor. Inoculation against smallpox was first performed in Thessaly by the Greek women, and the Greek doctors Emmanouel Timonis (1713, Oxford) and Jakovos Pylarinos (1715, Venice) made relevant scientific publications. The first leper colony opened in Chios Island. In Crete, Spinalonga was transformed into a leper island, which following the Independence War against Turkish occupation and the unification of Crete with Greece in 1913, was classified as an International Leper Hospital. Cholera struck Greece in 1853-1854 brought by the French troops during the Crimean War, and again during the Balkan Wars (1912-13) when the Bulgarian troops brought cholera to northern Greece. Due to successive wars, medical assistance was not always available, so desperate people turned many times to religion through processions in honor of local saints, for their salvation in epidemics.

  2. America's Opioid Epidemic: Supply and Demand Considerations.

    Science.gov (United States)

    Clark, David J; Schumacher, Mark A

    2017-11-01

    America is in the midst of an opioid epidemic characterized by aggressive prescribing practices, highly prevalent opioid misuse, and rising rates of prescription and illicit opioid overdose-related deaths. Medical and lay public sentiment have become more cautious with respect to prescription opioid use in the past few years, but a comprehensive strategy to reduce our reliance on prescription opioids is lacking. Addressing this epidemic through reductions in unnecessary access to these drugs while implementing measures to reduce demand will be important components of any comprehensive solution. Key supply-side measures include avoiding overprescribing, reducing diversion, and discouraging misuse through changes in drug formulations. Important demand-side measures center around educating patients and clinicians regarding the pitfalls of opioid overuse and methods to avoid unnecessary exposure to these drugs. Anesthesiologists, by virtue of their expertise in the use of these drugs and their position in guiding opioid use around the time of surgery, have important roles to play in reducing patient exposure to opioids and providing education about appropriate use. Aside from the many immediate steps that can be taken, clinical and basic research directed at understanding the interaction between pain and opioid misuse is critical to identifying the optimal use of these powerful pain relievers in clinical practice.

  3. Nepalese origin of cholera epidemic in Haiti.

    Science.gov (United States)

    Frerichs, R R; Keim, P S; Barrais, R; Piarroux, R

    2012-06-01

    Cholera appeared in Haiti in October 2010 for the first time in recorded history. The causative agent was quickly identified by the Haitian National Public Health Laboratory and the United States Centers for Disease Control and Prevention as Vibrio cholerae serogroup O1, serotype Ogawa, biotype El Tor. Since then, >500 000 government-acknowledged cholera cases and >7000 deaths have occurred, the largest cholera epidemic in the world, with the real death toll probably much higher. Questions of origin have been widely debated with some attributing the onset of the epidemic to climatic factors and others to human transmission. None of the evidence on origin supports climatic factors. Instead, recent epidemiological and molecular-genetic evidence point to the United Nations peacekeeping troops from Nepal as the source of cholera to Haiti, following their troop rotation in early October 2010. Such findings have important policy implications for shaping future international relief efforts. © 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.

  4. [The HIV/AIDS Epidemic in Cambodia].

    Science.gov (United States)

    Soda, K; Morio, S; Tajima, K; Kitamura, K; Toba, M; Ito, A; Kihara, M; Ichikawa, S; Imai, M; Mizushima, S; Ohshige, K

    1997-05-01

    In December 1995 and March 1996, we visited institutes which were conducting epidemiological studied of HIV/AIDS in Cambodia, and obtained data for further collaborative study between Japan and Cambodia. Data included information on AIDS patients and HIV infected persons, and behavioral epidemiology of CSWs (Commercial Sex Workers). The cumulative reported number of AIDS patients and HIV infected persons in Cambodia was 86 and 2,536 cases respectively in 1995. The cause of infection was mostly heterosexual contact with very few cases from injecting drug use (IDU) and other causes. The seroprevalence rate of HIV antibody among donated blood rapidly increased from 0.08% in 1991 to 4.47% in 1995, and those among CSWs and pregnant women were 37.9% and 2.6%, respectively, in 1995. The average rate of condom use among CSWs was 66%, but the rate of usual usage was only 14%. These results indicate that the HIV/AIDS epidemic had spread rapidly through CSWs, that it had been spread among peoples in communities, and that usage of condoms among CSWs was insufficient in Cambodia. Without strong countermeasures against HIV/AIDS in this country, HIV/AIDS epidemic may spread significantly to not only peoples in this country but also those in neighbouring countries in the future.

  5. Colliding Epidemics and the Rise of Cryptococcosis

    Directory of Open Access Journals (Sweden)

    Christina C. Chang

    2015-12-01

    Full Text Available Discovered more than 100 years ago as a human pathogen, the Cryptococcus neoformans–Cryptococcus gattii (C. neoformans–C. gattii complex has seen a large global resurgence in its association with clinical disease in the last 30 years. First isolated in fermenting peach juice, and identified as a human pathogen in 1894 in a patient with bone lesions, this environmental pathogen has now found niches in soil, trees, birds, and domestic pets. Cryptococcosis is well recognized as an opportunistic infection and was first noted to be associated with reticuloendothelial cancers in the 1950s. Since then, advances in transplant immunology, medical science and surgical techniques have led to increasing numbers of solid organ transplantations (SOT and hematological stem cell transplantations being performed, and the use of biological immunotherapeutics in increasingly high-risk and older individuals, have contributed to the further rise in cryptococcosis. Globally, however, the major driver for revivification of cryptococcosis is undoubtedly the HIV epidemic, particularly in Sub-Saharan Africa where access to care and antiretroviral therapy remains limited and advanced immunodeficiency, poverty and malnutrition remains the norm. As a zoonotic disease, environmental outbreaks of both human and animal cryptococcosis have been reported, possibly driven by climate change. This is best exemplified by the resurgence of C. gattii infection in Vancouver Island, Canada, and the Pacific Northwest of the United States since 1999. Here we describe how the colliding epidemics of HIV, transplantation and immunologics, climate change and migration have contributed to the rise of cryptococcosis.

  6. Epidemic contact tracing via communication traces.

    Science.gov (United States)

    Farrahi, Katayoun; Emonet, Rémi; Cebrian, Manuel

    2014-01-01

    Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  7. Epidemic contact tracing via communication traces.

    Directory of Open Access Journals (Sweden)

    Katayoun Farrahi

    Full Text Available Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  8. Molecular Typing of Pathogenic Leptospira Serogroup Icterohaemorrhagiae Strains Circulating in China during the Past 50 Years.

    Directory of Open Access Journals (Sweden)

    Cuicai Zhang

    2015-05-01

    Full Text Available Leptospirosis is one of the most important neglected tropical infectious diseases worldwide. Icterohaemorrhagiae has been throughout recent history, and still is, the predominant serogroup of this pathogen in China. However, very little in detail is known about the serovars or genotypes of this serogroup.In this study, 120 epidemic strains from five geographically diverse regions in China collected over a 50 year period (1958~2008, and 8 international reference strains characterized by 16S rRNA sequencing and MLST analysis. 115, 11 and 2 strains were identified as L. interrogans, L. borgpetersenii, and L. kirschneri, respectively. 17 different STs were identified including 69 ST1 strains, 18 ST17, 18 ST128, 9 ST143 and 2 ST209. The remaining 12 strains belonged to 12 different STs. eBURST analysis demonstrated that, among the clonal complexes isolated (CCs, CC1 accounted for 73.3% (88/120 strains representing three STs: ST1, ST128 and ST98. ST1 was the most likely ancestral strain of this CC, followed by singleton CC17 (17/120 and CC143 (11/120. Further analysis of adding 116 serogroup Icterohaemorrhagiae strains in the MLST database and studies previously described using global eBURST analysis and MST dendrogram revealed relatively similar ST clustering patterns with five main CCs and 8 singletons among these 244 strains. CC17 was found to be the most prevalent clone of pathogenic Leptospira circulating worldwide. This is the first time, to our knowledge, that ST1 and ST17 strains were distributed among 4 distinct serovars, indicating a highly complicated relationship between serovars and STs.Our studies demonstrated a high level of genetic diversity in the serogroup Icterohaemorrhagiae strains. Distinct from ST17 or ST37 circulating elsewhere, ST1 included in CC1, has over the past 50 years or so, proven to be the most prevalent ST of pathogenic leptospires isolated in China. Moreover, the complicated relationship between STs and serovars

  9. Molecular Typing of Pathogenic Leptospira Serogroup Icterohaemorrhagiae Strains Circulating in China during the Past 50 Years

    Science.gov (United States)

    Zhang, Cuicai; Yang, Huimian; Li, Xiuwen; Cao, Zhiqiang; Zhou, Haijian; Zeng, Linzi; Xu, Jianmin; Xu, Yinghua; Chang, Yung-Fu; Guo, Xiaokui; Zhu, Yongzhang; Jiang, Xiugao

    2015-01-01

    Background Leptospirosis is one of the most important neglected tropical infectious diseases worldwide. Icterohaemorrhagiae has been throughout recent history, and still is, the predominant serogroup of this pathogen in China. However, very little in detail is known about the serovars or genotypes of this serogroup. Methodology/Principal Findings In this study, 120 epidemic strains from five geographically diverse regions in China collected over a 50 year period (1958~2008), and 8 international reference strains characterized by 16S rRNA sequencing and MLST analysis. 115, 11 and 2 strains were identified as L. interrogans, L. borgpetersenii, and L. kirschneri, respectively. 17 different STs were identified including 69 ST1 strains, 18 ST17, 18 ST128, 9 ST143 and 2 ST209. The remaining 12 strains belonged to 12 different STs. eBURST analysis demonstrated that, among the clonal complexes isolated (CCs), CC1 accounted for 73.3% (88/120) strains representing three STs: ST1, ST128 and ST98. ST1 was the most likely ancestral strain of this CC, followed by singleton CC17 (17/120) and CC143 (11/120). Further analysis of adding 116 serogroup Icterohaemorrhagiae strains in the MLST database and studies previously described using global eBURST analysis and MST dendrogram revealed relatively similar ST clustering patterns with five main CCs and 8 singletons among these 244 strains. CC17 was found to be the most prevalent clone of pathogenic Leptospira circulating worldwide. This is the first time, to our knowledge, that ST1 and ST17 strains were distributed among 4 distinct serovars, indicating a highly complicated relationship between serovars and STs. Conclusions/Significance Our studies demonstrated a high level of genetic diversity in the serogroup Icterohaemorrhagiae strains. Distinct from ST17 or ST37 circulating elsewhere, ST1 included in CC1, has over the past 50 years or so, proven to be the most prevalent ST of pathogenic leptospires isolated in China. Moreover, the

  10. Environmental Burkholderia cenocepacia Strain Enhances Fitness by Serial Passages during Long-Term Chronic Airways Infection in Mice

    Directory of Open Access Journals (Sweden)

    Alessandra Bragonzi

    2017-11-01

    Full Text Available Burkholderia cenocepacia is an important opportunistic pathogen in cystic fibrosis (CF patients, and has also been isolated from natural environments. In previous work, we explored the virulence and pathogenic potential of environmental B. cenocepacia strains and demonstrated that they do not differ from clinical strains in some pathogenic traits. Here, we investigated the ability of the environmental B. cenocepacia Mex1 strain, isolated from the maize rhizosphere, to persist and increase its virulence after serial passages in a mouse model of chronic infection. B. cenocepacia Mex1 strain, belonging to the recA lineage IIIA, was embedded in agar beads and challenged into the lung of C57Bl/6 mice. The mice were sacrificed after 28 days from infection and their lungs were tested for bacterial loads. Agar beads containing the pool of B. cenocepacia colonies from the four sequential passages were used to infect the mice. The environmental B. cenocepacia strain showed a low incidence of chronic infection after the first passage; after the second, third and fourth passages in mice, its ability to establish chronic infection increased significantly and progressively up to 100%. Colonial morphology analysis and genetic profiling of the Mex1-derived clones recovered after the fourth passage from infected mice revealed that they were indistinguishable from the challenged strain both at phenotypic and genetic level. By testing the virulence of single clones in the Galleria mellonella infection model, we found that two Mex1-derived clones significantly increased their pathogenicity compared to the parental Mex1 strain and behaved similarly to the clinical and epidemic B. cenocepacia LMG16656T. Our findings suggest that serial passages of the environmental B. cenocepacia Mex1 strain in mice resulted in an increased ability to determine chronic lung infection and the appearance of clonal variants with increased virulence in non-vertebrate hosts.

  11. Unusual dengue virus 3 epidemic in Nicaragua, 2009.

    Directory of Open Access Journals (Sweden)

    Gamaliel Gutierrez

    2011-11-01

    Full Text Available The four dengue virus serotypes (DENV1-4 cause the most prevalent mosquito-borne viral disease affecting humans worldwide. In 2009, Nicaragua experienced the largest dengue epidemic in over a decade, marked by unusual clinical presentation, as observed in two prospective studies of pediatric dengue in Managua. From August 2009-January 2010, 212 dengue cases were confirmed among 396 study participants at the National Pediatric Reference Hospital. In our parallel community-based cohort study, 170 dengue cases were recorded in 2009-10, compared to 13-65 cases in 2004-9. In both studies, significantly more patients experienced "compensated shock" (poor capillary refill plus cold extremities, tachycardia, tachypnea, and/or weak pulse in 2009-10 than in previous years (42.5% [90/212] vs. 24.7% [82/332] in the hospital study (p<0.001 and 17% [29/170] vs. 2.2% [4/181] in the cohort study (p<0.001. Signs of poor peripheral perfusion presented significantly earlier (1-2 days in 2009-10 than in previous years according to Kaplan-Meier survival analysis. In the hospital study, 19.8% of subjects were transferred to intensive care, compared to 7.1% in previous years - similar to the cohort study. DENV-3 predominated in 2008-9, 2009-10, and 2010-11, and full-length sequencing revealed no major genetic changes from 2008-9 to 2010-11. In 2008-9 and 2010-11, typical dengue was observed; only in 2009-10 was unusual presentation noted. Multivariate analysis revealed only "2009-10" as a significant risk factor for Dengue Fever with Compensated Shock. Interestingly, circulation of pandemic influenza A-H1N1 2009 in Managua was shifted such that it overlapped with the dengue epidemic. We hypothesize that prior influenza A H1N1 2009 infection may have modulated subsequent DENV infection, and initial results of an ongoing study suggest increased risk of shock among children with anti-H1N1-2009 antibodies. This study demonstrates that parameters other than serotype, viral

  12. Simulations of a epidemic model with parameters variation analysis for the dengue fever

    Science.gov (United States)

    Jardim, C. L. T. F.; Prates, D. B.; Silva, J. M.; Ferreira, L. A. F.; Kritz, M. V.

    2015-09-01

    Mathematical models can be widely found in the literature for describing and analyzing epidemics. The models that use differential equations to represent mathematically such description are specially sensible to parameters involved in the modelling. In this work, an already developed model, called SIR, is analyzed when applied to a scenario of a dengue fever epidemic. Such choice is powered by the existence of useful tools presented by a variation of this original model, which allow an inclusion of different aspects of the dengue fever disease, as its seasonal characteristics, the presence of more than one strain of the vector and of the biological factor of cross-immunity. The analysis and results interpretation are performed through numerical solutions of the model in question, and a special attention is given to the different solutions generated by the use of different values for the parameters present in this model. Slight variations are performed either dynamically or statically in those parameters, mimicking hypothesized changes in the biological scenario of this simulation and providing a source of evaluation of how those changes would affect the outcomes of the epidemic in a population.

  13. Fitting the HIV epidemic in Zambia: a two-sex micro-simulation model.

    Directory of Open Access Journals (Sweden)

    Pauline M Leclerc

    Full Text Available BACKGROUND: In describing and understanding how the HIV epidemic spreads in African countries, previous studies have not taken into account the detailed periods at risk. This study is based on a micro-simulation model (individual-based of the spread of the HIV epidemic in the population of Zambia, where women tend to marry early and where divorces are not frequent. The main target of the model was to fit the HIV seroprevalence profiles by age and sex observed at the Demographic and Health Survey conducted in 2001. METHODS AND FINDINGS: A two-sex micro-simulation model of HIV transmission was developed. Particular attention was paid to precise age-specific estimates of exposure to risk through the modelling of the formation and dissolution of relationships: marriage (stable union, casual partnership, and commercial sex. HIV transmission was exclusively heterosexual for adults or vertical (mother-to-child for children. Three stages of HIV infection were taken into account. All parameters were derived from empirical population-based data. Results show that basic parameters could not explain the dynamics of the HIV epidemic in Zambia. In order to fit the age and sex patterns, several assumptions were made: differential susceptibility of young women to HIV infection, differential susceptibility or larger number of encounters for male clients of commercial sex workers, and higher transmission rate. The model allowed to quantify the role of each type of relationship in HIV transmission, the proportion of infections occurring at each stage of disease progression, and the net reproduction rate of the epidemic (R(0 = 1.95. CONCLUSIONS: The simulation model reproduced the dynamics of the HIV epidemic in Zambia, and fitted the age and sex pattern of HIV seroprevalence in 2001. The same model could be used to measure the effect of changing behaviour in the future.

  14. Epidemic spreading on heterogeneous networks with identical infectivity

    International Nuclear Information System (INIS)

    Yang, Rui; Wang, Bing-Hong; Ren, Jie; Bai, Wen-Jie; Shi, Zhi-Wen; Wang, Wen-Xu; Zhou, Tao

    2007-01-01

    In this Letter, we propose a modified susceptible-infected-recovered (SIR) model, in which each node is assigned with an identical capability of active contacts, A, at each time step. In contrast to the previous studies, we find that on scale-free networks, the density of the recovered individuals in the present model shows a threshold behavior. We obtain the analytical results using the mean-field theory and find that the threshold value equals 1/A, indicating that the threshold value is independent of the topology of the underlying network. The simulations agree well with the analytic results. Furthermore, we study the time behavior of the epidemic propagation and find a hierarchical dynamics with three plateaus. Once the highly connected hubs are reached, the infection pervades almost the whole network in a progressive cascade across smaller degree classes. Then, after the previously infected hubs are recovered, the disease can only propagate to the class of smallest degree till the infected individuals are all recovered. The present results could be of practical importance in the setup of dynamic control strategies

  15. Statistics of Epidemics in Networks by Passing Messages

    Science.gov (United States)

    Shrestha, Munik Kumar

    financial contagion gets worse with too much diversification. We also predict that financial system exhibits "robust yet fragile" behavior, with regions of the parameter space where contagion is rare but catastrophic whenever it occurs. In further results, we develop a message-passing approach to recurrent state epidemics like susceptible-infectious-susceptible and susceptible-infectious-recovered-susceptible where nodes can return to previously inhabited states and multiple waves of infection can pass through the population. Given that message-passing has been applied exclusively to models with one-way state changes like susceptible-infectious and susceptible-infectious-recovered, we develop message-passing for recurrent epidemics based on a new class of differential equations and demonstrate that our approach is simple and efficiently approximates results obtained from Monte Carlo simulation, and that the accuracy of message-passing is often superior to the pair approximation (which also takes second-order correlations into account).

  16. Characterization of a Hepatitis B virus strain in southwestern Paraná, Brazil, presenting mutations previously associated with anti-HBs Resistance Caracterização de uma cepa de hepatite por vírus B no sudoeste do Paraná, Brasil, apresentando mutações previamente associadas à resistência anti-HBs

    Directory of Open Access Journals (Sweden)

    Dennis Armando Bertolini

    2010-02-01

    Full Text Available The present study investigated if hepatitis B virus (HBV mutants circulate in the southwestern region of the State of Paraná, Brazil, by analyzing samples from children who received immunoprophylaxis but were born to HBV carrier mothers. Samples from 25 children were screened for HBV serum markers and for HBV DNA by PCR. Only one sample was positive for HBsAg, anti-HBs and HBV DNA, although the child had been vaccinated. Analysis of the S gene sequence of this sample showed the presence of a proline at position 105, a serine at position 114, three threonines at positions 115, 116 and 140, and a glutamine at position 129. The presence of these amino acids, except for serine at position 114, has been related to monoclonal or polyclonal therapy with anti-HBs after liver transplantation, whereas the presence of threonine at position 116 has been described in immunized children from Singapore. This finding demonstrates the possible circulation of HBV strains resistant to hepatitis B immunoprophylaxis in southwestern Paraná, Brazil. The genotype of the sample was identified as genotype D, which is frequently found in the region studied. Since 36% of the children had received incomplete or no immunoprophylaxis, more extensive follow-up of children born to HBsAg-positive mothers is needed.O presente estudo investigou se mutantes do vírus da hepatite B (HBV circulam na região Sudoeste do Estado do Paraná, Brasil, analisando amostras de crianças que receberam a imunoprofilaxia por terem nascido de mães portadoras do HBV. Amostras de 25 crianças foram analisadas para os marcadores sorológicos do HBV e para o DNA-HBV por PCR. Somente uma amostra foi positiva para AgHBs, anti-HBs e DNA-HBV, apesar da criança ter sido vacinada. Análises da seqüência do gene S desta amostra mostrou a presença de uma prolina na posição 105, uma serina na posição 114, três treoninas nas posições 115, 116 e 140, e uma glutamina na posição 129. A presen

  17. Placental complications after a previous cesarean section

    OpenAIRE

    Milošević Jelena; Lilić Vekoslav; Tasić Marija; Radović-Janošević Dragana; Stefanović Milan; Antić Vladimir

    2009-01-01

    Introduction The incidence of cesarean section has been rising in the past 50 years. With the increased number of cesarean sections, the number of pregnancies with the previous cesarean section rises as well. The aim of this study was to establish the influence of the previous cesarean section on the development of placental complications: placenta previa, placental abruption and placenta accreta, as well as to determine the influence of the number of previous cesarean sections on the complic...

  18. The levelling off of the obesity epidemic since the year 1999--a review of evidence and perspectives

    DEFF Research Database (Denmark)

    Rokholm, B; Baker, J L; Sørensen, T I A

    2010-01-01

    obesity trends to identify the driving forces behind the epidemic. It is important to emphasize that the levelling off is not tantamount to calling off the epidemic. Additionally, it is worthwhile to keep in mind that previous stable phases have been followed by further increases in the prevalence...... evidence for heterogeneity in the obesity trends across socioeconomic status (SES) groups was found. The levelling off was less evident in the lower-SES groups. No obvious differences between genders were identified. We discussed potential explanations for a levelling off and the utility of investigating...

  19. Molecular differentiation of historic phage-type 80/81 and contemporary epidemic Staphylococcus aureus

    Science.gov (United States)

    DeLeo, Frank R.; Kennedy, Adam D.; Chen, Liang; Wardenburg, Juliane Bubeck; Kobayashi, Scott D.; Mathema, Barun; Braughton, Kevin R.; Whitney, Adeline R.; Villaruz, Amer E.; Martens, Craig A.; Porcella, Stephen F.; McGavin, Martin J.; Otto, Michael; Musser, James M.; Kreiswirth, Barry N.

    2011-01-01

    Staphylococcus aureus is a bacterial pathogen known to cause infections in epidemic waves. One such epidemic was caused by a clone known as phage-type 80/81, a penicillin-resistant strain that rose to world prominence in the late 1950s. The molecular underpinnings of the phage-type 80/81 outbreak have remained unknown for decades, nor is it understood why related S. aureus clones became epidemic in hospitals in the early 1990s. To better understand the molecular basis of these epidemics, we sequenced the genomes of eight S. aureus clinical isolates representative of the phage-type 80/81 clone, the Southwest Pacific clone [a community-associated methicillin-resistant S. aureus (MRSA) clone], and contemporary S. aureus clones, all of which are genetically related and belong to the same clonal complex (CC30). Genome sequence analysis revealed that there was coincident divergence of these clones from a recent common ancestor, a finding that resolves controversy about the evolutionary history of the lineage. Notably, we identified nonsynonymous SNPs in genes encoding accessory gene regulator C (agrC) and α-hemolysin (hla)—molecules important for S. aureus virulence—that were present in virtually all contemporary CC30 hospital isolates tested. Compared with the phage-type 80/81 and Southwest Pacific clones, contemporary CC30 hospital isolates had reduced virulence in mouse infection models, the result of SNPs in agrC and hla. We conclude that agr and hla (along with penicillin resistance) were essential for world dominance of phage-type 80/81 S. aureus, whereas key SNPs in contemporary CC30 clones restrict these pathogens to hospital settings in which the host is typically compromised. PMID:22025717

  20. Unsynchronized influenza epidemics in two neighboring subtropical cities

    Directory of Open Access Journals (Sweden)

    Xiujuan Tang

    2018-04-01

    Full Text Available Objective: The aim of this study was to examine the synchrony of influenza epidemics between Hong Kong and Shenzhen, two neighboring subtropical cities in South China. Methods: Laboratory-confirmed influenza data for the period January 2006 to December 2016 were obtained from the Shenzhen Center for Disease Control and Prevention and the Department of Health in Hong Kong. The population data were retrieved from the 2011 population censuses. The weekly rates of laboratory-confirmed influenza cases were compared between Shenzhen and Hong Kong. Results: Unsynchronized influenza epidemics between Hong Kong and Shenzhen were frequently observed during the study period. Influenza A/H1N1 caused a more severe pandemic in Hong Kong in 2009, but the subsequent seasonal epidemics showed similar magnitudes in both cities. Two influenza A/H3N2 dominant epidemic waves were seen in Hong Kong in 2015, but these epidemics were very minor in Shenzhen. More influenza B epidemics occurred in Shenzhen than in Hong Kong. Conclusions: Influenza epidemics appeared to be unsynchronized between Hong Kong and Shenzhen most of the time. Given the close geographical locations of these two cities, this could be due to the strikingly different age structures of their populations. Keywords: Influenza epidemics, Synchrony, Shenzhen, Hong Kong

  1. Risk from the frontlines of a hidden epidemic sexuality, masculinities ...

    African Journals Online (AJOL)

    Risk from the frontlines of a hidden epidemic sexuality, masculinities and social pressures among men who have sex with men in South Africa: an overview. ... These factors are discussed in this paper with stress put particularly on the hiddenness of the MSM HIV epidemic, and it is concluded that the complex mix of factors ...

  2. Epidemic cerebrospinal meningitis in children at Federal Medical ...

    African Journals Online (AJOL)

    Epidemic meningococcal meningitis is a major public health problem still affecting tropical countries, particularly in Sub-Saharan Africa, which lies within African meningitis belt. Repeated large scale epidemics of CSM have been reported in northern Nigeria for the past four decades. It is one of the important causes of ...

  3. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    G. Magiorkinis (Gkikas); K. Angelis (Konstantinos); I. Mamais (Ioannis); Katzourakis, A. (Aris); A. Hatzakis (Angelos); J. Albert (Jan); Lawyer, G. (Glenn); O. Hamouda (Osamah); D. Struck (Daniel); J. Vercauteren (Jurgen); A. Wensing (Amj); I. Alexiev (Ivailo); B. Åsjö (Birgitta); C. Balotta (Claudia); Gomes, P. (Perpétua); R.J. Camacho (Ricardo Jorge); S. Coughlan (Suzie); A. Griskevicius (Algirdas); Z. Grossman (Zehava); Horban, A. (Anders); L.G. Kostrikis (Leondios); Lepej, S.J. (Snjezana J.); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen; D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.C. Schmit; A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); Stylianou, D.C. (Dora C.); C.A.B. Boucher (Charles); Nikolopoulos, G. (Georgios); Vasylyeva, T. (Tetyana); Friedman, S.R. (Samuel R.); D.A.M.C. van de Vijver (David); G. Angarano (Guiseppe); M.L. Chaix (Marie Laure); A. de Luca (Andrea); K. Korn (Klaus); Loveday, C. (Clive); V. Soriano (Virtudes); S. Yerly (Sabine); M. Zazzi; A.M. Vandamme (Anne Mieke); D. Paraskevis (Dimitrios)

    2016-01-01

    textabstractHuman immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa

  4. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J.; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G.; Lepej, Snjezana J.; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C.; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R.; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne Mieke; Paraskevis, Dimitrios

    2016-01-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti

  5. An information strategy for the epidemic control chain

    NARCIS (Netherlands)

    Visser, T.; Dijkman, J.J.; Grijpink, J.H.A.M.|info:eu-repo/dai/nl/095130861; Plomp, M.G.A.|info:eu-repo/dai/nl/313946809; Seignette, P.

    2011-01-01

    This article presents the results of the chain analysis of the epidemic control chain according to the method of chain-computerisation. The goal of the epidemic control chain is to prevent the disruption of society that is caused by disease or excess of preventive measures. The current

  6. On The Travelling Wave Solution For An SEIR Epidemic Disease ...

    African Journals Online (AJOL)

    We present the travelling wave solution for a Susceptible, Exposed, Infective and Removed (SEIR) epidemic disease model. For this SEIR model, the disease is driven by both the latent and infective class (the diffusion term is included in both classes). The population is closed. Keywords: Epidemic model, spatial spread, ...

  7. The cholera epidemic in South Africa, 1980 - 1987

    African Journals Online (AJOL)

    1991-05-04

    May 4, 1991 ... During the cholera epidemic in South Africa, 1980-1987,. 25251 cases of cholera were bacteriologically proven. The case-fatality rate was 1,4%. Outbreaks occurred in the summer rainfall season. Age-specific aUack rates followed the pattern typically found during the 'epidemic phase' of the disease in.

  8. Resilience of epidemics for SIS model on networks.

    Science.gov (United States)

    Lu, Dan; Yang, Shunkun; Zhang, Jiaquan; Wang, Huijuan; Li, Daqing

    2017-08-01

    Epidemic propagation on complex networks has been widely investigated, mostly with invariant parameters. However, the process of epidemic propagation is not always constant. Epidemics can be affected by various perturbations and may bounce back to its original state, which is considered resilient. Here, we study the resilience of epidemics on networks, by introducing a different infection rate λ 2 during SIS (susceptible-infected-susceptible) epidemic propagation to model perturbations (control state), whereas the infection rate is λ 1 in the rest of time. Noticing that when λ 1 is below λ c , there is no resilience in the SIS model. Through simulations and theoretical analysis, we find that even for λ 2  < λ c , epidemics eventually could bounce back if the control duration is below a threshold. This critical control time for epidemic resilience, i.e., cd max , seems to be predicted by the diameter (d) of the underlying network, with the quantitative relation cd max ∼ d α . Our findings can help to design a better mitigation strategy for epidemics.

  9. Resilience of epidemics for SIS model on networks

    Science.gov (United States)

    Lu, Dan; Yang, Shunkun; Zhang, Jiaquan; Wang, Huijuan; Li, Daqing

    2017-08-01

    Epidemic propagation on complex networks has been widely investigated, mostly with invariant parameters. However, the process of epidemic propagation is not always constant. Epidemics can be affected by various perturbations and may bounce back to its original state, which is considered resilient. Here, we study the resilience of epidemics on networks, by introducing a different infection rate λ2 during SIS (susceptible-infected-susceptible) epidemic propagation to model perturbations (control state), whereas the infection rate is λ1 in the rest of time. Noticing that when λ1 is below λc, there is no resilience in the SIS model. Through simulations and theoretical analysis, we find that even for λ2 < λc, epidemics eventually could bounce back if the control duration is below a threshold. This critical control time for epidemic resilience, i.e., cdmax, seems to be predicted by the diameter (d) of the underlying network, with the quantitative relation cdmax ˜ dα. Our findings can help to design a better mitigation strategy for epidemics.

  10. The cholera epidemic in South Africa, 1980 - 1987 Epidemiological ...

    African Journals Online (AJOL)

    During the cholera epidemic in South Africa, 1980-1987, 25251 cases of cholera were bacteriologically proven. The case-fatality rate was 1,4%. Outbreaks occurred in the summer rainfall season. Age-specific aUack rates followed the pattern typically found during the 'epidemic phase' of the disease in most years. The vast ...

  11. development of an epidemic early warning system in Mpwapwa

    African Journals Online (AJOL)

    In some cases, mean:2$D method is used to determine thresholds for malaria epidemics. This involves the calculation of the long-term mean of monthly malaria cases (derived from a minimum 5- year data set from which abnormal years have been excluded) and an epidemic threshold set at two times the standard deviation ...

  12. Control of African swine fever epidemics in industrialized swine populations

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Bøtner, Anette; Mortensen, Sten

    2016-01-01

    resulted in marginal improvements to the control of the epidemics. However, adding testing of dead animals in the protection and surveillance zones was predicted to be the optimal control scenario for an ASF epidemic in industrialized swine populations without contact to wild boar. This optimal scenario...

  13. Gendered Epidemics and Systems of Power in Africa: A Feminist ...

    African Journals Online (AJOL)

    The article uses case studies, extracted from published epidemic stories and interprets these cases from a feminist and power analytical framework. The results suggest that while a disease or an epidemic affect a group of individuals, systemic factors regarding responsible governance and the role of national politics and ...

  14. Haemophilus influenzae type f meningitis in a previously healthy boy

    DEFF Research Database (Denmark)

    Ronit, Andreas; Berg, Ronan M G; Bruunsgaard, Helle

    2013-01-01

    Non-serotype b strains of Haemophilus influenzae are extremely rare causes of acute bacterial meningitis in immunocompetent individuals. We report a case of acute bacterial meningitis in a 14-year-old boy, who was previously healthy and had been immunised against H influenzae serotype b (Hib......). The causative pathogen was identified as H influenzae serotype f (Hif), and was successfully treated with ceftriaxone. An immunological evaluation revealed transient low levels of immunoglobulins but no apparent immunodeficiency was found 2 years after the clinical insult....

  15. Structural Analysis of Histo-Blood Group Antigen Binding Specificity in a Norovirus GII.4 Epidemic Variant: Implications for Epochal Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Shanker, Sreejesh; Choi, Jae-Mun; Sankaran, Banumathi; Atmar, Robert L.; Estes, Mary K.; Prasad, B.V. Venkataram (Baylor); (LBNL)

    2012-03-23

    Susceptibility to norovirus (NoV), a major pathogen of epidemic gastroenteritis, is associated with histo-blood group antigens (HBGAs), which are also cell attachment factors for this virus. GII.4 NoV strains are predominantly associated with worldwide NoV epidemics with a periodic emergence of new variants. The sequence variations in the surface-exposed P domain of the capsid protein resulting in differential HBGA binding patterns and antigenicity are suggested to drive GII.4 epochal evolution. To understand how temporal sequence variations affect the P domain structure and contribute to epochal evolution, we determined the P domain structure of a 2004 variant with ABH and secretor Lewis HBGAs and compared it with the previously determined structure of a 1996 variant. We show that temporal sequence variations do not affect the binding of monofucosyl ABH HBGAs but that they can modulate the binding strength of difucosyl Lewis HBGAs and thus could contribute to epochal evolution by the potentiated targeting of new variants to Lewis-positive, secretor-positive individuals. The temporal variations also result in significant differences in the electrostatic landscapes, likely reflecting antigenic variations. The proximity of some of these changes to the HBGA binding sites suggests the possibility of a coordinated interplay between antigenicity and HBGA binding in epochal evolution. From the observation that the regions involved in the formation of the HBGA binding sites can be conformationally flexible, we suggest a plausible mechanism for how norovirus disassociates from salivary mucin-linked HBGA before reassociating with HBGAs linked to intestinal epithelial cells during its passage through the gastrointestinal tract.

  16. Fractional virus epidemic model on financial networks

    Directory of Open Access Journals (Sweden)

    Balci Mehmet Ali

    2016-01-01

    Full Text Available In this study, we present an epidemic model that characterizes the behavior of a financial network of globally operating stock markets. Since the long time series have a global memory effect, we represent our model by using the fractional calculus. This model operates on a network, where vertices are the stock markets and edges are constructed by the correlation distances. Thereafter, we find an analytical solution to commensurate system and use the well-known differential transform method to obtain the solution of incommensurate system of fractional differential equations. Our findings are confirmed and complemented by the data set of the relevant stock markets between 2006 and 2016. Rather than the hypothetical values, we use the Hurst Exponent of each time series to approximate the fraction size and graph theoretical concepts to obtain the variables.

  17. Open data mining for Taiwan's dengue epidemic.

    Science.gov (United States)

    Wu, ChienHsing; Kao, Shu-Chen; Shih, Chia-Hung; Kan, Meng-Hsuan

    2018-03-13

    By using a quantitative approach, this study examines the applicability of data mining technique to discover knowledge from open data related to Taiwan's dengue epidemic. We compare results when Google trend data are included or excluded. Data sources are government open data, climate data, and Google trend data. Research findings from analysis of 70,914 cases are obtained. Location and time (month) in open data show the highest classification power followed by climate variables (temperature and humidity), whereas gender and age show the lowest values. Both prediction accuracy and simplicity decrease when Google trends are considered (respectively 0.94 and 0.37, compared to 0.96 and 0.46). The article demonstrates the value of open data mining in the context of public health care. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Spatiotemporal epidemic models for rabies among animals

    Directory of Open Access Journals (Sweden)

    Shigui Ruan

    2017-08-01

    Full Text Available Rabies is a serious concern to public health and wildlife management worldwide. Over the last three decades, various mathematical models have been proposed to study the transmission dynamics of rabies. In this paper we provide a mini-review on some reaction-diffusion models describing the spatial spread of rabies among animals. More specifically, we introduce the susceptible-exposed-infectious models for the spatial transmission of rabies among foxes (Murray et al., 1986, the spatiotemporal epidemic model for rabies among raccoons (Neilan and Lenhart, 2011, the diffusive rabies model for skunk and bat interactions (Bonchering et al., 2012, and the reaction-diffusion model for rabies among dogs (Zhang et al., 2012. Numerical simulations on the spatiotemporal dynamics of these models from these papers are presented.

  19. Did acetaminophen provoke the autism epidemic?

    Science.gov (United States)

    Good, Peter

    2009-12-01

    Schultz et al (2008) raised the question whether regression into autism is triggered, not by the measles-mumps-rubella (MMR) vaccine, but by acetaminophen (Tylenol) given for its fever and pain. Considerable evidence supports this contention, most notably the exponential rise in the incidence of autism since 1980, when acetaminophen began to replace aspirin for infants and young children. The impetus for this shift - a Centers for Disease Control and Prevention warning that aspirin was associated with Reye's syndrome - has since been compellingly debunked. If aspirin is not to be feared as a cause of Reyes syndrome, and acetaminophen is to be feared as a cause of autism, can the autism epidemic be reversed by replacing acetaminophen with aspirin or other remedies?

  20. Multilingual event extraction for epidemic detection.

    Science.gov (United States)

    Lejeune, Gaël; Brixtel, Romain; Doucet, Antoine; Lucas, Nadine

    2015-10-01

    This paper presents a multilingual news surveillance system applied to tele-epidemiology. It has been shown that multilingual approaches improve timeliness in detection of epidemic events across the globe, eliminating the wait for local news to be translated into major languages. We present here a system to extract epidemic events in potentially any language, provided a Wikipedia seed for common disease names exists. The Daniel system presented herein relies on properties that are common to news writing (the journalistic genre), the most useful being repetition and saliency. Wikipedia is used to screen common disease names to be matched with repeated characters strings. Language variations, such as declensions, are handled by processing text at the character-level, rather than at the word level. This additionally makes it possible to handle various writing systems in a similar fashion. As no multilingual ground truth existed to evaluate the Daniel system, we built a multilingual corpus from the Web, and collected annotations from native speakers of Chinese, English, Greek, Polish and Russian, with no connection or interest in the Daniel system. This data set is available online freely, and can be used for the evaluation of other event extraction systems. Experiments for 5 languages out of 17 tested are detailed in this paper: Chinese, English, Greek, Polish and Russian. The Daniel system achieves an average F-measure of 82% in these 5 languages. It reaches 87% on BEcorpus, the state-of-the-art corpus in English, slightly below top-performing systems, which are tailored with numerous language-specific resources. The consistent performance of Daniel on multiple languages is an important contribution to the reactivity and the coverage of epidemiological event detection systems. Most event extraction systems rely on extensive resources that are language-specific. While their sophistication induces excellent results (over 90% precision and recall), it restricts their

  1. Quasi-Neutral Theory of Epidemic Outbreaks

    Science.gov (United States)

    Pinto, Oscar A.; Muñoz, Miguel A.

    2011-01-01

    Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for “accidental pathogens” which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi) neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi)-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way. PMID:21760930

  2. Epidemic Dynamics in Open Quantum Spin Systems

    Science.gov (United States)

    Pérez-Espigares, Carlos; Marcuzzi, Matteo; Gutiérrez, Ricardo; Lesanovsky, Igor

    2017-10-01

    We explore the nonequilibrium evolution and stationary states of an open many-body system that displays epidemic spreading dynamics in a classical and a quantum regime. Our study is motivated by recent experiments conducted in strongly interacting gases of highly excited Rydberg atoms where the facilitated excitation of Rydberg states competes with radiative decay. These systems approximately implement open quantum versions of models for population dynamics or disease spreading where species can be in a healthy, infected or immune state. We show that in a two-dimensional lattice, depending on the dominance of either classical or quantum effects, the system may display a different kind of nonequilibrium phase transition. We moreover discuss the observability of our findings in laser driven Rydberg gases with particular focus on the role of long-range interactions.

  3. Chernobyl: Symptom of a worrying psychological epidemic

    International Nuclear Information System (INIS)

    Pretre, S.

    1991-01-01

    The Chernobyl psychological epidemic was already latent well prior to 1986 fully broke out after the accident, and continues to spread. It must be halted. But how can we counter a belief which has taken on the appearance of reality. It is the unknown, linked to alarming symbols, which sustains fear. To get beyond this state, radioactivity, ionizing radiation and nuclear energy have to become as ordinary as air travel and electronic calculators. In a climate of confidence and openness, it should be possible to successfully communicate several solid scientific reference points by first targeting teachers, doctors, and journalists. Thirty years ago, nuclear energy was presented as a universal panacea (clean, safe, and renewable). Now things have swung to the other extreme, and it is presented as diabolical. We have shifted from a symbolically white level to a symbolically black level, and both are misleading. It is high time to rejoin the world of facts, a world full of shades of gray

  4. Determinants of STD epidemics: implications for phase appropriate intervention strategies.

    Science.gov (United States)

    Aral, S O

    2002-04-01

    Determinants of evolving epidemics of sexually transmitted diseases (STD) are equally influenced by the evolution of the STD epidemics themselves and by the evolution of human societies. A temporal approach to STD transmission dynamics suggests the need to monitor infectivity, rate of exposure between infected and susceptible individuals, and duration of infectiousness in societies. Different indicators may be used to monitor rate of exposure in the general population and in core groups. In addition, underlying determinants of STD epidemics such as poverty, inequality, racial/ethnic discrimination, unemployment, sex ratio, volume of migration, and health care coverage and quality are important variables to monitor through a surveillance system focused on social context. Ongoing large scale societal changes including urbanisation, globalisation, increasing inequality, and increasing volume of migrant populations may affect the evolution of STD epidemics. Globalised STD epidemics could pose a major challenge to local public health systems.

  5. Epidemic spreading between two coupled subpopulations with inner structures

    Science.gov (United States)

    Ruan, Zhongyuan; Tang, Ming; Gu, Changgui; Xu, Jinshan

    2017-10-01

    The structure of underlying contact network and the mobility of agents are two decisive factors for epidemic spreading in reality. Here, we study a model consisting of two coupled subpopulations with intra-structures that emphasizes both the contact structure and the recurrent mobility pattern of individuals simultaneously. We show that the coupling of the two subpopulations (via interconnections between them and round trips of individuals) makes the epidemic threshold in each subnetwork to be the same. Moreover, we find that the interconnection probability between two subpopulations and the travel rate are important factors for spreading dynamics. In particular, as a function of interconnection probability, the epidemic threshold in each subpopulation decreases monotonously, which enhances the risks of an epidemic. While the epidemic threshold displays a non-monotonic variation as travel rate increases. Moreover, the asymptotic infected density as a function of travel rate in each subpopulation behaves differently depending on the interconnection probability.

  6. Progenitor “Mycobacterium canettii” clone responsible for lymph node tuberculosis epidemic, Djibouti.

    Science.gov (United States)

    Blouin, Yann; Cazajous, Géraldine; Dehan, Céline; Soler, Charles; Vong, Rithy; Hassan, Mohamed Osman; Hauck, Yolande; Boulais, Christian; Andriamanantena, Dina; Martinaud, Christophe; Martin, Émilie; Pourcel, Christine; Vergnaud, Gilles

    2014-01-01

    “Mycobacterium canettii,” an opportunistic human pathogen living in an unknown environmental reservoir, is the progenitor species from which Mycobacterium tuberculosis emerged. Since its discovery in 1969, most of the ≈70 known M. canettii strains were isolated in the Republic of Djibouti, frequently from expatriate children and adults. We show here, by whole-genome sequencing, that most strains collected from February 2010 through March 2013, and associated with 2 outbreaks of lymph node tuberculosis in children, belong to a unique epidemic clone within M. canettii. Evolution of this clone, which has been recovered regularly since 1983, may mimic the birth of M. tuberculosis. Thus, recognizing this organism and identifying its reservoir are clinically important.

  7. Evolutionary changes in the capsid P2 region of Australian strains of the norovirus GII.Pe_GII.4.

    Science.gov (United States)

    Bruggink, Leesa D; Moselen, Jean M; Roberts, Jason A; Marshall, John A

    2017-07-01

    The protruding (P) 2 region of the norovirus capsid is thought to include hypervariable sites involved in receptor binding. This study examines the changes that occurred in the P2 region of GII.Pe_GII.4 norovirus in the course of its evolution from a precursor phase (2008-2009), to an intermediate phase (2010) and finally to an epidemic phase (2012-2015). Twenty-two P2 region amino acid (aa) sequences (166 aa long) from all phases of the evolution of the virus were compared and the changes analysed.Results/key findings. Twenty sites in the P2 region underwent aa change and of these, 10 corresponded to previously proposed hypervariable sites and 10 to novel hypervariable sites. It was notable that aa changes at two sites, X and Y, only emerged as the epidemic phase progressed. 3D computer modelling of the P2 region indicated that neither X nor Y were in the uppermost 'crown', but further down in the 'neck' portion. The location of X and Y and the nature of aa change at Y suggest these sites were important in enhancing the structural integrity of the capsid, which in turn may have facilitated the longer term viability of the virus. The current study helps establish the validity of previously proposed hypervariable sites in the P2 region as well as indicating new ones. It also provides quantitative and qualitative data on how these sites changed over the evolutionary history of a particular norovirus strain.

  8. Ebola epidemic exposes the pathology of the global economic and political system.

    Science.gov (United States)

    Sanders, David; Sengupta, Amit; Scott, Vera

    2015-01-01

    While the current Ebola epidemic spiraled out of control to become the biggest in history, the global public health response has been criticized as "too little, too late." Many, like the World Health Organization, are asking what lessons have been learned from this epidemic. We present an analysis of the political economy of this Ebola outbreak that reveals the importance of addressing the social determinants that facilitated the exposure of populations, previously unaffected by Ebola Virus Disease, to infection and restricted the capacity for an effective medical response. To prevent further such crises, the global public health community has a responsibility to advocate for health system investment and development and for fundamental pro-poor changes to economic and power relations in the region. © The Author(s) 2015.

  9. Tracking the Origin and Deciphering the Phylogenetic Relationship of Porcine Epidemic Diarrhea Virus in Ecuador

    Directory of Open Access Journals (Sweden)

    Maritza Barrera

    2017-01-01

    Full Text Available In 2010, new Chinese strains of porcine epidemic diarrhea virus (PEDV, clinically more severe than the classical strains, emerged. These strains were spread to United States in 2013 through an intercontinental transmission from China with further spreading across the world, evidencing the emergent nature of these strains. In the present study, an analysis of PEDV field sequences from Ecuador was conducted by comparing all the PEDV S gene sequences available in the GenBank database. Phylogenetic comparisons and Bayesian phylogeographic inference based on complete S gene sequences were also conducted to track the origin and putative route of PEDV. The sequence from the PED-outbreak in Ecuador was grouped into the clade II of PEDV genogroup 2a together with other sequences of isolates from Mexico, Canada, and United States. The phylogeographic study revealed the emergence of the Chinese PEDV strains, followed by spreading to US in 2013, from US to Korea, and later the introduction of PEDV to Canada, Mexico, and Ecuador directly from the US. The sources of imports of live swine in Ecuador in 2014 were mainly from Chile and US. Thus, this movement of pigs is suggested as the main way for introducing PEDV to Ecuador.

  10. Tracking the Origin and Deciphering the Phylogenetic Relationship of Porcine Epidemic Diarrhea Virus in Ecuador.

    Science.gov (United States)

    Barrera, Maritza; Garrido-Haro, Ana; Vaca, María S; Granda, Danilo; Acosta-Batallas, Alfredo; Pérez, Lester J

    2017-01-01

    In 2010, new Chinese strains of porcine epidemic diarrhea virus (PEDV), clinically more severe than the classical strains, emerged. These strains were spread to United States in 2013 through an intercontinental transmission from China with further spreading across the world, evidencing the emergent nature of these strains. In the present study, an analysis of PEDV field sequences from Ecuador was conducted by comparing all the PEDV S gene sequences available in the GenBank database. Phylogenetic comparisons and Bayesian phylogeographic inference based on complete S gene sequences were also conducted to track the origin and putative route of PEDV. The sequence from the PED-outbreak in Ecuador was grouped into the clade II of PEDV genogroup 2a together with other sequences of isolates from Mexico, Canada, and United States. The phylogeographic study revealed the emergence of the Chinese PEDV strains, followed by spreading to US in 2013, from US to Korea, and later the introduction of PEDV to Canada, Mexico, and Ecuador directly from the US. The sources of imports of live swine in Ecuador in 2014 were mainly from Chile and US. Thus, this movement of pigs is suggested as the main way for introducing PEDV to Ecuador.

  11. Preoperative screening: value of previous tests.

    Science.gov (United States)

    Macpherson, D S; Snow, R; Lofgren, R P

    1990-12-15

    To determine the frequency of tests done in the year before elective surgery that might substitute for preoperative screening tests and to determine the frequency of test results that change from a normal value to a value likely to alter perioperative management. Retrospective cohort analysis of computerized laboratory data (complete blood count, sodium, potassium, and creatinine levels, prothrombin time, and partial thromboplastin time). Urban tertiary care Veterans Affairs Hospital. Consecutive sample of 1109 patients who had elective surgery in 1988. At admission, 7549 preoperative tests were done, 47% of which duplicated tests performed in the previous year. Of 3096 previous results that were normal as defined by hospital reference range and done closest to the time of but before admission (median interval, 2 months), 13 (0.4%; 95% CI, 0.2% to 0.7%), repeat values were outside a range considered acceptable for surgery. Most of the abnormalities were predictable from the patient's history, and most were not noted in the medical record. Of 461 previous tests that were abnormal, 78 (17%; CI, 13% to 20%) repeat values at admission were outside a range considered acceptable for surgery (P less than 0.001, frequency of clinically important abnormalities of patients with normal previous results with those with abnormal previous results). Physicians evaluating patients preoperatively could safely substitute the previous test results analyzed in this study for preoperative screening tests if the previous tests are normal and no obvious indication for retesting is present.

  12. Automatic electromagnetic valve for previous vacuum

    International Nuclear Information System (INIS)

    Granados, C. E.; Martin, F.

    1959-01-01

    A valve which permits the maintenance of an installation vacuum when electric current fails is described. It also lets the air in the previous vacuum bomb to prevent the oil ascending in the vacuum tubes. (Author)

  13. Whole-Genome Characterization of Epidemic Neisseria meningitidis Serogroup C and Resurgence of Serogroup W, Niger, 2015

    Science.gov (United States)

    Kretz, Cecilia B.; Retchless, Adam C.; Sidikou, Fati; Issaka, Bassira; Ousmane, Sani; Schwartz, Stephanie; Tate, Ashley H.; Pana, Assimawè; Njanpop-Lafourcade, Berthe-Marie; Nzeyimana, Innocent; Nse, Ricardo Obama; Deghmane, Ala-Eddine; Hong, Eva; Brynildsrud, Ola Brønstad; Novak, Ryan T.; Meyer, Sarah A.; Oukem-Boyer, Odile Ouwe Missi; Ronveaux, Olivier; Caugant, Dominique A.; Taha, Muhamed-Kheir

    2016-01-01

    In 2015, Niger reported the largest epidemic of Neisseria meningitidis serogroup C (NmC) meningitis in sub-Saharan Africa. The NmC epidemic coincided with serogroup W (NmW) cases during the epidemic season, resulting in a total of 9,367 meningococcal cases through June 2015. To clarify the phylogenetic association, genetic evolution, and antibiotic determinants of the meningococcal strains in Niger, we sequenced the genomes of 102 isolates from this epidemic, comprising 81 NmC and 21 NmW isolates. The genomes of 82 isolates were completed, and all 102 were included in the analysis. All NmC isolates had sequence type 10217, which caused the outbreaks in Nigeria during 2013–2014 and for which a clonal complex has not yet been defined. The NmC isolates from Niger were substantially different from other NmC isolates collected globally. All NmW isolates belonged to clonal complex 11 and were closely related to the isolates causing recent outbreaks in Africa. PMID:27649262

  14. Detection and partial characterization of simian immunodeficiency virus SIVsm strains from bush meat samples from rural Sierra Leone.

    Science.gov (United States)

    Apetrei, Cristian; Metzger, Michael J; Richardson, David; Ling, Binhua; Telfer, Paul T; Reed, Patricia; Robertson, David L; Marx, Preston A

    2005-02-01

    Human immunodeficiency virus type 2 (HIV-2) originated from simian immunodeficiency viruses (SIVs) that naturally infect sooty mangabeys (SMs; Cercocebus atys). In order to further investigate the relationship between HIV-2 and SIVsm, the SIV specific to the SM, we characterized seven new SIVsm strains from SMs sold in Sierra Leone markets as bush meat. The gag, pol, and env sequences showed that, while the viruses of all seven SMs belonged to the SIVsm-HIV-2 lineage, they were highly divergent viruses, in spite of the fact that most of the samples originated from the same geographical region. They clustered in three lineages, two of which have been previously reported. Two of the new SIVsm strains clustered differently in gag and env phylogenetic trees, suggesting SIVsm recombination that had occurred in the past. In spite of the fact that our study doubles the number of known SIVsm strains from wild SMs, none of the simian strains were close to the groups in which HIV-2 was epidemic (groups A and B).

  15. [Antibiotic susceptibility of Vibrio cholerae 01: evolution after prolonged curative and preventive use during the 2004 cholera epidemics in Douala (Cameroon)].

    Science.gov (United States)

    Guévart, E; Solle, J; Mouangue, A; Noeske, J; Bita, A; Fonkoua, M-C; Ndayo Wouafo, M

    2006-06-01

    Antibiotics were extensively used, both for curative as for prophylactic purposes, to prevent an explosive spread of the 2004 cholera epidemic in Douala. It was thus necessary to control the antibiotic susceptibility of Vibrio cholerae. The authors had for aim to describe the epidemic, the use of antibiotics, and to follow the susceptibility of V. cholerae. The 14 hospitals in the study all used the same diagnostic, treatment, and preventive protocols, as well as in community practice with home visits. All cases were clinically confirmed and reported. Samples were systematically taken at the beginning and at the end of the epidemic, and randomly during the epidemic. Each identified strain was tested by the disk method for antibiotic susceptibility. Between January and September 2004, 5013 patients and 177,353 people in contact with the patients were given a single dose of doxycycline or amoxicillin for 3 days. Sixty-nine deaths were recorded (lethality 1.37%). One hundred (and) eleven strains of V. cholerae were identified in 187 samples. All of them were resistant to sulfamides and colistin, but susceptible to cyclins, betalactams, and fluoroquinolones, without any modification during the 8 months of follow-up. Despite the risk of a massive and prolonged use of antibiotics, strictly prescribed and controlled, no resistance developed in the identified strain. Chemoprophylaxis must follow rigorous protocols and be continuously monitored.

  16. Concomitant and previous osteoporotic vertebral fractures.

    Science.gov (United States)

    Lenski, Markus; Büser, Natalie; Scherer, Michael

    2017-04-01

    Background and purpose - Patients with osteoporosis who present with an acute onset of back pain often have multiple fractures on plain radiographs. Differentiation of an acute osteoporotic vertebral fracture (AOVF) from previous fractures is difficult. The aim of this study was to investigate the incidence of concomitant AOVFs and previous OVFs in patients with symptomatic AOVFs, and to identify risk factors for concomitant AOVFs. Patients and methods - This was a prospective epidemiological study based on the Registry of Pathological Osteoporotic Vertebral Fractures (REPAPORA) with 1,005 patients and 2,874 osteoporotic vertebral fractures, which has been running since February 1, 2006. Concomitant fractures are defined as at least 2 acute short-tau inversion recovery (STIR-) positive vertebral fractures that happen concomitantly. A previous fracture is a STIR-negative fracture at the time of initial diagnostics. Logistic regression was used to examine the influence of various variables on the incidence of concomitant fractures. Results - More than 99% of osteoporotic vertebral fractures occurred in the thoracic and lumbar spine. The incidence of concomitant fractures at the time of first patient contact was 26% and that of previous fractures was 60%. The odds ratio (OR) for concomitant fractures decreased with a higher number of previous fractures (OR =0.86; p = 0.03) and higher dual-energy X-ray absorptiometry T-score (OR =0.72; p = 0.003). Interpretation - Concomitant and previous osteoporotic vertebral fractures are common. Risk factors for concomitant fractures are a low T-score and a low number of previous vertebral fractures in cases of osteoporotic vertebral fracture. An MRI scan of the the complete thoracic and lumbar spine with STIR sequence reduces the risk of under-diagnosis and under-treatment.

  17. Extinction times in the subcritical stochastic SIS logistic epidemic.

    Science.gov (United States)

    Brightwell, Graham; House, Thomas; Luczak, Malwina

    2018-01-31

    Many real epidemics of an infectious disease are not straightforwardly super- or sub-critical, and the understanding of epidemic models that exhibit such complexity has been identified as a priority for theoretical work. We provide insights into the near-critical regime by considering the stochastic SIS logistic epidemic, a well-known birth-and-death chain used to model the spread of an epidemic within a population of a given size N. We study the behaviour of the process as the population size N tends to infinity. Our results cover the entire subcritical regime, including the "barely subcritical" regime, where the recovery rate exceeds the infection rate by an amount that tends to 0 as [Formula: see text] but more slowly than [Formula: see text]. We derive precise asymptotics for the distribution of the extinction time and the total number of cases throughout the subcritical regime, give a detailed description of the course of the epidemic, and compare to numerical results for a range of parameter values. We hypothesise that features of the course of the epidemic will be seen in a wide class of other epidemic models, and we use real data to provide some tentative and preliminary support for this theory.

  18. H3N2v and other influenza epidemic risk based on age-specific estimates of sero-protection and contact network interactions.

    Directory of Open Access Journals (Sweden)

    Danuta M Skowronski

    Full Text Available Cases of a novel swine-origin influenza A(H3N2 variant (H3N2v have recently been identified in the US, primarily among children. We estimated potential epidemic attack rates (ARs based on age-specific estimates of sero-susceptibility and social interactions. A contact network model previously established for the Greater Vancouver Area (GVA, Canada was used to estimate average epidemic (infection ARs for the emerging H3N2v and comparator viruses (H1N1pdm09 and an extinguished H3N2 seasonal strain based on typical influenza characteristics, basic reproduction number (R(0, and effective contacts taking into account age-specific sero-protection rates (SPRs. SPRs were assessed in sera collected from the GVA in 2009 or earlier (pre-H1N1pdm09 and fall 2010 (post-H1N1pdm09, seasonal A/Brisbane/10/2007(H3N2, and H3N2v by hemagglutination inhibition (HI assay. SPR was assigned per convention based on proportion with HI antibody titre ≥40 (SPR40. Recognizing that the HI titre ≥40 was established as the 50%sero-protective threshold we also explored for ½SPR40, SPR80 and a blended gradient defined as: ¼SPR20, ½SPR40, ¾SPR80, SPR160. Base case analysis assumed R(0 = 1.40, but we also explored R(0 as high as 1.80. With R(0 = 1.40 and SPR40, simulated ARs were well aligned with field observations for H1N1pdm09 incidence (AR: 32%, sporadic detections without a third epidemic wave post-H1N1pdm09 (negligible AR<0.1% as well as A/Brisbane/10/2007(H3N2 seasonal strain extinction and antigenic drift replacement (negligible AR<0.1%. Simulated AR for the novel swine-origin H3N2v was 6%, highest in children 6-11years (16%. However, with modification to SPR thresholds per above, H3N2v AR ≥20% became possible. At SPR40, H3N2v AR ≥10%, ≥15% or ≥30%, occur if R(0≥1.48, ≥1.56 or ≥1.86, respectively. Based on conventional assumptions, the novel swine-origin H3N2v does not currently pose a substantial pandemic threat. If H3N2v epidemics do occur

  19. Uterine rupture without previous caesarean delivery

    DEFF Research Database (Denmark)

    Thisted, Dorthe L. A.; H. Mortensen, Laust; Krebs, Lone

    2015-01-01

    OBJECTIVE: To determine incidence and patient characteristics of women with uterine rupture during singleton births at term without a previous caesarean delivery. STUDY DESIGN: Population based cohort study. Women with term singleton birth, no record of previous caesarean delivery and planned...... vaginal delivery (n=611,803) were identified in the Danish Medical Birth Registry (1997-2008). Medical records from women recorded with uterine rupture during labour were reviewed to ascertain events of complete uterine rupture. Relative Risk (RR) and adjusted Relative Risk Ratio (aRR) of complete uterine...... rupture with 95% confidence intervals (95% CI) were ascertained according to characteristics of the women and of the delivery. RESULTS: We identified 20 cases with complete uterine rupture. The incidence of complete uterine rupture among women without previous caesarean delivery was about 3...

  20. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    Science.gov (United States)

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  1. Epidemic Spread in Networks Induced by Deactivation Mechanism

    Science.gov (United States)

    Yu, Xiao-Ling; Wu, Xiao; Zhang, Duan-Ming; Li, Zhi-Hao; Liang, Fang; Wang, Xiao-Yu

    2008-05-01

    We have studied the topology and epidemic spreading behaviors on the networks in which deactivation mechanism and long-rang connection are coexisted. By means of numerical simulation, we find that the clustering coefficient C and the Pearson correlation coefficient r decrease with increasing long-range connection μ and the topological state of the network changes into that of BA model at the end (when μ = 1). For the Susceptible Infect Susceptible model of epidemics, the epidemic threshold can reach maximum value at μ = 0.4 and presents two different variable states around μ = 0.4.

  2. Emergence of cfr-Mediated Linezolid Resistance in a Methicillin-Resistant Staphylococcus aureus Epidemic Clone Isolated from Patients with Cystic Fibrosis.

    Science.gov (United States)

    de Dios Caballero, Juan; Pastor, María Dolores; Vindel, Ana; Máiz, Luis; Yagüe, Genoveva; Salvador, Carme; Cobo, Marta; Morosini, María-Isabel; del Campo, Rosa; Cantón, Rafael

    2015-12-14

    Resistance to linezolid (LZD) in methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients with cystic fibrosis (CF) is due mainly to ribosomal mutations. We report on four CF patients with LZD-resistant MRSA bronchopulmonary infections by strains carrying the cfr gene. Strains from one patient also harbored the G2576U mutation (23S rRNA) and the G139R substitution (L3 protein). All strains belonged to the epidemic clone ST125 MRSA IVc. Our results support the monitoring of LZD resistance emergence in CF and non-CF MRSA isolates. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  3. Emergence of canine distemper virus strains with modified molecular signature and enhanced neuronal tropism leading to high mortality in wild carnivores.

    Science.gov (United States)

    Origgi, F C; Plattet, P; Sattler, U; Robert, N; Casaubon, J; Mavrot, F; Pewsner, M; Wu, N; Giovannini, S; Oevermann, A; Stoffel, M H; Gaschen, V; Segner, H; Ryser-Degiorgis, M-P

    2012-11-01

    An ongoing canine distemper epidemic was first detected in Switzerland in the spring of 2009. Compared to previous local canine distemper outbreaks, it was characterized by unusually high morbidity and mortality, rapid spread over the country, and susceptibility of several wild carnivore species. Here, the authors describe the associated pathologic changes and phylogenetic and biological features of a multiple highly virulent canine distemper virus (CDV) strain detected in and/or isolated from red foxes (Vulpes vulpes), Eurasian badgers (Meles meles), stone (Martes foina) and pine (Martes martes) martens, from a Eurasian lynx (Lynx lynx), and a domestic dog. The main lesions included interstitial to bronchointerstitial pneumonia and meningopolioencephalitis, whereas demyelination--the classic presentation of CDV infection--was observed in few cases only. In the brain lesions, viral inclusions were mainly in the nuclei of the neurons. Some significant differences in brain and lung lesions were observed between foxes and mustelids. Swiss CDV isolates shared together with a Hungarian CDV strain detected in 2004. In vitro analysis of the hemagglutinin protein from one of the Swiss CDV strains revealed functional and structural differences from that of the reference strain A75/17, with the Swiss strain showing increased surface expression and binding efficiency to the signaling lymphocyte activation molecule (SLAM). These features might be part of a novel molecular signature, which might have contributed to an increase in virus pathogenicity, partially explaining the high morbidity and mortality, the rapid spread, and the large host spectrum observed in this outbreak.

  4. Molecular diversity and high virulence of Legionella pneumophila strains isolated from biofilms developed within a warm spring of a thermal spa

    Directory of Open Access Journals (Sweden)

    Chaabna Zineddine

    2013-01-01

    Full Text Available Abstract Background Several cases of legionellosis have been diagnosed in the same French thermal spa in 1986, 1994 and 1997. L. pneumophila serogroup 1 (Lp1 strains have been isolated from several patients, but the source of contamination was not identified despite the presence of different Lp1 in water samples of the three natural springs feeding the spa at this period. Results Our strategy was to investigate L. pneumophila (Lp strains from natural biofilms developed in a sulphur-rich warm spring of this contaminated site. Biofilm analysis revealed the presence of three Lp serogroups (Lp1, Lp10 and Lp12. Surprisingly, Lp10 and Lp12 were not reported in the previous described studies from water samples. Besides, the new seven Lp1 we isolated exhibit a high molecular diversity and have been differentiated in five classes according to their DNA genome patterns obtained by PFGE and mip sequences. It must be noted that these DNA patterns are original and unknown in databases. Interestingly, the 27 Lp environmental strains we isolated display a higher cytotoxicity and virulence towards the amoeba Acanthamoeba castellanii than those of known Lp1 epidemic strains. Conclusion The characteristics of Legionella pneumophila Lp1 strains isolated from the warm spring are in agreement with their presence in biofilms and their probable long-term persistence in this ecosystem.

  5. Hypervariability generated by natural selection in an extracellular complement-inhibiting protein of serotype M1 strains of group A Streptococcus.

    Science.gov (United States)

    Stockbauer, K E; Grigsby, D; Pan, X; Fu, Y X; Mejia, L M; Cravioto, A; Musser, J M

    1998-03-17

    In many countries, M1 strains of the human pathogenic bacterium group A Streptococcus are the most common serotype recovered from patients with invasive disease episodes. Strains of this serotype express an extracellular protein that inhibits complement [streptococcal inhibitor of complement (Sic)] and is therefore believed to be a virulence factor. Comparative sequence analysis of the 915-bp sic gene in 165 M1 organisms recovered from diverse localities and infection types identified 62 alleles. Inasmuch as multilocus enzyme electrophoresis and pulsed-field gel electrophoresis previously showed that most M1 organisms represent a distinct streptococcal clone, the extent of sic gene polymorphism was unexpected. The level of polymorphism greatly exceeds that recorded for all other genes examined in serotype M1 strains. All insertions and deletions are in frame, and virtually all nucleotide substitutions alter the amino acid sequence of the Sic protein. These molecular features indicate that structural change in Sic is mediated by natural selection. Study of 70 strains recovered from two temporally distinct epidemics of streptococcal infections in the former East Germany found little sharing of Sic variants among strains recovered in the different time periods. Taken together, the data indicate that sic is a uniquely variable gene and provide insight into a potential molecular mechanism contributing to fluctuations in streptococcal disease frequency and severity.

  6. Complete Genome Sequence of Neisseria meningitidis Serogroup A Strain NMA510612, Isolated from a Patient with Bacterial Meningitis in China

    OpenAIRE

    Zhang, Yan; Yang, Jian; Xu, Li; Zhu, Yafang; Liu, Bo; Shao, Zhujun; Zhang, Xiaobing; Jin, Qi

    2014-01-01

    Serogroup A meningococcal strains have been involved in several pandemics and a series of epidemics worldwide in the past. Determination of the genome sequence of the prevalent genotype strain will help us understand the genetic background of the evolutionary and epidemiological properties of these bacteria. We sequenced the complete genome of Neisseria meningitidis NMA510612, a clinical isolate from a patient with meningococcal meningitis.

  7. INTRODUCTION Previous reports have documented a high ...

    African Journals Online (AJOL)

    pregnancy if they were married, educated, had dental insurance, previously used dental services when not pregnant, or had knowledge about the possible connection between oral health and pregnancy outcome8. The purpose of this study was to explore the factors determining good oral hygiene among pregnant women ...

  8. Empowerment perceptions of educational managers from previously ...

    African Journals Online (AJOL)

    The perceptions of educational manag ers from previously disadvantaged primary and high schools in the Nelson Mandela Metropole regarding the issue of empowerment are outlined and the perceptions of educational managers in terms of various aspects of empowerment at different levels reflected. A literature study ...

  9. Management of choledocholithiasis after previous gastrectomy.

    Science.gov (United States)

    Anwer, S; Egan, R; Cross, N; Guru Naidu, S; Somasekar, K

    2017-09-01

    Common bile duct stones in patients with a previous gastrectomy can be a technical challenge because of the altered anatomy. This paper presents the successful management of two such patients using non-traditional techniques as conventional endoscopic retrograde cholangiopancreatography was not possible.

  10. Laboratory Grouping Based on Previous Courses.

    Science.gov (United States)

    Doemling, Donald B.; Bowman, Douglas C.

    1981-01-01

    In a five-year study, second-year human physiology students were grouped for laboratory according to previous physiology and laboratory experience. No significant differences in course or board examination performance were found, though correlations were found between predental grade-point averages and grouping. (MSE)

  11. Lack of Involvement of Fenton Chemistry in Death of Methicillin-Resistant and Methicillin-Sensitive Strains of Staphylococcus aureus and Destruction of Their Genomes on Wet or Dry Copper Alloy Surfaces.

    Science.gov (United States)

    Warnes, Sarah L; Keevil, C William

    2016-01-29

    The pandemic of hospital-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has declined, but the evolution of strains with enhanced virulence and toxins and the increase of community-associated infections are still a threat. In previous studies, 10(7) MRSA bacteria applied as simulated droplet contamination were killed on copper and brass surfaces within 90 min. However, contamination of surfaces is often via finger tips and dries rapidly, and it may be overlooked by cleaning regimes (unlike visible droplets). In this new study, a 5-log reduction of a hardy epidemic strain of MRSA (epidemic methicillin-resistant S. aureus 16 [EMRSA-16]) was observed following 10 min of contact with copper, and a 4-log reduction was observed on copper nickel and cartridge brass alloys in 15 min. A methicillin-sensitive S. aureus (MSSA) strain from an osteomyelitis patient was killed on copper surfaces in 15 min, and 4-log and 3-log reductions occurred within 20 min of contact with copper nickel and cartridge brass, respectively. Bacterial respiration was compromised on copper surfaces, and superoxide was generated as part of the killing mechanism. In addition, destruction of genomic DNA occurs on copper and brass surfaces, allaying concerns about horizontal gene transfer and copper resistance. Incorporation of copper alloy biocidal surfaces may help to reduce the spread of this dangerous pathogen. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  12. Spatially explicit modelling of cholera epidemics

    Science.gov (United States)

    Finger, F.; Bertuzzo, E.; Mari, L.; Knox, A. C.; Gatto, M.; Rinaldo, A.

    2013-12-01

    Epidemiological models can provide crucial understanding about the dynamics of infectious diseases. Possible applications range from real-time forecasting and allocation of health care resources to testing alternative intervention mechanisms such as vaccines, antibiotics or the improvement of sanitary conditions. We apply a spatially explicit model to the cholera epidemic that struck Haiti in October 2010 and is still ongoing. The dynamics of susceptibles as well as symptomatic and asymptomatic infectives are modelled at the scale of local human communities. Dissemination of Vibrio cholerae through hydrological transport and human mobility along the road network is explicitly taken into account, as well as the effect of rainfall as a driver of increasing disease incidence. The model is calibrated using a dataset of reported cholera cases. We further model the long term impact of several types of interventions on the disease dynamics by varying parameters appropriately. Key epidemiological mechanisms and parameters which affect the efficiency of treatments such as antibiotics are identified. Our results lead to conclusions about the influence of different intervention strategies on the overall epidemiological dynamics.

  13. Epidemic surveillance using an electronic medical record: an empiric approach to performance improvement.

    Directory of Open Access Journals (Sweden)

    Hongzhang Zheng

    Full Text Available Electronic medical records (EMR form a rich repository of information that could benefit public health. We asked how structured and free-text narrative EMR data should be combined to improve epidemic surveillance for acute respiratory infections (ARI.Eight previously characterized ARI case detection algorithms (CDA were applied to historical EMR entries to create authentic time series of daily ARI case counts (background. An epidemic model simulated influenza cases (injection. From the time of the injection, cluster-detection statistics were applied daily on paired background+injection (combined and background-only time series. This cycle was then repeated with the injection shifted to each week of the evaluation year. We computed: a the time from injection to the first statistical alarm uniquely found in the combined dataset (Detection Delay; b how often alarms originated in the background-only dataset (false-alarm rate, or FAR; and c the number of cases found within these false alarms (Caseload. For each CDA, we plotted the Detection Delay as a function of FAR or Caseload, over a broad range of alarm thresholds.CDAs that combined text analyses seeking ARI symptoms in clinical notes with provider-assigned diagnostic codes in order to maximize the precision rather than the sensitivity of case-detection lowered Detection Delay at any given FAR or Caseload.An empiric approach can guide the integration of EMR data into case-detection methods that improve both the timeliness and efficiency of epidemic detection.

  14. [Epidemic of infectious disease with echovirus type 16--epidemic in Tono area, Gifu Prefecture in 1984].

    Science.gov (United States)

    Miwa, C; Watanabe, Y

    1990-07-01

    During the period from May to August, 1984, an epidemic of infectious disease with echovirus type 16 occurred in Tono area of southeast in Gifu prefecture. This virus caused children to have different clinical symptoms, one was a exanthem disease and another was aseptic meningitis. These cases confirmed by virological and serological methods were 48 cases, that is, patients with aseptic meningitis were 24 cases and patients with exanthem disease were 24 cases. By serological examination of antibody against echovirus type 16, it was confirmed that this virus type invaded Gifu Prefecture before 1984.

  15. Increasing clinical virulence in two decades of the Italian HIV epidemic.

    Directory of Open Access Journals (Sweden)

    Viktor Müller

    2009-05-01

    Full Text Available The recent origin and great evolutionary potential of HIV imply that the virulence of the virus might still be changing, which could greatly affect the future of the pandemic. However, previous studies of time trends of HIV virulence have yielded conflicting results. Here we used an established methodology to assess time trends in the severity (virulence of untreated HIV infections in a large Italian cohort. We characterized clinical virulence by the decline slope of the CD4 count (n = 1423 patients and the viral setpoint (n = 785 patients in untreated patients with sufficient data points. We used linear regression models to detect correlations between the date of diagnosis (ranging 1984-2006 and the virulence markers, controlling for gender, exposure category, age, and CD4 count at entry. The decline slope of the CD4 count and the viral setpoint displayed highly significant correlation with the date of diagnosis pointing in the direction of increasing virulence. A detailed analysis of riskgroups revealed that the epidemics of intravenous drug users started with an apparently less virulent virus, but experienced the strongest trend towards steeper CD4 decline among the major exposure categories. While our study did not allow us to exclude the effect of potential time trends in host factors, our findings are consistent with the hypothesis of increasing HIV virulence. Importantly, the use of an established methodology allowed for a comparison with earlier results, which confirmed that genuine differences exist in the time trends of HIV virulence between different epidemics. We thus conclude that there is not a single global trend of HIV virulence, and results obtained in one epidemic cannot be extrapolated to others. Comparison of discordant patterns between riskgroups and epidemics hints at a converging trend, which might indicate that an optimal level of virulence might exist for the virus.

  16. Interactions among symbionts operate across scales to influence parasite epidemics.

    Science.gov (United States)

    Halliday, Fletcher W; Umbanhowar, James; Mitchell, Charles E

    2017-10-01

    Parasite epidemics may be influenced by interactions among symbionts, which can depend on past events at multiple spatial scales. Within host individuals, interactions can depend on the sequence in which symbionts infect a host, generating priority effects. Across host individuals, interactions can depend on parasite phenology. To test the roles of parasite interactions and phenology in epidemics, we embedded multiple cohorts of sentinel plants, grown from seeds with and without a vertically transmitted symbiont, into a wild host population, and tracked foliar infections caused by three common fungal parasites. Within hosts, parasite growth was influenced by coinfections, but coinfections were often prevented by priority effects among symbionts. Across hosts, parasite phenology altered host susceptibility to secondary infections, symbiont interactions and ultimately the magnitude of parasite epidemics. Together, these results indicate that parasite phenology can influence parasite epidemics by altering the sequence of infection and interactions among symbionts within host individuals. © 2017 John Wiley & Sons Ltd/CNRS.

  17. Context analysis for epidemic control in the Netherlands

    NARCIS (Netherlands)

    Huizer, Y.L.; Kraaij-Dirkzwager, M.M.; Timen, A.; Schuitmaker-Warnaar, T.J.; van Steenbergen, J.E.

    2014-01-01

    When epidemics occur, experts advise the Ministries on effective control measures. There is uncertainty in the translation of epidemiological evidence into effective outbreak management interventions, due to contradicatory problem perspectives, diverse interests and time pressure. Several models

  18. Stochastic population and epidemic models persistence and extinction

    CERN Document Server

    Allen, Linda J S

    2015-01-01

    This monograph provides a summary of the basic theory of branching processes for single-type and multi-type processes. Classic examples of population and epidemic models illustrate the probability of population or epidemic extinction obtained from the theory of branching processes. The first chapter develops the branching process theory, while in the second chapter two applications to population and epidemic processes of single-type branching process theory are explored. The last two chapters present multi-type branching process applications to epidemic models, and then continuous-time and continuous-state branching processes with applications. In addition, several MATLAB programs for simulating stochastic sample paths  are provided in an Appendix. These notes originated as part of a lecture series on Stochastics in Biological Systems at the Mathematical Biosciences Institute in Ohio, USA. Professor Linda Allen is a Paul Whitfield Horn Professor of Mathematics in the Department of Mathematics and Statistics ...

  19. Topology dependent epidemic spreading velocity in weighted networks

    International Nuclear Information System (INIS)

    Duan, Wei; Qiu, Xiaogang; Quax, Rick; Lees, Michael; Sloot, Peter M A

    2014-01-01

    Many diffusive processes occur on structured networks with weighted links, such as disease spread by airplane transport or information diffusion in social networks or blogs. Understanding the impact of weight-connectivity correlations on epidemic spreading in weighted networks is crucial to support decision-making on disease control and other diffusive processes. However, a real understanding of epidemic spreading velocity in weighted networks is still lacking. Here we conduct a numerical study of the velocity of a Reed–Frost epidemic spreading process in various weighted network topologies as a function of the correlations between edge weights and node degrees. We find that a positive weight-connectivity correlation leads to a faster epidemic spreading compared to an unweighted network. In contrast, we find that both uncorrelated and negatively correlated weight distributions lead to slower spreading processes. In the case of positive weight-connectivity correlations, the acceleration of spreading velocity is weak when the heterogeneity of weight distribution increases. (paper)

  20. Modeling and Analysis of Epidemic Diffusion with Population Migration

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2013-01-01

    Full Text Available An improved Susceptible-Infected-Susceptible (SIS epidemic diffusion model with population migration between two cities is modeled. Global stability conditions for both the disease-free equilibrium and the endemic equilibrium are analyzed and proved. The main contribution of this paper is reflected in epidemic modeling and analysis which considers unequal migration rates, and only susceptible individuals can migrate between the two cities. Numerical simulation shows when the epidemic diffusion system is stable, number of infected individuals in one city can reach zero, while the number of infected individuals in the other city is still positive. On the other hand, decreasing population migration in only one city seems not as effective as improving the recovery rate for controlling the epidemic diffusion.

  1. [Epidemics and disease during the Revolution Period in Mexico].

    Science.gov (United States)

    Sanfilippo-Borrás, José

    2010-01-01

    The health condition in Mexico was bad around de beginning of the revolutionary period. The movement of troops led the development of epidemics like yellow fever, typhus, smallpox, and influenza that were enhance with natural disasters and hunger in whole country, from cost to cost and in the north big cities like Monterrey, Guadalajara and Saltillo. Doctor Liceaga conducted a well planned campaign against yellow fever eradicating water stagnant deposits in order to combat the vector transmission, the Aedes aegypti, mosquito with satisfactory results. The first smallpox epidemic in the XX Century in Mexico was in 1916. The Mexican physicians used the smallpox vaccine against this epidemic. An American physician named Howard Taylor Ricketts arrived to Mexico for studying the typhus transmission. Accidentally he had been infected and finally, he died from typhus. Definitively, the epidemics predominate along de revolutionary period in Mexico.

  2. Spatial spread of the West Africa Ebola epidemic.

    Science.gov (United States)

    Kramer, Andrew M; Pulliam, J Tomlin; Alexander, Laura W; Park, Andrew W; Rohani, Pejman; Drake, John M

    2016-08-01

    Controlling Ebola outbreaks and planning an effective response to future emerging diseases are enhanced by understanding the role of geography in transmission. Here we show how epidemic expansion may be predicted by evaluating the relative probability of alternative epidemic paths. We compared multiple candidate models to characterize the spatial network over which the 2013-2015 West Africa epidemic of Ebola virus spread and estimate the effects of geographical covariates on transmission during peak spread. The best model was a generalized gravity model where the probability of transmission between locations depended on distance, population density and international border closures between Guinea, Liberia and Sierra Leone and neighbouring countries. This model out-performed alternative models based on diffusive spread, the force of infection, mobility estimated from cell phone records and other hypothesized patterns of spread. These findings highlight the importance of integrated geography to epidemic expansion and may contribute to identifying both the most vulnerable unaffected areas and locations of maximum intervention value.

  3. Epidemic cholera in Latin America: spread and routes of transmission.

    Science.gov (United States)

    Guthmann, J P

    1995-12-01

    In the most recent epidemic of cholera in Latin America, nearly a million cases were reported and almost 9000 people died between January 1991 and December 1993. The epidemic spread rapidly from country to country, affecting in three years all the countries of Latin America except Uruguay and the Caribbean. Case-control studies carried out in Peru showed a significant association between drinking water and risk of disease. Cholera was associated with the consumption of unwashed fruit and vegetables, with eating food from street vendors and with contaminated crabmeat transported in travellers' luggage. This article documents the spread of the epidemic and its routes of transmission and discusses whether the introduction of the epidemic to Peru and its subsequent spread throughout the continent could have been prevented.

  4. HIV/AIDS Epidemic in the United States

    Science.gov (United States)

    ... The Basics The HIV/AIDS Epidemic in the United States: The Basics Published: Apr 11, 2018 Facebook Twitter ... become known as AIDS were reported in the United States in June of 1981. 1 Today, there are ...

  5. Epidemic spread in bipartite network by considering risk awareness

    Science.gov (United States)

    Han, She; Sun, Mei; Ampimah, Benjamin Chris; Han, Dun

    2018-02-01

    Human awareness plays an important role in the spread of infectious diseases and the control of propagation patterns. Exploring the interplay between human awareness and epidemic spreading is a topic that has been receiving increasing attention. Considering the fact, some well-known diseases only spread between different species we propose a theoretical analysis of the Susceptible-Infected-Susceptible (SIS) epidemic spread from the perspective of bipartite network and risk aversion. Using mean field theory, the epidemic threshold is calculated theoretically. Simulation results are consistent with the proposed analytic model. The results show that, the final infection density is negative linear with the value of individuals' risk awareness. Therefore, the epidemic spread could be effectively suppressed by improving individuals' risk awareness.

  6. 2,500-year Evolution of the Term Epidemic

    Science.gov (United States)

    Martin-Granel, Estelle

    2006-01-01

    The term epidemic (from the Greek epi [on] plus demos [people]), first used by Homer, took its medical meaning when Hippocrates used it as the title of one of his famous treatises. At that time, epidemic was the name given to a collection of clinical syndromes, such as coughs or diarrheas, occurring and propagating in a given period at a given location. Over centuries, the form and meaning of the term have changed. Successive epidemics of plague in the Middle Ages contributed to the definition of an epidemic as the propagation of a single, well-defined disease. The meaning of the term continued to evolve in the 19th-century era of microbiology. Its most recent semantic evolution dates from the last quarter of the 20th century, and this evolution is likely to continue in the future. PMID:16707055

  7. Underrecognition of Dengue during 2013 Epidemic in Luanda, Angola.

    Science.gov (United States)

    Sharp, Tyler M; Moreira, Rosa; Soares, Maria José; Miguel da Costa, Lúis; Mann, Jennifer; DeLorey, Mark; Hunsperger, Elizabeth; Muñoz-Jordán, Jorge L; Colón, Candimar; Margolis, Harold S; de Caravalho, Adelaide; Tomashek, Kay M

    2015-08-01

    During the 2013 dengue epidemic in Luanda, Angola, 811 dengue rapid diagnostic test-positive cases were reported to the Ministry of Health. To better understand the magnitude of the epidemic and identify risk factors for dengue virus (DENV) infection, we conducted cluster surveys around households of case-patients and randomly selected households 6 weeks after the peak of the epidemic. Of 173 case cluster participants, 16 (9%) exhibited evidence of recent DENV infection. Of 247 random cluster participants, 25 (10%) had evidence of recent DENV infection. Of 13 recently infected participants who had a recent febrile illness, 7 (54%) had sought medical care, and 1 (14%) was hospitalized with symptoms consistent with severe dengue; however, none received a diagnosis of dengue. Behavior associated with protection from DENV infection included recent use of mosquito repellent or a bed net. These findings suggest that the 2013 dengue epidemic was larger than indicated by passive surveillance data.

  8. Type 2 diabetes: the emerging epidemic | Rheeder | South African ...

    African Journals Online (AJOL)

    Abstract. This article reports on the prevalence of diabetes in South Africa and gives projections for the epidemic proportions that this disease may take by the year 2030. South African Family Practice Vol. 48 (10) 2006: pp. 20 ...

  9. The Topological Weighted Centroid (TWC): A topological approach to the time-space structure of epidemic and pseudo-epidemic processes

    Science.gov (United States)

    Buscema, Massimo; Massini, Giulia; Sacco, Pier Luigi

    2018-02-01

    This paper offers the first systematic presentation of the topological approach to the analysis of epidemic and pseudo-epidemic spatial processes. We introduce the basic concepts and proofs, at test the approach on a diverse collection of case studies of historically documented epidemic and pseudo-epidemic processes. The approach is found to consistently provide reliable estimates of the structural features of epidemic processes, and to provide useful analytical insights and interpretations of fragmentary pseudo-epidemic processes. Although this analysis has to be regarded as preliminary, we find that the approach's basic tenets are strongly corroborated by this first test and warrant future research in this vein.

  10. Previously unknown organomagnesium compounds in astrochemical context

    OpenAIRE

    Ruf, Alexander

    2018-01-01

    We describe the detection of dihydroxymagnesium carboxylates (CHOMg) in astrochemical context. CHOMg was detected in meteorites via ultrahigh-resolving chemical analytics and represents a novel, previously unreported chemical class. Thus, chemical stability was probed via quantum chemical computations, in combination with experimental fragmentation techniques. Results propose the putative formation of green-chemical OH-Grignard-type molecules and triggered fundamental questions within chemica...

  11. [Placental complications after a previous cesarean section].

    Science.gov (United States)

    Milosević, Jelena; Lilić, Vekoslav; Tasić, Marija; Radović-Janosević, Dragana; Stefanović, Milan; Antić, Vladimir

    2009-01-01

    The incidence of cesarean section has been rising in the past 50 years. With the increased number of cesarean sections, the number of pregnancies with the previous cesarean section rises as well. The aim of this study was to establish the influence of the previous cesarean section on the development of placental complications: placenta previa, placental abruption and placenta accreta, as well as to determine the influence of the number of previous cesarean sections on the complication development. The research was conducted at the Clinic of Gynecology and Obstetrics in Nis covering 10-year-period (from 1995 to 2005) with 32358 deliveries, 1280 deliveries after a previous cesarean section, 131 cases of placenta previa and 118 cases of placental abruption. The experimental groups was presented by the cases of placenta previa or placental abruption with prior cesarean section in obstetrics history, opposite to the control group having the same conditions but without a cesarean section in medical history. The incidence of placenta previa in the control group was 0.33%, opposite to the 1.86% incidence after one cesarean section (pcesarean sections and as high as 14.28% after three cesarean sections in obstetric history. Placental abruption was recorded as placental complication in 0.33% pregnancies in the control group, while its incidence was 1.02% after one cesarean section (pcesarean sections. The difference in the incidence of intrapartal hysterectomy between the group with prior cesarean section (0.86%) and without it (0.006%) shows a high statistical significance (pcesarean section is an important risk factor for the development of placental complications.

  12. The deterministic SIS epidemic model in a Markovian random environment.

    Science.gov (United States)

    Economou, Antonis; Lopez-Herrero, Maria Jesus

    2016-07-01

    We consider the classical deterministic susceptible-infective-susceptible epidemic model, where the infection and recovery rates depend on a background environmental process that is modeled by a continuous time Markov chain. This framework is able to capture several important characteristics that appear in the evolution of real epidemics in large populations, such as seasonality effects and environmental influences. We propose computational approaches for the determination of various distributions that quantify the evolution of the number of infectives in the population.

  13. Effects of epidemic threshold definition on disease spread statistics

    Science.gov (United States)

    Lagorio, C.; Migueles, M. V.; Braunstein, L. A.; López, E.; Macri, P. A.

    2009-03-01

    We study the statistical properties of SIR epidemics in random networks, when an epidemic is defined as only those SIR propagations that reach or exceed a minimum size sc. Using percolation theory to calculate the average fractional size of an epidemic, we find that the strength of the spanning link percolation cluster P∞ is an upper bound to . For small values of sc, P∞ is no longer a good approximation, and the average fractional size has to be computed directly. We find that the choice of sc is generally (but not always) guided by the network structure and the value of T of the disease in question. If the goal is to always obtain P∞ as the average epidemic size, one should choose sc to be the typical size of the largest percolation cluster at the critical percolation threshold for the transmissibility. We also study Q, the probability that an SIR propagation reaches the epidemic mass sc, and find that it is well characterized by percolation theory. We apply our results to real networks (DIMES and Tracerouter) to measure the consequences of the choice sc on predictions of average outcome sizes of computer failure epidemics.

  14. Predictive analysis effectiveness in determining the epidemic disease infected area

    Science.gov (United States)

    Ibrahim, Najihah; Akhir, Nur Shazwani Md.; Hassan, Fadratul Hafinaz

    2017-10-01

    Epidemic disease outbreak had caused nowadays community to raise their great concern over the infectious disease controlling, preventing and handling methods to diminish the disease dissemination percentage and infected area. Backpropagation method was used for the counter measure and prediction analysis of the epidemic disease. The predictive analysis based on the backpropagation method can be determine via machine learning process that promotes the artificial intelligent in pattern recognition, statistics and features selection. This computational learning process will be integrated with data mining by measuring the score output as the classifier to the given set of input features through classification technique. The classification technique is the features selection of the disease dissemination factors that likely have strong interconnection between each other in causing infectious disease outbreaks. The predictive analysis of epidemic disease in determining the infected area was introduced in this preliminary study by using the backpropagation method in observation of other's findings. This study will classify the epidemic disease dissemination factors as the features for weight adjustment on the prediction of epidemic disease outbreaks. Through this preliminary study, the predictive analysis is proven to be effective method in determining the epidemic disease infected area by minimizing the error value through the features classification.

  15. Prediction of invasion from the early stage of an epidemic.

    Science.gov (United States)

    Pérez-Reche, Francisco J; Neri, Franco M; Taraskin, Sergei N; Gilligan, Christopher A

    2012-09-07

    Predictability of undesired events is a question of great interest in many scientific disciplines including seismology, economy and epidemiology. Here, we focus on the predictability of invasion of a broad class of epidemics caused by diseases that lead to permanent immunity of infected hosts after recovery or death. We approach the problem from the perspective of the science of complexity by proposing and testing several strategies for the estimation of important characteristics of epidemics, such as the probability of invasion. Our results suggest that parsimonious approximate methodologies may lead to the most reliable and robust predictions. The proposed methodologies are first applied to analysis of experimentally observed epidemics: invasion of the fungal plant pathogen Rhizoctonia solani in replicated host microcosms. We then consider numerical experiments of the susceptible-infected-removed model to investigate the performance of the proposed methods in further detail. The suggested framework can be used as a valuable tool for quick assessment of epidemic threat at the stage when epidemics only start developing. Moreover, our work amplifies the significance of the small-scale and finite-time microcosm realizations of epidemics revealing their predictive power.

  16. A simple model for behaviour change in epidemics

    Directory of Open Access Journals (Sweden)

    Brauer Fred

    2011-02-01

    Full Text Available Abstract Background People change their behaviour during an epidemic. Infectious members of a population may reduce the number of contacts they make with other people because of the physical effects of their illness and possibly because of public health announcements asking them to do so in order to decrease the number of new infections, while susceptible members of the population may reduce the number of contacts they make in order to try to avoid becoming infected. Methods We consider a simple epidemic model in which susceptible and infectious members respond to a disease outbreak by reducing contacts by different fractions and analyze the effect of such contact reductions on the size of the epidemic. We assume constant fractional reductions, without attempting to consider the way in which susceptible members might respond to information about the epidemic. Results We are able to derive upper and lower bounds for the final size of an epidemic, both for simple and staged progression models. Conclusions The responses of uninfected and infected individuals in a disease outbreak are different, and this difference affects estimates of epidemic size.

  17. Parasite transmission in social interacting hosts: Monogenean epidemics in guppies

    Science.gov (United States)

    Johnson, Mirelle B.; Lafferty, Kevin D.; van Oosterhout, Cock; Cable, Joanne

    2011-01-01

    Background Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. Methodology/Principal Findings Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata). Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria), and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. Conclusions/Significance These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

  18. Parasite transmission in social interacting hosts: monogenean epidemics in guppies.

    Directory of Open Access Journals (Sweden)

    Mirelle B Johnson

    Full Text Available BACKGROUND: Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. METHODOLOGY/PRINCIPAL FINDINGS: Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata. Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria, and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. CONCLUSIONS/SIGNIFICANCE: These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

  19. The fundamental drivers of the obesity epidemic.

    Science.gov (United States)

    James, W P T

    2008-03-01

    Most policy makers do not yet understand that the obesity epidemic is a normal population response to the dramatic reduction in the demand for physical activity and the major changes in the food supply of countries over the last 40 years. A national focus on individual behaviour reflects a failure to confront the facts. Thus, the changes in food supply and physical environment are socioeconomically driven, and the health sector simply picks up the consequences. Urbanization alone in China has reduced daily energy expenditure by about 300-400 kcal d(-1) and cycling/bussing or going to work by car determines another variation of 200 kcal d(-1). Thus, energy demands may have dropped with additional TV/media, mechanization and computerized changes by 400-800 kcal d(-1), so weight gain and obesity are inevitable for most or all the population. Food intake should have fallen substantially despite the community's focus on the value of food after all the food crises of the past. Yet, Chinese fat and sugar intakes are escalating, and these policy-mediated features are amplified by the primeval biological drive for those commodities with specialized taste buds for fatty acids, meat, sugar and salt. Yet, traditionally, Chinese diets had negligible sugar, and 25-year-old data show that the optimum diet for Chinese contains 15% fat. Policies relating to food imports, agriculture, food quality standards, appropriate food traffic light labelling, price adjustments and controlled access to unhealthy foods are all within the grasp of the Chinese government. China has traditionally been far more responsive to the value of policies which limit inequalities and establish standards of care than many western governments, who have yet to recognize that the individualistic free-market approach to obesity prevention is guaranteed to fail. China could therefore lead the way: if it follows western approaches, the health and economic burden will become unsustainable.

  20. The global epidemic of atherosclerotic cardiovascular disease.

    Science.gov (United States)

    Yusuf, Salim; Ounpuu, Stephanie; Anand, Sonia

    2002-01-01

    Of the 50 million deaths that occur in the world, 40 million occur in developing countries. Already a substantial proportion of these deaths are due to cardiovascular diseases. It is projected that by the year 2025 well over 80-90% of all the cardiovascular diseases in the world will be occurring in low income and middle income countries. This increase in cardiovascular disease is due to a number of causes which include the following: (1) conquest of deaths in childhood and infancy from nutritional deficiencies and infection; (2) urbanization with increasing levels of obesity; (3) increasing longevity of the population so that a higher proportion of individuals reach the age when they are subject to chronic diseases, and (4) increasing use of tobacco worldwide. In most countries in the world other than those in the West, the burden of disease is still due to a combination of infections and nutritional disorders as well as those due to chronic diseases. This double burden of disease poses a challenge that is not only medical and epidemiological, but also social and political. Tackling this projected global epidemic of cardiovascular disease therefore needs policies that combine sound knowledge of prevention, good clinical care, but also deals with the allocation of resources for both individual level and community level preventive strategies. The former involves dealing with high-risk individuals through appropriate medical and therapeutic interventions. The latter involves societal level changes including laws that curb the use of tobacco, and strategies that promote physical activities, and appropriate nutrition. Copyright 2002 S. Karger AG, Basel

  1. Ongoing dengue epidemic - Angola, June 2013.

    Science.gov (United States)

    2013-06-21

    On April 1, 2013, the Public Health Directorate of Angola announced that six cases of dengue had been reported to the Ministry of Health of Angola (MHA). As of May 31, a total of 517 suspected dengue cases had been reported and tested for dengue with a rapid diagnostic test (RDT). A total of 313 (60.5%) specimens tested positive for dengue, including one from a patient who died. All suspected cases were reported from Luanda Province, except for two from Malanje Province. Confirmatory diagnostic testing of 49 specimens (43 RDT-positive and six RDT-negative) at the CDC Dengue Branch confirmed dengue virus (DENV) infection in 100% of the RDT-positive specimens and 50% of the RDT-negative specimens. Only DENV-1 was detected by molecular diagnostic testing. Phylogenetic analysis indicated this virus has been circulating in the region since at least 1968, strongly suggesting that dengue is endemic in Angola. Health-care professionals throughout Angola should be aware of the ongoing epidemic, the recommended practices for clinical management of dengue patients, and the need to report cases to MHA. Persons in Angola should seek medical care for acute febrile illness to reduce the risk for developing complications. Laboratory-confirmed dengue also has been reported from seven countries on four continents among persons who had recently traveled to Luanda, including 79 persons from Portugal. Angola is the third of four African countries to report a dengue outbreak in 2013. Persons returning from Africa with acute febrile illness should seek medical care, including testing for DENV infection, and suspected cases should be reported to public health authorities.

  2. Defining Moments in MMWR History: The AIDS Epidemic, Pneumocystis Pneumonia --- Los Angeles 1981

    Centers for Disease Control (CDC) Podcasts

    2017-12-01

    On June 5, 1981, MMWR published a report of Pneumocystis pneumonia in five previously healthy young gay men in Los Angeles, California. This report was later acknowledged as the first published account of what would become known as human immunodeficiency virus, or HIV, and acquired immunodeficiency syndrome, or AIDS. It was the first of many MMWR reports that led to a better understanding of this new condition. In this podcast, Dr. Harold Jaffe recalls CDC’s investigation and response to the AIDS Epidemic.  Created: 12/1/2017 by MMWR.   Date Released: 12/1/2017.

  3. Spatiotemporal dynamics of the HIV-1 CRF06_cpx epidemic in Western Africa.

    Science.gov (United States)

    Delatorre, Edson; Bello, Gonzalo

    2013-05-15

    To investigate the origin and spatiotemporal dynamics of dissemination of the HIV-1 CRF06_cpx clade in western Africa. A total of 180 HIV-1 CRF06_cpx-like pol sequences isolated from 12 different countries from west and west-central Africa over a period of 16 years (1995-2010) were analyzed. Evolutionary, phylogeographic and demographic parameters were jointly estimated from sequence data using a Bayesian coalescent-based method and combined with molecular epidemiology and spatial accessibility data. The CRF06_cpx most probably emerged in Burkina Faso in 1979 (1970-1985). From Burkina Faso, the virus was first disseminated to Mali and Nigeria during the 1980s and later to other countries from west and west-central Africa. Demographic reconstruction indicates that the CRF06_cpx epidemic grew exponentially during the 1980s, with a median growth rate of 0.82 year (0.60-1.09 year), and after stabilize. We found a negative correlation between CRF06_cpx prevalence and the geographical distance to Burkina Faso's capital. Regional accessibility information agrees with the overall geographical range of the CRF06_cpx, but not fully explains the highly heterogeneous distribution pattern of this CRF at regional level. The CRF06_cpx epidemic in western Africa probably emerged at the late 1970s and grew during the 1980s at a rate comparable to the HIV-1 epidemics in the United States and Europe. Burkina Faso seems to be the most important epicenter of dissemination of the HIV-1 CRF06_cpx strain at regional level. The explanation for the current geographical distribution of CRF06_cpx is probably multifactorial.

  4. Books average previous decade of economic misery.

    Science.gov (United States)

    Bentley, R Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20(th) century since the Depression, we find a strong correlation between a 'literary misery index' derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade.

  5. Induced vaginal birth after previous caesarean section

    Directory of Open Access Journals (Sweden)

    Akylbek Tussupkaliyev

    2016-11-01

    Full Text Available Introduction The rate of operative birth by Caesarean section is constantly rising. In Kazakhstan, it reaches 27 per cent. Research data confirm that the percentage of successful vaginal births after previous Caesarean section is 50–70 per cent. How safe the induction of vaginal birth after Caesarean (VBAC remains unclear. Methodology The studied techniques of labour induction were amniotomy of the foetal bladder with the vulsellum ramus, intravaginal administration of E1 prostaglandin (Misoprostol, and intravenous infusion of Oxytocin-Richter. The assessment of rediness of parturient canals was conducted by Bishop’s score; the labour course was assessed by a partogram. The effectiveness of labour induction techniques was assessed by the number of administered doses, the time of onset of regular labour, the course of labour and the postpartum period and the presence of complications, and the course of the early neonatal period, which implied the assessment of the child’s condition, described in the newborn development record. The foetus was assessed by medical ultrasound and antenatal and intranatal cardiotocography (CTG. Obtained results were analysed with SAS statistical processing software. Results The overall percentage of successful births with intravaginal administration of Misoprostol was 93 per cent (83 of cases. This percentage was higher than in the amniotomy group (relative risk (RR 11.7 and was similar to the oxytocin group (RR 0.83. Amniotomy was effective in 54 per cent (39 of cases, when it induced regular labour. Intravenous oxytocin infusion was effective in 94 per cent (89 of cases. This percentage was higher than that with amniotomy (RR 12.5. Conclusions The success of vaginal delivery after previous Caesarean section can be achieved in almost 70 per cent of cases. At that, labour induction does not decrease this indicator and remains within population boundaries.

  6. [Cholera epidemic of 2004 in Dakar, Senegal: epidemiologic, clinical and therapeutic aspects].

    Science.gov (United States)

    Ndour, C T; Manga, N M; Ká, R; Dia-Badiane, N M; Fortez, L; Seydi, M; Soumaré, M; Sow, A I; Diop, B M; Sow, P S

    2006-02-01

    During the cholera epidemic that occurred in Dakar, Senegal in 2004, we treated a total of 593 confirmed or suspected cases in our department. The purpose of this report is to describe epidemiologic, clinical, bacteriologic and therapeutic aspects of these cases. Study was conducted at the infectious diseases clinic from October 11 to December 20, 2004. Mean patient age was 30 years and the sex ratio was 133. The likely source of contamination was food or water intake in 92% of cases. The duration of the epidemic was short (75 days). Onset was sudden in 98% of cases and the main clinical manifestations were watery diarrhoea (95%) and vomiting (78%). The mean delay between symptoms and hospitalization was 11 hours and the number of stools before admission to the hospital was greater than 10 in 23% of cases. At the time of admission 119 patients (20.1%) were severely dehydrated. A total of 250 coprocultures were performed. Results were positive in 145 cases (58%) including 112 (44%) for Vibrio cholerae 01. Antibiotic testing carried out on 36 strains demonstrated excellent sensitivity to doxycycine and pefloxacine but resistance to cotrimoxazole, amoxicilline and chloramphenicol. Oral rehydration therapy was used in most cases (61%). The mortality rate was 0.5%. Cholera is a medical emergency that can have a favourable prognosis with properly organized management.

  7. Is the New Heroin Epidemic Really New? Racializing Heroin.

    Science.gov (United States)

    Bowser, Benjamin; Fullilove, Robert; Word, Carl

    2017-01-01

    Heroin abuse as an outcome of the prior use of painkillers increased rapidly over the past decade. This "new epidemic" is unique because the new heroin users are primarily young White Americans in rural areas of virtually every state. This commentary argues that the painkiller-to-heroin transition could not be the only cause of heroin use on such a scale and that the new and old heroin epidemics are linked. The social marketing that so successfully drove the old heroin epidemic has innovated and expanded due to the use of cell-phones, text messaging and the "dark web" which requires a Tor browser, and software that allows one to communicate with encrypted sites without detection. Central city gentrification has forced traffickers to take advantage of larger and more lucrative markets. A second outcome is that urban black and Latino communities are no longer needed as heroin stages areas for suburban and exurban illicit drug distribution. Drug dealing can be done directly in predominantly white suburbs and rural areas without the accompanying violence associated with the old epidemic. Denial of the link between the new and old heroin epidemics racially segregates heroin users and more proactive prevention and treatment in the new epidemic than in the old. It also cuts off a half-century of knowledge about the supply-side of heroin drug dealing and the inevitable public policy measures that will have to be implemented to effectively slow and stop both the old and new epidemic. Copyright © 2016 National Medical Association. Published by Elsevier Inc. All rights reserved.

  8. Could the Recent Zika Epidemic Have Been Predicted?

    Science.gov (United States)

    Vecchi, G. A.; Munoz, A. G.; Thomson, M. C.; Stewart-Ibarra, A. M.; Chourio, X.; Nájera, P.; Moran, Z.; Yang, X.

    2017-12-01

    Given knowledge at the time, the recent 2015-2016 zika virus (ZIKV) epidemic probably could not have been predicted. Without the prior knowledge of ZIKV being already present in South America, and given the lack of understanding of key epidemiologic processes and long-term records of ZIKV cases in the continent, the best related prediction could be carried out for the potential risk of a generic Aedes-borne disease epidemic. Here we use a recently published two-vector basic reproduction number model to assess the predictability of the conditions conducive to epidemics of diseases like zika, chikungunya, or dengue, transmitted by the independent or concurrent presence of Aedes aegypti and Aedes albopictus. We compare the potential risk of transmission forcing the model with the observed climate and with state-of-the-art operational forecasts from the North American Multi Model Ensemble (NMME), finding that the predictive skill of this new seasonal forecast system is highest for multiple countries in Latin America and the Caribbean during the December-February and March-May seasons, and slightly lower—but still of potential use to decision-makers—for the rest of the year. In particular, we find that above-normal suitable conditions for the occurrence of the zika epidemic at the beginning of 2015 could have been successfully predicted at least 1 month in advance for several zika hotspots, and in particular for Northeast Brazil: the heart of the epidemic. Nonetheless, the initiation and spread of an epidemic depends on the effect of multiple factors beyond climate conditions, and thus this type of approach must be considered as a guide and not as a formal predictive tool of vector-borne epidemics.

  9. Could the Recent Zika Epidemic Have Been Predicted?

    Directory of Open Access Journals (Sweden)

    Ángel G. Muñoz

    2017-07-01

    Full Text Available Given knowledge at the time, the recent 2015–2016 zika virus (ZIKV epidemic probably could not have been predicted. Without the prior knowledge of ZIKV being already present in South America, and given the lack of understanding of key epidemiologic processes and long-term records of ZIKV cases in the continent, the best related prediction could be carried out for the potential risk of a generic Aedes-borne disease epidemic. Here we use a recently published two-vector basic reproduction number model to assess the predictability of the conditions conducive to epidemics of diseases like zika, chikungunya, or dengue, transmitted by the independent or concurrent presence of Aedes aegypti and Aedes albopictus. We compare the potential risk of transmission forcing the model with the observed climate and with state-of-the-art operational forecasts from the North American Multi Model Ensemble (NMME, finding that the predictive skill of this new seasonal forecast system is highest for multiple countries in Latin America and the Caribbean during the December-February and March-May seasons, and slightly lower—but still of potential use to decision-makers—for the rest of the year. In particular, we find that above-normal suitable conditions for the occurrence of the zika epidemic at the beginning of 2015 could have been successfully predicted at least 1 month in advance for several zika hotspots, and in particular for Northeast Brazil: the heart of the epidemic. Nonetheless, the initiation and spread of an epidemic depends on the effect of multiple factors beyond climate conditions, and thus this type of approach must be considered as a guide and not as a formal predictive tool of vector-borne epidemics.

  10. On the Use of Human Mobility Proxies for Modeling Epidemics

    Science.gov (United States)

    Tizzoni, Michele; Bajardi, Paolo; Decuyper, Adeline; Kon Kam King, Guillaume; Schneider, Christian M.; Blondel, Vincent; Smoreda, Zbigniew; González, Marta C.; Colizza, Vittoria

    2014-01-01

    Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i) official census surveys, (ii) proxy mobility data extracted from mobile phone call records, and (iii) the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies should therefore be

  11. Human mobility and time spent at destination: impact on spatial epidemic spreading.

    Science.gov (United States)

    Poletto, Chiara; Tizzoni, Michele; Colizza, Vittoria

    2013-12-07

    Host mobility plays a fundamental role in the spatial spread of infectious diseases. Previous theoretical works based on the integration of network theory into the metapopulation framework have shown that the heterogeneities that characterize real mobility networks favor the propagation of epidemics. Nevertheless, the studies conducted so far assumed the mobility process to be either Markovian (in which the memory of the origin of each traveler is lost) or non-Markovian with a fixed traveling time scale (in which individuals travel to a destination and come back at a constant rate). Available statistics however show that the time spent by travelers at destination is characterized by wide fluctuations, ranging from a single day up to several months. Such varying length of stay crucially affects the chance and duration of mixing events among hosts and may therefore have a strong impact on the spread of an emerging disease. Here, we present an analytical and a computational study of epidemic processes on a complex subpopulation network where travelers have memory of their origin and spend a heterogeneously distributed time interval at their destination. Through analytical calculations and numerical simulations we show that the heterogeneity of the length of stay alters the expression of the threshold between local outbreak and global invasion, and, moreover, it changes the epidemic behavior of the system in case of a global outbreak. Additionally, our theoretical framework allows us to study the effect of changes in the traveling behavior in response to the infection, by considering a scenario in which sick individuals do not leave their home location. Finally, we compare the results of our non-Markovian framework with those obtained with a classic Markovian approach and find relevant differences between the two, in the estimate of the epidemic invasion potential, as well as of the timing and the pattern of its spatial spread. These results highlight the importance of

  12. Epidemic Reconstruction in a Phylogenetics Framework: Transmission Trees as Partitions of the Node Set.

    Science.gov (United States)

    Hall, Matthew; Woolhouse, Mark; Rambaut, Andrew

    2015-12-01

    The use of genetic data to reconstruct the transmission tree of infectious disease epidemics and outbreaks has been the subject of an increasing number of studies, but previous approaches have usually either made assumptions that are not fully compatible with phylogenetic inference, or, where they have based inference on a phylogeny, have employed a procedure that requires this tree to be fixed. At the same time, the coalescent-based models of the pathogen population that are employed in the methods usually used for time-resolved phylogeny reconstruction are a considerable simplification of epidemic process, as they assume that pathogen lineages mix freely. Here, we contribute a new method that is simultaneously a phylogeny reconstruction method for isolates taken from an epidemic, and a procedure for transmission tree reconstruction. We observe that, if one or more samples is taken from each host in an epidemic or outbreak and these are used to build a phylogeny, a transmission tree is equivalent to a partition of the set of nodes of this phylogeny, such that each partition element is a set of nodes that is connected in the full tree and contains all the tips corresponding to samples taken from one and only one host. We then implement a Monte Carlo Markov Chain (MCMC) procedure for simultaneous sampling from the spaces of both trees, utilising a newly-designed set of phylogenetic tree proposals that also respect node partitions. We calculate the posterior probability of these partitioned trees based on a model that acknowledges the population structure of an epidemic by employing an individual-based disease transmission model and a coalescent process taking place within each host. We demonstrate our method, first using simulated data, and then with sequences taken from the H7N7 avian influenza outbreak that occurred in the Netherlands in 2003. We show that it is superior to established coalescent methods for reconstructing the topology and node heights of the

  13. Epidemic Reconstruction in a Phylogenetics Framework: Transmission Trees as Partitions of the Node Set.

    Directory of Open Access Journals (Sweden)

    Matthew Hall

    2015-12-01

    Full Text Available The use of genetic data to reconstruct the transmission tree of infectious disease epidemics and outbreaks has been the subject of an increasing number of studies, but previous approaches have usually either made assumptions that are not fully compatible with phylogenetic inference, or, where they have based inference on a phylogeny, have employed a procedure that requires this tree to be fixed. At the same time, the coalescent-based models of the pathogen population that are employed in the methods usually used for time-resolved phylogeny reconstruction are a considerable simplification of epidemic process, as they assume that pathogen lineages mix freely. Here, we contribute a new method that is simultaneously a phylogeny reconstruction method for isolates taken from an epidemic, and a procedure for transmission tree reconstruction. We observe that, if one or more samples is taken from each host in an epidemic or outbreak and these are used to build a phylogeny, a transmission tree is equivalent to a partition of the set of nodes of this phylogeny, such that each partition element is a set of nodes that is connected in the full tree and contains all the tips corresponding to samples taken from one and only one host. We then implement a Monte Carlo Markov Chain (MCMC procedure for simultaneous sampling from the spaces of both trees, utilising a newly-designed set of phylogenetic tree proposals that also respect node partitions. We calculate the posterior probability of these partitioned trees based on a model that acknowledges the population structure of an epidemic by employing an individual-based disease transmission model and a coalescent process taking place within each host. We demonstrate our method, first using simulated data, and then with sequences taken from the H7N7 avian influenza outbreak that occurred in the Netherlands in 2003. We show that it is superior to established coalescent methods for reconstructing the topology and node

  14. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, Tina Kold; Bonde, J P

    1998-01-01

    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  15. Genotypic diversity of Legionella pneumophila in environmental and clinical strains assessed by Sequence-Based Typing, in association with retrospective clinical surveillance in Northern Italy.

    Science.gov (United States)

    Bianchi, Annalisa; Pregliasco, Fabrizio Ernesto; Consonni, Michela; Tesauro, Marina

    2016-06-02

    The study aimed to evidence previous cases of legionellosis or proven or suspected pneumonia in seven hospital facilities for the mentally disabled in Northern Italy, where no clinical surveillance had been previously carried out. An additional aim was to highlight the occurrence of strains of Legionella pneumophila of clinical and environmental origin by Sequence-Based Typing (SBT), comparing them to world surveillance. A clinical survey was perfomed from 2003-2012, analyzing 615 medical records for hospital- and community-acquired pneumonia, with particular attention to legionellosis. Clinical (n=4) and environmental (n=25) isolates of Legionella pneumophila, isolated in the same period (2003-2012), were characterized by SBT and the Sequence Types (STs) compared with the European Working Group for Legionella Infections (EWGLI) database. Surveillance revealed that there were seven detected cases of legionellosis; most pneumonia cases could not be confirmed by diagnostic tests because of the disabilities of the patients and their lack of cooperation. The same ST was found in two of the clinical strains and also in a corresponding environment, i.e. ST685 and ST16, and two clinical strains belonging to the same ST (ST1). The other environmental strains were isolated in department with confirmed/suspected clinical cases. Five other STs found in this study were new to the database: ST685 was isolated both from a patient and from water; ST694, ST1181, ST1370 and ST1371 have not been described previously. The study confirmed that the routine collection and analysis of environmental strains may be an important strategy for preventing sporadic and epidemic cases of legionellosis, in association with clinical surveillance.

  16. Proteomics Analysis Reveals Previously Uncharacterized Virulence Factors in Vibrio proteolyticus

    Directory of Open Access Journals (Sweden)

    Ann Ray

    2016-07-01

    Full Text Available Members of the genus Vibrio include many pathogens of humans and marine animals that share genetic information via horizontal gene transfer. Hence, the Vibrio pan-genome carries the potential to establish new pathogenic strains by sharing virulence determinants, many of which have yet to be characterized. Here, we investigated the virulence properties of Vibrio proteolyticus, a Gram-negative marine bacterium previously identified as part of the Vibrio consortium isolated from diseased corals. We found that V. proteolyticus causes actin cytoskeleton rearrangements followed by cell lysis in HeLa cells in a contact-independent manner. In search of the responsible virulence factor involved, we determined the V. proteolyticus secretome. This proteomics approach revealed various putative virulence factors, including active type VI secretion systems and effectors with virulence toxin domains; however, these type VI secretion systems were not responsible for the observed cytotoxic effects. Further examination of the V. proteolyticus secretome led us to hypothesize and subsequently demonstrate that a secreted hemolysin, belonging to a previously uncharacterized clan of the leukocidin superfamily, was the toxin responsible for the V. proteolyticus-mediated cytotoxicity in both HeLa cells and macrophages. Clearly, there remains an armory of yet-to-be-discovered virulence factors in the Vibrio pan-genome that will undoubtedly provide a wealth of knowledge on how a pathogen can manipulate host cells.

  17. Porcine Epidemic Diarrhea in Europe: In-Detail Analyses of Disease Dynamics and Molecular Epidemiology.

    Science.gov (United States)

    Hanke, Dennis; Pohlmann, Anne; Sauter-Louis, Carola; Höper, Dirk; Stadler, Julia; Ritzmann, Mathias; Steinrigl, Adi; Schwarz, Bernd-Andreas; Akimkin, Valerij; Fux, Robert; Blome, Sandra; Beer, Martin

    2017-07-06

    Porcine epidemic diarrhea (PED) is an acute and highly contagious enteric disease of swine caused by the eponymous virus (PEDV) which belongs to the genus Alphacoronavirus within the Coronaviridae virus family. Following the disastrous outbreaks in Asia and the United States, PEDV has been detected also in Europe. In order to better understand the overall situation, the molecular epidemiology, and factors that might influence the most variable disease impact; 40 samples from swine feces were collected from different PED outbreaks in Germany and other European countries and sequenced by shot-gun next-generation sequencing. A total of 38 new PEDV complete coding sequences were generated. When compared on a global scale, all investigated sequences from Central and South-Eastern Europe formed a rather homogeneous PEDV S INDEL cluster, suggesting a recent re-introduction. However, in-detail analyses revealed two new clusters and putative ancestor strains. Based on the available background data, correlations between clusters and location, farm type or clinical presentation could not be established. Additionally, the impact of secondary infections was explored using the metagenomic data sets. While several coinfections were observed, no correlation was found with disease courses. However, in addition to the PEDV genomes, ten complete viral coding sequences from nine different data sets were reconstructed each representing new virus strains. In detail, three pasivirus A strains, two astroviruses, a porcine sapelovirus, a kobuvirus, a porcine torovirus, a posavirus, and an enterobacteria phage were almost fully sequenced.

  18. Recombinant Viruses Initiated the Early HIV-1 Epidemic in Burkina Faso

    Science.gov (United States)

    Fonjungo, Peter N.; Kalish, Marcia L.; Schaefer, Amanda; Rayfield, Mark; Mika, Jennifer; Rose, Laura E.; Heslop, Orville; Soudré, Robert; Pieniazek, Danuta

    2014-01-01

    We analyzed genetic diversity and phylogenetic relationships among 124 HIV-1 and 19 HIV-2 strains in sera collected in 1986 from patients of the state hospital in Ouagadougou, Burkina Faso. Phylogenetic analysis of the HIV-1 env gp41 region of 65 sequences characterized 37 (56.9%) as CRF06_cpx strains, 25 (38.5%) as CRF02_AG, 2 (3.1%) as CRF09_cpx, and 1 (1.5%) as subtype A. Similarly, phylogenetic analysis of the protease (PR) gene region of 73 sequences identified 52 (71.2%) as CRF06_cpx, 15 (20.5%) as CRF02_AG, 5 (6.8%) as subtype A, and 1 (1.4%) was a unique strain that clustered along the B/D lineage but basal to the node connecting the two lineages. HIV-2 PR or integrase (INT) groups A (n = 17 [89.5%]) and B (n = 2 [10.5%]) were found in both monotypic (n = 11) and heterotypic HIV-1/HIV-2 (n = 8) infections, with few HIV-2 group B infections. Based on limited available sampling, evidence suggests two recombinant viruses, CRF06_cpx and CRF02_AG, appear to have driven the beginning of the mid-1980s HIV-1 epidemic in Burkina Faso. PMID:24647246

  19. Isolation and characterization of a variant porcine epidemic diarrhea virus in China

    Directory of Open Access Journals (Sweden)

    Pan Yongfei

    2012-09-01

    Full Text Available Abstract An outbreak of diarrhea in pigs started in Guangdong, South China in January 2011. Cases were characterized by watery diarrhea, dehydration and vomiting, with 80–100% morbidity and 50–90% mortality in suckling piglets. The causative agent of the diarrhea was ultimately identified as porcine epidemic diarrhea virus (PEDV. In this study, we isolated a PEDV strain designated CHGD-01 from piglet intestines using Vero cell cultures, and its specific cytopathic effects were confirmed in susceptible cells by direct immunofluorescence testing and electron microscopy. The complete genome of CHGD-01 was shown to be 28,035 nucleotides in length, with a similar structure to that of PEDV reference strains. Phylogenetic analyses based on the whole genome revealed that CHGD-01 shared nucleotide sequence identities of 98.2–98.4% with two other Chinese isolates reported in the same year, thus constituting a new cluster. Amino acid sequence analysis based on individual virus genes indicated a close relationship between the spike protein gene of CHGD-01 and the field strain KNU0802 in Korea. Its ORF3 and nucleoprotein genes, however, were divergent from all other sequenced PEDV isolate clusters and therefore formed a new group, suggesting a new variant PEDV isolate in China. Further studies will be required to determine the immunogenicity and pathogenicity of this new variant.

  20. New emergence pattern with variant porcine epidemic diarrhea viruses, South Korea, 2012-2015.

    Science.gov (United States)

    Chung, Hee-Chun; Lee, Jee-Hoon; Nguyen, Van Giap; Huynh, Thi My Le; Lee, Ga-Eun; Moon, Hyoung-Joon; Park, Seong-Jun; Kim, Hye-Kwon; Park, Bong Kyun

    2016-12-02

    Since outbreaks of porcine epidemic diarrhea virus (PEDV) in the United States in 2013, explosive outbreaks of PED in South Korea have infected all age groups of pigs in 2014-2015year. This study analyzed a large collection of the Spike protein coding gene to infer the spatial-temporal diffusion history of PEDV. The studying results suggested that PEDVs in Korea belonged to different genogroups. While classical G1 was continuingly circulating between provinces of Korea, the pandemic G2a were recently introduced from China and USA. By the application of Bayesian phylogeographical analysis, this study demonstrated the spatial-temporal transmission of PEDVs within Korea. Of the recent emerged G2a viruses, J3142 strains showed potential recombination breakpoint (376-2,143nt) of S1 gene between KNU1303_Korea strain_G2a (KJ451046) and 45RWVCF0712_Thailand strain_G2b (KF724935). The pandemic G2a virus was partial neutralized by the antibodies invoked by the G1- based PED vaccine virus. Copyright © 2016. Published by Elsevier B.V.

  1. Isolation and characterization of a variant porcine epidemic diarrhea virus in China.

    Science.gov (United States)

    Pan, Yongfei; Tian, Xiaoyan; Li, Wei; Zhou, Qingfeng; Wang, Dongdong; Bi, Yingzuo; Chen, Feng; Song, Yanhua

    2012-09-12

    An outbreak of diarrhea in pigs started in Guangdong, South China in January 2011. Cases were characterized by watery diarrhea, dehydration and vomiting, with 80-100% morbidity and 50-90% mortality in suckling piglets. The causative agent of the diarrhea was ultimately identified as porcine epidemic diarrhea virus (PEDV). In this study, we isolated a PEDV strain designated CHGD-01 from piglet intestines using Vero cell cultures, and its specific cytopathic effects were confirmed in susceptible cells by direct immunofluorescence testing and electron microscopy. The complete genome of CHGD-01 was shown to be 28,035 nucleotides in length, with a similar structure to that of PEDV reference strains. Phylogenetic analyses based on the whole genome revealed that CHGD-01 shared nucleotide sequence identities of 98.2-98.4% with two other Chinese isolates reported in the same year, thus constituting a new cluster. Amino acid sequence analysis based on individual virus genes indicated a close relationship between the spike protein gene of CHGD-01 and the field strain KNU0802 in Korea. Its ORF3 and nucleoprotein genes, however, were divergent from all other sequenced PEDV isolate clusters and therefore formed a new group, suggesting a new variant PEDV isolate in China. Further studies will be required to determine the immunogenicity and pathogenicity of this new variant.

  2. Recombinant viruses initiated the early HIV-1 epidemic in Burkina Faso.

    Directory of Open Access Journals (Sweden)

    Peter N Fonjungo

    Full Text Available We analyzed genetic diversity and phylogenetic relationships among 124 HIV-1 and 19 HIV-2 strains in sera collected in 1986 from patients of the state hospital in Ouagadougou, Burkina Faso. Phylogenetic analysis of the HIV-1 env gp41 region of 65 sequences characterized 37 (56.9% as CRF06_cpx strains, 25 (38.5% as CRF02_AG, 2 (3.1% as CRF09_cpx, and 1 (1.5% as subtype A. Similarly, phylogenetic analysis of the protease (PR gene region of 73 sequences identified 52 (71.2% as CRF06_cpx, 15 (20.5% as CRF02_AG, 5 (6.8% as subtype A, and 1 (1.4% was a unique strain that clustered along the B/D lineage but basal to the node connecting the two lineages. HIV-2 PR or integrase (INT groups A (n = 17 [89.5%] and B (n = 2 [10.5%] were found in both monotypic (n = 11 and heterotypic HIV-1/HIV-2 (n = 8 infections, with few HIV-2 group B infections. Based on limited available sampling, evidence suggests two recombinant viruses, CRF06_cpx and CRF02_AG, appear to have driven the beginning of the mid-1980s HIV-1 epidemic in Burkina Faso.

  3. Taxing Soda: Strategies for Dealing with the Obesity and Diabetes Epidemic.

    Science.gov (United States)

    Maa, John

    2016-01-01

    Over the past several decades, the United States has been experiencing a twin epidemic of obesity and type 2 diabetes. Recently, advocacy efforts to tax sugary drinks, place warning labels on soda, improve nutritional labeling, and reduce sugar overconsumption have swept across the nation to address public health concerns from sugary drinks that strain our nation's health-care resources. In this article, the historical and scientific framework of this public health policy and valuable lessons learned from implementation efforts thus far will be examined to shape the next steps forward for the movement. Additional goals of this article are to share a surgeon's perspective about trends in bariatric surgery and the link between obesity and type 2 diabetes as a result of peripheral insulin resistance.

  4. Reconstructing the AIDS epidemic among injection drug users in Brazil

    Directory of Open Access Journals (Sweden)

    Mariana A. Hacker

    2006-04-01

    Full Text Available The HIV/AIDS epidemic among injection drug users (IDUs in Brazil has been unique in terms of temporal and geographical contrasts. This analysis explores these contrasts through the use of multilevel modeling. Standardized AIDS incidence rates among IDUs for Brazilian municipalities (1986-2000 were used as the dependent variable, with a set of social indicators as independent variables (covariates. In some States of the North/Northeast, the epidemic among IDUs has been incipient. The São Paulo epidemic extended to reach a network of municipalities, most of which located far from the capital. More recently, on a smaller scale, a similar extension has been observed in the southernmost States of the country. Both "number of physicians per inhabitant" and "standard distance to the State capital" were found to be associated with AIDS incidence. AIDS cases among IDUs appeared to cluster in wealthier, more developed municipalities. The relative weight of such extensive dissemination in key, heavily populated States prevails in the Brazilian IDU epidemic, defining a central-western-southeastern strip of wealthier middle-sized municipalities and more recently a southern strip of municipalities deeply affected by the epidemic in this population.

  5. Reconstructing the AIDS epidemic among injection drug users in Brazil.

    Science.gov (United States)

    Hacker, Mariana A; Leite, Iuri C; Renton, Adrian; Torres, Tania Guillén de; Gracie, Renata; Bastos, Francisco I

    2006-04-01

    The HIV/AIDS epidemic among injection drug users (IDUs) in Brazil has been unique in terms of temporal and geographical contrasts. This analysis explores these contrasts through the use of multilevel modeling. Standardized AIDS incidence rates among IDUs for Brazilian municipalities (1986-2000) were used as the dependent variable, with a set of social indicators as independent variables (covariates). In some States of the North/Northeast, the epidemic among IDUs has been incipient. The São Paulo epidemic extended to reach a network of municipalities, most of which located far from the capital. More recently, on a smaller scale, a similar extension has been observed in the southernmost States of the country. Both "number of physicians per inhabitant" and "standard distance to the State capital" were found to be associated with AIDS incidence. AIDS cases among IDUs appeared to cluster in wealthier, more developed municipalities. The relative weight of such extensive dissemination in key, heavily populated States prevails in the Brazilian IDU epidemic, defining a central-western-southeastern strip of wealthier middle-sized municipalities and more recently a southern strip of municipalities deeply affected by the epidemic in this population.

  6. Epidemic Intelligence. Langmuir and the Birth of Disease Surveillance

    Directory of Open Access Journals (Sweden)

    Lyle Fearnley

    2010-12-01

    Full Text Available In the wake of the SARS and influenza epidemics of the past decade, one public health solution has become a refrain: surveillance systems for detection of disease outbreaks. This paper is an effort to understand how disease surveillance for outbreak detection gained such paramount rationality in contemporary public health. The epidemiologist Alexander Langmuir is well known as the creator of modern disease surveillance. But less well known is how he imagined disease surveillance as one part of what he called “epidemic intelligence.” Langmuir developed the practice of disease surveillance during an unprecedented moment in which the threat of biological warfare brought civil defense experts and epidemiologists together around a common problem. In this paper, I describe how Langmuir navigated this world, experimenting with new techniques and rationales of epidemic control. Ultimately, I argue, Langmuir′s experiments resulted in a set of techniques and infrastructures – a system of epidemic intelligence – that transformed the epidemic as an object of human art.

  7. Game theory of social distancing in response to an epidemic.

    Directory of Open Access Journals (Sweden)

    Timothy C Reluga

    2010-05-01

    Full Text Available Social distancing practices are changes in behavior that prevent disease transmission by reducing contact rates between susceptible individuals and infected individuals who may transmit the disease. Social distancing practices can reduce the severity of an epidemic, but the benefits of social distancing depend on the extent to which it is used by individuals. Individuals are sometimes reluctant to pay the costs inherent in social distancing, and this can limit its effectiveness as a control measure. This paper formulates a differential-game to identify how individuals would best use social distancing and related self-protective behaviors during an epidemic. The epidemic is described by a simple, well-mixed ordinary differential equation model. We use the differential game to study potential value of social distancing as a mitigation measure by calculating the equilibrium behaviors under a variety of cost-functions. Numerical methods are used to calculate the total costs of an epidemic under equilibrium behaviors as a function of the time to mass vaccination, following epidemic identification. The key parameters in the analysis are the basic reproduction number and the baseline efficiency of social distancing. The results show that social distancing is most beneficial to individuals for basic reproduction numbers around 2. In the absence of vaccination or other intervention measures, optimal social distancing never recovers more than 30% of the cost of infection. We also show how the window of opportunity for vaccine development lengthens as the efficiency of social distancing and detection improve.

  8. Epidemic spread over networks with agent awareness and social distancing

    KAUST Repository

    Paarporn, Keith

    2016-04-20

    We study an SIS epidemic model over an arbitrary connected network topology when the agents receive personalized information about the current epidemic state. The agents utilize their available information to either reduce interactions with their neighbors (social distancing) when they believe the epidemic is currently prevalent or resume normal interactions when they believe there is low risk of becoming infected. The information is a weighted combination of three sources: 1) the average states of nodes in contact neighborhoods 2) the average states of nodes in an information network 3) a global broadcast of the average epidemic state of the network. A 2n-state Markov Chain is first considered to model the disease dynamics with awareness, from which a mean-field discrete-time n-state dynamical system is derived, where each state corresponds to an agent\\'s probability of being infected. The nonlinear model is a lower bound of its linearized version about the origin. Hence, global stability of the origin (the diseasefree equilibrium) in the linear model implies global stability in the nonlinear model. When the origin is not stable, we show the existence of a nontrivial fixed point in the awareness model, which obeys a strict partial order in relation to the nontrivial fixed point of the dynamics without distancing. In simulations, we define two performance metrics to understand the effectiveness agent awareness has in reducing the spread of an epidemic. © 2015 IEEE.

  9. Mefloquine and its oxazolidine derivative compound are active against drug-resistant Mycobacterium tuberculosis strains and in a murine model of tuberculosis infection.

    Science.gov (United States)

    Rodrigues-Junior, Valnês S; Villela, Anne D; Gonçalves, Raoni S B; Abbadi, Bruno Lopes; Trindade, Rogério Valim; López-Gavín, Alexandre; Tudó, Griselda; González-Martín, Julian; Basso, Luiz Augusto; de Souza, Marcus V N; Campos, Maria Martha; Santos, Diógenes Santiago

    2016-08-01

    Repurposing of drugs to treat tuberculosis (TB) has been considered an alternative to overcome the global TB epidemic, especially to combat drug-resistant forms of the disease. Mefloquine has been reported as a potent drug to kill drug-resistant strains of Mycobacterium tuberculosis. In addition, mefloquine-derived molecules have been synthesised and their effectiveness against mycobacteria has been assessed. In this work, we demonstrate for the first time the activities of mefloquine and its oxazolidine derivative compound 1E in a murine model of TB infection following administration of both drugs by the oral route. The effects of associations between mefloquine or 1E with the clinically used antituberculosis drugs isoniazid, rifampicin, ethambutol, moxifloxacin and streptomycin were also investigated. Importantly, combination of mefloquine with isoniazid and of 1E with streptomycin showed a two-fold decrease in their minimum inhibitory concentrations (MICs). Moreover, no tested combinations demonstrated antagonist interactions. Here we describe novel evidence on the activity of mefloquine and 1E against a series of quinolone-resistant M. tuberculosis strains. These data show MICs against quinolone-resistant strains (0.5-8 µg/mL) similar to or lower than those previously reported for multidrug-resistant strains. Taking these results together, we can suggest the use of mefloquine or 1E in combination with clinically available drugs, especially in the case of resistant forms of TB. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  10. [Chikungunya, La Réunion and Mayotte, 2005-2006: an epidemic without a story?].

    Science.gov (United States)

    Flahault, Antoine; Aumont, Gilles; Boisson, Véronique; de Lamballerile, Xavier; Favier, François; Fontenille, Didier; Gaüzère, Bernard-Alex; Journeaux, Sophie; Lotteau, Vincent; Paupy, Christophe; Sanquer, Marie-Anne; Setbon, Michel

    2007-01-01

    Many triggering factors for onset of emerging infectious diseases are now recognised, such as: globalisation, demographic increase, population movements, international trade, urbanisation, forest destruction, climate changes, loss in biodiversity, and extreme life conditions such as poverty, famine and war. Epidemic burden is often leading to disasters, in terms of human losses, as well as economic, political or social consequences. These outbreaks may jeopardize within a few weeks or months, industry, trade, or tourism. While dengue and its most severe forms (hemorrhagic and shock syndrome) is spreading all over the tropical world, another arbovirosis, chikungunya disease dramatically spread in Indian Ocean islands where 30 to 75% of population were infected in 2005 and 2006, and then extended its progression towards India, Sri Lanka, Indonesia, Malaysia, Maldives islands with more than a million people infected with the East-African strain, replacing the former Asian strain which was known to prevail more than 30 years ago in India. Patients experience sequelae with disability, work loss, and rarely severe outcome recently identified in La Réunion and Mayotte (French overseas territories). No country, no part of the world may consider itself as protected against such events. However, consequences of emerging or re-emerging diseases are more and more unacceptable when they impact the poorest countries of the world. Viruses, bacteria, as well as wild animals, birds, or arthropods are not stopped by borders. It is time now to promote barriers against infectious diseases, including prevention, anticipation, disease surveillance and research. This is not only for humanitarian reasons, but also for contributing to a sustainable development with equity for worldwide population. This report presents comprehensive actions taken in 2006 for tracing the epidemic and mobilise research, as requested to the task force set up by the Prime Minister by March 20, 2006.

  11. Global Changes in Food Supply and the Obesity Epidemic.

    Science.gov (United States)

    Zobel, Emilie H; Hansen, Tine W; Rossing, Peter; von Scholten, Bernt Johan

    2016-12-01

    We explore how a global shift in the food system caused by global economic growth, increase in available food per capita and in food processing is a driver of the obesity epidemic. Economic development in most areas of the world has resulted in increased purchasing power and available per capita food. Supermarkets and a growing fast-food industry have transformed our dietary pattern. Ultra-processed food rich on sugars and saturated fat is now the major source of energy in most countries. The shift in food supply is considered a major driver of the obesity epidemic and the increasing prevalence of accompanying complications, such as type 2 diabetes, cardiovascular disease and cancer. However, the global shift might also have direct effects on the increase in type 2 diabetes, cardiovascular disease and cancer, independently of overweight and obesity. The shift in the food supply is a major driver of the obesity epidemic.

  12. Acanthamoeba keratitis in South India: a longitudinal analysis of epidemics.

    Science.gov (United States)

    Lalitha, Prajna; Lin, Charles C; Srinivasan, Muthiah; Mascarenhas, Jeena; Prajna, N Venkatesh; Keenan, Jeremy D; McLeod, Stephen D; Acharya, Nisha R; Lietman, Thomas M; Porco, Travis C

    2012-04-01

    In light of the increased incidence of contact lens associated Acanthamoeba keratitis in recent years, this study analyzed longitudinal trends of its incidence among predominantly non-contact lens wearers in a high-volume referral center in South India. A retrospective analysis of microbiology laboratory records at the Aravind Eye Hospital from 1988-2009 was performed. The Maximum Excess Events Test (MEET) was used to identify epidemics of Acanthamoeba keratitis. There were a total of 38,529 unique cases of infectious keratitis evaluated over this time period, of which 372 were culture-positive for Acanthamoeba. Only three cases (0.9%) of Acanthamoeba keratitis occurred among contact lens wearers. MEET identified unique Acanthamoeba keratitis epidemics in 1993 and 2002. Discrete epidemics of Acanthamoeba keratitis occurred among a rural, non-contact lens wearing, population in South India in 1993 and 2002.

  13. The paralytic poliomyelitis epidemic of 1978 in Jordan: epidemiological implications

    Science.gov (United States)

    Khuri-Bulos, Najwa; Melnick, Joseph L.; Hatch, Milford H.; Dawod, Saleh T.

    1984-01-01

    Poliomyelitis is endemic in Jordan, but until 1978 there were no epidemics. In that year, 66 children were admitted to the Jordan University Hospital with a paralytic illness, compared with 13 in 1979 and 11 in 1980. The epidemic reached a peak in the summer and fall of 1978. While 54% of the patients had not received any vaccine, 19% had received 3 doses of oral poliovaccine; 82% of the cases were in children less than 2 years of age, and all belonged to the lower socioeconomic group. There were 28 deaths with complications of the disease. Poliovirus was isolated from 10 out of 14 rectal swab samples examined (9 with poliovirus 1, 1 with poliovirus 2), and from 4 out of 13 throat specimens from the same patients. It is concluded that as a result of improving living standards in Jordan and neighbouring countries, more epidemics may occur unless immunization efforts against poliomyelitis are intensified. PMID:6609022

  14. Epidemic Forecasting is Messier Than Weather Forecasting: The Role of Human Behavior and Internet Data Streams in Epidemic Forecast.

    Science.gov (United States)

    Moran, Kelly R; Fairchild, Geoffrey; Generous, Nicholas; Hickmann, Kyle; Osthus, Dave; Priedhorsky, Reid; Hyman, James; Del Valle, Sara Y

    2016-12-01

    Mathematical models, such as those that forecast the spread of epidemics or predict the weather, must overcome the challenges of integrating incomplete and inaccurate data in computer simulations, estimating the probability of multiple possible scenarios, incorporating changes in human behavior and/or the pathogen, and environmental factors. In the past 3 decades, the weather forecasting community has made significant advances in data collection, assimilating heterogeneous data steams into models and communicating the uncertainty of their predictions to the general public. Epidemic modelers are struggling with these same issues in forecasting the spread of emerging diseases, such as Zika virus infection and Ebola virus disease. While weather models rely on physical systems, data from satellites, and weather stations, epidemic models rely on human interactions, multiple data sources such as clinical surveillance and Internet data, and environmental or biological factors that can change the pathogen dynamics. We describe some of similarities and differences between these 2 fields and how the epidemic modeling community is rising to the challenges posed by forecasting to help anticipate and guide the mitigation of epidemics. We conclude that some of the fundamental differences between these 2 fields, such as human behavior, make disease forecasting more challenging than weather forecasting. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  15. EPIDEMIC RISE IN THE INCIDENCE OF INFLUENZA IN ST. PETERSBURG IN 2016

    Directory of Open Access Journals (Sweden)

    N. S. Bashketova

    2017-01-01

    Full Text Available Inf luenza and acute respiratory viral infections (ARVI account for up to 90% of the total reported infectious morbidity annually in Russia. The economic damage from these infections reaches 86% of the economic losses associated with infectious diseases. As a result of antigenic drift or a shift, new variants of the inf luenza virus, including pandemic strains, appear. In 2009, an inf luenza pandemic arose due to the shifter version of the inf luenza A (H1N1 pdm09 virus. This virus caused epidemic rises of inf luenza in the world in subsequent years. The aim of the study was to describe the epidemic process of inf luenza in January–March 2016 in St. Petersburg. Materials and methods. The incidence of inf luenza and acute respiratory viral infections in St. Petersburg was recorded according to statistical coupons by age groups of the population. Examined nasopharyngeal f lushes received no later than 3–4 days from the onset of the disease, and in case of a lethal outcome — sectional material (bronchi, trachea, lungs, spleen tissues. The detection of RNA of inf luenza viruses was carried out in RT-PCR (Amplicenc Inf luenza virus A/B, Amplicenc Inf luenza virus A/H1-swine-FL, Amplicenc Inf luenza virus A типа-FL,  «Interlabservice», Moscow. Isolation of inf luenza viruses from the clinical material was carried out on culture by the MDSC cell. Isolates were typed in RTGA with diagnostic sera to reference and epidemic inf luenza viruses. Isolation of inf luenza viruses from the clinical material was carried out on culture by the MDSC cell. Isolates were typed in RTGA with diagnostic sera to reference and epidemic inf luenza viruses. Results. In 2016, the incidence of inf luenza in St. Petersburg was 81.38 per 100 000 population and was 4.1 times higher than the incidence rate in 2015. The epidemic rise in the incidence of inf luenza and ARVI began with the 3rd calendar week, lasted 6 weeks, with a peak incidence at the 5th calendar week

  16. Characterization of Erwinia amylovora strains from different host plants using repetitive-sequences PCR analysis, and restriction fragment length polymorphism and short-sequence DNA repeats of plasmid pEA29.

    Science.gov (United States)

    Barionovi, D; Giorgi, S; Stoeger, A R; Ruppitsch, W; Scortichini, M

    2006-05-01

    The three main aims of the study were the assessment of the genetic relationship between a deviating Erwinia amylovora strain isolated from Amelanchier sp. (Maloideae) grown in Canada and other strains from Maloideae and Rosoideae, the investigation of the variability of the PstI fragment of the pEA29 plasmid using restriction fragment length polymorphism (RFLP) analysis and the determination of the number of short-sequence DNA repeats (SSR) by DNA sequence analysis in representative strains. Ninety-three strains obtained from 12 plant genera and different geographical locations were examined by repetitive-sequences PCR using Enterobacterial Repetitive Intergenic Consensus, BOX and Repetitive Extragenic Palindromic primer sets. Upon the unweighted pair group method with arithmetic mean analysis, a deviating strain from Amelanchier sp. was analysed using amplified ribosomal DNA restriction analysis (ARDRA) analysis and the sequencing of the 16S rDNA gene. This strain showed 99% similarity to other E. amylovora strains in the 16S gene and the same banding pattern with ARDRA. The RFLP analysis of pEA29 plasmid using MspI and Sau3A restriction enzymes showed a higher variability than that previously observed and no clear-cut grouping of the strains was possible. The number of SSR units reiterated two to 12 times. The strains obtained from pear orchards showing for the first time symptoms of fire blight had a low number of SSR units. The strains from Maloideae exhibit a wider genetic variability than previously thought. The RFLP analysis of a fragment of the pEA29 plasmid would not seem a reliable method for typing E. amylovora strains. A low number of SSR units was observed with first epidemics of fire blight. The current detection techniques are mainly based on the genetic similarities observed within the strains from the cultivated tree-fruit crops. For a more reliable detection of the fire blight pathogen also in wild and ornamentals Rosaceous plants the genetic

  17. Global panel of HIV-1 Env reference strains for standardized assessments of vaccine-elicited neutralizing antibodies.

    Science.gov (United States)

    deCamp, Allan; Hraber, Peter; Bailer, Robert T; Seaman, Michael S; Ochsenbauer, Christina; Kappes, John; Gottardo, Raphael; Edlefsen, Paul; Self, Steve; Tang, Haili; Greene, Kelli; Gao, Hongmei; Daniell, Xiaoju; Sarzotti-Kelsoe, Marcella; Gorny, Miroslaw K; Zolla-Pazner, Susan; LaBranche, Celia C; Mascola, John R; Korber, Bette T; Montefiori, David C

    2014-03-01

    Standardized assessments of HIV-1 vaccine-elicited neutralizing antibody responses are complicated by the genetic and antigenic variability of the viral envelope glycoproteins (Envs). To address these issues, suitable reference strains are needed that are representative of the global epidemic. Several panels have been recommended previously, but no clear answers have been available on how many and which strains are best suited for this purpose. We used a statistical model selection method to identify a global panel of reference Env clones from among 219 Env-pseudotyped viruses assayed in TZM-bl cells with sera from 205 HIV-1-infected individuals. The Envs and sera were sampled globally from diverse geographic locations and represented all major genetic subtypes and circulating recombinant forms of the virus. Assays with a panel size of only nine viruses adequately represented the spectrum of HIV-1 serum neutralizing activity seen with the larger panel of 219 viruses. An optimal panel of nine viruses was selected and augmented with three additional viruses for greater genetic and antigenic coverage. The spectrum of HIV-1 serum neutralizing activity seen with the final 12-virus panel closely approximated the activity seen with subtype-matched viruses. Moreover, the final panel was highly sensitive for detection of many of the known broadly neutralizing antibodies. For broader assay applications, all 12 Env clones were converted to infectious molecular clones using a proviral backbone carrying a Renilla luciferase reporter gene (Env.IMC.LucR viruses). This global panel should facilitate highly standardized assessments of vaccine-elicited neutralizing antibodies across multiple HIV-1 vaccine platforms in different parts of the world. An effective HIV-1 vaccine will need to overcome the extraordinary genetic variability of the virus, where most variation occurs in the viral envelope glycoproteins that are the sole targets for neutralizing antibodies. Efforts to elicit

  18. Reemergence of enterovirus 71 epidemic in northern Taiwan, 2012.

    Science.gov (United States)

    Luo, Shu-Ting; Chiang, Pai-Shan; Chung, Wan-Yu; Chia, Min-Yuan; Tsao, Kuo-Chien; Wang, Ying-Hsiang; Lin, Tzou-Yien; Lee, Min-Shi

    2015-01-01

    Enterovirus 71 (EV71) belongs to picornavirus family and could be classified phylogenetically into three major genogroups (A, B and C) including 11 genotypes (A, B1-B5 and C1-C5). Since 1997, EV71 has caused large-scale of epidemics with neurological complications in Asian children. In Taiwan, nationwide EV71 epidemics with different predominant genotypes have occurred cyclically since 1998. A nationwide EV71 epidemic occurred again in 2012. We conducted genetic and antigenic characterizations of the 2012 epidemic. Chang Gung Memorial Hospital (CGMH) is a medical center in northern Taiwan. In CGMH, specimens were collected from pediatric inpatients with suspected enterovirus infections for virus isolation. Enterovirus isolates were serotyped and genotyped and sera from EV71 inpatients were collected for measuring neutralizing antibody titers. There were 10, 16 and 99 EV71 inpatients identified in 2010, 2011 and 2012, respectively. There were 82 EV71 isolates genotyped, which identified 17 genotype C4a viruses and 65 genotype B5 viruses. The genotype B5 viruses were not detected until November 2011 and caused epidemics in 2012. Interestingly, the B5-2011 viruses were genetically distinguishable from the B5 viruses causing the 2008 epidemic and are likely introduced from China or Southeastern Asia. Based on antigenic analysis, minor antigenic variations were detected among the B5-2008, B5-2011, C4a-2008 and C4a-2012 viruses but these viruses antigenically differed from genotype A. Genotype B5 and C4a viruses antigenically differ from genotype A viruses which have disappeared globally for 30 years but have been detected in China since 2008. Enterovirus surveillance should monitor genetic and antigenic variations of EV71.

  19. Deletion of a 197-Amino-Acid Region in the N-Terminal Domain of Spike Protein Attenuates Porcine Epidemic Diarrhea Virus in Piglets.

    Science.gov (United States)

    Hou, Yixuan; Lin, Chun-Ming; Yokoyama, Masaru; Yount, Boyd L; Marthaler, Douglas; Douglas, Arianna L; Ghimire, Shristi; Qin, Yibin; Baric, Ralph S; Saif, Linda J; Wang, Qiuhong

    2017-07-15

    We previously isolated a porcine epidemic diarrhea virus (PEDV) strain, PC177, by blind serial passaging of the intestinal contents of a diarrheic piglet in Vero cell culture. Compared with the highly virulent U.S. PEDV strain PC21A, the tissue culture-adapted PC177 (TC-PC177) contains a 197-amino-acid (aa) deletion in the N-terminal domain of the spike (S) protein. We orally inoculated neonatal, conventional suckling piglets with TC-PC177 or PC21A to compare their pathogenicities. Within 7 days postinoculation, TC-PC177 caused mild diarrhea and lower fecal viral RNA shedding, with no mortality, whereas PC21A caused severe clinical signs and 55% mortality. To investigate whether infection with TC-PC177 can induce cross-protection against challenge with a highly virulent PEDV strain, all the surviving piglets were challenged with PC21A at 3 weeks postinoculation. Compared with 100% protection in piglets initially inoculated with PC21A, 88% and 100% TC-PC177- and mock-inoculated piglets had diarrhea following challenge, respectively, indicating incomplete cross-protection. To investigate whether this 197-aa deletion was the determinant for the attenuation of TC-PC177, we generated a mutant (icPC22A-S1Δ197) bearing the 197-aa deletion from an infectious cDNA clone of the highly virulent PEDV PC22A strain (infectious clone PC22A, icPC22A). In neonatal gnotobiotic pigs, the icPC22A-S1Δ197 virus caused mild to moderate diarrhea, lower titers of viral shedding, and no mortality, whereas the icPC22A virus caused severe diarrhea and 100% mortality. Our data indicate that deletion of this 197-aa fragment in the spike protein can attenuate a highly virulent PEDV, but the virus may lose important epitopes for inducing robust protective immunity. IMPORTANCE The emerging, highly virulent PEDV strains have caused substantial economic losses worldwide. However, the virulence determinants are not established. In this study, we found that a 197-aa deletion in the N-terminal region

  20. Transmission of new CRF07_BC Strains with 7 amino acid deletion in Gag p6

    Directory of Open Access Journals (Sweden)

    Jianxin Lu

    2011-02-01

    Full Text Available Abstract A 7 amino acid deletion in Gag p6 (P6delta7 emerged in Chinese prevalent HIV-1 strain CRF07_BC from different epidemic regions. It is important to determine whether this mutation could be transmitted and spread. In this study, HIV-1 Gag sequences from 5 different epidemic regions in China were collected to trace the transmission linkage and to analyze genetic evolution of P6delta7 strains. The sequence analysis demonstrated that P6delta7 is a CRF07_BC specific deletion, different P6delta7 strains could be originated from different parental CRF07_BC recombinants in different epidemic regions, and the transmission of P6delta7 strain has occurred in IDU populations. This is for the first time to identify the transmission linkage for P6delta7 strains and serves as a wake-up call for further monitoring in the future; In addition, P6delta7 deletion may represent an evolutionary feature which might exert influence on the fitness of CRF07_BC strain.

  1. Network Performance Improvement under Epidemic Failures in Optical Transport Networks

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée

    2013-01-01

    In this paper we investigate epidemic failure spreading in large- scale GMPLS-controlled transport networks. By evaluating the effect of the epidemic failure spreading on the network, we design several strategies for cost-effective network performance improvement via differentiated repair times....... First we identify the most vulnerable and the most strategic nodes in the network. Then, via extensive simulations we show that strategic placement of resources for improved failure recovery has better performance than randomly assigning lower repair times among the network nodes. Our OPNET simulation...... model can be used during the network planning process for facilitating cost- effective network survivability design....

  2. Epidemic spreading on networks based on stress response

    Science.gov (United States)

    Nian, Fuzhong; Yao, Shuanglong

    2017-06-01

    Based on the stress responses of individuals, the susceptible-infected-susceptible epidemic model was improved on the small-world networks and BA scale-free networks and the simulations were implemented and analyzed. Results indicate that the behaviors of individual’s stress responses could induce the epidemic spreading resistance and adaptation at the network level. This phenomenon showed that networks were learning how to adapt to the disease and the evolution process could improve their immunization to future infectious diseases and would effectively prevent the spreading of infectious diseases.

  3. Network Performance Improvement under Epidemic Failures in Optical Transport Networks

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée

    2013-01-01

    In this paper we investigate epidemic failure spreading in large- scale GMPLS-controlled transport networks. By evaluating the effect of the epidemic failure spreading on the network, we design several strategies for cost-effective network performance improvement via differentiated repair times....... First we identify the most vulnerable and the most strategic nodes in the network. Then, via extensive simulations we show that strategic placement of resources for improved failure recovery has better performance than randomly assigning lower repair times among the network nodes. Our OPNET simulation...

  4. Resolving epidemic network failures through differentiated repair times

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée; Manzano, Marc

    2015-01-01

    In this study, the authors investigate epidemic failure spreading in large-scale transport networks under generalisedmulti-protocol label switching control plane. By evaluating the effect of the epidemic failure spreading on the network,they design several strategies for cost-effective network...... performance improvement via differentiated repair times. First, theyidentify the most vulnerable and the most strategic nodes in the network. Then, via extensive event-driven simulations theyshow that strategic placement of resources for improved failure recovery has better performance than randomly...

  5. Reiter′s Disease - Clinical Profile of Epidemic Form

    Directory of Open Access Journals (Sweden)

    H S Girgia

    1980-01-01

    Full Text Available Absence of urethritis need not exclude the possiblity of Reiter′s disease in young males where conjunctivitis and polyarthritis are cardinal features. Appearance of cutaneous lesion early in the course of the disease heralds a poor prognosis specially in the rare epidemic form of the disease. Two cases of Reiter′s disease are reported. Both belonged to the dysentric type of the disease; sometimes ref to as the epidemic form. Relatively high dose of steroids necessary to control symptoms.

  6. Random migration processes between two stochastic epidemic centers.

    Science.gov (United States)

    Sazonov, Igor; Kelbert, Mark; Gravenor, Michael B

    2016-04-01

    We consider the epidemic dynamics in stochastic interacting population centers coupled by random migration. Both the epidemic and the migration processes are modeled by Markov chains. We derive explicit formulae for the probability distribution of the migration process, and explore the dependence of outbreak patterns on initial parameters, population sizes and coupling parameters, using analytical and numerical methods. We show the importance of considering the movement of resident and visitor individuals separately. The mean field approximation for a general migration process is derived and an approximate method that allows the computation of statistical moments for networks with highly populated centers is proposed and tested numerically. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Ebola Virus Epidemic in West Africa and Beyond

    Directory of Open Access Journals (Sweden)

    Oscar G Gómez-Duarte

    2014-10-01

    Full Text Available Is there a reason to fear that an Ebola outbreak may strike Latin America? The fear may not be unreasonable taking into account the history of epidemics that have affected the American continent since colonization times in 1492. Old World small pox epidemics spread and killed millions of Native Americans north and south from the equator. Imported West Nile virus infections reported in New York in 1999 dramatically spread East to West of the United States. Most recently, Chikungunya virus arrived to Central America in 2013 and has already infected close to 1 million people in Mexico, Central American countries, Brazil, Colombia, Ecuador, Guyanas, Paraguay, and Venezuela.

  8. A sociocultural study of koro epidemics in Guangdong, China.

    Science.gov (United States)

    Tseng, W S; Mo, K M; Hsu, J; Li, L S; Ou, L W; Chen, G Q; Jiang, D W

    1988-12-01

    Koro, a culture-related psychiatric disorder characterized by panic due to fear of genital retraction, occurred as the rare phenomenon of koro epidemics in a remote region of Guangdong, China, in 1984-1985 and 1987. The sociocultural and historical backgrounds of the area are described. The life pattern and attitudes toward supernatural beings and the commonly shared folk belief of evil-induced genital retraction were considered grounds for the panic, while the community's anxious reaction and hysterical atmosphere facilitated the intensification and recurrence of the episodes. Geographic seclusion associated with localism in folk beliefs and practices may have kept the epidemics confined to the region.

  9. [The Prevalence and prevention of Cattle Epidemics in Song dynasty].

    Science.gov (United States)

    Han, Yi

    2011-07-01

    Cattle epidemics broke out many times in Song Dynasty due to pasture transferring to south, abnormal climate, poor stabling hygiene and climatic sickness caused by migration. Mass Mortality and reduction of animal agriculture productivity threatened the stable production of grain, which influenced society and attracted attention from all social classes. Based on the principle of 'prevention before sicken' and 'contagion protection after sicken', the government took a series of medical and economical actions for prevention, such as veterinarians dispatching, drugs providing, pasturage rule regulating, law modifying (cattle trade permitted) and new farm implements popularization (to prevent missing the opportunity of cultivation), which was effective for Cattle Epidemics prevention at that time.

  10. Epidemic Increase in Methicillin-resistant Staphylococcus aureus in Copenhagen

    DEFF Research Database (Denmark)

    Westh, Henrik; Boye, Kit; Bartels, Mette Damkjær

    2006-01-01

    INTRODUCTION: We have found an epidemic increase in methicillin-resistant Staphylococcus aureus (MRSA) in Copenhagen. The increase has a complex background and involves hospitals, nursing homes and persons nursed in their own home. MATERIAL AND METHODS: We found 33 MRSA patients in 2003 and 121...... in 2004. All isolates have been spa-typed and epidemiologic information collected. RESULTS: The number of MRSA cases has a doubling time of about six months. The epidemic has been caused by many different MRSA types and 31 staphylococcus protein A genotypes (spa types). MRSA has caused several hospital...

  11. Suppressing traffic-driven epidemic spreading by use of the efficient routing protocol

    International Nuclear Information System (INIS)

    Yang, Han-Xin; Wu, Zhi-Xi

    2014-01-01

    Despite extensive work on the interplay between traffic dynamics and epidemic spreading, the control of epidemic spreading by routing strategies has not received adequate attention. In this paper, we study the impact of an efficient routing protocol on epidemic spreading. In the case of infinite node-delivery capacity, where the traffic is free of congestion, we find that that there exist optimal values of routing parameter, leading to the maximal epidemic threshold. This means that epidemic spreading can be effectively controlled by fine tuning the routing scheme. Moreover, we find that an increase in the average network connectivity and the emergence of traffic congestion can suppress the epidemic outbreak. (paper)

  12. Proteomics Analysis Reveals Previously Uncharacterized Virulence Factors in Vibrio proteolyticus.

    Science.gov (United States)

    Ray, Ann; Kinch, Lisa N; de Souza Santos, Marcela; Grishin, Nick V; Orth, Kim; Salomon, Dor

    2016-07-26

    Members of the genus Vibrio include many pathogens of humans and marine animals that share genetic information via horizontal gene transfer. Hence, the Vibrio pan-genome carries the potential to establish new pathogenic strains by sharing virulence determinants, many of which have yet to be characterized. Here, we investigated the virulence properties of Vibrio proteolyticus, a Gram-negative marine bacterium previously identified as part of the Vibrio consortium isolated from diseased corals. We found that V. proteolyticus causes actin cytoskeleton rearrangements followed by cell lysis in HeLa cells in a contact-independent manner. In search of the responsible virulence factor involved, we determined the V. proteolyticus secretome. This proteomics approach revealed various putative virulence factors, including active type VI secretion systems and effectors with virulence toxin domains; however, these type VI secretion systems were not responsible for the observed cytotoxic effects. Further examination of the V. proteolyticus secretome led us to hypothesize and subsequently demonstrate that a secreted hemolysin, belonging to a previously uncharacterized clan of the leukocidin superfamily, was the toxin responsible for the V. proteolyticus-mediated cytotoxicity in both HeLa cells and macrophages. Clearly, there remains an armory of yet-to-be-discovered virulence factors in the Vibrio pan-genome that will undoubtedly provide a wealth of knowledge on how a pathogen can manipulate host cells. The pan-genome of the genus Vibrio is a potential reservoir of unidentified toxins that can provide insight into how members of this genus have successfully risen as emerging pathogens worldwide. We focused on Vibrio proteolyticus, a marine bacterium that was previously implicated in virulence toward marine animals, and characterized its interaction with eukaryotic cells. We found that this bacterium causes actin cytoskeleton rearrangements and leads to cell death. Using a

  13. Rates of induced abortion in Denmark according to age, previous births and previous abortions

    Directory of Open Access Journals (Sweden)

    Marie-Louise H. Hansen

    2009-11-01

    Full Text Available Background: Whereas the effects of various socio-demographic determinants on a woman's risk of having an abortion are relatively well-documented, less attention has been given to the effect of previous abortions and births. Objective: To study the effect of previous abortions and births on Danish women's risk of an abortion, in addition to a number of demographic and personal characteristics. Data and methods: From the Fertility of Women and Couples Dataset we obtained data on the number of live births and induced abortions by year (1981-2001, age (16-39, county of residence and marital status. Logistic regression analysis was used to estimate the influence of the explanatory variables on the probability of having an abortion in a relevant year. Main findings and conclusion: A woman's risk of having an abortion increases with the number of previous births and previous abortions. Some interactions were was found in the way a woman's risk of abortion varies with calendar year, age and parity. The risk of an abortion for women with no children decreases while the risk of an abortion for women with children increases over time. Furthermore, the risk of an abortion decreases with age, but relatively more so for women with children compared to childless women. Trends for teenagers are discussed in a separate section.

  14. Complex networks and agent-based models of HIV epidemic

    NARCIS (Netherlands)

    Zarrabi, N.

    2013-01-01

    In this thesis, we explore the limits of multi-scale models by looking into the HIV data present at different scales (from molecular and cellular to epidemiological scales). We build data-driven models and perform network analysis in order to understand the dynamics of HIV epidemic at different

  15. Perspectives of Spatial Scale in a Wildland Forest Epidemic

    Science.gov (United States)

    W.W. Dillon; S.E. Haas; D.M. Rizzo; R.K. Meentemeyer

    2014-01-01

    The challenge of observing interactions between plant pathogens, their hosts, and environmental heterogeneity across multiple spatial scales commonly limits our ability to understand and manage wildland forest epidemics. Using the forest pathogen Phytophthora ramorum as a case study, we established 20 multiscale field sites to analyze how host-...

  16. EDITORIAL Plagiarism - time to strike at the epidemic

    African Journals Online (AJOL)

    admin

    Plagiarism - time to strike at the epidemic. Lukman Yusuf1, Abraham Aseffa2. We live in a globalized world where information is instantly shared across continents. The number of biomedical journals available for reference is quite enormous and there is a sudden huge surge of free open access journals in the last few years ...

  17. Obesity and kidney disease: hidden consequences of the epidemic ...

    African Journals Online (AJOL)

    Obesity has become a worldwide epidemic, and its prevalence has been projected to grow by 40% in the next decade. This increasing prevalence has implications for the risk of diabetes, cardiovascular disease and also for Chronic Kidney Disease. A high body mass index is one of the strongest risk factors for new-onset ...

  18. Epidemic Processes on Complex Networks : Modelling, Simulation and Algorithms

    NARCIS (Netherlands)

    Van de Bovenkamp, R.

    2015-01-01

    Local interactions on a graph will lead to global dynamic behaviour. In this thesis we focus on two types of dynamic processes on graphs: the Susceptible-Infected-Susceptilbe (SIS) virus spreading model, and gossip style epidemic algorithms. The largest part of this thesis is devoted to the SIS

  19. One Hundred Years in the Making: The Global Tobacco Epidemic.

    Science.gov (United States)

    Wipfli, Heather; Samet, Jonathan M

    2016-01-01

    Today's global tobacco epidemic may represent one of the first instances of the globalization of a noninfectious cause of disease. This article focuses on the first century of the global tobacco epidemic and its current status, reviewing the current and projected future of the global tobacco epidemic and the steps that are in progress to end it. In the United States and many countries of Western Europe, tobacco consumption peaked during the 1960s and 1970s and declined as tobacco control programs were initiated, motivated by the evidence indicting smoking as a leading cause of disease. Despite this policy advancement and the subsequent reductions in tobacco consumption, the global tobacco epidemic continued to grow exponentially in the later years of the twentieth century, as the multinational companies sought new markets to replace those shrinking in high-income countries. In response, between 2000 and 2004, the World Health Organization developed its first public health treaty, the Framework Convention on Tobacco Control, which entered into force in 2005. An accompanying package of interventions has been implemented. New approaches to tobacco control, including plain packaging and single representation of brands, have been implemented by Australia and Uruguay, respectively, but have been challenged by the tobacco industry.

  20. Examination of the Obesity Epidemic from a Behavioral Perspective

    Science.gov (United States)

    Shields, A. Tamlyn

    2009-01-01

    Obesity prevalence has doubled among adults and overweight has tripled among children since 1980. This article discusses behavioral approaches to the obesity epidemic, focusing on recent environmental changes, the resulting behaviors, and possible solutions. Over the last 4 decades, time spent in sedentary activities, the consumption of fast food,…

  1. The looming epidemic of diabetes-associated tuberculosis

    DEFF Research Database (Denmark)

    Harries, A D; Lin, Y; Satyanarayana, S

    2011-01-01

    The prevalence of diabetes mellitus is increasing at a dramatic rate, and countries in Asia, particularly India and China, will bear the brunt of this epidemic. Persons with diabetes have a significantly increased risk of active tuberculosis (TB), which is two to three times higher than in persons...

  2. Antiretroviral Medication Adherence During The Ebola Epidemic In ...

    African Journals Online (AJOL)

    The 2014 Ebola outbreak is the largest in history and the first in West Africa. The outbreak affected multiple countries in West Africa. Worldwide, there have been 28,639 cases of Ebola virus disease and 11,316 deaths at 13 March 2016 in the world's worst recorded Ebola epidemic in Guinea, Liberia, and Sierra Leone.

  3. Gendered Epidemics and Systems of Power in Africa: A Feminist ...

    African Journals Online (AJOL)

    we, as women's health researchers and experts, ensure that knowledge and information about epidemics is shared timeously especially to those who are affected first? Because the systems of power and knowledge demand that knowledge only becomes relevant if one collaborates with the right people, if one quotes.

  4. An "Epidemic" of Adolescent Pregnancy? Some Historical and Policy Considerations.

    Science.gov (United States)

    Vinovskis, Maris A.

    Adolescent pregnancy (AP) is explored from historical and policy perspectives. The "epidemic" of AP, with 4 out of every 10 teenage girls becoming pregnant, is typically portrayed as a recent and unprecedented problem that requires massive federal intervention, but the problem is not new. Chapter 1 analyzes adolescent sexuality, AP, and…

  5. Spatial Big Data Analytics of Influenza Epidemic in Vellore, India.

    Science.gov (United States)

    Lopez, Daphne; Gunasekaran, M; Murugan, B Senthil; Kaur, Harpreet; Abbas, Kaja M

    2014-10-01

    The study objective is to develop a big spatial data model to predict the epidemiological impact of influenza in Vellore, India. Large repositories of geospatial and health data provide vital statistics on surveillance and epidemiological metrics, and valuable insight into the spatiotemporal determinants of disease and health. The integration of these big data sources and analytics to assess risk factors and geospatial vulnerability can assist to develop effective prevention and control strategies for influenza epidemics and optimize allocation of limited public health resources. We used the spatial epidemiology data of the HIN1 epidemic collected at the National Informatics Center during 2009-2010 in Vellore. We developed an ecological niche model based on geographically weighted regression for predicting influenza epidemics in Vellore, India during 2013-2014. Data on rainfall, temperature, wind speed, humidity and population are included in the geographically weighted regression analysis. We inferred positive correlations for H1N1 influenza prevalence with rainfall and wind speed, and negative correlations for H1N1 influenza prevalence with temperature and humidity. We evaluated the results of the geographically weighted regression model in predicting the spatial distribution of the influenza epidemic during 2013-2014.

  6. Avian Flu Epidemic 2003: Public health consequences. Executive summary

    NARCIS (Netherlands)

    Bosman A; Mulder YM; Leeuw JRJ de; Meijer A; Du Ry van Beest Holle M; Kamst RA; Velden PG van der; Conyn-van Spaendonck MAE; Koopmans MPG; Ruijten MWMM; Instituut voor Psychotrauma; CIE; MGO; LIS

    2004-01-01

    Executive summary Avian flu epidemic 2003: public health consequences.Risk factors, health, well-being, health care needs and preventive measures during the H7N7 avian flu outbreak control in the Netherlands.An estimated thousand people, possibly more have been infected with avian flu during the

  7. Neoliberal science, Chinese style: Making and managing the 'obesity epidemic'.

    Science.gov (United States)

    Greenhalgh, Susan

    2016-08-01

    Science and Technology Studies has seen a growing interest in the commercialization of science. In this article, I track the role of corporations in the construction of the obesity epidemic, deemed one of the major public health threats of the century. Focusing on China, a rising superpower in the midst of rampant, state-directed neoliberalization, I unravel the process, mechanisms, and broad effects of the corporate invention of an obesity epidemic. Largely hidden from view, Western firms were central actors at every stage in the creation, definition, and governmental management of obesity as a Chinese disease. Two industry-funded global health entities and the exploitation of personal ties enabled actors to nudge the development of obesity science and policy along lines beneficial to large firms, while obscuring the nudging. From Big Pharma to Big Food and Big Soda, transnational companies have been profiting from the 'epidemic of Chinese obesity', while doing little to effectively treat or prevent it. The China case suggests how obesity might have been constituted an 'epidemic threat' in other parts of the world and underscores the need for global frameworks to guide the study of neoliberal science and policymaking.

  8. Efficient mitigation strategies for epidemics in rural regions.

    Directory of Open Access Journals (Sweden)

    Caterina Scoglio

    Full Text Available Containing an epidemic at its origin is the most desirable mitigation. Epidemics have often originated in rural areas, with rural communities among the first affected. Disease dynamics in rural regions have received limited attention, and results of general studies cannot be directly applied since population densities and human mobility factors are very different in rural regions from those in cities. We create a network model of a rural community in Kansas, USA, by collecting data on the contact patterns and computing rates of contact among a sampled population. We model the impact of different mitigation strategies detecting closely connected groups of people and frequently visited locations. Within those groups and locations, we compare the effectiveness of random and targeted vaccinations using a Susceptible-Exposed-Infected-Recovered compartmental model on the contact network. Our simulations show that the targeted vaccinations of only 10% of the sampled population reduced the size of the epidemic by 34.5%. Additionally, if 10% of the population visiting one of the most popular locations is randomly vaccinated, the epidemic size is reduced by 19%. Our results suggest a new implementation of a highly effective strategy for targeted vaccinations through the use of popular locations in rural communities.

  9. Cardiovascular disease: A Global Epidemic extending into Sub ...

    African Journals Online (AJOL)

    Background: Cardiovascular disease is a global epidemic; the prevalence is currently stable in the developed world but is on a rapid rise in the developing world particularly in Sub-Saharan Africa. It is the commonest cause of morbidity and mortality globally. Its victims are older in the developed world but younger in Africa ...

  10. Information Spreading in Epidemics and in Communication Networks

    DEFF Research Database (Denmark)

    Uekermann, Florian Philipp

    The PhD thesis revolves mainly around models of disease spreading and human behavior. We present models for different epidemic patterns of infectious diseases. This includes investigations of the trajectory of the 2014 Ebola outbreak in West-Africa, influenza evolution and the seasonal dynamics...

  11. The epidemic of childhood obesity | du Toit | South African Medical ...

    African Journals Online (AJOL)

    South African Medical Journal. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 93, No 1 (2003) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. The epidemic of childhood obesity. G du Toit, M-T van der Merwe. Abstract.

  12. Community intervention for the emerging epidemic of non ...

    African Journals Online (AJOL)

    Community intervention for the emerging epidemic of non-communicable diseases. Thandi Puoane, Hazel Bradley, Gail Hughes. Abstract. No Abstract. South African Journal of Clinical Nutrition Vol. 19(2) 2006: 56-62. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD ...

  13. An Epidemic of Oroya Fever in the Peruvian Andes

    Science.gov (United States)

    1990-01-01

    Marafion River in regions with elevations of 600-2,450 m in Co- the Department of Ancash. Pomabamba Prov- 6 lumbia. Ecuador. Peru. Chile , Bolivia...lipopolysaccharide T’he epidemic began during the rainy season. (Difco laboratories. Detroit. M11) and Brucella November to May. Many of the lPrsi cases re

  14. Addressing the "Epidemic" of Overweight Children by Using the Internet

    Science.gov (United States)

    Coleman, Mick; Wallinga, Charlotte; Bales, Diane

    2009-01-01

    The Internet can be of great assistance to early childhood teachers in planning educational activities for the classroom and with families. This article explores how early childhood teachers can use resources online to address what has been called an "epidemic" of overweight children. Guidelines for using online resources are presented. (Contains…

  15. Topology dependent epidemic spreading velocity in weighted networks

    NARCIS (Netherlands)

    Duan, W.; Quax, R.; Lees, M.; Qiu, X.; Sloot, P.M.A.

    2014-01-01

    Many diffusive processes occur on structured networks with weighted links, such as disease spread by airplane transport or information diffusion in social networks or blogs. Understanding the impact of weight-connectivity correlations on epidemic spreading in weighted networks is crucial to support

  16. The chemical bases of the various AIDS epidemics: recreational ...

    Indian Academy of Sciences (India)

    Unknown

    [Duesberg P, Koehnlein C and Rasnick D 2003 The chemical bases of the various AIDS epidemics: recreational drugs, anti-viral chemo- ..... on AIDS in 1984 made a coherent case for lifestyle- or chemical AIDS, caused by recreational drugs or malnu- trition. 3. 1984: The virus-AIDS hypothesis takes over. By 1983 AIDS had ...

  17. Malaria Epidemics in Dembia, Northwest Ethiopia 1952 – 1953

    African Journals Online (AJOL)

    unhcc

    1Department of History, Bahir Dar University, Email: fantahun@gmail.com, Phone: +251-911759867. Original article ... Objective: The main objective of this study is to investigate the history of the 1952/53 malaria epidemic in. Dembia and the scale of its devastation. ... In sub-Saharan Africa, malaria still claims 1-2 million ...

  18. Formal kinetics of H1N1 epidemic

    Directory of Open Access Journals (Sweden)

    Gurevich Konstantin G

    2009-09-01

    Full Text Available Abstract Background The formal kinetics of the H1N1 epidemic seems to take the form of an exponential curve. There is a good correlation between this theoretical model and epidemiological data on the number of H1N1-infected people. But this formal model leads to paradoxes about the dates when everyone becomes infected: in Mexico this will happen after one year, then in the rest of the world. Further implications of the formal model The general limitations of this formal kinetics model are discussed. More detailed modeling is examined and the implications are examined in the light of currently available data. The evidence indicates that not more than 10% of the population is initially resistant to the H1N1 virus. Conclusion We are probably only at the initial stage of development of the H1N1 epidemic. Increasing the number of H1N1-resistant people in future (e.g. due to vaccination may influence the dynamics of epidemic development. At present, the development of the epidemic depends only on the number of people in the population who are initially resistant to the virus.

  19. Understanding Virtual Epidemics: Children's Folk Conceptions of a Computer Virus

    Science.gov (United States)

    Kafai, Yasmin B.

    2008-01-01

    Our work investigates the annual outbreak of Whypox, a virtual epidemic in Whyville.net, a virtual world with over 1.2 million registered players ages 8-16. We examined online and classroom participants' understanding of a computer virus using surveys and design activities. Our analyses reveal that students have a mostly naive understanding of a…

  20. Using a Human Ecosystems Approach to the Obesity Epidemic

    Science.gov (United States)

    Painter, James E.; Painter, Rosemary; Wang, Xinyue; Schuster, Margaret

    2017-01-01

    Obesity has been increasing in all age groups worldwide for the past several decades. Yet for hundreds of years before the last quarter of the 20th century, obesity was not an issue. The etiology and the cure for the obesity epidemic have been elusive. Weight reduction diets and behavior therapy have not produced the desired results. Perhaps…

  1. Strengthening HIV surveillance: measurements to track the epidemic ...

    African Journals Online (AJOL)

    Surveillance for HIV as a public health initiative requires timely, detailed and robust data to systematically understand burden of infection, transmission patterns, direct prevention efforts, guide funding, identify new infections and predict future trends in the epidemic. The methods for HIV surveillance have evolved to reliably ...

  2. Dynamics of cholera epidemics with impulsive vaccination and disinfection.

    Science.gov (United States)

    Sisodiya, Omprakash Singh; Misra, O P; Dhar, Joydip

    2018-04-01

    Waterborne diseases have a tremendous influence on human life. The contaminated drinking water causes water-borne disease like cholera. Pulse vaccination is an important and effective strategy for the elimination of infectious diseases. A waterborne disease like cholera can also be controlled by using impulse technique. In this paper, we have proposed a delayed SEIRB epidemic model with impulsive vaccination and disinfection. We have studied the pulse vaccination strategy and sanitation to control the cholera disease. The existence and stability of the disease-free and endemic periodic solution are investigated both analytically and numerically. It is shown that there exists an infection-free periodic solution, using the impulsive dynamical system defined by the stroboscopic map. It is observed that the infection-free periodic solution is globally attractive when the impulse period is less than some critical value. From the analysis of the model, we have obtained a sufficient condition for the permanence of the epidemic with pulse vaccination. The main highlight of this paper is to introduce impulse technique along with latent period into the SEIRB epidemic model to investigate the role of pulse vaccination and disinfection on the dynamics of the cholera epidemics. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Young adults and aids epidemics: their perception awareness ...

    African Journals Online (AJOL)

    Background: Education and awareness is important in appreciating the seriousness of a disease, and in arousing feeling of concern about an epidemic in any society. Continuing trend show a disproportionate increase in new incidences of HIV infection among young adults in sub-Sahara Africa. This study aimed to ...

  4. Epidemics in Networks : Modeling, Optimization and Security Games

    NARCIS (Netherlands)

    Omic, J.

    2010-01-01

    Epidemic theory has wide range of applications in computer networks, from spreading of malware to the information dissemination algorithms. Our society depends more strongly than ever on such computer networks. Many of these networks rely to a large extent on decentralization and self-organization.

  5. The epidemic of Athens, 430 - 426 BC | Retief | South African ...

    African Journals Online (AJOL)

    ... number of scholars who studied the subject, Thucydides' description does not accurately fit any existing disease, but we suggest that analysis of the signs and symptoms, considered in conjunction with significant epidemiological evidence, narrows down the many possibilities to epidemic typhus, plague, arboviral disease ...

  6. Overcrowding and disease epidemics in colonial Lagos: rethinking ...

    African Journals Online (AJOL)

    Thus, it degenerated to overcrowding and disease epidemics as epitomised by the outbreak of tuberculosis and bubonic plague in 1919 and between 1924 and 1930 respectively. The paper, therefore, concludes that with the available evidence at our disposal, it is obvious that the road and railway were constructed to ...

  7. Etoposide for epidemic Kaposi's sarcoma: a phase II study

    NARCIS (Netherlands)

    Bakker, P. J.; Danner, S. A.; Lange, J. M.; Veenhof, K. H.

    1988-01-01

    Fourteen untreated patients with epidemic Kaposi's sarcoma stages III and IV were treated with etoposide 150 mg/m2 on 3 consecutive days every 4 weeks. No responses were observed. Myelosuppression was severe with white blood count WHO grade 3-4 in nine patients and with platelets WHO grade 3-4 in

  8. Understanding the epidemic of HIV in South Africa

    African Journals Online (AJOL)

    2. The intrinsic doubling time does not differ significantly among the provinces. 3. The average length of the intrinsic doubling time is 12.0 months (95% Cl. 11.3 - 12.8 months). ... Epidemiology Research Unit, PO Box 30606, Braamfontein, 2017. Brian Williams. ... the intrinsic growth rate of the epidemic (the rate of increase.

  9. Effect of risk perception on epidemic spreading in temporal networks

    Science.gov (United States)

    Moinet, Antoine; Pastor-Satorras, Romualdo; Barrat, Alain

    2018-01-01

    Many progresses in the understanding of epidemic spreading models have been obtained thanks to numerous modeling efforts and analytical and numerical studies, considering host populations with very different structures and properties, including complex and temporal interaction networks. Moreover, a number of recent studies have started to go beyond the assumption of an absence of coupling between the spread of a disease and the structure of the contacts on which it unfolds. Models including awareness of the spread have been proposed, to mimic possible precautionary measures taken by individuals that decrease their risk of infection, but have mostly considered static networks. Here, we adapt such a framework to the more realistic case of temporal networks of interactions between individuals. We study the resulting model by analytical and numerical means on both simple models of temporal networks and empirical time-resolved contact data. Analytical results show that the epidemic threshold is not affected by the awareness but that the prevalence can be significantly decreased. Numerical studies on synthetic temporal networks highlight, however, the presence of very strong finite-size effects, resulting in a significant shift of the effective epidemic threshold in the presence of risk awareness. For empirical contact networks, the awareness mechanism leads as well to a shift in the effective threshold and to a strong reduction of the epidemic prevalence.

  10. Understanding the epidemic of HIV in South Africa | Williams | South ...

    African Journals Online (AJOL)

    Objectives. To investigate the magnitude and the time course of the HIV epidemic in the provinces of South Africa from the antenatal clinic HIV surveys. Design. We analysed the data on the provincial prevalences of HIV infection from 1990 to 1996 using maximum likelihood methods to determine the intrinsic growth rate and ...

  11. Some Empirical Notes on the Epo Epidemic in Professional Cycling

    Science.gov (United States)

    Lodewijkx, Hein F. M.; Brouwer, Bram

    2011-01-01

    The 1990-2010 period in professional cycling is labeled by some as the epo epidemic. Surprisingly, performance enhancement by epo and blood doping is not that clear-cut for endurance athletes, leading to the question whether doping indeed strongly influenced cyclists' performances from the 1990s onwards. We examined the records (1947-2008) of the…

  12. A study of the 2006 Chikungunya epidemic outbreak in Mauritius ...

    African Journals Online (AJOL)

    Chikungunya epidemic outbreaks have affected more than 1 million people in 2005-2006 in many Indian Ocean islands and in India. Mauritius experienced a major outbreak in February/March 2006 following a minor outbreak in April/May 2005. No cases have been registered on the island since August 2006.

  13. Is There an Epidemic of Child or Adolescent Depression?

    Science.gov (United States)

    Costello, E. Jane; Erkanli, Alaattin; Angold, Adrian

    2006-01-01

    Background: Both the professional and the general media have recently published concerns about an "epidemic" of child and adolescent depression. Reasons for this concern include (1) increases in antidepressant prescriptions, (2) retrospective recall by successive birth cohorts of adults, (3) rising adolescent suicide rates until 1990,…

  14. Traveling Wave Solutions in a Reaction-Diffusion Epidemic Model

    OpenAIRE

    Wang, Sheng; Liu, Wenbin; Guo, Zhengguang; Wang, Weiming

    2013-01-01

    We investigate the traveling wave solutions in a reaction-diffusion epidemic model. The existence of the wave solutions is derived through monotone iteration of a pair of classical upper and lower solutions. The traveling wave solutions are shown to be unique and strictly monotonic. Furthermore, we determine the critical minimal wave speed.

  15. Epidemic Hysteria in Schools: An International and Historical Overview.

    Science.gov (United States)

    Bartholomew, Robert E.; Sirois, Francois

    1996-01-01

    Examines the characteristic features of epidemic hysteria reports in school settings. Discovers three distinct symptom patterns: (1) mass motor hysteria (psychomotor alterations due to preexisting stress); (2) mass anxiety hysteria (extreme anxiety following the redefinition of a mundane event); and (3) mass pseudo-hysteria (relabeling of mundane…

  16. The Opioid Epidemic: 7 Things Educators Need to Know

    Science.gov (United States)

    Welsh, Justine W.; Rappaport, Nancy; Tretyak, Valeria

    2018-01-01

    Opioid abuse has become an epidemic in America and exposure to the drugs often begins in high school. This article shares some facts about opioid use and some signs and symptoms to look for in students who may be addicted to the drug. The authors also offer tips for educators on how to deal with the legal issues involved in assessing, reporting,…

  17. Molecular evolution and the natural history of select virus epidemics

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne

    Molecular evolution of pathogenic viruses with RNA based genomes is most often fast enough to leave an informative genomic sequence signal within a timeframe that is relevant for the study of both recent and on-­‐going epidemics (and epizootics). The true power of molecular evolutionary methodolo...

  18. The effect of awareness on networked SIS epidemics

    KAUST Repository

    Paarporn, Keith

    2017-01-05

    We study an SIS epidemic model over an arbitrary fixed network topology where the n agents, or nodes of the network, have partial information about the epidemic state. The agents react by distancing themselves from their neighbors when they believe the epidemic is currently prevalent. An agent\\'s awareness is weighted from three sources of information: the fraction of infected neighbors in their contact network, their social network, and a global broadcast of the fraction of infected nodes in the entire network. The dynamics of the benchmark (no awareness) and awareness models are described by discrete-time 2-state Markov chains. Through a coupling technique, we establish monotonicity properties between the benchmark and awareness models. Particularly, we show that the expectation of any increasing random variable on the space of sample paths, e.g. eradication time or total infections, is lower for the awareness model. In addition, we give a characterization for this difference of expectations in terms of the coupling distribution. In simulations, we evaluate how different sources of information affect the spread of an epidemic.

  19. Alkaline stabilization of manure slurry inactivates porcine epidemic diarrhea virus

    Science.gov (United States)

    The porcine epidemic diarrhea virus (PEDv) outbreak in North America has substantially impacted swine production since it causes nearly 100% mortality in infected pre-weaned piglets. The PED virus is transmitted via the fecal oral route and manure may remain a source of reinfection; therefore, prop...

  20. The chemical bases of the various AIDS epidemics: recreational ...

    Indian Academy of Sciences (India)

    Assuming immunodeficiency as the common denominator the US Centers for Disease Control (CDC) termed the epidemic, AIDS, for acquired immunodeficiency syndrome. From 1981–1984 leading researchers including those from the CDC proposed that recreational drug use was the cause of AIDS, because of exact ...

  1. The influence of the school year on measles epidemics

    DEFF Research Database (Denmark)

    Andreasen, Viggo

    The measles incidence record for Copenhagen 1880-1966 shows that the date of admission of new pupils has major impact on the structure of the epidemics, suggesting that measles transmission should be modelled in a way that accounts for the pulsed influx of new pupils. Assuming that the school year...

  2. The 1992 measles epidemic in Cape Town - a changing ...

    African Journals Online (AJOL)

    Over the last 6 years there has been a decline in the incidence of measles in Cape Town. However, during August 1992 an outbreak occurred, with cases reported at many schools in children presumably immunised. The objectives of this study were to characterise the epidemic in Cape Town and to determine possible ...

  3. A stochastic modeling of recurrent measles epidemic | Kassem ...

    African Journals Online (AJOL)

    A simple stochastic mathematical model is developed and investigated for the dynamics of measles epidemic. The model, which is a multi-dimensional diffusion process, includes susceptible individuals, latent (exposed), infected and removed individuals. Stochastic effects are assumed to arise in the process of infection of ...

  4. Using Clinicians’ Search Query Data to Monitor Influenza Epidemics

    Science.gov (United States)

    Santillana, Mauricio; Nsoesie, Elaine O.; Mekaru, Sumiko R.; Scales, David; Brownstein, John S.

    2014-01-01

    Search query information from a clinician's database, UpToDate, is shown to predict influenza epidemics in the United States in a timely manner. Our results show that digital disease surveillance tools based on experts' databases may be able to provide an alternative, reliable, and stable signal for accurate predictions of influenza outbreaks. PMID:25115873

  5. A hidden HIV epidemic among women in Vietnam

    NARCIS (Netherlands)

    Nguyen, Thu Anh; Oosterhoff, Pauline; Hardon, Anita; Tran, Hien Nguyen; Coutinho, Roel A.; Wright, Pamela

    2008-01-01

    Background: The HIV epidemic in Vietnam is still concentrated among high risk populations, including IDU and FSW. The response of the government has focused on the recognized high risk populations, mainly young male drug users. This concentration on one high risk population may leave other

  6. Virulence evolution at the front line of spreading epidemics.

    Science.gov (United States)

    Griette, Quentin; Raoul, Gaël; Gandon, Sylvain

    2015-11-01

    Understanding and predicting the spatial spread of emerging pathogens is a major challenge for the public health management of infectious diseases. Theoretical epidemiology shows that the speed of an epidemic is governed by the life-history characteristics of the pathogen and its ability to disperse. Rapid evolution of these traits during the invasion may thus affect the speed of epidemics. Here we study the influence of virulence evolution on the spatial spread of an epidemic. At the edge of the invasion front, we show that more virulent and transmissible genotypes are expected to win the competition with other pathogens. Behind the front line, however, more prudent exploitation strategies outcompete virulent pathogens. Crucially, even when the presence of the virulent mutant is limited to the edge of the front, the invasion speed can be dramatically altered by pathogen evolution. We support our analysis with individual-based simulations and we discuss the additional effects of demographic stochasticity taking place at the front line on virulence evolution. We confirm that an increase of virulence can occur at the front, but only if the carrying capacity of the invading pathogen is large enough. These results are discussed in the light of recent empirical studies examining virulence evolution at the edge of spreading epidemics. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  7. An epidemic of cockles-associated hepatitis A in Singapore.

    Science.gov (United States)

    Goh, K T; Chan, L; Ding, J L; Oon, C J

    1984-01-01

    An epidemic of serologically confirmed hepatitis A occurred between May and September 1983 in Singapore. The vehicle of transmission was traced to raw and partially cooked cockles, Anadara granosa, which had been imported from places with no sanitary control on the production. Strict controls on imported cockles are warranted.

  8. A social contagious model of the obesity epidemic

    Science.gov (United States)

    Huang, He; Yan, Zhijun; Chen, Yahong; Liu, Fangyan

    2016-11-01

    Obesity has been recognized as a global epidemic by WHO, followed by many empirical evidences to prove its infectiousness. However, the inter-person spreading dynamics of obesity are seldom studied. A distinguishing feature of the obesity epidemic is that it is driven by a social contagion process which cannot be perfectly described by the infectious disease models. In this paper, we propose a novel belief decision model based on the famous Dempster-Shafer theory of evidence to model obesity epidemic as the competing spread of two obesity-related behaviors: physical inactivity and physical activity. The transition of health states is described by an SIS model. Results reveal the existence of obesity epidemic threshold, above which obesity is quickly eradicated. When increasing the fading level of information spread, enlarging the clustering of initial obese seeds, or introducing small-world characteristics into the network topology, the threshold is easily met. Social discrimination against the obese people plays completely different roles in two cases: on one hand, when obesity cannot be eradicated, social discrimination can reduce the number of obese people; on the other hand, when obesity is eradicable, social discrimination may instead cause it breaking out.

  9. Predicting epidemic evolution on contact networks from partial observations.

    Directory of Open Access Journals (Sweden)

    Jacopo Bindi

    Full Text Available The massive employment of computational models in network epidemiology calls for the development of improved inference methods for epidemic forecast. For simple compartment models, such as the Susceptible-Infected-Recovered model, Belief Propagation was proved to be a reliable and efficient method to identify the origin of an observed epidemics. Here we show that the same method can be applied to predict the future evolution of an epidemic outbreak from partial observations at the early stage of the dynamics. The results obtained using Belief Propagation are compared with Monte Carlo direct sampling in the case of SIR model on random (regular and power-law graphs for different observation methods and on an example of real-world contact network. Belief Propagation gives in general a better prediction that direct sampling, although the quality of the prediction depends on the quantity under study (e.g. marginals of individual states, epidemic size, extinction-time distribution and on the actual number of observed nodes that are infected before the observation time.

  10. Vaccine efficacy in senescent mice challenged with recombinant SARS-CoV bearing epidemic and zoonotic spike variants.

    Directory of Open Access Journals (Sweden)

    Damon Deming

    2006-12-01

    Full Text Available In 2003, severe acute respiratory syndrome coronavirus (SARS-CoV was identified as the etiological agent of severe acute respiratory syndrome, a disease characterized by severe pneumonia that sometimes results in death. SARS-CoV is a zoonotic virus that crossed the species barrier, most likely originating from bats or from other species including civets, raccoon dogs, domestic cats, swine, and rodents. A SARS-CoV vaccine should confer long-term protection, especially in vulnerable senescent populations, against both the 2003 epidemic strains and zoonotic strains that may yet emerge from animal reservoirs. We report the comprehensive investigation of SARS vaccine efficacy in young and senescent mice following homologous and heterologous challenge.Using Venezuelan equine encephalitis virus replicon particles (VRP expressing the 2003 epidemic Urbani SARS-CoV strain spike (S glycoprotein (VRP-S or the nucleocapsid (N protein from the same strain (VRP-N, we demonstrate that VRP-S, but not VRP-N vaccines provide complete short- and long-term protection against homologous strain challenge in young and senescent mice. To test VRP vaccine efficacy against a heterologous SARS-CoV, we used phylogenetic analyses, synthetic biology, and reverse genetics to construct a chimeric virus (icGDO3-S encoding a synthetic S glycoprotein gene of the most genetically divergent human strain, GDO3, which clusters among the zoonotic SARS-CoV. icGD03-S replicated efficiently in human airway epithelial cells and in the lungs of young and senescent mice, and was highly resistant to neutralization with antisera directed against the Urbani strain. Although VRP-S vaccines provided complete short-term protection against heterologous icGD03-S challenge in young mice, only limited protection was seen in vaccinated senescent animals. VRP-N vaccines not only failed to protect from homologous or heterologous challenge, but resulted in enhanced immunopathology with eosinophilic

  11. Zika virus epidemic: the newest international emergency

    Directory of Open Access Journals (Sweden)

    Ruth Minamisava

    2016-03-01

    production, accurate diagnosis and treatment, training for caring for neurological syndromes and congenital malformations. (iii          Measures for travelers: counseling, disinfestation of aircrafts and airports. (iv          Sharing of information. Some inquiries have been made about the magnitude of this epidemic and its association with microcephaly and neurological disorders(4-5. It is reasonable to consider that there is an underreporting of microcephaly in the records of the Live Births Information System in Brazil. It is also to be expected that, after the national alert, the number of suspected cases would rise. When there is an increase or the implementation of surveillance, this always results in higher sensitivity of detection of suspected/reported cases with an increase in false positives. For these reasons, it is possible to say that part of the increase in reported cases of microcephaly may be attributable to the current intense surveillance. What is inconceivable, however, is that the prevalence of microcephaly in northeastern Brazil is 10 to 20 times higher than in other countries(6. At present, there are hypotheses that the Zika virus may have an etiologic and/or pathophysiological role for these events, which is usually rare. What seems indisputable is the gravity of the situation. Health managers cannot wait for high-level scientific evidence. Care and prudence when assessing is advisable, and the same goes for avoiding premature conclusions. However, given the potential threat, we have a duty to at least protect pregnant women and their fetuses. The current situation poses many challenges that we need to face and it seems logical that Brazil take the lead in beginning the actions. We recognize in our history both the success in the fight against yellow fever early in the last century and also our recent inefficiency in the fight against the Aedes aegypti mosquito to control dengue and chikungunya. It is necessary to create, renew, and

  12. Rainfall mediations in the spreading of epidemic cholera

    Science.gov (United States)

    Righetto, L.; Bertuzzo, E.; Mari, L.; Schild, E.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2013-10-01

    Following the empirical evidence of a clear correlation between rainfall events and cholera resurgence that was observed in particular during the recent outbreak in Haiti, a spatially explicit model of epidemic cholera is re-examined. Specifically, we test a multivariate Poisson rainfall generator, with parameters varying in space and time, as a driver of enhanced disease transmission. The relevance of the issue relates to the key insight that predictive mathematical models may provide into the course of an ongoing cholera epidemic aiding emergency management (say, in allocating life-saving supplies or health care staff) or in evaluating alternative management strategies. Our model consists of a set of dynamical equations (SIRB-like i.e. subdivided into the compartments of Susceptible, Infected and Recovered individuals, and including a balance of Bacterial concentrations in the water reservoir) describing a connected network of human communities where the infection results from the exposure to excess concentrations of pathogens in the water. These, in turn, are driven by rainfall washout of open-air defecation sites or cesspool overflows, hydrologic transport through waterways and by mobility of susceptible and infected individuals. We perform an a posteriori analysis (from the beginning of the epidemic in October 2010 until December 2011) to test the model reliability in predicting cholera cases and in testing control measures, involving vaccination and sanitation campaigns, for the ongoing epidemic. Even though predicting reliably the timing of the epidemic resurgence proves difficult due to rainfall inter-annual variability, we find that the model can reasonably quantify the total number of reported infection cases in the selected time-span. We then run a multi-seasonal prediction of the course of the epidemic until December 2015, to investigate conditions for further resurgences and endemicity of cholera in the region with a view to policies which may bring to

  13. Molecular characterization of the spike gene of the porcine epidemic diarrhea virus in Mexico, 2013-2016.

    Science.gov (United States)

    Lara-Romero, Rocío; Gómez-Núñez, Luis; Cerriteño-Sánchez, José Luis; Márquez-Valdelamar, Laura; Mendoza-Elvira, Susana; Ramírez-Mendoza, Humberto; Rivera-Benítez, José Francisco

    2018-04-01

    In Mexico, the first outbreaks suggestive of the circulation of the porcine epidemic diarrhea virus (PEDV) were identified at the beginning of July 2013. To identify the molecular characteristics of the PEDV Spike (S) gene in Mexico, 116 samples of the intestine and diarrhea of piglets with clinical signs of porcine epidemic diarrhea (PED) were obtained. Samples were collected from 14 farms located in six states of Mexico (Jalisco, Puebla, Sonora, Veracruz, Guanajuato, and Michoacán) from 2013 to 2016. To identify PEDV, we used real-time RT-PCR to discriminate between non-INDEL and INDEL strains. We chose samples according to state and year to characterize the S gene. After amplification of the S gene, the obtained products were sequenced and assembled. The complete amino acid sequences of the spike protein were used to perform an epitope analysis, which was used to determine null mutations in regions SS2, SS6, and 2C10 compared to the sequences of G2. A phylogenetic analysis determined the circulation of G2b and INDEL strains in Mexico. However, several mutations were recorded in the collagenase equivalent (COE) region that were related to the change in polarity and charge of the amino acid residues. The PEDV strain circulating in Jalisco in 2016 has an insertion of three amino acids ( 232 LGL 234 ) and one change in the antigenic site of the COE region, and strains from the years 2015 and 2016 changed the index of the surface probability, which could be related to the re-emergence of disease outbreaks.

  14. The severe acute respiratory syndrome epidemic in mainland China dissected

    Directory of Open Access Journals (Sweden)

    Wuchun Cao

    2011-02-01

    Full Text Available This paper provides a review of a recently published series of studies that give a detailed and comprehensive documentation of the severe acute respiratory syndrome (SARS epidemic in mainland China, which severely struck the country in the spring of 2003. The epidemic spanned a large geographical extent but clustered in two areas: first in Guangdong Province, and about 3 months later in Beijing with its surrounding areas. Reanalysis of all available epidemiological data resulted in a total of 5327 probable cases of SARS, of whom 343 died. The resulting case fatality ratio (CFR of 6.4% was less than half of that in other SARS-affected countries or areas, and this difference could only partly be explained by younger age of patients and higher number of community acquired infections. Analysis of the impact of interventions demonstrated that strong political commitment and a centrally coordinated response was the most important factor to control SARS in mainland China, whereas the most stringent control measures were all initiated when the epidemic was already dying down. The long-term economic consequence of the epidemic was limited, much consumption was merely postponed, but for Beijing irrecoverable losses to the tourist sector were considerable. An important finding from a cohort study was that many former SARS patients currently suffer from avascular osteo­necrosis, as a consequence of the treatment with corticosteroids during their infection. The SARS epidemic provided valuable information and lessons relevant in controlling outbreaks of newly emerging infectious diseases, and has led to fundamental reforms of the Chinese health system. In particular, a comprehensive nation-wide internet-based disease reporting system was established.

  15. The Cappadocia mesothelioma epidemic: its influence in Turkey and abroad.

    Science.gov (United States)

    Emri, Salih A

    2017-06-01

    The epidemic of mesothelioma in Cappadocia, Turkey, is unprecedented in medical history. In three Cappadocian villages, Karain, Tuzkoy and "old" Sarihidir, about 50% of all deaths (including neonatal deaths and traffic fatalities) have been caused by mesothelioma. No other epidemic in medical history has caused such a high incidence of death. This is even more unusual when considering that (I) epidemics are caused by infectious agents, not cancer, and (II) mesothelioma is a rare cancer. World-wide mesothelioma incidence varies between 1/10 6 in areas with no asbestos industry to about 10-30/10 6 in areas with asbestos industry. This article reviews how the mesothelioma epidemic was discovered in Cappadocia by Dr. Baris (my mentor), how we initially linked the epidemic to erionite exposure, and later (with Dr. Carbone) to the interaction between genetic predisposition and environmental exposure. Our team's work had an important positive impact on the lives of those living in Cappadocia and also in many genetically predisposed families living around the world. I will discuss how the work that started in three remote Cappadocian villages led to the award of a NCI P01 grant to support our studies. Our studies proved that genetics modulates mineral fiber carcinogenesis and led to the discovery that carriers of germline BAP1 mutations have a very high risk of developing mesothelioma and other malignancies. A new, very active field of research developed following our discoveries to elucidate the mechanism by which BAP1 modulates mineral fiber carcinogenesis as well as to identify additional genes that when mutated increase the risk of mesothelioma and other environmentally related cancers. I am the only surviving member of this research team who saw all the phases of this research and I believe it is important to provide an accurate report, which hopefully will inspire others.

  16. Outbreak of epidemic keratoconjunctivitis caused by adenovirus in medical residents.

    Science.gov (United States)

    Melendez, Carlos Pantoja; Florentino, Margarita Matias; Martinez, Irma Lopez; Lopez, Herlinda Mejia

    2009-01-01

    The present work documents an outbreak of epidemic keratoconjunctivitis among ophthalmology residents, its influence in the presentation of the community cases, the use of molecular techniques for its diagnosis, and the implementation of successful control measures for its containment. Isolation of the etiologic agent was achieved using cultured African green monkey kidney epithelial cells (VERO). Through molecular tests, such as polymerase chain reaction (PCR) and DNA sequencing, the genotype of the isolated virus was identified. The sequences obtained were aligned with data reported in the NCBI GenBank. A scheme of outbreak control measures was designed to enforce correct sanitary measures in the clinic. The statistical program, Epi info 2002, and openepi were used to determine the attack rate. The Excel Microsoft program was used to elaborate the endemic channel. Nine of the ten samples studied were isolated from the culture and identified by Adenovirus-specifc PCR. Sequencing allowed identification of Ad8 as the agent responsible for the outbreak. The attack rate was 24.39 cases per 100. The epidemic curve allowed identification of a disseminated source in the Institute of Ophthalmology "Conde de Valenciana." It was not possible to calculate the incubation periods among the cases. The endemic channel showed the presence of an epidemic keratoconjunctivitis among the patients that had been cared for at the out-patient services of the institute. One outbreak of a disseminated source caused by Ad8 was detected in the institute among its medical residents, probably associated with relaxation of the habitual sanitary measures during an epidemic of hemorrhagic conjunctivitis among the patients cared for at the institute. The proposed scheme to control the outbreak allowed for its containment and controlled the epidemic of associated cases.

  17. A recent increase in AIDS at Lyon University Hospitals: patient characteristics and comparisons with previous years.

    Science.gov (United States)

    Baratin, D; Marceillac, E; Trepo, C; Cotte, L; Peyramond, D; Chidiac, C; Touraine, J L; Livrozet, J M; Fabry, J; Vanhems, P

    2006-01-01

    A 36% increase in the incidence of AIDS was observed in 2002/2003 compared with 2000/2001 at Lyon University Hospitals. We compared the characteristics of these patients with the characteristics of those diagnosed previously with AIDS. Data for all patients with AIDS diagnosed at Lyon University Hospitals were analyzed. The data were collected prospectively. Multiple logistic regression was used for analysis. The variables independently associated with an AIDS diagnosis in 2002/2003 compared with the 1985-1989 period were: homosexual exposure [odds ratio (OR) 0.4; 95% confidence interval (CI) 0.2-0.8]; heterosexual exposure in an endemic area (OR 22.5; 95% CI 6.8-74.8), compared with other exposure to HIV; lymphoma as initial AIDS event (OR 10.3; 95% CI 2.7-39.1) compared with Pneumocystis carinii pneumonia; and age at first AIDS event aged 34-38 years (OR 2.5; 95% CI 1.0-6.4), aged 39-46 years (OR 5.1; 95% CI 2.2-11.8), and aged 47-84 years (OR 10.6; 95% CI 4.5-25.1) compared with aged <30 years. The variables independently associated with an AIDS diagnosis in 2002/2003 compared with the 1997/2001 period were age at first AIDS event aged 34-38 years (OR 0.4; 95% CI 0.2-0.9) compared with aged <30 years. Recently diagnosed AIDS patients differed from those diagnosed previously, showing an epidemic switch in different populations. The characteristics of the AIDS population in 2002/2003 might reflect public health messages disseminated around 10 years ago or more for the prevention of HIV transmission. Anticipation of populations affected by the AIDS epidemic is difficult.

  18. Host predilection and transmissibility of vesicular stomatitis New Jersey virus strains in domestic cattle (Bos taurus and swine (Sus scrofa

    Directory of Open Access Journals (Sweden)

    Smith Paul F

    2012-10-01

    Full Text Available Abstract Background Epidemiologic data collected during epidemics in the western United States combined with limited experimental studies involving swine and cattle suggest that host predilection of epidemic vesicular stomatitis New Jersey virus (VSNJV strains results in variations in clinical response, extent and duration of virus shedding and transmissibility following infection in different hosts. Laboratory challenge of livestock with heterologous VSNJV strains to investigate potential viral predilections for these hosts has not been thoroughly investigated. In separate trials, homologous VSNJV strains (NJ82COB and NJ82AZB, and heterologous strains (NJ06WYE and NJOSF [Ossabaw Island, sand fly] were inoculated into cattle via infected black fly bite. NJ82AZB and NJ06WYE were similarly inoculated into swine. Results Clinical scores among viruses infecting cattle were significantly different and indicated that infection with a homologous virus resulted in more severe clinical presentation and greater extent and duration of viral shedding. No differences in clinical severity or extent and duration of viral shedding were detected in swine. Conclusions Differences in clinical presentation and extent and duration of viral shedding may have direct impacts on viral spread during epidemics. Viral transmission via animal-to-animal contact and insect vectored transmission are likely to occur at higher rates when affected animals are presenting severe clinical signs and shedding high concentrations of virus. More virulent viral strains resulting in more severe disease in livestock hosts are expected to spread more rapidly and greater distances during epidemics than those causing mild or inapparent signs.

  19. Host predilection and transmissibility of vesicular stomatitis New Jersey virus strains in domestic cattle (Bos taurus) and swine (Sus scrofa).

    Science.gov (United States)

    Smith, Paul F; Howerth, Elizabeth W; Carter, Deborah; Gray, Elmer W; Noblet, Raymond; Berghaus, Roy D; Stallknecht, David E; Mead, Daniel G

    2012-10-03

    Epidemiologic data collected during epidemics in the western United States combined with limited experimental studies involving swine and cattle suggest that host predilection of epidemic vesicular stomatitis New Jersey virus (VSNJV) strains results in variations in clinical response, extent and duration of virus shedding and transmissibility following infection in different hosts. Laboratory challenge of livestock with heterologous VSNJV strains to investigate potential viral predilections for these hosts has not been thoroughly investigated. In separate trials, homologous VSNJV strains (NJ82COB and NJ82AZB), and heterologous strains (NJ06WYE and NJOSF [Ossabaw Island, sand fly]) were inoculated into cattle via infected black fly bite. NJ82AZB and NJ06WYE were similarly inoculated into swine. Clinical scores among viruses infecting cattle were significantly different and indicated that infection with a homologous virus resulted in more severe clinical presentation and greater extent and duration of viral shedding. No differences in clinical severity or extent and duration of viral shedding were detected in swine. Differences in clinical presentation and extent and duration of viral shedding may have direct impacts on viral spread during epidemics. Viral transmission via animal-to-animal contact and insect vectored transmission are likely to occur at higher rates when affected animals are presenting severe clinical signs and shedding high concentrations of virus. More virulent viral strains resulting in more severe disease in livestock hosts are expected to spread more rapidly and greater distances during epidemics than those causing mild or inapparent signs.

  20. Epidemic gasoline exposures following Hurricane Sandy.

    Science.gov (United States)

    Kim, Hong K; Takematsu, Mai; Biary, Rana; Williams, Nicholas; Hoffman, Robert S; Smith, Silas W

    2013-12-01

    Major adverse climatic events (MACEs) in heavily-populated areas can inflict severe damage to infrastructure, disrupting essential municipal and commercial services. Compromised health care delivery systems and limited utilities such as electricity, heating, potable water, sanitation, and housing, place populations in disaster areas at risk of toxic exposures. Hurricane Sandy made landfall on October 29, 2012 and caused severe infrastructure damage in heavily-populated areas. The prolonged electrical outage and damage to oil refineries caused a gasoline shortage and rationing unseen in the USA since the 1970s. This study explored gasoline exposures and clinical outcomes in the aftermath of Hurricane Sandy. Prospectively collected, regional poison control center (PCC) data regarding gasoline exposure cases from October 29, 2012 (hurricane landfall) through November 28, 2012 were reviewed and compared to the previous four years. The trends of gasoline exposures, exposure type, severity of clinical outcome, and hospital referral rates were assessed. Two-hundred and eighty-three gasoline exposures were identified, representing an 18 to 283-fold increase over the previous four years. The leading exposure route was siphoning (53.4%). Men comprised 83.0% of exposures; 91.9% were older than 20 years of age. Of 273 home-based calls, 88.7% were managed on site. Asymptomatic exposures occurred in 61.5% of the cases. However, minor and moderate toxic effects occurred in 12.4% and 3.5% of cases, respectively. Gastrointestinal (24.4%) and pulmonary (8.4%) symptoms predominated. No major outcomes or deaths were reported. Hurricane Sandy significantly increased gasoline exposures. While the majority of exposures were managed at home with minimum clinical toxicity, some patients experienced more severe symptoms. Disaster plans should incorporate public health messaging and regional PCCs for public health promotion and toxicological surveillance.