Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention.

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Okumu, Fredros O; Chipwaza, Beatrice; Madumla, Edith P; Mbeyela, Edgar; Lingamba, Geoffrey; Moore, Jason; Ntamatungro, Alex J; Kavishe, Deo R; Moore, Sarah J

2012-11-19

Bio-efficacy and residual activity of insecticides used for indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs) were assessed against laboratory-reared and wild populations of the malaria vector, Anopheles arabiensis in south eastern Tanzania. Implications of the findings are examined in the context of potential synergies and redundancies where IRS and LLINs are combined. Bioassays were conducted monthly for six months on three LLIN types (Olyset® PermaNet 2.0®,and Icon Life®) and three IRS treatments (2 g/m2 pirimiphos-methyl, 2 g/m2 DDT and 0.03 g/m2 lambda-cyhalothrin, sprayed on mud walls and palm ceilings of experimental huts). Tests used susceptible laboratory-reared An. arabiensis exposed in cones (nets and IRS) or wire balls (nets only). Susceptibility of wild populations was assessed using WHO diagnostic concentrations and PCR for knock-down resistance (kdr) genes. IRS treatments killed ≥ 85% of mosquitoes exposed on palm ceilings and ≥ 90% of those exposed on mud walls, but up to 50% of this toxicity decayed within 1-3 months, except for DDT. By 6th month, only 7.5%, 42.5% and 30.0% of mosquitoes died when exposed to ceilings sprayed with pirimiphos-methyl, DDT or lambda-cyhalothrin respectively, while 12.5%, 36.0% and 27.5% died after exposure to mud walls sprayed with the same insecticides. In wire-ball assays, mortality decreased from 98.1% in 1st month to 92.6% in 6th month in tests on PermaNet 2.0®, from 100% to 61.1% on Icon Life® and from 93.2% to 33.3% on Olyset® nets. In cone bioassays, mortality reduced from 92.8% in 1st month to 83.3% in 6th month on PermaNet 2.0®, from 96.9% to 43.80% on Icon Life® and from 85.6% to 14.6% on Olyset®. Wild An. arabiensis were 100% susceptible to DDT, 95.8% to deltamethrin, 90.2% to lambda cyhalothrin and 95.2% susceptible to permethrin. No kdr gene mutations were detected. In bioassays where sufficient contact with treated surfaces is assured, LLINs and IRS kill high

Efficacy of Olyset® Plus, a new long-lasting insecticidal net incorporating permethrin and piperonyl-butoxide against multi-resistant malaria vectors [corrected].

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Cédric Pennetier

Full Text Available Due to the rapid extension of pyrethroid resistance in malaria vectors worldwide, manufacturers are developing new vector control tools including insecticide mixtures containing at least two active ingredients with different mode of action as part of insecticide resistance management. Olyset® Plus is a new long-lasting insecticidal net (LLIN incorporating permethrin and a synergist, piperonyl butoxide (PBO, into its fibres in order to counteract metabolic-based pyrethroid resistance of mosquitoes. In this study, we evaluated the efficacy of Olyset® Plus both in laboratory and field against susceptible and multi-resistant malaria vectors and compared with Olyset Net, which is a permethrin incorporated into polyethylene net. In laboratory, Olyset® Plus performed better than Olyset® Net against susceptible Anopheles gambiae strain with a 2-day regeneration time owing to an improved permethrin bleeding rate with the new incorporation technology. It also performed better than Olyset® Net against multiple resistant populations of An. gambiae in experimental hut trials in West Africa. Moreover, the present study showed evidence for a benefit of incorporating a synergist, PBO, with a pyrethroid insecticide into mosquito netting. These results need to be further validated in a large-scale field trial to assess the durability and acceptability of this new tool for malaria vector control.

Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention

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Okumu Fredros O

2012-11-01

Full Text Available Abstract Background Bio-efficacy and residual activity of insecticides used for indoor residual spraying (IRS and long-lasting insecticide nets (LLINs were assessed against laboratory-reared and wild populations of the malaria vector, Anopheles arabiensis in south eastern Tanzania. Implications of the findings are examined in the context of potential synergies and redundancies where IRS and LLINs are combined. Methods Bioassays were conducted monthly for six months on three LLIN types (Olyset® PermaNet 2.0®,and Icon Life® and three IRS treatments (2 g/m2 pirimiphos-methyl, 2 g/m2 DDT and 0.03 g/m2 lambda-cyhalothrin, sprayed on mud walls and palm ceilings of experimental huts. Tests used susceptible laboratory-reared An. arabiensis exposed in cones (nets and IRS or wire balls (nets only. Susceptibility of wild populations was assessed using WHO diagnostic concentrations and PCR for knock-down resistance (kdr genes. Results IRS treatments killed ≥ 85% of mosquitoes exposed on palm ceilings and ≥ 90% of those exposed on mud walls, but up to 50% of this toxicity decayed within 1–3 months, except for DDT. By 6th month, only 7.5%, 42.5% and 30.0% of mosquitoes died when exposed to ceilings sprayed with pirimiphos-methyl, DDT or lambda-cyhalothrin respectively, while 12.5%, 36.0% and 27.5% died after exposure to mud walls sprayed with the same insecticides. In wire-ball assays, mortality decreased from 98.1% in 1st month to 92.6% in 6th month in tests on PermaNet 2.0®, from 100% to 61.1% on Icon Life® and from 93.2% to 33.3% on Olyset® nets. In cone bioassays, mortality reduced from 92.8% in 1st month to 83.3% in 6th month on PermaNet 2.0®, from 96.9% to 43.80% on Icon Life® and from 85.6% to 14.6% on Olyset®. Wild An. arabiensis were 100% susceptible to DDT, 95.8% to deltamethrin, 90.2% to lambda cyhalothrin and 95.2% susceptible to permethrin. No kdr gene mutations were detected. Conclusions In bioassays where sufficient contact with

Scepticism towards insecticide treated mosquito nets for malaria control in a rural community in northwestern Tanzania

DEFF Research Database (Denmark)

Nnko, Soori; Whyte, Susan Reynolds; Geissler, Wenzel

2012-01-01

in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional...... attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria...

Willingness to pay for insecticide-treated nets in Berehet District, Amhara Region, Northern Ethiopia: implication of social marketing.

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Aleme, Adisu; Girma, Eshetu; Fentahun, Netsanet

2014-01-01

Understanding the feasibility of achieving widespread coverage with Insecticide-Treated Nets has to be preceded by learning how people value the Insecticide-Treated Nets and estimating the potential demand and willingness to pay so that sustainability of the intervention can be assured. The objective of this study was to determine willingness to pay for Insecticide-Treated Nets among households in Berehet District, Northern Ethiopia. A community-based cross-sectional study was conducted using both quantitative and qualitative methods in five randomly selected Kebeles from January-February 2012. Open ended contingent valuation technique with follow-up method was used. Qualitative data were collected through focus group discussions and observation methods. Binary logistic regression was used to determine the association between dependent and independent variables. The average number of individuals per Insecticide-Treated Nets was 3.83. Nearly 68.5% persons had willingness to buy Insecticide-Treated Nets if they have access to these Nets. The median maximum price a person is willingness to pay for blue rectangular Insecticide-Treated Net was 20 ETB. People had willingness to pay 30 ETB for blue and white conical insecticide-treated nets. Working on knowledge of malaria (OR=0.68, CI (0.47, 0.98; ppay Insecticide-Treated Nets. Respondents who prefer Kebele/place/ to buy Insecticide-Treated Net for rectangular shape had a significant association with a willingness to pay for Insecticide-Treated Nets (OR=1.92, CI= 1.07-3.92). Promotions, products, price and place had significant association with willingness to pay for Insecticide-Treated Nets. Designing a social marketing strategy helps ensure sustainable supply of Insecticide-Treated Nets and proper use of Insecticide-Treated Nets.

Ownership and Use of Insecticide-Treated Nets among People Living in Malaria Endemic Areas of Eastern Myanmar.

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Aung, Tin; Wei, Chongyi; McFarland, Willi; Aung, Ye Kyaw; Khin, Hnin Su Su

2016-01-01

Myanmar has the highest burden of malaria in the Greater Mekong. However, there is limited information on ownership and use of insecticide-treated nets (ITNs) in areas of Myanmar most severely affected by malaria. We describe ownership and use of ITNs among people in the malaria-endemic eastern parts of Myanmar and factors associated with ITN use. A cross-sectional household survey using a multi-stage cluster design was conducted in malaria-endemic townships in eastern Myanmar during the high malaria season of August to September, 2014. An effective ITN was defined as 1) a long-lasting insecticide-treated net obtained within the past three years, or 2) any net treated with insecticide within the past year. In 4,679 households, the average number of ITNs per household was higher in rural compared to urban areas (0.6 vs. 0.4, p Myanmar in comparison to the goal of one for every two household members. Use of ITNs was low even when present. Findings are of concern given the study areas were part of enhanced efforts to reduce artemisinin-resistant malaria. Nonetheless, groups vulnerable to malaria such as individuals in rural settings, lower socio-economic households, and workers in high mosquito exposure jobs, had higher rates of ITN ownership. Malaria knowledge was linked to effective ITN use suggesting that distribution campaigns should be complemented by behavior change communications.

Comparing insecticide-treated bed net use to Plasmodium falciparum infection among schoolchildren living near Lake Victoria, Kenya.

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Okoyo, Collins; Mwandawiro, Charles; Kihara, Jimmy; Simiyu, Elses; Gitonga, Caroline W; Noor, Abdisalan M; Njenga, Sammy M; Snow, Robert W

2015-12-22

Under trial conditions insecticide-treated nets have been shown to provide significant clinical and mortality protection under a range of malaria transmission intensity conditions. There are, however, few operational impact data, notably in very intense transmission conditions. This study, reports on malaria infection among Kenyan schoolchildren living in areas of intense malaria transmission and their reported use of insecticide-treated bed nets. 5188 children in 54 schools were randomly sampled from seven counties surrounding Lake Victoria between May and June 2014. A questionnaire was administered to schoolchildren in classes 2-6 on the use of a long-lasting, insecticide-treated net (LLIN) the night before the survey and provided a single blood sample for a rapid diagnostic test for malaria infection. Analysis of the impact of insecticide-treated net use on malaria prevalence was undertaken using a multivariable, mixed effects, logistic regression at 95% confidence interval (CI), taking into account hierarchical nature of the data and results adjusted for school clusters. The overall prevalence of malaria infection was 48.7%, two-thirds (67.9%) of the children reported using LLIN, 91.3% of the children reported that their households own at least one LLIN and the household LLIN coverage was 2.5 persons per one LLIN. The prevalence of infection showed variation across the counties, with prevalence being highest in Busia (66.9%) and Homabay (51.8%) counties, and lowest in Migori County (29.6%). Generally, malaria parasite prevalence differed between age groups and gender with the highest prevalence occurring in children below 7 years (50.6%) and males (52.2%). Adjusting for county and school, there was a significant reduction in odds of malaria infection among the schoolchildren who reported LLIN use the previous night by 14 % (aOR 0.86, 95% CI 0.74-0.98, P provide protection against infection among school-aged children.

Scepticism towards insecticide treated mosquito nets for malaria ...

African Journals Online (AJOL)

Scepticism towards insecticide treated mosquito nets for malaria control in rural ... especially among under-five year children and pregnant women in poor rural ... through social marketing strategy for malaria control prior to the introduction of ...

The effect of insecticide-treated bed net on malarial parasitaemia ...

African Journals Online (AJOL)

AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... nets sold by a social marketing project were used as the intervention group. ... Keywords: Insecticide-treated bed net, Effectiveness, Malaria control, South-South Nigeria.

Long-lasting insecticidal nets are synergistic with mass drug administration for interruption of lymphatic filariasis transmission in Nigeria.

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Abel Eigege

Full Text Available In central Nigeria Anopheles mosquitoes transmit malaria and lymphatic filariasis (LF. The strategy used for interrupting LF transmission in this area is annual mass drug administration (MDA with albendazole and ivermectin, but after 8 years of MDA, entomological evaluations in sentinel villages showed continued low-grade mosquito infection rates of 0.32%. After long-lasting insecticidal net (LLIN distribution by the national malaria program in late 2010, however, we were no longer able to detect infected vectors over a 24-month period. This is evidence that LLINs are synergistic with MDA in interrupting LF transmission.

Determinants of use of insecticide-treated nets among pregnant women in Nigeria

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Ezire O

2015-06-01

Full Text Available Onoriode Ezire,1 Samson B Adebayo,2 Omokhudu Idogho,3 Elijah A Bamgboye,4 Ernest Nwokolo5 1Research and Evaluation Division, Society for Family Health, Abuja, 2National Agency for Food and Drug Administration and Control, Abuja, 3Enhancing Nigeria’s Response to HIV & AIDS, Abuja, 4Medical Statistics, University of Ibadan, Ibadan, 5Society for Family Health, Abuja, Nigeria Background: Malaria in pregnancy is still a major health issue in Nigeria, accounting for about 33% of cause of maternal death. Despite massive efforts to make insecticide-treated net (ITN available to pregnant women in Nigeria, the use is still low. This study was conducted to identify facilitators and inhibitors for the use of ITN/long-lasting insecticidal net (LLIN among pregnant women in Nigeria.Methods: Data were obtained from the 2011 State-Specific HIV & AIDS, Reproductive and Child Health Survey conducted in 18 states of Nigeria. The survey was a population-based study among men and women of reproductive age living in households in rural and urban areas of Nigeria. Multistage cluster sampling technique was used to select eligible respondents. The sample size per state was 960 respondents. Data were collected between October and November 2011. The analysis was done using Statistical Package for Social Sciences (SPSS version 20.Results: A total of 11.5% of the respondents were pregnant at the time of the survey of which 73.2% lived in rural location and approximately 70% were either not educated or attained at most a primary school education. A total of 93.2% of respondents have heard of net, 82.6% were confident that they can hang or use a net, and 64.6% owned an ITN/LLIN in their household while the actual use was just 19.2%. We found education, location (urban–rural, confidence to use a net, and knowledge that the use of a net can protect a pregnant woman from malaria to be significant at 5% level. The number of nets owned per household, the length of time the net

Social marketing of insecticide-treated bed net for malaria control ...

African Journals Online (AJOL)

Background: The effectiveness of the insecticide-treated bed net in reducing the morbidity and mortality associated with malaria has been proved at all levels of malaria transmission. Several models on how to achieve massive coverage have been suggested, but social marketing of the nets is highly favoured for its ...

Traditional nets interfere with the uptake of long-lasting insecticidal nets in the Peruvian Amazon: the relevance of net preference for achieving high coverage and use.

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Koen Peeters Grietens

Full Text Available While coverage of long-lasting insecticide-treated nets (LLIN has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru.The study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses.A total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2% than in those with walls (73.8% (OR = 5.2, 95CI [2.2; 12.3], p<0.001.Net preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent, appropriate quantitative and qualitative

Modelling the impact of the long-term use of insecticide-treated bed nets on Anopheles mosquito biting time.

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Ferreira, Claudia P; Lyra, Silas P; Azevedo, Franciane; Greenhalgh, David; Massad, Eduardo

2017-09-15

Evidence of changing in biting and resting behaviour of the main malaria vectors has been mounting up in recent years as a result of selective pressure by the widespread and long-term use of insecticide-treated bed nets (ITNs), and indoor residual spraying. The impact of resistance behaviour on malaria intervention efficacy has important implications for the epidemiology and malaria control programmes. In this context, a theoretical framework is presented to understand the mechanisms determining the evolution of feeding behaviour under the pressure of use of ITNs. An agent-based stochastic model simulates the impact of insecticide-treated bed nets on mosquito fitness by reducing the biting rates, as well as increasing mortality rates. The model also incorporates a heritability function that provides the necessary genetic plasticity upon which natural selection would act to maximize the fitness under the pressure of the control strategy. The asymptotic equilibrium distribution of mosquito population versus biting time is shown for several daily uses of ITNs, and the expected disruptive selection on this mosquito trait is observed in the simulations. The relative fitness of strains that bite at much earlier time with respect to the wild strains, when a threshold of about 50% of ITNs coverage highlights the hypothesis of a behaviour selection. A sensitivity analysis has shown that the top three parameters that play a dominant role on the mosquito fitness are the proportion of individuals using bed nets and its effectiveness, the impact of bed nets on mosquito oviposition, and the mosquito genetic plasticity related to changing in biting time. By taking the evolutionary aspect into account, the model was able to show that the long-term use of ITNs, although representing an undisputed success in reducing malaria incidence and mortality in many affected areas, is not free of undesirable side effects. From the evolutionary point of view of the parasite virulence, it

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra state, Nigeria

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Mbachu Chinyere O

2012-05-01

Full Text Available Abstract Background In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs to the general population and delivered free Artemisinin-based Combination Therapy (ACT to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. Methods A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. Results It was found that 80.5 % of the households had an LLIN and 64.4 % of the households stated that they actually used the nets the previous night. The findings showed that 42.3 % of pregnant women who had fever within the past month received ACTs, while 37.5 % of children ≪5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1–5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. Conclusions The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups.

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra State, Nigeria.

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Mbachu, Chinyere O; Onwujekwe, Obinna E; Uzochukwu, Benjamin S C; Uchegbu, Eloka; Oranuba, Joseph; Ilika, Amobi L

2012-05-22

In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs) to the general population and delivered free Artemisinin-based Combination Therapy (ACT) to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES) population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS) methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. It was found that 80.5% of the households had an LLIN and 64.4% of the households stated that they actually used the nets the previous night. The findings showed that 42.3% of pregnant women who had fever within the past month received ACTs, while 37.5% of children<5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1-5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups.

Predicting the impact of insecticide-treated bed nets on malaria transmission: the devil is in the detail

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Novak Robert J

2009-11-01

Full Text Available Abstract Background Insecticide-treated bed nets (ITNs, including long-lasting insecticidal nets (LLINs, play a primary role in global campaigns to roll back malaria in tropical Africa. Effectiveness of treated nets depends on direct impacts on individual mosquitoes including killing and excite-repellency, which vary considerably among vector species due to variations in host-seeking behaviours. While monitoring and evaluation programmes of ITNs have focuses on morbidity and all-cause mortality in humans, local entomological context receives little attention. Without knowing the dynamics of local vector species and their responses to treated nets, it is difficult to predict clinical outcomes when ITN applications are scaled up across African continent. Sound model frameworks incorporating intricate interactions between mosquitoes and treated nets are needed to develop the predictive capacity for scale-up applications of ITNs. Methods An established agent-based model was extended to incorporate the direct outcomes, e.g. killing and avoidance, of individual mosquitoes exposing to ITNs in a hypothetical village setting with 50 houses and 90 aquatic habitats. Individual mosquitoes were tracked throughout the life cycle across the landscape. Four levels of coverage, i.e. 40, 60, 80 and 100%, were applied at the household level with treated houses having only one bed net. By using Latin hypercube sampling scheme, parameters governing killing, diverting and personal protection of net users were evaluated for their relative roles in containing mosquito populations, entomological inoculation rates (EIRs and malaria incidence. Results There were substantial gaps in coverage between households and individual persons, and 100% household coverage resulted in circa 50% coverage of the population. The results show that applications of ITNs could give rise to varying impacts on population-level metrics depending on values of parameters governing interactions of

Predicting the impact of insecticide-treated bed nets on malaria transmission: the devil is in the detail.

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Gu, Weidong; Novak, Robert J

2009-11-16

Insecticide-treated bed nets (ITNs), including long-lasting insecticidal nets (LLINs), play a primary role in global campaigns to roll back malaria in tropical Africa. Effectiveness of treated nets depends on direct impacts on individual mosquitoes including killing and excite-repellency, which vary considerably among vector species due to variations in host-seeking behaviours. While monitoring and evaluation programmes of ITNs have focuses on morbidity and all-cause mortality in humans, local entomological context receives little attention. Without knowing the dynamics of local vector species and their responses to treated nets, it is difficult to predict clinical outcomes when ITN applications are scaled up across African continent. Sound model frameworks incorporating intricate interactions between mosquitoes and treated nets are needed to develop the predictive capacity for scale-up applications of ITNs. An established agent-based model was extended to incorporate the direct outcomes, e.g. killing and avoidance, of individual mosquitoes exposing to ITNs in a hypothetical village setting with 50 houses and 90 aquatic habitats. Individual mosquitoes were tracked throughout the life cycle across the landscape. Four levels of coverage, i.e. 40, 60, 80 and 100%, were applied at the household level with treated houses having only one bed net. By using Latin hypercube sampling scheme, parameters governing killing, diverting and personal protection of net users were evaluated for their relative roles in containing mosquito populations, entomological inoculation rates (EIRs) and malaria incidence. There were substantial gaps in coverage between households and individual persons, and 100% household coverage resulted in circa 50% coverage of the population. The results show that applications of ITNs could give rise to varying impacts on population-level metrics depending on values of parameters governing interactions of mosquitoes and treated nets at the individual level

Determining and addressing obstacles to the effective use of long-lasting insecticide-impregnated nets in rural Tanzania

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Benziger Peter W

2009-12-01

Full Text Available Abstract Background The objective of this project was to achieve high, sustainable levels of net coverage in a village in rural Tanzania by combining free distribution of long-lasting insecticide-impregnated nets (LLINs with community-tailored education. In Tanzania, malaria is the leading cause of morbidity and mortality. Although malaria bed nets have a well-established role in reducing disease burden, few rural households have access to nets, and effective use depends on personal practices and attitudes. Methods Five practices and attitudes inconsistent with effective LLIN use were identified from household interviews (n = 10. A randomized survey of villagers (n = 132 verified local prevalence of these practices and attitudes. Community leaders held an educational session for two members of every household addressing these practice and attitudes, demonstrating proper LLIN use, and emphasizing behaviour modification. Attendees received one or two LLINs per household. Surveys distributed three weeks (n = 104 and 15 months (n = 104 post-intervention assessed corrected practices and attitudes. Project efficacy was defined by correction of baseline practices and attitudes as well as high rates of reported daily net use, with statistical significance determined by chi-square test. Results Baseline interviews and surveys revealed incorrect practices and attitudes regarding 1 use of nets in dry season, 2 need to retreat LLINs, 3 children napping under nets, 4 need to repair nets, and 5 net procurement as a priority, with 53- 88.6% incorrect responses (11.4-47% correct responses. A three-week follow-up demonstrated 83-95% correct responses. Fifteen-month follow-up showed statistically significant (p Conclusions Results suggest that addressing community-specific practices and attitudes prior to LLIN distribution promotes consistent and correct use, and helps change attitudes towards bed nets as a preventative health measure. Future LLIN distributions

Mass distribution of free insecticide-treated nets do not interfere with continuous net distribution in Tanzania.

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Eze, Ikenna C; Kramer, Karen; Msengwa, Amina; Mandike, Renata; Lengeler, Christian

2014-05-27

To protect the most vulnerable groups from malaria (pregnant women and infants) the Tanzanian Government introduced a subsidy (voucher) scheme in 2004, on the basis of a public-private partnership. These vouchers are provided to pregnant women at their first antenatal care visit and mothers of infants at first vaccination. The vouchers are redeemed at registered retailers for a long-lasting insecticidal net against the payment of a modest top-up price. The present work analysed a large body of data from the Tanzanian National Voucher Scheme, focusing on interactions with concurrent mass distribution campaigns of free nets. In an ecologic study involving all regions of Tanzania, voucher redemption data for the period 2007-2011, as well as data on potential determinants of voucher redemption were analysed. The four outcome variables were: pregnant woman and infant voucher redemption rates, use of treated bed nets by all household members and by under- five children. Each of the outcomes was regressed with selected determinants, using a generalized estimating equation model and accounting for regional data clustering. There was a consistent improvement in voucher redemption rates over the selected time period, with rates >80% in 2011. The major determinants of redemption rates were the top-up price paid by the voucher beneficiary, the retailer- clinic ratio, and socio-economic status. Improved redemption rates after 2009 were most likely due to reduced top-up prices (following a change in policy). Redemption rates were not affected by two major free net distribution campaigns. During this period, there was a consistent improvement in net use across all the regions, with rates of up to 75% in 2011. The key components of the National Treated Nets Programme (NATNETS) seem to work harmoniously, leading to a high level of net use in the entire population. This calls for the continuation of this effort in Tanzania and for emulation by other countries with endemic malaria.

"We are supposed to take care of it": a qualitative examination of care and repair behaviour of long-lasting, insecticide-treated nets in Nasarawa State, Nigeria.

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Hunter, Gabrielle C; Scandurra, Leah; Acosta, Angela; Koenker, Hannah; Obi, Emmanuel; Weber, Rachel

2014-08-14

The longevity of long-lasting insecticidal nets (LLIN) under field conditions has important implications for malaria vector control. The behaviour of bed net users, including net care and repair, may protect or damage bed nets and impact the physical integrity of nets. However, this behaviour, and the motivating and inhibiting factors, is not well understood. Qualitative research methods were used to examine behaviour, attitudes and norms around damage, care and repair of LLINs. Eighteen in-depth interviews (IDI) and six focus group discussions (FGD) were conducted with LLIN users in two local government areas of Nasarawa State, Nigeria. A brief background questionnaire with the 73 participants prior to IDIs or FGDs collected additional data on demographics, net use, and care and repair behaviour. Respondents cited that the major causes of damage to bed nets are primarily children, followed by rodents, everyday handling that is not gentle, and characteristics of sleeping spaces. Caring for nets was perceived as both preventing damage by careful handling and keeping the net clean, which may lead to over-washing of LLINs. Repairing a damaged net was considered something that net users should do and the responsibility of adults in the household. Despite this, reported frequency of net repair was low (18%). Motivations for taking care of and repairing nets centred around caring for one's family, avoiding mosquito bites, saving money, and maintaining the positive opinion of others by keeping a clean and intact net. Barriers to net care and repair related to time availability and low perceived value of bed nets or of one's health. This study provides novel and valuable insights on the perceptions and attitudes of LLIN users in Nasarawa, Nigeria on the durability of bed nets, how to care for and repair nets, and for what reasons. Communication around net care should stress proper daily storage of nets, regular net inspections, prompt repairs, and clarify misconceptions

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda

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Strachan Daniel

2010-04-01

Full Text Available Abstract Background In Uganda, long-lasting insecticidal nets (LLIN have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Methods Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY. These effects were calculated for the total number of LLINs delivered and for those retained and used. Results After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja and 99% (ANC Adjumani were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja. Economic cost for ANC distribution were considerably higher (USD 2.27 compared to campaign costs (USD 1.23 in Adjumani. Conclusions Targeted campaigns and routine ANC

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda.

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Kolaczinski, Jan H; Kolaczinski, Kate; Kyabayinze, Daniel; Strachan, Daniel; Temperley, Matilda; Wijayanandana, Nayantara; Kilian, Albert

2010-04-20

In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used. After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani. Targeted campaigns and routine ANC services can both achieve high LLIN retention and use among

Entomological determinants of insecticide-treated bed net effectiveness in Western Myanmar

NARCIS (Netherlands)

Smithuis, Frank M.; Kyaw, Moe Kyaw; Phe, U. Ohn; van der Broek, Ingrid; Katterman, Nina; Rogers, Colin; Almeida, Patrick; Kager, Piet A.; Stepniewska, Kasia; Lubell, Yoel; Simpson, Julie A.; White, Nicholas J.

2013-01-01

In a large cluster randomized control trial of insecticide-treated bed nets (ITN) in Western Myanmar the malaria protective effect of ITN was found to be highly variable and, in aggregate, the effect was not statistically significant. A coincident entomological investigation measured malaria vector

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets.

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Seo, Mikyung Kelly; Baker, Peter; Ngo, Karen Ngoc-Lan

2014-02-24

New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered 'very cost-effective'. From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine's ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs' duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. The results showed that vaccinating Malawian children with RTS,S vaccines was very cost-effective from both a societal and a

Evaluation of the effects of repeated hand washing, sunlight, smoke and dirt on the persistence of deltamethrin on insecticide-treated nets.

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Kayedi, M H; Lines, J D; Haghdoost, A A; Vatandoost, M H; Rassi, Y; Khamisabady, K

2008-08-01

Field studies were carried out in Iran to evaluate the effect of various factors (washing, sun, smoke, dust and dirt) on the residual insecticidal activity of PermaNet (a brand of long-lasting insecticidal net), and on nets conventionally treated with deltamethrin (K-O Tab), using bioassay tests. Thirty-two nets were washed five or 15 times, and eight nets were not washed at all. Nets were washed vigorously in cold tap water (17 degrees C, pH 8.9) with a detergent. Hand rubbing continued for 3min. After washing, some nets were exposed to dense smoke from a dung-hay fire for 3min and were also left exposed to the dusty wind between washes. One group of nets was exposed to the sunlight for the full 3-d interval between washes; another was exposed to sunlight for just 3h after each wash; two other groups were kept in the shade. There was a significantly greater loss of activity in nets exposed to the sun throughout the 3-d interval between washes: that is, for a total of 15 to 45 d. However, short sunlight exposure (maximum 3h between washes) during drying did not have any effect. We did not find any significant effect of exposure to dirt, dust and smoke after washing. It is concluded that the effect of sun is much smaller than that of washing, and that drying nets for a few hours in the sun is not harmful.

Long-lasting insecticidal net source, ownership and use in the context of universal coverage: a household survey in eastern Rwanda.

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Kateera, Fredrick; Ingabire, Chantal M; Hakizimana, Emmanuel; Rulisa, Alexis; Karinda, Parfait; Grobusch, Martin P; Mutesa, Leon; van Vugt, Michèle; Mens, Petra F

2015-10-06

Universal long-lasting insecticidal net (LLIN) coverage (ULC) has reduced malaria morbidity and mortality across Africa. Although information is available on bed net use in specific groups, such as pregnant women and children under 5 years, there is paucity of data on their use among the general population. Bed net source, ownership and determinants of use among individuals from households in an eastern Rwanda community 8 months after a ULC were characterized. Using household-based, interviewer-administered questionnaires and interviewer-direct observations, data on bed net source, ownership and key determinants of net use, including demographics, socio-economic status indicators, house structure characteristics, as well as of bed net quantity, type and integrity, were collected from 1400 randomly selected households. Univariate and mixed effects logistic regression modelling was done to assess for determinants of bed net use. A total of 1410 households and 6598 individuals were included in the study. Overall, the proportion of households with at least one net was 92 % while bed net usage was reported among 72 % of household members. Of the households surveyed, a total ownership of 2768 nets was reported, of which about 96 % were reportedly LLINs received from the ULC. By interviewer-physical observation, 88 % of the nets owned were of the LLIN type with the remaining 12 % did not carry any mark to enable type recognition. The odds of bed net use were significantly lower among males and individuals: from households of low socio-economic status, from households with economic status, number of bed nets and type and number of sleeping spaces were key determinants of bed net use. To maximize impact of ULC, strategies that target males as well as those that ensure ITN coverage for all, address barriers to feasible and convenient bed net use including covering over all sleeping space types, and provide net hanging supports, are needed.

Rapid Increase in Ownership and Use of Long-Lasting Insecticidal Nets and Decrease in Prevalence of Malaria in Three Regional States of Ethiopia (2006-2007

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Estifanos Biru Shargie

2010-01-01

Full Text Available Following recent large scale-up of malaria control interventions in Ethiopia, this study aimed to compare ownership and use of long-lasting insecticidal nets (LLIN, and the change in malaria prevalence using two population-based household surveys in three regions of the country. Each survey used multistage cluster random sampling with 25 households per cluster. Household net ownership tripled from 19.6% in 2006 to 68.4% in 2007, with mean LLIN per household increasing from 0.3 to 1.2. Net use overall more than doubled from 15.3% to 34.5%, but in households owning LLIN, use declined from 71.7% to 48.3%. Parasitemia declined from 4.1% to 0.4%. Large scale-up of net ownership over a short period of time was possible. However, a large increase in net ownership was not necessarily mirrored directly by increased net use. Better targeting of nets to malaria-risk areas and sustained behavioural change communication are needed to increase and maintain net use.

Benefit of insecticide-treated nets, curtains and screening on vector borne diseases, excluding malaria: a systematic review and meta-analysis

NARCIS (Netherlands)

Wilson, A.L.; Dhiman, R.C.; Kitron, U.; Scott, T.W.; Berg, van den H.; Lindsay, S.W.

2014-01-01

Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated

Use of insecticide-treated mosquito nets for children under five years ...

African Journals Online (AJOL)

2011-06-13

Jun 13, 2011 ... Background: Insecticide-treated nets (ITNs) have proven to be one of the most effective means of reducing malaria morbidity and mortality in children and pregnant women. This study is carried out to determine the practice and determinants of ITN use for children under five years among care givers in an ...

KINET: a social marketing programme of treated nets and net treatment for malaria control in Tanzania, with evaluation of child health and long-term survival.

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Schellenberg, J R; Abdulla, S; Minja, H; Nathan, R; Mukasa, O; Marchant, T; Mponda, H; Kikumbih, N; Lyimo, E; Manchester, T; Tanner, M; Lengeler, C

1999-01-01

We present a large-scale social marketing programme of insecticide-treated nets in 2 rural districts in southwestern Tanzania (population 350,000) and describe how the long-term child health and survival impact will be assessed. Formative and market research were conducted in order to understand community perceptions, knowledge, attitudes and practice with respect to the products to be socially marketed. We identified Zuia Mbu (Kiswahili for 'prevent mosquitoes') as a suitable brand name for both treated nets and single-dose insecticide treatment sachets. A mix of public and private sales outlets is used for distribution. In the first stage of a stepped introduction 31 net agents were appointed and trained in 18 villages: 15 were shop owners, 14 were village leaders, 1 was a parish priest and 1 a health worker. For net treatment 37 young people were appointed in the same villages and trained as agents. Further institutions in both districts such as hospitals, development projects and employers were also involved in distribution. Promotion for both products was intense and used a variety of channels. A total of 22,410 nets and 8072 treatments were sold during the first year: 18 months after launching, 46% of 312 families with children aged under 5 years reported that their children were sleeping under treated nets. A strong evaluation component in over 50,000 people allows assessment of the long-term effects of insecticide-treated nets on child health and survival, anaemia in pregnancy, and the costs of the intervention. This evaluation is based on cross-sectional surveys, and case-control and cohort studies.

Can Long-lasting Insecticide-treated Bednets with Holes Protect Children from Malaria?

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Nonaka, Daisuke; Maazou, Abani; Yamagata, Shigeo; Oumarou, Issofou; Uchida, Takako; Jg Yacouba, Honoré; Toma, Nami; Takeuchi, Rie; Kobayashi, Jun; Mizoue, Tetsuya

2014-09-01

Although long-lasting insecticide-treated bednets (LLINs) have been widely used for malaria control, little is known about how the condition of LLINs affects the risk of malaria infection. The objective of this cross-sectional study was to examine the association between the use of LLINs with holes and caregiver-reported malaria diagnosed in children under five years of age (U5). Data were collected in Boboye health district, Niger, in 2010. Surveyors conducted interviews and bednet inspections in 1,034 households. If a household had a U5 child, the surveyor asked the caregiver whether the child had experienced a fever episode in the past two weeks that entailed standard treatment for uncomplicated malaria at a healthcare facility. The authors analyzed the association between the use of LLINs with holes and caregiver-reported malaria episodes in U5 children using logistic regression, adjusted for possible confounders. Of the 1,165 children included in the analysis, approximately half (53.3%) used an intact LLIN while far fewer (10.6%) used a LLIN with holes. Compared to children using an intact LLIN, children using a LLIN with holes were significantly more likely to have a caregiver-reported malaria episode (8.7% vs. 17.1%; odds ratio: 2.23; 95% confidence interval: 1.24-4.01). In this study site, LLINs with holes were less protective than intact LLINs.

Comparison of the laboratory standard washing using CIPAC washing agent and the domestic washing on three recommended types of long-lasting insecticidal mosquito nets.

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Ouattara, Jean Pierre Nabléni; Louwagie, Johanna; Pigeon, Olivier; Spanoghe, Pieter

2013-01-01

One of the best ways to prevent malaria is the use of insecticide-treated bed nets. Manufacturers pursue easier, safer and more efficient nets. Hence, many studies on the efficacy and wash resistance using World Health Organization standards have been reported. The commonly used detergent is "Savon de Marseille", because it closely resembles actually used soaps. At the 54(th) Collaborative International Pesticides Analytical Council (CIPAC) Technical Meeting in 2010, it was suggested to replace it by a standardized "CIPAC washing agent". The aim of this study was to investigate the difference between a laboratory hand washing simulation using the CIPAC washing agent (method-1) and a domestic washing (method-2) on different bed nets, as well as the effect of the drying process on the release of active ingredient. Interceptor®, Permanet®2.0 and Netprotect® nets were used in three treatments, each repeated 20 times. The first treatment included method-1 washing and indoor drying. The second treatment included method-2 washing and indoor drying. The third treatment used method-2 washing and UV-drying. The residual insecticide contents were determined using gas chromatography. The washing procedure and the number of washes have a significant effect on the release of active ingredient. Statistically, the two washing methods have the same effect on removing the active ingredient from the Interceptor® and Permanet®2.0 net, but a significantly different influence on the Netprotect® nets. The drying process has no significant effect on the insecticide. Both washing procedures affected the amount of insecticide remaining on nets independently of the impregnation technology. The active ingredient decreases with the number of washing cycles following an exponential or logarithmic model for coated nets. The laboratory hand washing simulation had more impact on the decrease of active ingredient content of the Netprotect® nets. All net types seemed to be effectively

Comparison of the laboratory standard washing using CIPAC washing agent and the domestic washing on three recommended types of long-lasting insecticidal mosquito nets.

Directory of Open Access Journals (Sweden)

Jean Pierre Nabléni Ouattara

Full Text Available One of the best ways to prevent malaria is the use of insecticide-treated bed nets. Manufacturers pursue easier, safer and more efficient nets. Hence, many studies on the efficacy and wash resistance using World Health Organization standards have been reported. The commonly used detergent is "Savon de Marseille", because it closely resembles actually used soaps. At the 54(th Collaborative International Pesticides Analytical Council (CIPAC Technical Meeting in 2010, it was suggested to replace it by a standardized "CIPAC washing agent". The aim of this study was to investigate the difference between a laboratory hand washing simulation using the CIPAC washing agent (method-1 and a domestic washing (method-2 on different bed nets, as well as the effect of the drying process on the release of active ingredient.Interceptor®, Permanet®2.0 and Netprotect® nets were used in three treatments, each repeated 20 times. The first treatment included method-1 washing and indoor drying. The second treatment included method-2 washing and indoor drying. The third treatment used method-2 washing and UV-drying. The residual insecticide contents were determined using gas chromatography.The washing procedure and the number of washes have a significant effect on the release of active ingredient. Statistically, the two washing methods have the same effect on removing the active ingredient from the Interceptor® and Permanet®2.0 net, but a significantly different influence on the Netprotect® nets. The drying process has no significant effect on the insecticide.Both washing procedures affected the amount of insecticide remaining on nets independently of the impregnation technology. The active ingredient decreases with the number of washing cycles following an exponential or logarithmic model for coated nets. The laboratory hand washing simulation had more impact on the decrease of active ingredient content of the Netprotect® nets. All net types seemed to be

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico.

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Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J; Kroeger, Axel; Manrique-Saide, Pablo

2015-02-01

Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Insecticide-treated nets mass distribution campaign: benefits and lessons in Zambia.

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Masaninga, Freddie; Mukumbuta, Nawa; Ndhlovu, Ketty; Hamainza, Busiku; Wamulume, Pauline; Chanda, Emmanuel; Banda, John; Mwanza-Ingwe, Mercy; Miller, John M; Ameneshewa, Birkinesh; Mnzava, Abraham; Kawesha-Chizema, Elizabeth

2018-04-24

Zambia was an early adopter of insecticide-treated nets strategy in 2001, and policy for mass distribution with long-lasting insecticidal nets (LLINs) in 2005. Since then, the country has implemented mass distribution supplemented with routine delivery through antenatal care and under five clinics in health facilities. The national targets of universal (100%) coverage and 80% utilization of LLINs have not been attained. Free mass LLIN distribution campaign in Zambia offers important lessons to inform future campaigns in the African region. This study reviewed LLIN free mass distribution campaign information derived from Zambia's national and World Health Organization Global Malaria Programme annual reports and strategic plans published between 2001 and 2016. In 2014, a nationwide mass distribution campaign in Zambia delivered all the 6.0 million LLINs in 6 out of 10 provinces in 4 months between June and September before the onset of the rainy season. Compared with 235,800 LLINs and 2.9 million LLINs distributed on a rolling basis in 2008 and 2013, respectively, the 2014 mass campaign, which distributed 6 million LLINs represented the largest one-time-nationwide LLIN distribution in Zambia. The province (Luapula) with highest malaria transmission, mostly with rural settings recorded 98-100% sleeping spaces in homes covered with LLINs. The percentage of households owning at least 1 LLIN increased from 50.9% in 2006 to 77.7% in 2015. The 2014 mass campaign involved a coordinated response with substantial investments into macro (central) and micro (district) level planning, capacity building, tracking and logistics management supported by a new non-health sector partnership landscape. Coordination of LLIN distribution and logistics benefited from the mobile phone technology to transmit "real time" data on commodity tracking that facilitated timely delivery to districts. Free mass distribution of LLINs policy was adopted in 2005 in Zambia. Consistently implemented

Effectiveness of insecticide-treated and untreated nets to prevent malaria in India.

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Van Remoortel, Hans; De Buck, Emmy; Singhal, Maneesh; Vandekerckhove, Philippe; Agarwal, Satya P

2015-08-01

India is the most malaria-endemic country in South-East Asia, resulting in a high socio-economic burden. Insecticide-treated or untreated nets are effective interventions to prevent malaria. As part of an Indian first-aid guideline project, we aimed to investigate the magnitude of this effect in India. We searched MEDLINE, Embase and Central to systematically review Indian studies on the effectiveness of treated or untreated vs. no nets. Parasite prevalence and annual parasite incidence served as malaria outcomes. The overall effect was investigated by performing meta-analyses and calculating the pooled risk ratios (RR) and incidence rate ratios. Of 479 articles, we finally retained 16 Indian studies. Untreated nets decreased the risk of parasite prevalence compared to no nets [RR 0.69 (95% CI; 0.55, 0.87) in high-endemic areas, RR 0.49 (95% CI; 0.28, 0.84) in low-endemic areas], as was the case but more pronounced for treated nets [RR 0.35 (95% CI; 0.26, 0.47) in high-endemic areas, risk ratio 0.16 (95% CI; 0.06, 0.44) in low-endemic areas]. Incidence rate ratios showed a similar observation: a significantly reduced rate of parasites in the blood for untreated nets vs. no nets, which was more pronounced in low-endemic areas and for those who used treated nets. The average effect of treated nets (vs. no nets) on parasite prevalence was higher in Indian studies (RR 0.16-0.35) than in non-Indian studies (data derived from a Cochrane systematic review; RR 0.58-0.87). Both treated and untreated nets have a clear protective effect against malaria in the Indian context. This effect is more pronounced there than in other countries. © 2015 John Wiley & Sons Ltd.

Insecticide mixtures for mosquito net impregnation against malaria vectors

Directory of Open Access Journals (Sweden)

Corbel V.

2002-09-01

Full Text Available Insecticides belonging to the pyrethroid family are the only compounds currently available for the treatment of mosquito nets. Unfortunately, some malaria vector species have developed resistance to pyrethroids and the lack of alternative chemical categories is a great concern. One strategy for resistance management would be to treat mosquito nets with a mixture associating two insecticides having different modes of action. This study presents the results obtained with insecticide mixtures containing several proportions of bifenthrin (a pyrethroid insecticide and carbosulfan (a carbamate insecticide. The mixtures were sprayed on mosquito net samples and their efficacy were tested against a susceptible strain of Anopheles gambiae, the major malaria vector in Africa. A significant synergism was observed with a mixture containing 25 mg/m2 of bifenthrin (half the recommended dosage for treated nets and 6.25 mg/m2 of carbosulfan (about 2 % of the recommended dosage. The observed mortality was significantly more than expected in the absence of any interaction (80 % vs 41 % and the knock-down effect was maintained, providing an effective barrier against susceptible mosquitoes.

Scepticism towards insecticide treated mosquito nets for malaria control in rural community in north-western Tanzania.

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Nnko, Soori E; Whyte, Susan R; Geissler, Wenzel P; Aagaard-Hansen, Jens

2012-04-01

Despite existence of effective tools for malaria control, malaria continues to be one of the leading killer diseases especially among under-five year children and pregnant women in poor rural populations of Sub Saharan Africa. In Tanzania Mainland the disease contributes to 39.4% of the total OPD attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional approach that tend to study low uptake of health interventions in terms of structural practical constraints--cost, accessibility, everyday priorities--or in terms of cognition--insufficient knowledge of benefits e.g. ignorance of public health messages. This paper has shown that, the majority of people who could afford the prices of ITNs and who knew where to obtain the insecticides did not necessarily buy them. This suggests that, although people tend to report cost-related factors as a barrier against the use of ITNs, there are other critical concerns at work. Without underestimating the practical factors, our study have recommended to consider critical examinations of those other concerns that hinder optimal utilization of ITN for malaria control, and the basis for those concerns.

Effect of insecticide-treated bed nets on house-entry by malaria mosquitoes: The flight response recorded in a semi-field study in Kenya.

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Spitzen, Jeroen; Koelewijn, Teun; Mukabana, W Richard; Takken, Willem

2017-08-01

Insecticide-treated nets are currently a major tool to reduce malaria transmission. Their level of repellency affects contact of the mosquito with the net, but may also influence the mosquito's entry into the house. The response of host-seeking malaria mosquitoes approaching the eave of an experimental house was recorded within a large screen house. We compared entry- and exit rates in relation to the presence in the house of different insecticide-treated bed nets (ITNs) with an untreated net. Mosquitoes were lured towards the house by dispensing a synthetic host-odour blend from within the net in the house. Complementary WHO bioassays revealed that the treated nets caused high knock-down- and mortality responses to the Anopheles gambiae sensu stricto strain tested. The proportion of mosquitoes that came into view of the cameras and subsequently entered the house did not differ between treated nets and the untreated net. Treated nets did not affect proportions of mosquitoes that exited the house and departed from view around the eave. However, the percentage of house-leaving and re-entering mosquitoes when an insecticide- treated net was present, was lower than in the presence of an untreated net. Our results indicated that there was no spatial repellent effect from pyrethroid-treated nets that influences house-entry at eave level. It is argued that the toxic effect of treated bed nets resulted in a reduced number of mosquitoes re-entering the house, which could thereby affect malaria transmission in neighbouring, unprotected houses. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique.

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Faulde, Michael K; Nehring, Oliver

2012-08-01

New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p time from 55 to 75 %, the corresponding 100 % kill time (p time of etofenprox from 42 to 50 % (p = 0.004), the 100 % kill time from 25 to 38 % (p biting protection, even at low concentrations. One hundred percent biting and probing protection of stored LLIRNs was preserved for 83 weeks with the 5,930 mg/m(2) DEET and 2,139 mg/m(2) etofenprox LLIRN, for 72 weeks with the 5,002 mg/m(2) DEET and 2,349 mg/m(2) etofenprox LLIRN, for 63 weeks with the 3,590 mg/m(2) DEET and 1,208 mg/m(2) permethrin LLRN, and for 61 weeks with the 4,711 mg/m(2) DEET and 702 mg/m(2) etofenprox LLIRN. Because 100 % bite protection with up to 75 % quicker contact toxicity of pyrethroids were documented, synergistic toxicological and repellent effects of multi-layer polymer

Host-seeking activity of a Tanzanian population of Anopheles arabiensis at an insecticide treated bed net.

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Parker, Josephine E A; Angarita Jaimes, Natalia C; Gleave, Katherine; Mashauri, Fabian; Abe, Mayumi; Martine, Jackline; Towers, Catherine E; Towers, David; McCall, Philip J

2017-07-04

Understanding how mosquitoes respond to long lasting insecticide treated nets (LLINs) is fundamental to sustaining the effectiveness of this essential control tool. We report on studies with a tracking system to investigate behaviour of wild anophelines at an LLIN, in an experimental hut at a rural site in Mwanza, Tanzania. Groups of adult female mosquitoes (n = 10 per replicate) reared from larvae of a local population, identified as predominantly (95%) Anopheles arabiensis, were released in the hut. An infrared video tracking system recorded flight and net contact activity over 1 h as the mosquitoes attempted to reach a supine human volunteer within a bed net (either a deltamethrin-treated LLIN or an untreated control net). A range of activities, including flight path, position in relation to the bed net and duration of net contact, were quantified and compared between treatments. The total time that female An. arabiensis spent in flight around LLINs was significantly lower than at untreated nets [F(1,10) = 9.26, p = 0.012], primarily due to a substantial reduction in the time mosquitoes spent in persistent 'bouncing' flight [F(1,10) = 18.48, p = 0.002]. Most activity occurred at the net roof but significantly less so with LLINs (56.8% of total) than untreated nets [85.0%; Χ 2 (15) = 234.69, p Activity levels at the bed net directly above the host torso were significantly higher with untreated nets (74.2%) than LLINs [38.4%; Χ 2 (15) = 33.54, p = 0.004]. 'Visiting' and 'bouncing' rates were highest above the volunteer's chest in untreated nets (39.9 and 50.4%, respectively) and LLINs [29.9 and 42.4%; Χ 2 (13) = 89.91, p activity over 60 min was significantly more rapid for LLINs [F(1,10) = 6.81, p = 0.026], reiterating an 'attract and kill' rather than a repellent mode of action. The study has demonstrated the potential for detailed investigations of behaviour of wild mosquito populations under field conditions. The results validate

Low long-lasting insecticide nets (LLINs use among household members for protection against mosquito bite in kersa, Eastern Ethiopia

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Gobena Tesfaye

2012-10-01

Full Text Available Abstract Background In Ethiopia, despite the increasing availability of long-lasting insecticide treated nets (LLINs, the LLINs use among LLINs owning households has not been satisfactory. Identifying the circumstances and the associated factors is necessary to achieve the Millennium Development Goal targets. We aimed to assess barriers related with LLIN use at the household level. Methods A cross sectional survey was conducted in Kersa Demographic Surveillance and Health Research Center (KDS-HRC from October to November 2010. A total of 2867 households were selected from a surveillance database using a simple random sampling technique. The data were collected by interviewing women, direct observation of LLINs conditions and use, and in-depth interviewing of key informants. Multivariate analysis was used to determine independent predictors of LLIN non-use. Results Of the total surveyed households, 65.5% (1879 had at least one LLIN, but 33.5% (630 LLINs owned households had used at least one LLIN the night before the survey. Low educational level of women, low awareness on malaria prevention, unavailability of separate sleeping room, LLIN colour preference, and unavailability of enough LLINs to the household members were the main barriers to LLIN use. A supplementary qualitative interview with key informants also identified that poor condition of LLINs; undermining the extent of malaria; and using the LLIN for other purposes as the main reasons for non-use. Conclusions This study indicates that only about one third of LLIN owned households are actually using at least one LLIN for protection against mosquito bite. Thus, majority of the residents are at higher risk of mosquito bite and acquiring of malaria infection. Households living in fringe zone are not benefiting from the LLIN protection. Further progress in malaria prevention can be achieved by specifically targeting populations in fringe zones and conducting focused public education to

N-player mosquito net game: individual and social rationality in the misuse of insecticide-treated nets.

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Honjo, Keita; Satake, Akiko

2014-02-07

Many governmental and non-governmental organizations have distributed insecticide-treated nets (ITNs) to malaria endemic areas, which contributed to the reduction of malaria deaths. However, some people in malaria endemic areas used ITNs for alternative purposes such as fishery and agriculture. It is unclear why people threatened by malaria misuse ITNs. Here we develop a N-player mosquito net game, and theoretically show that the misuse of ITNs might be underpinned by individual and social rationality. In the mosquito net game, each player uses ITNs for malaria prevention or alternative purposes. The proper ITN use decreases the probability of malaria infection, while the improper ITN use increases the player's labor productivity. Each player's expected payoff is influenced by other players' strategies. We found that the misuse of ITNs can be a Pareto efficient Nash equilibrium. The maximum number of players using ITNs for malaria prevention is limited by insecticidal effectiveness of ITNs and extra income from ITN misuse. Furthermore, we found that players in a low-income community are attracted to the misuse of ITNs even if the probability of malaria infection is high. Introduction of a tax on ITN misuse was shown to be effective to motivate the players to use ITNs for malaria prevention. Our results demonstrate that understanding decision making of people in malaria endemic areas is essential to design more effective malaria control programs. © 2013 Published by Elsevier Ltd. All rights reserved.

Long-Lasting Insecticide Net Ownership, Access and Use in Southwest Ethiopia: A Community-Based Cross-Sectional Study.

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Seyoum, Dinberu; Speybroeck, Niko; Duchateau, Luc; Brandt, Patrick; Rosas-Aguirre, Angel

2017-10-27

Introduction : A large proportion of the Ethiopian population (approximately 68%) lives in malaria risk areas. Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the malaria prevention and control strategy in the country. This study assessed the ownership, access and use of LLNs in the malaria endemic southwest Ethiopia. Methods: A community-based cross-sectional study was conducted in southwest Ethiopia during October-November 2015, including 836 households from sixteen villages around Gilgel-Gibe dam area. Indicators of ownership, access and use of LLINs were derived following the Roll Back Malaria (RBM) guidelines. Factors associated with failure for both LLIN access and use were analysed at household level using a multivariate logistic regression model. Results: The proportion of households with at least one LLIN was 82.7% (95% CI: 80.0, 85.1). However, only 68.9% (95% CI: 65.6, 71.9) had enough LLINs to cover all family members (with ≥one LLIN for every two persons). While 75.3% (95% CI: 68.4, 83.0) of the population was estimated to have accessed to LLINs, only 63.8% (95% CI: 62.3, 65.2) reported to have used a LLIN the previous night. The intra-household gap (i.e., households owning at least one LLIN, but unable to cover all family members) and the behavioral gap (i.e., household members who did not sleep under a LLIN despite having access to one) were 16.8% and 10.5%, respectively. Age, marital status and education of household heads, as well as household size and cooking using firewood were associated with the access to enough LLINs within households. Decreased access to LLINs at households was the main determinant for not achieving ≥80% household members sleeping under a LLIN the previous night. Other associated factors were household size and education level of household head. Conclusions: LLIN coverage levels in study villages remain below national targets of 100% for ownership and 80% for use. The access to

Impact of malaria related messages on insecticide-treated net (ITN) use for malaria prevention in Ghana

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Owusu Adjah, Ebenezer S; Panayiotou, Andrie G

2014-01-01

Background: Media messages have been used in Ghana to promote insecticide-treated net (ITN)/bed net usage in an effort to impact on malaria prevention. The aim of this study was to assess the effect of such malaria-related messages delivered through electronic/print media and by volunteers/health workers on the use of ITNs by children living in a household. Methods: Data was collected from September to November of 2008 using a structured, interviewer-administered questionnaire by the Ghana St...

Use and acceptance of long lasting insecticidal net screens for dengue prevention in Acapulco, Guerrero, Mexico.

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Jones, Catrin H; Benítez-Valladares, David; Guillermo-May, Guillermo; Dzul-Manzanilla, Felipe; Che-Mendoza, Azael; Barrera-Pérez, Mario; Selem-Salas, Celia; Chablé-Santos, Juan; Sommerfeld, Johannes; Kroeger, Axel; O'Dempsey, Timothy; Medina-Barreiro, Anuar; Manrique-Saide, Pablo

2014-08-14

Dengue, recognized by the WHO as the most important mosquito-borne viral disease in the world, is a growing problem. Currently, the only effective way of preventing dengue is vector control. Standard methods have shown limited effect, and there have been calls to develop new integrated vector management approaches. One novel tool, protecting houses with long lasting insecticidal screens on doors and windows, is being trialled in a cluster randomised controlled trial by a joint UADY/WHO TDR/IDRC study in various districts of Acapulco, Mexico, with exceptionally high levels of crime and insecurity.This study investigated the community's perspectives of long lasting insecticidal screens on doors and windows in homes and in schools, in order to ascertain their acceptability, to identify challenges to further implementation and opportunities for future improvements. This was a sequential mixed-methods study. The quantitative arm contained a satisfaction survey administered to 288 houses that had received the intervention examining their perspectives of both the intervention and dengue prevention in general. The qualitative arm consisted of Focus Group Discussions (FGDs) with those who had accepted the intervention and key informant interviews with: schoolteachers to discuss the use of the screens in schools, program staff, and community members who had refused the intervention. Overall satisfaction and acceptance of the screens was very high, with only some operational and technical complaints relating to screen fragility and the installation process. However, the wider social context of urban violence and insecurity was a major barrier to screen acceptance. Lack of information dissemination and community collaboration were identified as project weaknesses. The screens are widely accepted by the population, but the project implementation could be improved by reassuring the community of its legitimacy in the context of insecurity. More community engagement and better

The effect of holes in long-lasting insecticidal nets on malaria in Malawi: results from a case-control study.

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Minta, Anna A; Landman, Keren Z; Mwandama, Dyson A; Shah, Monica P; Eng, Jodi L Vanden; Sutcliffe, James F; Chisaka, Joseph; Lindblade, Kim A; Mathanga, Don P; Steinhardt, Laura C

2017-10-02

Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria prevention. Holes develop in LLINs over time and compromise their physical integrity, but how holes affect malaria transmission risk is not well known. After a nationwide mass LLIN distribution in July 2012, a study was conducted to assess the relationship between LLIN damage and malaria. From March to September 2013, febrile children ages 6-59 months who consistently slept under LLINs (every night for 2 weeks before illness onset) were enrolled in a case-control study at Machinga District Hospital outpatient department. Cases were positive for Plasmodium falciparum asexual parasites by microscopy while controls were negative. Digital photographs of participants' LLINs were analysed using an image-processing programme to measure holes. Total hole area was classified by quartiles and according to the World Health Organization's proportionate hole index (pHI) cut-offs [ 790 cm 2 (too torn)]. Number of holes by location and size, and total hole area, were compared between case and control LLINs using non-parametric analyses and logistic regression. Of 248 LLINs analysed, 97 (39%) were from cases. Overall, 86% of LLINs had at least one hole. The median number of holes of any size was 9 [interquartile range (IQR) 3, 22], and most holes were located in the lower halves of the nets [median 7 (IQR 2, 16)]. There were no differences in number or location of holes between LLINs used by cases and controls. The median total hole area was 10 cm 2 (IQR 2, 125) for control LLINs and 8 cm 2 (IQR 2, 47) for case LLINs (p = 0.10). Based on pHI, 109 (72%) control LLINs and 83 (86%) case LLINs were in "good" condition. Multivariable modeling showed no association between total hole area and malaria, controlling for child age, caregiver education, and iron versus thatched roof houses. LLIN holes were not associated with increased odds of malaria in this study. However, most of the LLINs were in relatively good

Large-scale implementation of disease control programmes: a cost-effectiveness analysis of long-lasting insecticide-treated bed net distribution channels in a malaria-endemic area of western Kenya-a study protocol.

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Gama, Elvis; Were, Vincent; Ouma, Peter; Desai, Meghna; Niessen, Louis; Buff, Ann M; Kariuki, Simon

2016-11-21

Historically, Kenya has used various distribution models for long-lasting insecticide-treated bed nets (LLINs) with variable results in population coverage. The models presently vary widely in scale, target population and strategy. There is limited information to determine the best combination of distribution models, which will lead to sustained high coverage and are operationally efficient and cost-effective. Standardised cost information is needed in combination with programme effectiveness estimates to judge the efficiency of LLIN distribution models and options for improvement in implementing malaria control programmes. The study aims to address the information gap, estimating distribution cost and the effectiveness of different LLIN distribution models, and comparing them in an economic evaluation. Evaluation of cost and coverage will be determined for 5 different distribution models in Busia County, an area of perennial malaria transmission in western Kenya. Cost data will be collected retrospectively from health facilities, the Ministry of Health, donors and distributors. Programme-effectiveness data, defined as the number of people with access to an LLIN per 1000 population, will be collected through triangulation of data from a nationally representative, cross-sectional malaria survey, a cross-sectional survey administered to a subsample of beneficiaries in Busia County and LLIN distributors' records. Descriptive statistics and regression analysis will be used for the evaluation. A cost-effectiveness analysis will be performed from a health-systems perspective, and cost-effectiveness ratios will be calculated using bootstrapping techniques. The study has been evaluated and approved by Kenya Medical Research Institute, Scientific and Ethical Review Unit (SERU number 2997). All participants will provide written informed consent. The findings of this economic evaluation will be disseminated through peer-reviewed publications. Published by the BMJ Publishing

Inequalities in purchase of mosquito nets and willingness to pay for insecticide-treated nets in Nigeria: Challenges for malaria control interventions

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Hanson Kara

2004-03-01

Full Text Available Abstract Objective To explore the equity implications of insecticide-treated nets (ITN distribution programmes that are based on user charges. Methods A questionnaire was used to collect information on previous purchase of untreated nets and hypothetical willingness to pay (WTP for ITNs from a random sample of householders. A second survey was conducted one month later to collect information on actual purchases of ITNs. An economic status index was used for characterizing inequity. Major findings The lower economic status quintiles were less likely to have previously purchased untreated nets and also had a lower hypothetical and actual WTP for ITNs. Conclusion ITN distribution programmes need to take account of the diversity in WTP for ITNs if they are to ensure equity in access to the nets. This could form part of the overall poverty reduction strategy.

Determinants of Ownership and Utilization of Insecticide-Treated Bed Nets for Malaria Control in Eastern Ethiopia

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Sibhatu Biadgilign

2012-01-01

Full Text Available Background. Malaria remains a major cause of mortality and morbidity in the world, and particularly in sub-Saharan Africa. Objectives. The aim of this study was to determine ownership and utilization of ITNs among households with children under five in the previous night. Methods. A community based cross-sectional study was conducted in Gursum district in Eastern Ethiopia. A total of 335 households were surveyed using a pretested structured questionnaire administered though house-to-house interviews. Results. Household ownership for at least one mosquito net and use of nets were 62.4% (95% CI 57.2–67.6% and 21.5% (95% CI 17.1–25.9%, respectively. Households who received or were told about ITN in the last 6 months were three times more likely to have used it than those who were not (OR 3.25; 95% CI 1.5–7.10. Households whose heads were engaged as a farmer (adjusted OR 0.137; 95% CI: 0.04–0.50 and housewife (OR 0.26; 95% CI: 0.08–0.82 were less likely to use ITN than those of other occupations. Conclusion. The findings indicate low ITN ownership and utilization among the households. Intensive health education and community mobilization effort should be employed to increase the possession and proper utilization of insecticide treated bed nets.

Netting the malaria menace: Distribution and utilization of long-lasting insecticidal net in a malaria endemic area in Bankura, West Bengal.

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Mukhopadhyay, D K; Basu, S S; Roy, D; Das, N; Akbar, F; Sarkar, G N

2016-03-01

Long-lasting insecticidal net (LLIN) is considered to be a highly effective intervention against malaria under National Vector Borne Disease Control Programme in India. A cross-sectional study was undertaken to assess the coverage and utilization of LLIN and the factors related thereto. A survey of 1300 households was carried out in Ranibandh block of Bankura district in West Bengal, India, using lot quality assurance sampling (LQAS) method. Coverage/utilization of 80% was considered as minimum acceptable norm. The weighted sample size was calculated from each village of the block. The sociodemographic, economic information of the household along with the availability and use of LLIN was collected through interview and observation. In total, 7320 individuals including 840 children ≤ 5 yr were visited. Overall coverage of adequate LLIN was 65.4% (± 1.5%) and for children ≤ 5 yr, it was 60.5% (± 1.3%). Overall, 66.1% (± 1.4%) people of all ages and 63.7% (± 1.4%) children ≤ 5 yr slept under LLINs in the night before the survey. Out of 26 sub-centres, distribution of LLINs in 10 sub-centres was below the accepted norm, whereas utilization was sub-optimal in 19 sub-centres. In only 18.2% (± 0.5%) households, LLINs remained hanging during daytime. Poverty, caste, education, perception regarding malarial morbidity and preventive action of LLIN were associated significantly with the distribution of LLIN. Similarly, poverty (AOR = 2.14), threat perception regarding malarial morbidity (AOR = 1.51) and mortality (AOR = 2.52) were positively associated with the use of LLIN. Full utilization of bednets by under-fives of the households was higher in villages with sub-centres. Around two-third population of the study area was effectively covered with LLIN. Higher proportion of socially marginalized people received LLIN. Threat perception regarding malaria was directly associated with both receipt and use of LLIN. Behaviour change communication on utilization along

Longlasting insecticidal nets for prevention of Leishmania donovani infection in India and Nepal: paired cluster randomised trial

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Picado, Albert; Singh, Shri Prakash; Rijal, Suman

2010-01-01

To test the effectiveness of large scale distribution of longlasting nets treated with insecticide in reducing the incidence of visceral leishmaniasis in India and Nepal.......To test the effectiveness of large scale distribution of longlasting nets treated with insecticide in reducing the incidence of visceral leishmaniasis in India and Nepal....

Implementation strategies to increase access and demand of long-lasting insecticidal nets: a before-and-after study and scale-up process in Mozambique.

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Arroz, Jorge A H; Mendis, Chandana; Pinto, Liliana; Candrinho, Baltazar; Pinto, João; Martins, Maria do Rosário O

2017-10-25

The universal coverage bed nets campaign is a proven health intervention promoting increased access, ownership, and use of bed nets to reduce malaria burden. This article describes the intervention and implementation strategies that Mozambique carried out recently in order to improve access and increase demand for long-lasting insecticidal nets (LLINs). A before-and-after study with a control group was used during Stage I of the implementation process. The following strategies were tested in Stage I: (1) use of coupons during household registration; (2) use of stickers to identify the registered households; (3) new LLIN ascription formula (one LLIN for every two people). In Stage II, the following additional strategies were implemented: (4) mapping and micro-planning; (5) training; and (6) supervision. Odds ratio (OR) and 95% confidence interval (CI) were used to compare and establish differences between intervened and control districts in Stage I. Main outcomes were: percentage of LLINs distributed, percentage of target households benefited. In Stage I, 87.8% (302,648) of planned LLINs were distributed in the intervention districts compared to 77.1% (219,613) in the control districts [OR: 2.14 (95% CI 2.11-2.16)]. Stage I results also showed that 80.6% (110,453) of households received at least one LLIN in the intervention districts compared to 72.8% (87,636) in the control districts [OR: 1.56 (95% CI 1.53-1.59)]. In Stage II, 98.4% (3,536,839) of the allocated LLINs were delivered, covering 98.6% (1,353,827) of the registered households. Stage I results achieved better LLINs and household coverage in districts with the newly implemented strategies. The results of stage II were also encouraging. Additional strategies adaptation is required for a wide-country LLIN campaign.

Frequent blood feeding enables insecticide-treated nets to reduce transmission by mosquitoes that bite predominately outdoors.

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Russell, Tanya L; Beebe, Nigel W; Bugoro, Hugo; Apairamo, Allan; Chow, Weng K; Cooper, Robert D; Collins, Frank H; Lobo, Neil F; Burkot, Thomas R

2016-03-10

The effectiveness of vector control on malaria transmission by long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) depends on the vectors entering houses to blood feed and rest when people are inside houses. In the Solomon Islands, significant reductions in malaria have been achieved in the past 20 years with insecticide-treated bed nets, IRS, improved diagnosis and treatment with artemisinin combination therapies; despite the preference of the primary vector, Anopheles farauti, to feed outdoors and early in the evening and thereby avoid potential exposure to insecticides. Rational development of tools to complement LLINs and IRS by attacking vectors outdoor requires detailed knowledge of the biology and behaviours of the target species. Malaria transmission in Central Province, Solomon Islands was estimated by measuring the components comprising the entomological inoculation rate (EIR) as well as the vectorial capacity of An. farauti. In addition, the daily and seasonal biting behaviour of An. farauti, was examined and the duration of the feeding cycle was estimated with a mark-release-recapture experiment. Anopheles farauti was highly exophagic with 72% captured by human landing catches (HLC) outside of houses. Three-quarters (76%) of blood feeding on humans was estimated to occur before 21.00 h. When the hourly location of humans was considered, the proportion of exposure to mosquito bites on humans occurring indoors (πi) was only 0.130 ± 0.129. Peak densities of host seeking An. farauti occurred between October and January. The annual EIR was estimated to be 2.5 for 2012 and 33.2 for 2013. The length of the feeding cycle was 2.1 days. The short duration of the feeding cycle by this species offers an explanation for the substantial control of malaria that has been achieved in the Solomon Islands by LLINs and IRS. Anopheles farauti is primarily exophagic and early biting, with 13% of mosquitoes entering houses to feed late at night during

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial.

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Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-02-01

Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4-6 weeks after the second intervention (March to April 2014). Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Health Effects of Long-Term Exposure to Insecticide-Treated Mosquito Nets in the Control of Malaria in Endemic Regions, Revised

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Ebere C. Anyanwu

2006-01-01

Full Text Available The endemicity of malaria in tropical areas of the world persists, especially in countries south of Saharan Africa. The efforts and concerns invested by the World Health Organization and other health agencies to eradicate malaria are commendable. However, in spite of all these efforts, the loss in economic and human resources continues. In a previous report, the long-term health effects of insecticide-impregnated bednet (IIBN use were highlighted with the expectation of attracting serious thoughts and further research on the issue. This present paper is an update on that expectation. Results from a comprehensive literature search show that not much work has been done on the effects of long-term exposure to IIBNs in combating malarial infection. The efficacy of IIBNs is not in question. What is in question is whether long-term exposure to IIBNs have any health effects. The aims and outcomes of the research found in the literature on the subject to date seem to support only the efficacy of the temporal use of plain bednets, but not the use of IIBNs, and do not tell much about the long-term effects of IIBN exposure. All pesticides are toxic by nature and present risks of adverse effects. While there is agreement that IIBNs can be effective in reducing malarial morbidity and mortality under field trials, a number of factors relating to their long-term-exposure health effects have yet to be determined. Further reliable research projects are recommended urgently. However, some of the anticipated behavioral effects caused by insecticidal use will be avoided by the use of untreated nets instead.

Low Utilization of Insecticide-Treated Bed Net among Pregnant Women in the Middle Belt of Ghana

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Grace Manu; Ellen Abrafi Boamah-Kaali; Lawrence Gyabaa Febir; Emmanuel Ayipah; Seth Owusu-Agyei; Kwaku Poku Asante

2017-01-01

Background. Malaria in pregnancy leads to low birth weight, premature birth, anaemia, and maternal and neonatal mortality. Use of insecticide-treated nets (ITNs) during pregnancy is one of the proven interventions to reduce the malaria burden. However, Ghana has not achieved its target for ITN use among pregnant women. Methods. A qualitative study was conducted in seven communities purposively selected from the middle belt of Ghana. Participants who had delivered in the six months prior to th...

Serological markers of sand fly exposure to evaluate insecticidal nets against visceral leishmaniasis in India and Nepal: a cluster-randomi trial

DEFF Research Database (Denmark)

Gidwani, K; Picado, A; Rijal, S

2011-01-01

Background: Visceral leishmaniasis is the world’ second largest vector-borne parasitic killer and a neglected tropical disease, prevalent in poor communities. Long-lasting insecticidal nets (LNs) are a low cost proven vector intervention method for malaria control; however, their effectiveness...

Effectiveness of a new long-lasting insecticidal nets delivery model in two rural districts of Mozambique: a before-after study.

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Arroz, Jorge A H; Candrinho, Baltazar; Mendis, Chandana; Varela, Pablo; Pinto, João; Martins, Maria do Rosário O

2018-02-05

In 2015, Mozambique piloted a new model of long-lasting insecticidal nets (LLINs) delivery in a campaign. The new delivery model was used in two rural districts were, and two others were considered as control, maintaining the old delivery model. The aim of this study is to compare the coverage of ownership and use of LLINs in intervention and control districts in Mozambique. A before-after design with control group was carried out 6 months after LLINs distribution. Using systematic probabilistic sampling, 1547 households were surveyed by means of a questionnaire. To find associations between the district categories (intervention and control) and the main outcomes of the study (LLIN ownership, use, and universal coverage achievement), odds ratio (OR) and respective confidence intervals were calculated. Of the 760 households surveyed in the intervention districts, 98.8% had at least one LLIN; of the 787 households surveyed in the control districts, 89.6% had at least one LLIN [OR: 9.7, 95% (CI 4.84-19.46)]. Around 95 and 87% of households owning at least one LLIN reported having slept under the LLIN the previous night in the intervention and control districts, respectively [OR: 3.2; 95% (CI 2.12-4.69)]. Seventy-one percent of the households surveyed achieved universal coverage in the intervention districts against 59.6% in the control districts [OR: 1.6; 95% (CI 1.33-2.03)]. The universal coverage campaign piloted with the new delivery model has increased LLINs ownership, use, and progression for reaching universal coverage targets in the community.

Replacement of Long Lasting Insecticide Treated Nets in Malarious ...

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Science, Technology and Arts Research Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 2 (2014) >. Log in or Register to get access to full text downloads.

The Effect of Long Lasting Insecticide Bed Net Use on Malaria Prevalence in the Tombel Health District, South West Region-Cameroon

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Eric B. Fokam

2016-01-01

Full Text Available Malaria remains a major public health problem in Africa, and its prevalence in Cameroon stands at 29%. Long Lasting Insecticide Nets (LLINs were distributed in 2011 to reduce malaria mortality and morbidity; however, assessment of this intervention is scanty. The present study in the Tombel health district (THD investigated the impact of this distribution on malaria prevalence. A total of 31,657 hospital records from 3 health facilities in 3 health areas for 2010–2013 were examined. Records for 2010 and 2011 provided predistribution baseline data, while those of 2012 and 2013 represented postdistribution data. 8,679 (27.4% patients were positive for malaria. Children below 5 years had the highest prevalence (40.7%. The number of confirmed cases was highest from June to August (peak rainy season. Malaria prevalence was higher in males (25.3% than in females (23.2%. Malaria prevalence increased in THD from 26.7% in 2010 to 30.7% in 2011 but dropped to 22.7% in 2012 and then increased in 2013 to 29.5%. There was an overall drop in the total number of confirmed malaria cases in 2012; this decrease was significant in Ebonji (p<0.001 and Nyasoso (p<0.015 health areas. The distribution of LLINs led to a short lived reduction in malaria prevalence in THD. LLIN distribution and other control activities should be reinforced to keep malaria prevalence low especially among the 0–5-year group.

The costs and effects of a nationwide insecticide-treated net programme: the case of Malawi

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Ortiz Juan

2005-05-01

Full Text Available Abstract Background Insecticide-treated nets (ITNs are a proven intervention to reduce the burden of malaria, yet there remains a debate as to the best method of ensuring they are universally utilized. This study is a cost-effectiveness analysis of an intervention in Malawi that started in 1998, in Blantyre district, before expanding nationwide. Over the 5-year period, 1.5 million ITNs were sold. Methods The costs were calculated retrospectively through analysis of expenditure data. Costs and effects were measured as cost per treated-net year (cost/TNY and cost per net distributed. Results The mean cost/TNY was calculated at $4.41, and the mean cost/ITN distributed at $2.63. It also shows evidence of economies of scale, with the cost/TNY falling from $7.69 in year one (72,196 ITN to $3.44 in year five (720,577 ITN. Cost/ITN distributed dropped from $5.04 to $1.92. Conclusion Combining targeting and social marketing has the potential of being both cost-effective and capable of achieving high levels of coverage, and it is possible that increasing returns to scale can be achieved.

The development of insecticide-treated durable wall lining for malaria control: insights from rural and urban populations in Angola and Nigeria

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Messenger Louisa A

2012-09-01

Full Text Available Abstract Background Durable lining (DL is a deltamethrin-impregnated polyethylene material, which is designed to cover domestic walls that would normally be sprayed with residual insecticide. The operational success of DL as a long-lasting insecticidal substrate will be dependent on a high level of user acceptability as households must maintain correctly installed linings on their walls for several years. Preliminary trials were undertaken to identify a material to develop into a marketable wall lining and to assess its level of acceptability among rural and urban populations. Methods In Angola (n=60, prototype DL and insecticide-treated plastic sheeting (ITPS were installed on urban house walls and ceilings, respectively, and acceptability was compared to indoor residual spraying (IRS (n=20 using a knowledge, attitude and practice (KAP questionnaire. In Nigeria (n=178, three materials (prototype DL, ITPS and insecticide-treated wall netting were distributed among rural and urban households. User opinions were gathered from focus group discussions, in-depth interviews and KAP questionnaires. Results In Angola, after two weeks, the majority of participants (98% expressed satisfaction with the products and identified the killing of insects as the materials’ principal benefits (73%. After one year, despite a loss of almost 50% of households to refugee repatriation, all 32 remaining households still asserted that they had liked the DL/ITPS in their homes and given the choice of intervention preferred DL/ITPS to IRS (94% or insecticide-treated nets (78%. In Nigeria, a dichotomy between rural and urban respondents emerged. Rural participants favoured wall adornments and accepted wall linings because of their perceived decorative value and entomological efficacy. By contrast, urban households preferred minimal wall decoration and rejected the materials based upon objections to their aesthetics and installation feasibility. Conclusions The high level

The development of insecticide-treated durable wall lining for malaria control: insights from rural and urban populations in Angola and Nigeria

Science.gov (United States)

2012-01-01

Background Durable lining (DL) is a deltamethrin-impregnated polyethylene material, which is designed to cover domestic walls that would normally be sprayed with residual insecticide. The operational success of DL as a long-lasting insecticidal substrate will be dependent on a high level of user acceptability as households must maintain correctly installed linings on their walls for several years. Preliminary trials were undertaken to identify a material to develop into a marketable wall lining and to assess its level of acceptability among rural and urban populations. Methods In Angola (n=60), prototype DL and insecticide-treated plastic sheeting (ITPS) were installed on urban house walls and ceilings, respectively, and acceptability was compared to indoor residual spraying (IRS) (n=20) using a knowledge, attitude and practice (KAP) questionnaire. In Nigeria (n=178), three materials (prototype DL, ITPS and insecticide-treated wall netting) were distributed among rural and urban households. User opinions were gathered from focus group discussions, in-depth interviews and KAP questionnaires. Results In Angola, after two weeks, the majority of participants (98%) expressed satisfaction with the products and identified the killing of insects as the materials’ principal benefits (73%). After one year, despite a loss of almost 50% of households to refugee repatriation, all 32 remaining households still asserted that they had liked the DL/ITPS in their homes and given the choice of intervention preferred DL/ITPS to IRS (94%) or insecticide-treated nets (78%). In Nigeria, a dichotomy between rural and urban respondents emerged. Rural participants favoured wall adornments and accepted wall linings because of their perceived decorative value and entomological efficacy. By contrast, urban households preferred minimal wall decoration and rejected the materials based upon objections to their aesthetics and installation feasibility. Conclusions The high level of acceptability

Implications of the western Kenya permethrin-treated bed net study for policy, program implementation, and future research

NARCIS (Netherlands)

Hawley, William A.; ter Kuile, Feiko O.; Steketee, Richard S.; Nahlen, Bernard L.; Terlouw, Dianne J.; Gimnig, John E.; Shi, Ya Ping; Vulule, John M.; Alaii, Jane A.; Hightower, Allen W.; Kolczak, Margarette S.; Kariuki, Simon K.; Phillips-Howard, Penelope A.

2003-01-01

The fifth, and probably last, large-scale, group-randomized, controlled trial of insecticide (permethrin)-treated bed nets (ITNs) showed that ITNs are efficacious in reducing all-cause post-neonatal mortality in an area of intense, perennial malaria transmission. The trial helped to define pregnant

Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon

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Eric B. Fokam

2017-03-01

Full Text Available Abstract Background Malaria is a serious health concern in Africa. In Cameroon, an endemic country where malaria remains a major public health problem, several control measures have been put in place among which the use of insecticide-treated bednets (LLINs/ITNs is considered one of the core vector control strategies. However, the greatest challenges include ownership and utilisation by individuals and households. Factors such as age, marital status, gender, education and occupation of the household head, household size, knowledge of bednets, socioeconomic status, and environmental factors have been suggested to have an impact on bednet ownership and utilisation in different settings. The present study sought to determine bednet ownership and utilisation rates and to assess the impact of predictive factors on bednet ownership and use in the Bamenda Health District (BHD of Cameroon. Methods A cross-sectional study involving 384 households was conducted in six health areas in the BHD. A structured and semi-structured questionnaire was used to collect data on demographic and household characteristics as well as information on their bednet ownership and utilisation. Descriptive statistics, bivariate and multivariate logistic regression analysis were performed. Results Frequency of bednet ownership was relatively high (63.5% with LLINs being most abundant (91.9%; the majority of households (87.7% obtained their bednets during the 2011 free distribution campaign. Utilisation was relatively high (69.3%, with negligence (29.3% and heat discomfort (26.7% accounting most for non-usage of bednets. Children less than 5 years (63% and pregnant women (60% most often used these nets. Households headed by a married couple, those with older household heads, household with smaller size (5–12 persons, and knowledge of bednets (good knowledge had positive impacts on bednet ownership (p < 0.05. The gender of the household head (males, their educational level

Effectiveness and Cost of Insecticide-Treated Bed Nets and Indoor Residual Spraying for the Control of Cutaneous Leishmaniasis: A Cluster-Randomized Control Trial in Morocco

Science.gov (United States)

Faraj, Chafika; Yukich, Joshua; Adlaoui, El Bachir; Wahabi, Rachid; Mnzava, Abraham Peter; Kaddaf, Mustapha; El Idrissi, Abderrahmane Laamrani; Ameur, Btissam; Kleinschmidt, Immo

2016-01-01

Cutaneous leishmaniasis (CL) remains an important public health problem in Morocco. A cluster-randomized trial was conducted with the following three study arms: 1) long-lasting insecticide-treated nets (LLINs) plus standard of care environmental management (SoC-EM), 2) indoor residual spraying (IRS) with α-cypermethrin plus SoC-EM, and 3) SoC-EM alone. Incidence of new CL cases by passive and active case detection, sandfly abundance, and cost and cost-effectiveness was compared between study arms over 5 years. Incidence of CL and sandfly abundance were significantly lower in the IRS arm compared with SoC-EM (CL incidence rate ratio = 0.32, 95% confidence interval [CI] = 0.15–0.69, P = 0.005 and sandfly abundance ratio = 0.39, 95% CI = 0.18–0.85, P = 0.022). Reductions in the LLIN arm of the study were not significant, possibly due to poor compliance. IRS was effective and more cost-effective for the prevention of CL in Morocco. PMID:26811431

Do Size and Insecticide Treatment Matter? Evaluation of Different Nets against Phlebotomus argentipes, the Vector of Visceral Leishmaniasis in Nepal.

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Murari Lal Das

Full Text Available In the Indian subcontinent, Leishmania donovani, the parasite causing visceral leishmaniasis (VL is transmitted by the sand fly vector Phlebotomus argentipes. Long lasting insecticide treated nets (LN have been postulated as alternative or complement to Indoor Residual Spraying but there are few field studies evaluating the entomological efficacy of different nets against this vector. We conducted two crossover trials in a VL endemic area in Nepal to compare the barrier effect of (1 LN with different mesh sizes (156 holes/inch2 vs 625 holes/inch2 and (2 alpha-cypermethrin treated LN and untreated nets having the same mesh size (156 holes/inch2. Each crossover trial had two arms consisting of a sequence of two different nets for 8 nights. We used 10 cattle sheds per trial. A cow placed under the net was used as bait. CDC light traps placed inside the nets were used to evaluate the number of P. argentipes crossing the net barrier. Negative binomial generalized estimating equation (GEE population-averaged models adjusted by night and sequence were used to estimate the barrier effect of the different nets. The crossover trials conducted in a rural village in Morang district (South-eastern Nepal demonstrated that reducing the size of the holes in treated nets (625 holes/inch2 increased the barrier effect of LN by 77% (95% confidence interval (CI: 56%-88% compared with treated nets with larger holes (156 holes/inch2. Treating nets with alpha-cypermethrin reduced the number of P. argentipes captured inside the nets by 77% (95% CI: 27%-93% compared with untreated nets. The effectiveness and acceptability of finer mesh pyrethroid treated LN should be tested for VL prevention in a randomized controlled trial.

Enhanced protection against malaria by indoor residual spraying in addition to insecticide treated nets: is it dependent on transmission intensity or net usage?

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Philippa A West

Full Text Available Insecticide treated nets (ITNs and indoor residual spraying (IRS are effective vector control tools that protect against malaria. There is conflicting evidence regarding whether using ITNs and IRS in combination provides additional benefit over using either of these methods alone. This study investigated factors that may modify the effect of the combined use of IRS and ITNs compared to using ITNs alone on malaria infection prevalence.Secondary analysis was carried out on data from a cluster randomised trial in north-west Tanzania. 50 clusters received ITNs from a universal coverage campaign; of these 25 were randomly allocated to additionally receive two rounds of IRS in 2012. In cross-sectional household surveys children 0.5-14 years old were tested for Plasmodium falciparum infections (PfPR two, six and ten months after the first IRS round.IRS protected those sleeping under nets (OR = 0.38, 95%CI 0.26-0.57 and those who did not (OR = 0.43, 95%CI 0.29-0.63. The protective effect of IRS was not modified by community level ITN use (ITN use = 50%, OR = 0.46, 95%CI 0.28-0.74. The additional protection from IRS was similar in low (<10% PfPR, OR = 0.38, 95%CI 0.19-0.75 and high transmission areas (≥10% PfPR, OR = 0.34, 95%CI 0.18-0.67. ITN use was protective at the individual-level regardless of whether the village had been sprayed (OR = 0.83, 95%CI 0.70-0.98. Living in a sprayed village was protective regardless of whether the individual slept under an ITN last night (OR = 0.41, 95%CI 0.29-0.58.Implementing IRS in addition to ITNs was beneficial for individuals from villages with a wide range of transmission intensities and net utilisation levels. Net users received additional protection from IRS. ITNs were providing some individual protection, even in this area with high levels of pyrethroid insecticide resistance. These results demonstrate that there is a supplementary benefit of IRS even when ITNs are effective.ClinicalTrials.gov NCT01697852.

Effectiveness of antenatal clinics to deliver intermittent preventive treatment and insecticide treated nets for the control of malaria in pregnancy in Kenya

NARCIS (Netherlands)

Hill, Jenny; Dellicour, Stephanie; Bruce, Jane; Ouma, Peter; Smedley, James; Otieno, Peter; Ombock, Maurice; Kariuki, Simon; Desai, Meghna; Hamel, Mary J.; ter Kuile, Feiko O.; Webster, Jayne

2013-01-01

Malaria in pregnancy can have devastating consequences for mother and baby. Coverage with the WHO prevention strategy for sub-Saharan Africa of intermittent-preventive-treatment (IPTp) with two doses of sulphadoxine-pyrimethamine (SP) and insecticide-treated-nets (ITNs) in pregnancy is low. We

Increased proportions of outdoor feeding among residual malaria vector populations following increased use of insecticide-treated nets in rural Tanzania

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Azizi Salum

2011-04-01

Full Text Available Abstract Background Insecticide-treated nets (ITNs and indoor residual spraying (IRS represent the front-line tools for malaria vector control globally, but are optimally effective where the majority of baseline transmission occurs indoors. In the surveyed area of rural southern Tanzania, bed net use steadily increased over the last decade, reducing malaria transmission intensity by 94%. Methods Starting before bed nets were introduced (1997, and then after two milestones of net use had been reached-75% community-wide use of untreated nets (2004 and then 47% use of ITNs (2009-hourly biting rates of malaria vectors from the Anopheles gambiae complex and Anopheles funestus group were surveyed. Results In 1997, An. gambiae s.l. and An. funestus mosquitoes exhibited a tendency to bite humans inside houses late at night. For An. gambiae s.l., by 2009, nocturnal activity was less (p = 0.0018. At this time, the sibling species composition of the complex had shifted from predominantly An. gambiae s.s. to predominantly An. arabiensis. For An. funestus, by 2009, nocturnal activity was less (p = 0.0054 as well as the proportion biting indoors (p An. funestus s.s. remained the predominant species within this group. As a consequence of these altered feeding patterns, the proportion (mean ± standard error of human contact with mosquitoes (bites per person per night occurring indoors dropped from 0.99 ± 0.002 in 1997 to 0.82 ± 0.008 in 2009 for the An. gambiae complex (p = 0.0143 and from 1.00 ± An. funestus complex (p = 0.0004 over the same time period. Conclusions High usage of ITNs can dramatically alter African vector populations so that intense, predominantly indoor transmission is replaced by greatly lowered residual transmission, a greater proportion of which occurs outdoors. Regardless of the underlying mechanism, the residual, self-sustaining transmission will respond poorly to further insecticidal measures within houses. Additional vector control

Effect of village-wide use of long-lasting insecticidal nets on visceral Leishmaniasis vectors in India and Nepal: a cluster randomized trial.

Science.gov (United States)

Picado, Albert; Das, Murari L; Kumar, Vijay; Kesari, Shreekant; Dinesh, Diwakar S; Roy, Lalita; Rijal, Suman; Das, Pradeep; Rowland, Mark; Sundar, Shyam; Coosemans, Marc; Boelaert, Marleen; Davies, Clive R

2010-01-26

Visceral leishmaniasis (VL) control in the Indian subcontinent is currently based on case detection and treatment, and on vector control using indoor residual spraying (IRS). The use of long-lasting insecticidal nets (LN) has been postulated as an alternative or complement to IRS. Here we tested the impact of comprehensive distribution of LN on the density of Phlebotomus argentipes in VL-endemic villages. A cluster-randomized controlled trial with household P. argentipes density as outcome was designed. Twelve clusters from an ongoing LN clinical trial--three intervention and three control clusters in both India and Nepal--were selected on the basis of accessibility and VL incidence. Ten houses per cluster selected on the basis of high pre-intervention P. argentipes density were monitored monthly for 12 months after distribution of LN using CDC light traps (LT) and mouth aspiration methods. Ten cattle sheds per cluster were also monitored by aspiration. A random effect linear regression model showed that the cluster-wide distribution of LNs significantly reduced the P. argentipes density/house by 24.9% (95% CI 1.80%-42.5%) as measured by means of LTs. The ongoing clinical trial, designed to measure the impact of LNs on VL incidence, will confirm whether LNs should be adopted as a control strategy in the regional VL elimination programs. The entomological evidence described here provides some evidence that LNs could be usefully deployed as part of the VL control program. ClinicalTrials.gov CT-2005-015374.

Equity and coverage of insecticide-treated bed nets in an area of intense transmission of Plasmodium falciparum in Tanzania

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Mtei Frank

2009-04-01

Full Text Available Abstract Background There is no clear consensus on the most sustainable and effective distribution strategy for insecticide treated bed nets (ITNs. Tanzania has been a leader in social marketing but it is still not clear if this can result in high and equitable levels of coverage. Methods A cluster-randomized survey of ITN and bed net ownership and use was conducted in a rural area exposed to intense Plasmodium falciparum transmission in NE Tanzania where ITN distribution had been subject to routine delivery of national strategies and episodic free distribution through local clinics. Data were collected on household assets to assess equity of ITN coverage and a rapid diagnostic test for malaria (RDT was performed in all ages. Results Among 598 households in four villages the use of any or insecticidal bed nets in children less than five years of age was 71% and 54% respectively. However there was a 19.8% increase in the number of bed nets per person (p Conclusion Marked inequity persists with the poorest households still experiencing the highest risk of malaria and the lowest ITN coverage. Abolition of this inequity within the foreseeable future is likely to require mass or targeted free distribution, but risks damaging what is otherwise an effective commercial market.

Impact of mass distribution of free long-lasting insecticidal nets on childhood malaria morbidity: The Togo National Integrated Child Health Campaign

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Sodahlon Yao K

2010-07-01

Full Text Available Abstract Background An evaluation of the short-term impact on childhood malaria morbidity of mass distribution of free long-lasting insecticidal nets (LLINs to households with children aged 9-59 months as part of the Togo National Integrated Child Health Campaign. Methods The prevalence of anaemia and malaria in children aged zero to 59 months was measured during two cross-sectional household cluster-sample surveys conducted during the peak malaria transmission, three months before (Sept 2004, n = 2521 and nine months after the campaign (Sept 2005, n = 2813 in three districts representative of Togo's three epidemiological malaria transmission regions: southern tropical coastal plains (Yoto, central fertile highlands (Ogou and northern semi-arid savannah (Tone. Results In households with children 65% in all 3 districts. Reported ITN use by children during the previous night was 35.9%, 43.8% and 80.6% in Yoto, Ogou and Tone, respectively. Rainfall patterns were comparable in both years. The overall prevalence of moderate to severe anaemia (Hb The effect was predominantly seen in children aged 18-59 months and in the two southern districts: PR (95% CI for moderate to severe anaemia and clinical malaria: Yoto 0.62 (0.44-0.88 and 0.49 (0.35-0.75; Ogou 0.54 (0.37-0.79 and 0.85 (0.57-1.27, respectively. Similar reductions occurred in children Conclusions A marked reduction in childhood malaria associated morbidity was observed in the year following mass distribution of free LLINs in two of the three districts in Togo. Sub-national level impact evaluations will contribute to a better understanding of the impact of expanding national malaria control efforts.

Material gain: bednets treated with insecticides improve the lives of ...

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

2011-07-15

... 700 mosquito nets each day, marketed under brand names such as "Health Net" and ... Material gain: bednets treated with insecticides improve the lives of Tanzanians. July 15, 2011. Image ... The kit is one of the key elements of PSI's Social Marketing of ... The national strategy will work to change this by involving the full ...

Modeling the effects of integrating larval habitat source reduction and insecticide treated nets for malaria control.

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Laith Yakob

Full Text Available Integrated vector management for malaria control has received a lot of recent interest. Attacking multiple points in the transmission cycle is hoped to act synergistically and improve upon current single-tool interventions based on the use of insecticide-treated bed nets (ITNs. In the present study, we theoretically examined the application of larval habitat source reduction with ITNs in reducing malaria transmission. We selected this type of environmental management to complement ITNs because of a potential secondary mode of action that both control strategies share. In addition to increasing vector mortality, ITNs reduce the rate at which female mosquitoes locate human hosts for blood feeding, thereby extending their gonotrophic cycle. Similarly, while reducing adult vector emergence and abundance, source reduction of larval habitats may prolong the cycle duration by extending delays in locating oviposition sites. We found, however, that source reduction of larval habitats only operates through this secondary mode of action when habitat density is below a critical threshold. Hence, we illustrate how this strategy becomes increasingly effective when larval habitats are limited. We also demonstrate that habitat source reduction is better suited to human populations of higher density and in the presence of insecticide resistance or when the insecticidal properties of ITNs are depleted.

Costs and effects of the Tanzanian national voucher scheme for insecticide-treated nets

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Hanson Kara

2008-02-01

Full Text Available Abstract Background The cost-effectiveness of insecticide-treated nets (ITNs in reducing morbidity and mortality is well established. International focus has now moved on to how best to scale up coverage and what financing mechanisms might be used to achieve this. The approach in Tanzania has been to deliver a targeted subsidy for those most vulnerable to the effects of malaria while at the same time providing support to the development of the commercial ITN distribution system. In October 2004, with funds from the Global Fund to Fight AIDS Tuberculosis and Malaria, the government launched the Tanzania National Voucher Scheme (TNVS, a nationwide discounted voucher scheme for ITNs for pregnant women and their infants. This paper analyses the costs and effects of the scheme and compares it with other approaches to distribution. Methods Economic costs were estimated using the ingredients approach whereby all resources required in the delivery of the intervention (including the user contribution are quantified and valued. Effects were measured in terms of number of vouchers used (and therefore nets delivered and treated nets years. Estimates were also made for the cost per malaria case and death averted. Results and Conclusion The total financial cost of the programme represents around 5% of the Ministry of Health's total budget. The average economic cost of delivering an ITN using the voucher scheme, including the user contribution, was $7.57. The cost-effectiveness results are within the benchmarks set by other malaria prevention studies. The Government of Tanzania's approach to scaling up ITNs uses both the public and private sectors in order to achieve and sustain the level of coverage required to meet the Abuja targets. The results presented here suggest that the TNVS is a cost-effective strategy for delivering subsidized ITNs to targeted vulnerable groups.

To assess whether indoor residual spraying can provide additional protection against clinical malaria over current best practice of long-lasting insecticidal mosquito nets in The Gambia: study protocol for a two-armed cluster-randomised trial

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Parker David

2011-06-01

Full Text Available Abstract Background Recently, there has been mounting interest in scaling-up vector control against malaria in Africa. It needs to be determined if indoor residual spraying (IRS with DDT will provide significant marginal protection against malaria over current best practice of long-lasting insecticidal nets (LLINs and prompt treatment in a controlled trial, given that DDT is currently the most persistent insecticide for IRS. Methods A 2 armed cluster-randomised controlled trial will be conducted to assess whether DDT IRS and LLINs combined provide better protection against clinical malaria in children than LLINs alone in rural Gambia. Each cluster will be a village, or a group of small adjacent villages; all clusters will receive LLINs and half will receive IRS in addition. Study children, aged 6 months to 13 years, will be enrolled from all clusters and followed for clinical malaria using passive case detection to estimate malaria incidence for 2 malaria transmission seasons in 2010 and 2011. This will be the primary endpoint. Exposure to malaria parasites will be assessed using light and exit traps followed by detection of Anopheles gambiae species and sporozoite infection. Study children will be surveyed at the end of each transmission season to estimate the prevalence of Plasmodium falciparum infection and the prevalence of anaemia. Discussion Practical issues concerning intervention implementation, as well as the potential benefits and risks of the study, are discussed. Trial Registration ISRCTN01738840 - Spraying And Nets Towards malaria Elimination (SANTE

Low Utilization of Insecticide-Treated Bed Net among Pregnant Women in the Middle Belt of Ghana

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Grace Manu

2017-01-01

Full Text Available Background. Malaria in pregnancy leads to low birth weight, premature birth, anaemia, and maternal and neonatal mortality. Use of insecticide-treated nets (ITNs during pregnancy is one of the proven interventions to reduce the malaria burden. However, Ghana has not achieved its target for ITN use among pregnant women. Methods. A qualitative study was conducted in seven communities purposively selected from the middle belt of Ghana. Participants who had delivered in the six months prior to this study were selected. In all, seven focus group discussions and twenty-four in-depth interviews were conducted between June and August 2010. Results. Respondents knew of the importance of ITNs and other malaria-preventive strategies. Factors such as financial access and missed opportunities of free distribution denied some pregnant women the opportunity to own or use an ITN. Reasons for not using ITNs during pregnancy included discomfort resulting from heat, smell of the net, and difficulty in hanging the net. Participants maintained their ITNs by preventing holes in the nets, retreatment, and infrequent washing. Conclusion. Pregnant women know about the causes and prevention of malaria. However, this knowledge is not transformed into practice due to lack of access to ITNs and sleeping discomforts among other logistical constraints.

Perceived Threat of Malaria and the Use of Insecticide Treated Bed ...

African Journals Online (AJOL)

2013-12-17

Dec 17, 2013 ... Keywords: malaria; children; insecticide treated nets; health belief model; .... including malaria, were usually handled by the only designated nurse. .... The familiar saying that “prevention is better and cheaper than cure” may ...

Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use

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Messenger Louisa A

2012-10-01

vector control product at the end of the trial (DL, IRS or LLITCs, DL consistently emerged as the most popular intervention regardless of the earlier household allocation. Conclusions Just as long-lasting insecticidal nets overcame several of the technical and logistical constraints associated with conventionally treated nets and then went to scale, this study demonstrates the potential of DL to sustain user compliance and overcome the operational challenges associated with IRS.

Decreased proportions of indoor feeding and endophily in Anopheles gambiae s.l. populations following the indoor residual spraying and insecticide-treated net interventions in Benin (West Africa).

Science.gov (United States)

Padonou, Gil Germain; Gbedjissi, Ghelus; Yadouleton, Anges; Azondekon, Roseric; Razack, Ossé; Oussou, Olivier; Gnanguenon, Virgile; Rock, Aikpon; Sezonlin, Michel; Akogbeto, Martin

2012-11-14

In many parts of Africa as in Benin, the main strategies of vector control are based on the scaling-up of Long Lasting Insecticide Treated Nets (LLITNs) and indoor residual spraying (IRS). The need to understand the biological implications of IRS in large scale and full coverage of LLITNs is paramount. It is in this context that the present study was conducted. It aims to evaluate the effect of a large scale IRS using a non-pyrethroid insecticide and full coverage of deltamethrin treated nets on the behavior of An. gambiae s.l. in the intervention areas compared to untreated areas used as controls. Mosquitoes were collected using human landing catches, pyrethrum spray catches and window exit traps to assess reduction of entry rate, endophily rate, endophagy rate and overall mortality rate in natural populations of An. gambiae s.l. before IRS and LLITNs intervention (2007) and after in 2008 and 2010. In the IRS arm, endophily rate was 67.13% before intervention and 4.5% after intervention, whereas in the control arm it was stable at 51.67% (P > 0 .05). In the LLITN arm endophily rates also decreased after intervention. After the IRS, no gravid mosquitoes were collected from all treated localities, but LLITN performance was not that spectacular. The proportion of mosquitoes biting indoors in the IRS arm decreased from 67.09% before intervention to 42.85% after intervention, compared to a low but significant decrease (71.31% to 57. 46%) in the LLITN arm.The use of vector control tools and behavior of the host would be the main factors that modify the behavior of taking a human blood meal observed on An. gambiae s.l. inside human dwellings. The impact on the behavior of An. gambiae s.l. observed with the bendiocarb used in IRS was highly effective compared with the free distribution of LLITNs in terms of mortality and the decrease of proportions of indoor feeding. Despite this efficacy, there is a need for complementary tools and research of alternative strategy

Decreased proportions of indoor feeding and endophily in Anopheles gambiae s.l. populations following the indoor residual spraying and insecticide-treated net interventions in Benin (West Africa

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Padonou Gil

2012-11-01

Full Text Available Abstract Background In many parts of Africa as in Benin, the main strategies of vector control are based on the scaling-up of Long Lasting Insecticide Treated Nets (LLITNs and indoor residual spraying (IRS. The need to understand the biological implications of IRS in large scale and full coverage of LLITNs is paramount. It is in this context that the present study was conducted. It aims to evaluate the effect of a large scale IRS using a non-pyrethroid insecticide and full coverage of deltamethrin treated nets on the behavior of An. gambiae s.l. in the intervention areas compared to untreated areas used as controls. Methods Mosquitoes were collected using human landing catches, pyrethrum spray catches and window exit traps to assess reduction of entry rate, endophily rate, endophagy rate and overall mortality rate in natural populations of An. gambiae s.l. before IRS and LLITNs intervention (2007 and after in 2008 and 2010. Results In the IRS arm, endophily rate was 67.13% before intervention and 4.5% after intervention, whereas in the control arm it was stable at 51.67% (P > 0 .05. In the LLITN arm endophily rates also decreased after intervention. After the IRS, no gravid mosquitoes were collected from all treated localities, but LLITN performance was not that spectacular. The proportion of mosquitoes biting indoors in the IRS arm decreased from 67.09% before intervention to 42.85% after intervention, compared to a low but significant decrease (71.31% to 57. 46% in the LLITN arm. The use of vector control tools and behavior of the host would be the main factors that modify the behavior of taking a human blood meal observed on An. gambiae s.l. inside human dwellings. Conclusion The impact on the behavior of An. gambiae s.l. observed with the bendiocarb used in IRS was highly effective compared with the free distribution of LLITNs in terms of mortality and the decrease of proportions of indoor feeding. Despite this efficacy, there is a need

Social determinants of long lasting insecticidal hammock use among the Ra-glai ethnic minority in Vietnam: implications for forest malaria control.

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Koen Peeters Grietens

Full Text Available BACKGROUND: Long-lasting insecticidal hammocks (LLIHs are being evaluated as an additional malaria prevention tool in settings where standard control strategies have a limited impact. This is the case among the Ra-glai ethnic minority communities of Ninh Thuan, one of the forested and mountainous provinces of Central Vietnam where malaria morbidity persist due to the sylvatic nature of the main malaria vector An. dirus and the dependence of the population on the forest for subsistence--as is the case for many impoverished ethnic minorities in Southeast Asia. METHODS: A social science study was carried out ancillary to a community-based cluster randomized trial on the effectiveness of LLIHs to control forest malaria. The social science research strategy consisted of a mixed methods study triangulating qualitative data from focused ethnography and quantitative data collected during a malariometric cross-sectional survey on a random sample of 2,045 study participants. RESULTS: To meet work requirements during the labor intensive malaria transmission and rainy season, Ra-glai slash and burn farmers combine living in government supported villages along the road with a second home at their fields located in the forest. LLIH use was evaluated in both locations. During daytime, LLIH use at village level was reported by 69.3% of all respondents, and in forest fields this was 73.2%. In the evening, 54.1% used the LLIHs in the villages, while at the fields this was 20.7%. At night, LLIH use was minimal, regardless of the location (village 4.4%; forest 6.4%. DISCUSSION: Despite the free distribution of insecticide-treated nets (ITNs and LLIHs, around half the local population remains largely unprotected when sleeping in their forest plot huts. In order to tackle forest malaria more effectively, control policies should explicitly target forest fields where ethnic minority farmers are more vulnerable to malaria.

Free distribution of insecticidal bed nets improves possession and preferential use by households and is equitable: findings from two cross-sectional surveys in thirteen malaria endemic districts of Bangladesh

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Ahmed Syed M

2011-12-01

Full Text Available Abstract Background BRAC, an indigenous non-governmental development organization (NGO, has been implementing a programme to prevent and control malaria in the 13 malaria-endemic districts of Bangladesh since 2007. One of the critical preventive interventions is the distribution of insecticidal bed nets (long-lasting insecticide-treated nets, LLINs and insecticide-treated ordinary nets, ITNs to the community free of cost. This study aimed to assess progress in the possession, preferential use, and knowledge on use of the LLIN/ITNs including the programme's avowed pro-poor inclination one and three and half years after intervention began. Methods A convenient sampling strategy based on malaria endemicity in the districts was adopted. First, thirty upazila (sub-district, with a population around 250,000s were selected at random, with high prevalent districts contributing more upazilas; second, from each upazila, one (2008 to two (2011 villages (covered by insecticidal bed net distribution programme were selected. From each village, households that had either one under-five child and/or a pregnant woman were included in the survey, one household being included only once. Data were collected using a pre-tested structured questionnaire. Results In all, 3,760 households in 2008 and 7,895 households in 2011 were surveyed for collecting relevant information. Proportion of households with at least one LLIN, and at least one LLIN/ITN increased (22-59 to 62-67% and 22-64% to 74-76% respectively over time, including increase in the mean number of LLIN/ITNs per household (≤ 1 to 1 +. The programme achieved > 80% coverage in sleeping under an LLIN/ITN in the case of under-five children and pregnant women, especially in the high-endemic districts. Knowledge regarding critical time of hanging the net also increased over time (7-22 to 44-54%, but remained low. The pro-poor inclination of the programme is reflected in the status of relevant indicators according

Efficacy of PermaNet® 2.0 and PermaNet® 3.0 against insecticide-resistant Anopheles gambiae in experimental huts in Côte d'Ivoire

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Koffi Alphonsine A

2011-06-01

Full Text Available Abstract Background Pyrethroid resistance in vectors could limit the efficacy of long-lasting insecticidal nets (LLINs because all LLINs are currently treated with pyrethroids. The goal of this study was to evaluate the efficacy and wash resistance of PermaNet® 3.0 compared to PermaNet® 2.0 in an area of high pyrethroid in Côte d'Ivoire. PermaNet® 3.0 is impregnated with deltamethrin at 85 mg/m2 on the sides of the net and with deltamethrin and piperonyl butoxide on the roof. PermaNet® 2.0 is impregnated with deltamethrin at 55 mg/m2 across the entire net. Methods The study was conducted in the station of Yaokoffikro, in central Côte d'Ivoire. The efficacy of intact unwashed and washed LLINs was compared over a 12-week period with a conventionally-treated net (CTN washed to just before exhaustion. WHO cone bioassays were performed on sub-sections of the nets, using wild-resistant An. gambiae and Kisumu strains. Mosquitoes were collected five days per week and were identified to genus and species level and classified as dead or alive, then unfed or blood-fed. Results Mortality rates of over 80% from cone bioassays with wild-caught pyrethroid-resistant An. gambiae s.s were recorded only with unwashed PermaNet® 3.0. Over 12 weeks, a total of 7,291 mosquitoes were collected. There were significantly more An. gambiae s.s. and Culex spp. caught in control huts than with other treatments (P An. gambiae s.s and Culex spp, were lower for the control than for other treatments (P 0.05 except for unwashed PermaNet® 3.0 (P Conclusions This study showed that unwashed PermaNet® 3.0 caused significantly higher mortality against pyrethroid resistant An. gambiae s.s and Culex spp than PermaNet® 2.0 and the CTN. The increased efficacy with unwashed PermaNet® 3.0 over PermaNet® 2.0 and the CTN was also demonstrated by higher KD and mortality rates (KD > 95% and mortality rate > 80% in cone bioassays performed with wild pyrethroid-resistant An. gambiae s

Different delivery mechanisms for insecticide-treated nets in rural Burkina Faso: a provider's perspective.

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Beiersmann, Claudia; De Allegri, Manuela; Tiendrebéogo, Justin; Yé, Maurice; Jahn, Albrecht; Mueller, Olaf

2010-12-04

Insecticide-treated nets (ITNs) have been confirmed to be a very effective tool in malaria control. Two different delivery strategies for roll-out of ITN programmes have been the focus of debate in the last years: free distribution and distribution through commercial marketing systems. They are now seen as complementary rather than opponent. Acceptance of these programmes by the community and involved providers is an important aspect influencing their sustainability. This paper looks at how providers perceived, understood and accepted two interventions involving two different delivery strategies (subsidized sales supported by social marketing and free distribution to pregnant women attending antenatal care services). The interventions took place in one province of north-western Burkina Faso in 2006 in the frame of a large randomized controlled ITN intervention study. For this descriptive qualitative study data were collected through focus group discussions and individual interviews. A total of four focus group discussions and eleven individual interviews have been conducted with the providers of the study interventions. The free distribution intervention was well accepted and perceived as running well. The health care staff had a positive and beneficial view of the intervention and did not feel overwhelmed by the additional workload. The social marketing intervention was also seen as positive by the rural shopkeepers. However, working in market economy, shopkeepers feared the risk of unsold ITNs, due to the low demand and capacity to pay for the product in the community. The combination of ITN free distribution and social marketing was in general well accepted by the different providers. However, low purchasing power of clients and the resulting financial insecurities of shopkeepers remain a challenge to ITN social marketing in rural SSA.

Individual and household factors associated with ownership of long-lasting insecticidal nets and malaria infection in south-central Ethiopia: a case-control study.

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Deressa, Wakgari

2017-10-06

A recent considerable decline in malaria morbidity and mortality in Ethiopia is likely to be followed by changes in the practice of effective preventive measures and malaria risk factors. This study aimed to identify determinants of long-lasting insecticidal nets (LLINs) ownership and risk of malaria infection. A matched case-control study of 191 case and 377 control households was conducted between October 2014 and November 2015 in Adami Tullu district in south-central Ethiopia. Cases were microscopy or rapid diagnostic test confirmed malaria patients identified at three health centers and nine health posts, and matched on age with two neighbourhood controls. Information was collected on socio-demographic factors, house structure, knowledge on malaria and ownership of LLINs. The logistic regression model was used to determine predictors of LLINs ownership and malaria infection. All cases were infections due to either Plasmodium falciparum (71.2%) or Plasmodium vivax (28.8%). About 31% of the study households had at least one LLINs. Significant determinants of LLINs ownership were household's head malaria knowledge [adjusted odds ratio (AOR) = 2.47, 95% confidence interval (CI) 1.44-4.22], educational status [read and write (AOR = 6.88, 95% CI 2.30-20.55), primary education or higher (AOR = 5.40, 95% CI 1.57-18.55)], farmer respondent (AOR = 0.35, 95% CI 0.17-0.76), having ≥ 3 sleeping areas (AOR = 6.71, 95% CI 2.40-18.77) and corrugated roof type (AOR = 2.49, 95% CI 1.36-4.58). This study was unable to identify important risk factors of malaria infection with regard to sex, household wealth index, house structure, ownership of LLINs, keeping livestock inside house, staying overnight outdoor or having malaria during the last 6 months. Household socio-economic status, educational status and knowledge on malaria were important predictors of LLINs ownership. Households with farmer respondents were less likely to own LLINs. Addressing these factors

Factors Influencing the Usage of Insecticide Treated Mosquito Nets ...

African Journals Online (AJOL)

Purpose: Malaria in Sudan is a leading cause of morbidity and mortality. ... treated mosquito nets (ITNs) for prevention of malaria among pregnant women. ... on malaria causes, 103 (99%) had good knowledge on malaria complications and ... and accessibility to ITNs were significantly associated with current usage of ITNs.

Wash-resistance of pirimiphos-methyl insecticide treatments of window screens and eave baffles for killing indoor-feeding malaria vector mosquitoes: an experimental hut trial, South East of Zambia.

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Chinula, Dingani; Sikaala, Chadwick H; Chanda-Kapata, Pascalina; Hamainza, Busiku; Zulu, Reuben; Reimer, Lisa; Chizema, Elizabeth; Kiware, Samson; Okumu, Fredros O; Killeen, Gerry

2018-04-13

The effectiveness of long-lasting insecticidal-treated nets (LLINs) and indoor residual spraying (IRS) for malaria control is threatened by resistance to commonly used pyrethroid insecticides. Rotations, mosaics, combinations, or mixtures of insecticides from different complementary classes are recommended by the World Health Organization (WHO) for mitigating against resistance, but many of the alternatives to pyrethroids are prohibitively expensive to apply in large national IRS campaigns. Recent evaluations of window screens and eave baffles (WSEBs) treated with pirimiphos-methyl (PM), to selectively target insecticides inside houses, demonstrated malaria vector mortality rates equivalent or superior to IRS. However, the durability of efficacy when co-applied with polyacrylate-binding agents (BA) remains to be established. This study evaluated whether WSEBs, co-treated with PM and BA have comparable wash resistance to LLINs and might therefore remain insecticidal for years rather than months. WHO-recommended wire ball assays of insecticidal efficacy were applied to polyester netting treated with or without BA plus 1 or 2 g/sq m PM. They were then tested for insecticidal efficacy using fully susceptible insectary-reared Anopheles gambiae mosquitoes, following 0, 5, 10, 15, then 20 washes as per WHO-recommended protocols for accelerated ageing of LLINs. This was followed by a small-scale field trial in experimental huts to measure malaria vector mortality achieved by polyester netting WSEBs treated with BA and 2 g/sq m PM after 0, 10 and then 20 standardized washes, alongside recently applied IRS using PM. Co-treatment with BA and either dosage of PM remained insecticidal over 20 washes in the laboratory. In experimental huts, WSEBs treated with PM plus BA consistently killed similar proportions of Anopheles arabiensis mosquitoes to PM-IRS (both consistently ≥ 94%), even after 20 washes. Co-treating WSEBs with both PM and BA results in wash

Insecticide-treated bed nets reduce plasma antibody levels and limit the repertoire of antibodies to Plasmodium falciparum variant surface antigens

DEFF Research Database (Denmark)

Askjaer, N; Maxwell, C; Chambo, W

2001-01-01

The use of insecticide-treated bed nets (ITN) has been documented to reduce malaria morbidity and mortality in areas with endemic malaria, but concerns have been raised that ITN usage could affect the acquisition of malaria immunity. Several lines of evidence have indicated that antibodies against...... variant surface antigens (VSA) are important in the development of naturally acquired immunity to Plasmodium falciparum malaria and may thus be good indicators of immune status. We have compared the levels of VSA antibodies in plasma from children who have used ITN for 4 years to levels in plasma from...

Human exposure to anopheline mosquitoes occurs primarily indoors, even for users of insecticide-treated nets in Luangwa Valley, South-east Zambia

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Seyoum Aklilu

2012-05-01

Full Text Available Abstract Background Current front line malaria vector control methods such as indoor residual spraying (IRS and long-lasting insecticidal nets (LLINs, rely upon the preference of many primary vectors to feed and/or rest inside human habitations where they can be targeted with domestically-applied insecticidal products. We studied the human biting behaviour of the malaria vector Anopheles funestus Giles and the potential malaria vector Anopheles quadriannulatus Theobald in Luangwa valley, south-east Zambia. Methods Mosquitoes were collected by human landing catch in blocks of houses with either combined use of deltamethrin-based IRS and LLINs or LLINs alone. Human behaviour data were collected to estimate how much exposure to mosquito bites indoors and outdoors occurred at various times of the night for LLIN users and non-users. Results Anopheles funestus and An. quadriannulatus did not show preference to bite either indoors or outdoors: the proportions [95% confidence interval] caught indoors were 0.586 [0.303, 0.821] and 0.624 [0.324, 0.852], respectively. However, the overwhelming majority of both species were caught at times when most people are indoors. The proportion of mosquitoes caught at a time when most people are indoors were 0.981 [0.881, 0.997] and 0.897 [0.731, 0.965], respectively, so the proportion of human exposure to both species occuring indoors was high for individuals lacking LLINs (An. funestus: 0.983 and An. quadriannulatus: 0.970, respectively. While LLIN users were better protected, more than half of their exposure was nevertheless estimated to occur indoors (An. funestus: 0.570 and An. quadriannulatus: 0.584. Conclusions The proportion of human exposure to both An. funestus and An. quadriannulatus occuring indoors was high in the area and hence both species might be responsive to further peri-domestic measures if these mosquitoes are susceptible to insecticidal products.

Different delivery mechanisms for insecticide-treated nets in rural Burkina Faso: a provider's perspective

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Jahn Albrecht

2010-12-01

Full Text Available Abstract Background Insecticide-treated nets (ITNs have been confirmed to be a very effective tool in malaria control. Two different delivery strategies for roll-out of ITN programmes have been the focus of debate in the last years: free distribution and distribution through commercial marketing systems. They are now seen as complementary rather than opponent. Acceptance of these programmes by the community and involved providers is an important aspect influencing their sustainability. This paper looks at how providers perceived, understood and accepted two interventions involving two different delivery strategies (subsidized sales supported by social marketing and free distribution to pregnant women attending antenatal care services. Methods The interventions took place in one province of north-western Burkina Faso in 2006 in the frame of a large randomized controlled ITN intervention study. For this descriptive qualitative study data were collected through focus group discussions and individual interviews. A total of four focus group discussions and eleven individual interviews have been conducted with the providers of the study interventions. Results The free distribution intervention was well accepted and perceived as running well. The health care staff had a positive and beneficial view of the intervention and did not feel overwhelmed by the additional workload. The social marketing intervention was also seen as positive by the rural shopkeepers. However, working in market economy, shopkeepers feared the risk of unsold ITNs, due to the low demand and capacity to pay for the product in the community. Conclusion The combination of ITN free distribution and social marketing was in general well accepted by the different providers. However, low purchasing power of clients and the resulting financial insecurities of shopkeepers remain a challenge to ITN social marketing in rural SSA.

Coverage of intermittent preventive treatment and insecticide-treated nets for the control of malaria during pregnancy in sub-Saharan Africa: a synthesis and meta-analysis of national survey data, 2009-11

NARCIS (Netherlands)

van Eijk, Anna Maria; Hill, Jenny; Larsen, David A.; Webster, Jayne; Steketee, Richard W.; Eisele, Thomas P.; ter Kuile, Feiko O.

2013-01-01

Pregnant women in malaria-endemic countries in sub-Saharan Africa are especially vulnerable to malaria. Recommended prevention strategies include intermittent preventive treatment with two doses of sulfadoxine-pyrimethamine and the use of insecticide-treated nets. However, progress with

Malaria in pregnant women in an area with sustained high coverage of insecticide-treated bed nets

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Mshinda Hassan

2008-07-01

Full Text Available Abstract Background Since 2000, the World Health Organization has recommended a package of interventions to prevent malaria during pregnancy and its sequelae that includes the promotion of insecticide-treated bed nets (ITNs, intermittent preventive treatment in pregnancy (IPTp, and effective case management of malarial illness. It is recommended that pregnant women in malaria-endemic areas receive at least two doses of sulphadoxine-pyrimethamine in the second and third trimesters of pregnancy. This study assessed the prevalence of placental malaria at delivery in women during 1st or 2nd pregnancy, who did not receive intermittent preventive treatment for malaria (IPTp in a malaria-endemic area with high bed net coverage. Methods A hospital-based cross-sectional study was done in Ifakara, Tanzania, where bed net coverage is high. Primi- and secundigravid women, who presented to the labour ward and who reported not using IPTp were included in the study. Self-report data were collected by questionnaire; whereas neonatal birth weight and placenta parasitaemia were measured directly at the time of delivery. Results Overall, 413 pregnant women were enrolled of which 91% reported to have slept under a bed net at home the previous night, 43% reported history of fever and 62% were primigravid. Malaria parasites were detected in 8% of the placenta samples; the geometric mean (95%CI placental parasite density was 3,457 (1,060–11,271 parasites/μl in primigravid women and 2,178 (881–5,383 parasites/μl in secundigravid women. Fifteen percent of newborns weighed Conclusion The observed incidence of LBW and prevalence of placental parasitaemia at delivery suggests that malaria remains a problem in pregnancy in this area with high bed net coverage when eligible women do not receive IPTp. Delivery of IPTp should be emphasized at all levels of implementation to achieve maximum community coverage.

Insecticide-treated net ownership and utilization and factors that influence their use in Itang, Gambella region, Ethiopia: cross-sectional study

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Watiro AH

2016-05-01

Full Text Available Aklilu Habte Watiro,1 Worku Awoke,2 1Médecins Sans Frontières OCA (MSF Holland Ethiopia Mission, Addis Ababa, 2Department of Epidemiology, School of Public Health, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia Background: Malaria remains a major public health problem in Ethiopia. Consequently, Ethiopia designed the 2011–2015, Malaria Prevention and Control Strategic Plan to fight the vector. It was discovered that most of the studies conducted on the use of insecticide-treated nets (ITNs were not in line with the strategic plan of the country. This study aimed to assess ITN ownership and utilization, and includes barriers related to its use among the target-area population at household (HH level. Materials and methods: A cross-sectional design was employed in Itang for this study. Data were collected by trained nurses through face-to-face interview and observation. A total of 845 participants were selected through multistage sampling, and the size was determined by using a single-population proportion formula. EPI Info and SPSS was used for analysis, and all necessary statistical association was computed in order to explain the outcome variable through explanatory variables of this study. Results: Among 845 HHs interviewed, 81.7% (690 had at least one ITN, while 52.3% (361 had used the ITN the night preceding the data-collection day. HH awareness of malaria prevention, number of ITNs, family size, number of family members sharing sleeping area/beds, sleeping patterns of adolescents, HH-head age, and inconvenience of using ITNs were found to be barriers to the use of ITNs in this study. Conclusion and recommendation: The study concluded that very few HHs owned ITNs and there was very low usage of ITNs. In recommendation, the regional health bureau and district health office should consider bigger nets that can accommodate family members who share the same sleeping area/bed in the area. Keywords: consistent

Increasing coverage and decreasing inequity in insecticide-treated bed net use among rural Kenyan children.

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Abdisalan M Noor

2007-08-01

Full Text Available Inexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs. In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups.We undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0-4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004, the introduction of heavily subsidized nets through clinics (2005, and the introduction of free mass distributed ITNs (2006. The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281; 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131, and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000. The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of the least poor, and the commercial

Bed net ownership in Kenya: the impact of 3.4 million free bed nets

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Vulule John

2010-06-01

Full Text Available Abstract Background In July and September 2006, 3.4 million long-lasting insecticide-treated bed nets (LLINs were distributed free in a campaign targeting children 0-59 months old (CU5s in the 46 districts with malaria in Kenya. A survey was conducted one month after the distribution to evaluate who received campaign LLINs, who owned insecticide-treated bed nets and other bed nets received through other channels, and how these nets were being used. The feasibility of a distribution strategy aimed at a high-risk target group to meet bed net ownership and usage targets is evaluated. Methods A stratified, two-stage cluster survey sampled districts and enumeration areas with probability proportional to size. Handheld computers (PDAs with attached global positioning systems (GPS were used to develop the sampling frame, guide interviewers back to chosen households, and collect survey data. Results In targeted areas, 67.5% (95% CI: 64.6, 70.3% of all households with CU5s received campaign LLINs. Including previously owned nets, 74.4% (95% CI: 71.8, 77.0% of all households with CU5s had an ITN. Over half of CU5s (51.7%, 95% CI: 48.8, 54.7% slept under an ITN during the previous evening. Nearly forty percent (39.1% of all households received a campaign net, elevating overall household ownership of ITNs to 50.7% (95% CI: 48.4, 52.9%. Conclusions The campaign was successful in reaching the target population, families with CU5s, the risk group most vulnerable to malaria. Targeted distribution strategies will help Kenya approach indicator targets, but will need to be combined with other strategies to achieve desired population coverage levels.

Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study

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Irish SR

2008-06-01

Full Text Available Abstract Background An important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time. Results There was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6–57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9–13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets. Conclusion As nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes.

Determinants of insecticide-treated net ownership and utilization among pregnant women in Nigeria

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Ankomah Augustine

2012-02-01

Full Text Available Abstract Background Malaria during pregnancy is a major public health problem in Nigeria leading to increase in the risk of maternal mortality, low birth weight and infant mortality. This paper is aimed at highlighting key predictors of the ownership of insecticide treated nets (ITNs and its use among pregnant women in Nigeria. Methods A total of 2348 pregnant women were selected by a multi-stage probability sampling technique. Structured interview schedule was used to elicit information on socio-demographic characteristics, ITN ownership, use, knowledge, behaviour and practices. Logistic regression was used to detect predictors of two indicators: ITN ownership, and ITN use in pregnancy among those who owned ITNs. Results ITN ownership was low; only 28.8% owned ITNs. Key predictors of ITN ownership included women who knew that ITNs prevent malaria (OR = 3.85; p p = 0.003. The use of ITNs was equally low with only 7.5% of all pregnant women, and 25.7% of all pregnant women who owned ITNs sleeping under a net. The predictors of ITN use in pregnancy among women who owned ITNs (N = 677 identified by logistic regression were: urban residence (OR = 1.87; p = 0.001; knowledge that ITNs prevent malaria (OR = 2.93; p p = 0.036. Educational level was not significantly related to any of the two outcome variables. Although registration at ANC is significantly associated with ownership of a bednet (perhaps through free ITN distribution this does not translate to significant use of ITNs. Conclusions ITN use lagged well behind ITN ownership. This seems to suggest that the current mass distribution of ITNs at antenatal facilities and community levels may not necessarily lead to use unless it is accompanied by behaviour change interventions that address the community level perceptions, misconceptions and positively position ITN as an effective prevention device to prevent malaria

The Effect of Mass Media Campaign on the Use of Insecticide-Treated Bed Nets among Pregnant Women in Nigeria

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A. Ankomah

2014-01-01

Full Text Available Background. Malaria during pregnancy is a major public health problem in Nigeria especially in malaria-endemic areas. It increases the risk of low birth weight and child/maternal morbidity/mortality. This paper addresses the impact of radio campaigns on the use of insecticide-treated bed nets among pregnant women in Nigeria. Methods. A total of 2,348 pregnant women were interviewed during the survey across 21 of Nigeria’s 36 states. Respondents were selected through a multistage sampling technique. Analysis was based on multivariate logistic regression. Results. Respondents who knew that sleeping under ITN prevents malaria were 3.2 times more likely to sleep under net (OR: 3.15; 95% CI: 2.28 to 4.33; P<0.0001. Those who listened to radio are also about 1.6 times more likely to use ITN (OR: 1.56; 95% CI: 1.07 to 2.28; P=0.020, while respondents who had heard of a specific sponsored radio campaign on ITN are 1.53 times more likely to use a bed net (P=0.019. Conclusion. Pregnant women who listened to mass media campaigns were more likely to adopt strategies to protect themselves from malaria. Therefore, behavior change communication messages that are aimed at promoting net use and antenatal attendance are necessary in combating malaria.

Insecticidal and sterilizing effect of Olyset Duo (R), a permethrin and pyriproxyfen mixture net against pyrethroid-susceptible and -resistant strains of Anopheles gambiae s.s. : a release-recapture assay in experimental huts

OpenAIRE

Djènontin, A.; Alou, L. P. A.; Koffi, A.; Zogo, B.; Duarte, E.; N'Guessan, R.; Moiroux, Nicolas; Pennetier, Cédric

2015-01-01

In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN), Olyset (R) Duo, incorporating a mixture of permethrin (PER) and the insect growth regulator (IGR), pyriproxyfen (PPF). An LN containing PPF alone and a classic Olyset (R) Net were tested in parallel as positive controls. The effect of progressive number of ho...

Changes in malaria burden and transmission in sentinel sites after the roll-out of long-lasting insecticidal nets in Papua New Guinea.

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Hetzel, Manuel W; Reimer, Lisa J; Gideon, Gibson; Koimbu, Gussy; Barnadas, Céline; Makita, Leo; Siba, Peter M; Mueller, Ivo

2016-06-14

Papua New Guinea exhibits a complex malaria epidemiology due to diversity in malaria parasites, mosquito vectors, human hosts, and their natural environment. Heterogeneities in transmission and burden of malaria at various scales are likely to affect the success of malaria control interventions, and vice-versa. This manuscript assesses changes in malaria prevalence, incidence and transmission in sentinel sites following the first national distribution of long-lasting insecticidal nets (LLINs). Before and after the distribution of LLINs, data collection in six purposively selected sentinel sites included clinical surveillance in the local health facility, household surveys and entomological surveys. Not all activities were carried out in all sites. Mosquitoes were collected by human landing catches. Diagnosis of malaria infection in humans was done by rapid diagnostic test, light microscopy and PCR for species confirmation. Following the roll-out of LLINs, the average monthly malaria incidence rate dropped from 13/1,000 population to 2/1,000 (incidence rate ratio = 0.12; 95 % CI: 0.09-0.17; P < 0.001). The average population prevalence of malaria decreased from 15.7 % pre-LLIN to 4.8 % post-LLIN (adjusted odds ratio = 0.26; 95 % CI: 0.20-0.33; P < 0.001). In general, reductions in incidence and prevalence were more pronounced in infections with P. falciparum than with P. vivax. Additional morbidity indicators (anaemia, splenomegaly, self-reported fever) showed a decreasing trend in most sites. Mean Anopheles man biting rates decreased from 83 bites/person/night pre-LLIN to 31 post-LLIN (P = 0.008). Anopheles species composition differed between sites but everywhere diversity was lower post-LLIN. In two sites, post-LLIN P. vivax infections in anophelines had decreased but P. falciparum infections had increased despite the opposite observation in humans. LLIN distribution had distinct effects on P. falciparum and P. vivax. Higher resilience of

Efficacy of PermaNet® 3.0 and PermaNet® 2.0 nets against laboratory-reared and wild Anopheles gambiae sensu lato populations in northern Tanzania.

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Kweka, Eliningaya J; Lyaruu, Lucile J; Mahande, Aneth M

2017-01-18

Mosquitoes have developed resistance against pyrethroids, the only class of insecticides approved for use on long-lasting insecticidal nets (LLINs). The present study sought to evaluate the efficacy of the pyrethroid synergist PermaNet® 3.0 LLIN versus the pyrethroid-only PermaNet® 2.0 LLIN, in an East African hut design in Lower Moshi, northern Tanzania. In this setting, resistance to pyrethroid insecticides has been identified in Anopheles gambiae mosquitoes. Standard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area where there was presence of a population of highly pyrethroid-resistant An. arabiensis mosquitoes. All nets used were subjected to cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition and personal protection rate were compared between untreated nets, unwashed LLINs and LLINs that were washed 20 times. Both washed and unwashed PermaNet® 2.0 and PermaNet® 3.0 LLINs had knockdown and mortality rates of 100% against a susceptible strain of An. gambiae sensu stricto. The adjusted mortality rate of the wild mosquito population after use of the unwashed PermaNet® 3.0 and PermaNet® 2.0 nets was found to be higher than after use of the washed PermaNet® 2.0 and PermaNet® 3.0 nets. Given the increasing incidence of pyrethroid resistance in An. gambiae mosquitoes in Tanzania, we recommend that consideration is given to its distribution in areas with pyrethroid-resistant malaria vectors within the framework of a national insecticide-resistance management plan.

Preventing childhood malaria in Africa by protecting adults from mosquitoes with insecticide-treated nets.

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Gerry F Killeen

2007-07-01

Full Text Available Malaria prevention in Africa merits particular attention as the world strives toward a better life for the poorest. Insecticide-treated nets (ITNs represent a practical means to prevent malaria in Africa, so scaling up coverage to at least 80% of young children and pregnant women by 2010 is integral to the Millennium Development Goals (MDG. Targeting individual protection to vulnerable groups is an accepted priority, but community-level impacts of broader population coverage are largely ignored even though they may be just as important. We therefore estimated coverage thresholds for entire populations at which individual- and community-level protection are equivalent, representing rational targets for ITN coverage beyond vulnerable groups.Using field-parameterized malaria transmission models, we show that high (80% use but exclusively targeted coverage of young children and pregnant women (representing <20% of the population will deliver limited protection and equity for these vulnerable groups. In contrast, relatively modest coverage (35%-65% use, with this threshold depending on ecological scenario and net quality of all adults and children, rather than just vulnerable groups, can achieve equitable community-wide benefits equivalent to or greater than personal protection.Coverage of entire populations will be required to accomplish large reductions of the malaria burden in Africa. While coverage of vulnerable groups should still be prioritized, the equitable and communal benefits of wide-scale ITN use by older children and adults should be explicitly promoted and evaluated by national malaria control programmes. ITN use by the majority of entire populations could protect all children in such communities, even those not actually covered by achieving existing personal protection targets of the MDG, Roll Back Malaria Partnership, or the US President's Malaria Initiative.

Insecticide-treated nets for the prevention of malaria in pregnancy: a systematic review of randomised controlled trials.

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Carol Gamble

2007-03-01

Full Text Available BACKGROUND: Protection from malaria with insecticide-treated bednets (ITNs during pregnancy is widely advocated, but evidence of benefit has been inconsistent. We undertook a systematic review of randomised trials. METHODS AND FINDINGS: Three cluster-randomised and two individually randomised trials met the inclusion criteria; four from Africa (n = 6,418 and one from Thailand (n = 223. In Africa, ITNs compared to no nets increased mean birth weight by 55 g (95% confidence interval [CI] 21-88, reduced low birth weight by 23% (relative risk [RR] 0.77, 95% CI 0.61-0.98, and reduced miscarriages/stillbirths by 33% (RR 0.67, 0.47-0.97 in the first few pregnancies. Placental parasitaemia was reduced by 23% in all gravidae (RR 0.77, 0.66-0.90. The effects were apparent in the cluster-randomised trials and the one individually randomised trial in Africa. The trial in Thailand, which randomised individuals to ITNs or untreated nets, showed reductions in anaemia and fetal loss in all gravidae, but not reductions in clinical malaria or low birth weight. CONCLUSIONS: ITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies. The potential impact of ITNs in pregnant women and their newborns in malaria regions outside Africa requires further research.

An exploratory study of treated-bed nets in Timor-Leste: patterns of intended and alternative usage

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Wilder-Smith Annelies

2011-07-01

Full Text Available Abstract Background The Timor-Leste Ministry of Health has recently finalized the National Malaria Control Strategy for 2010-2020. A key component of this roadmap is to provide universal national coverage with long-lasting insecticide-treated nets (LLINs in support of achieving the primary goal of reducing both morbidity and mortality from malaria by 30% in the first three years, followed by a further reduction of 20% by end of the programme cycle in 2020 1. The strategic plan calls for this target to be supported by a comprehensive information, education and communication (IEC programme; however, there is limited prior research into household and personal usage patterns to assist in the creation of targeted, effective, and socio-culturally specific behaviour change materials. Methods Nine separate focus group discussions (FGDs were carried out in Dili, Manatuto, and Covalima districts, Democratic Republic of Timor-Leste, in July 2010. These focus groups primarily explored themes of perceived malaria risk, causes of malaria, net usage patterns within families, barriers to correct and consistent usage, and the daily experience of users (both male and female in households with at least one net. Comprehensive qualitative analysis utilized open source analysis software. Results The primary determinants of net usage were a widespread perception that nets could or should only be used by pregnant women and young children, and the availability of sufficient sleeping space under a limited number of nets within households. Both nuisance biting and disease prevention were commonly cited as primary motivations for usage, while seasonality was not a significant factor. Long-term net durability and ease of hanging were seen as key attributes in net design preference. Very frequent washing cycles were common, potentially degrading net effectiveness. Finally, extensive re-purposing of nets (fishing, protecting crops was both reported and observed, and may

The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control.

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Oxborough, Richard M; N'Guessan, Raphael; Jones, Rebecca; Kitau, Jovin; Ngufor, Corine; Malone, David; Mosha, Franklin W; Rowland, Mark W

2015-03-24

The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides. The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission. Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically

Underpinning sustainable vector control through informed insecticide resistance management.

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Edward K Thomsen

Full Text Available There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions.A country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s.Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan.

Ownership and use of insecticide-treated nets during pregnancy in sub-Saharan Africa: a review.

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Singh, Megha; Brown, Graham; Rogerson, Stephen J

2013-08-01

Over the past decade, significant gains have been made in the implementation of malaria prevention measures in pregnancy in sub-Saharan Africa, including the distribution of insecticide-treated nets (ITNs). These have been shown to cause a reduction in the incidence of malaria and its consequences such as maternal anaemia, stillbirths and intrauterine growth restriction. Currently most nations in Africa have policies for distributing ITNs to pregnant women through various mechanisms, however coverage remains well below the targets. This review summarizes recent evidence regarding the correlation between ownership and use of ITNs and the determinants of both, in pregnancy in sub-Saharan Africa, and reviews interventions directed at improving coverage. A review of the literature using Pubmed, CINAHL and scanning of reference lists was conducted in October 2012 and 59 articles were selected for final review. The research obtained was a mixture of national and district level surveys, and a narrative synthesis of the data was undertaken. Ownership of ITNs varied from as low as 3% to greater than 80%, and the main determinants were found to be education level, knowledge of malaria, community involvement, socio-economic status and parity, although the significance of each varied between the different settings and studies reviewed. In more than half the settings where data were available, the combination of lack of availability and lack of use of an available net meant that less than half of all pregnancies received the recommended intervention. Supply and cost remain major barriers to achieving optimal coverage, but the additional important contributor to reduced efficiency of intervention was the clear discrepancy between ownership and use, with available ITN use below 60% in several settings. Cited reasons for not using an ITN, where one was available, included discomfort, problems with hanging up nets and lack of space, low awareness of need, and seasonal variations in

Prevalence of malaria across Papua New Guinea after initial roll-out of insecticide-treated mosquito nets.

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Hetzel, Manuel W; Morris, Hector; Tarongka, Nandao; Barnadas, Céline; Pulford, Justin; Makita, Leo; Siba, Peter M; Mueller, Ivo

2015-12-01

To assess the population prevalence of malaria in villages across Papua New Guinea (PNG) following the first roll-out of free long-lasting insecticidal nets (LLIN). Between October 2008 and August 2009, a household survey was conducted in 49 random villages in districts covered by the LLIN distribution campaign. The survey extended to 19 villages in sentinel sites that had not yet been covered by the campaign. In each village, 30 households were randomly sampled, household heads were interviewed and capillary blood samples were collected from all consenting household members for microscopic diagnosis of malaria. Malaria prevalence ranged from 0% to 49.7% with a weighted average of 12.1% (95% CI 9.5, 15.3) in the national sample. More people were infected with Plasmodium falciparum (7.0%; 95% CI 5.4, 9.1) than with P. vivax (3.8%; 95% CI 2.4, 5.7) or P. malariae (0.3%; 95% CI 0.1, 0.6). Parasitaemia was strongly age-dependent with a P. falciparum peak at age 5-9 years and a P. vivax peak at age 1-4 years, yet with differences between geographical regions. Individual LLIN use and high community coverage were associated with reduced odds of infection (OR = 0.64 and 0.07, respectively; both P < 0.001). Splenomegaly in children and anaemia were common morbidities attributable to malaria. Malaria prevalence across PNG is again at levels comparable to the 1970s. The strong association of LLIN use with reduced parasitaemia supports efforts to achieve and maintain high country-wide coverage. P. vivax infections will require special targeted approaches across PNG. © 2015 The Authors. Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

Mixture for Controlling Insecticide-Resistant Malaria Vectors

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Pennetier, Cédric; Costantini, Carlo; Corbel, Vincent; Licciardi, Séverine; Dabire, R. K.; Lapied, B.; Chandre, Fabrice; Hougard, Jean-Marc

2008-01-01

The spread of resistance to pyrethroids in the major Afrotropical malaria vectors Anopheles gambiae s.s. necessitates the development of new strategies to control resistant mosquito populations. To test the efficacy of nets treated with repellent and insecticide against susceptible and insecticide-resistant An. gambiae mosquito populations, we impregnated mosquito bed nets with an insect repellent mixed with a low dose of organophosphorous insecticide and tested them in a rice-growing area ne...

Efficacy of mosquito nets treated with a pyrethroid-organophosphorous mixture against Kdr- and Kdr+ malaria vectors (Anopheles gambiae

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Darriet F.

2003-12-01

Full Text Available In order to prevent the resistance of Anopheles gambiae s.l. to pyrethroids from spreading too quickly and to lengthen the effectiveness of insecticide impregnated mosquito nets, it has recently been suggested to use mixtures of insecticides that have different modes of action. This study presents the results obtained with tulle mosquito nets treated with bifenthrin (a pyrethroid] and chlorpyrifos-methyl (an organophosphorous both separately and in mixture on two strains of An. gambiae, one sensitive to all insecticides, and the other resistant to pyrethroids. The values of KDt50 and KDt95 and the mortality induced with the mixture of bifenthrin (25 mg/m2 and chlorpyrifos-methyl (4.5 mg/m2 show a significant synergistic effect on the strain of An. gambiae susceptible to insecticides. However, the tested combination does not induce any synergistic effect on the VKPR strain selected with permethrin, but only enhances the effectiveness of the two insecticides taken separately.

Control of Malaria Vector Mosquitoes by Insecticide-Treated Combinations of Window Screens and Eave Baffles.

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Killeen, Gerry F; Masalu, John P; Chinula, Dingani; Fotakis, Emmanouil A; Kavishe, Deogratius R; Malone, David; Okumu, Fredros

2017-05-01

We assessed window screens and eave baffles (WSEBs), which enable mosquitoes to enter but not exit houses, as an alternative to indoor residual spraying (IRS) for malaria vector control. WSEBs treated with water, the pyrethroid lambda-cyhalothrin, or the organophosphate pirimiphos-methyl, with and without a binding agent for increasing insecticide persistence on netting, were compared with IRS in experimental huts. Compared with IRS containing the same insecticide, WSEBs killed similar proportions of Anopheles funestus mosquitoes that were resistant to pyrethroids, carbamates and organochlorines and greater proportions of pyrethroid-resistant, early exiting An. arabiensis mosquitoes. WSEBs with pirimiphos-methyl killed greater proportions of both vectors than lambda-cyhalothrin or lambda-cyhalothrin plus pirimiphos-methyl and were equally efficacious when combined with binding agent. WSEBs required far less insecticide than IRS, and binding agents might enhance durability. WSEBs might enable affordable deployment of insecticide combinations to mitigate against physiologic insecticide resistance and improve control of behaviorally resistant, early exiting vectors.

Measures of Malaria Burden after Long-Lasting Insecticidal Net Distribution and Indoor Residual Spraying at Three Sites in Uganda: A Prospective Observational Study

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Katureebe, Agaba; Zinszer, Kate; Arinaitwe, Emmanuel; Charland, Katia; Kigozi, Ruth; Kilama, Maxwell; Nankabirwa, Joaniter; Yeka, Adoke; Mawejje, Henry; Mpimbaza, Arthur; Donnelly, Martin J.; Rosenthal, Philip J.; Lindsay, Steve W.; Staedke, Sarah G.; Smith, David L.; Kamya, Moses R.; Dorsey, Grant

2016-01-01

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are the primary vector control interventions used to prevent malaria in Africa. Although both interventions are effective in some settings, high-quality evidence is rarely available to evaluate their effectiveness following deployment by a national malaria control program. In Uganda, we measured changes in key malaria indicators following universal LLIN distribution in three sites, with the addition of IRS at one of these sites. Methods and Findings Comprehensive malaria surveillance was conducted from October 1, 2011, to March 31, 2016, in three sub-counties with relatively low (Walukuba), moderate (Kihihi), and high transmission (Nagongera). Between 2013 and 2014, universal LLIN distribution campaigns were conducted in all sites, and in December 2014, IRS with the carbamate bendiocarb was initiated in Nagongera. High-quality surveillance evaluated malaria metrics and mosquito exposure before and after interventions through (a) enhanced health-facility-based surveillance to estimate malaria test positivity rate (TPR), expressed as the number testing positive for malaria/number tested for malaria (number of children tested for malaria: Walukuba = 42,833, Kihihi = 28,790, and Nagongera = 38,690); (b) cohort studies to estimate the incidence of malaria, expressed as the number of episodes per person-year [PPY] at risk (number of children observed: Walukuba = 340, Kihihi = 380, and Nagongera = 361); and (c) entomology surveys to estimate household-level human biting rate (HBR), expressed as the number of female Anopheles mosquitoes collected per house-night of collection (number of households observed: Walukuba = 117, Kihihi = 107, and Nagongera = 107). The LLIN distribution campaign substantially increased LLIN coverage levels at the three sites to between 65.0% and 95.5% of households with at least one LLIN. In Walukuba, over the 28-mo post-intervention period

Effect of permethrin-treated bed nets on the spatial distribution of malaria vectors in western Kenya

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Gimnig, John E.; Kolczak, Margarette S.; Hightower, Allen W.; Vulule, John M.; Schoute, Erik; Kamau, Luna; Phillips-Howard, Penelope A.; ter Kuile, Feiko O.; Nahlen, Bernard L.; Hawley, William A.

2003-01-01

The effect of insecticide (permethrin)-treated bed nets (ITNs) on the spatial distribution of malaria vectors in neighboring villages lacking ITNs was studied during a randomized controlled trial of ITNs in western Kenya. There was a trend of decreased abundance of Anopheles gambiae with decreasing

A randomized placebo-controlled trial of intermittent preventive treatment in pregnant women in the context of insecticide treated nets delivered through the antenatal clinic.

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Clara Menéndez

2008-04-01

Full Text Available Current recommendations to prevent malaria in African pregnant women rely on insecticide treated nets (ITNs and intermittent preventive treatment (IPTp. However, there is no information on the safety and efficacy of their combined use.1030 pregnant Mozambican women of all gravidities received a long-lasting ITN during antenatal clinic (ANC visits and, irrespective of HIV status, were enrolled in a randomised, double blind, placebo-controlled trial, to assess the safety and efficacy of 2-dose sulphadoxine-pyrimethamine (SP. The main outcome was the reduction in low birth weight.Two-dose SP was safe and well tolerated, but was not associated with reductions in anaemia prevalence at delivery (RR, 0.92 [95% CI, 0.79-1.08], low birth weight (RR, 0.99 [95% CI, 0.70-1.39], or overall placental infection (p = 0.964. However, the SP group showed a 40% reduction (95% CI, 7.40-61.20]; p = 0.020 in the incidence of clinical malaria during pregnancy, and reductions in the prevalence of peripheral parasitaemia (7.10% vs 15.15% (p<0.001, and of actively infected placentas (7.04% vs 13.60% (p = 0.002. There was a reduction in severe anaemia at delivery of borderline statistical significance (p = 0.055. These effects were not modified by gravidity or HIV status. Reported ITN's use was more than 90% in both groups.Two-dose SP was associated with a reduction in some indicators, but these were not translated to significant improvement in other maternal or birth outcomes. The use of ITNs during pregnancy may reduce the need to administer IPTp. ITNs should be part of the ANC package in sub-Saharan Africa.ClinicalTrials.gov NCT00209781.

Insecticide-treated nets ownership and utilization among under-five children following the 2010 mass distribution in Burkina Faso.

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Diabaté, Souleymane; Druetz, Thomas; Bonnet, Emmanuel; Kouanda, Seni; Ridde, Valéry; Haddad, Slim

2014-09-04

Periodic mass distributions contribute significantly to universal access to insecticide-treated nets (ITNs). However, due to the limited number of nets distributed, needs remain unsatisfied, particularly in large households. This study was conducted in Kaya health district following the 2010 mass distribution of ITNs in Burkina Faso. Data were collected on the socio-economic and geo-spatial characteristics and ITN possession and utilization levels of 2,004 households. The study explored: 1) ITN access, in terms of intra-household saturation with ITNs (households with at least one ITN for every two members) correctly installed and in very good physical condition; and 2) factors influencing the decision to place under-five children under a net. Particular attention was given to vector control activities undertaken by mothers. Of the 2,004 households, 90% possessed at least one ITN. However, intra-household saturation with ITNs was below 60% in small households and below 20% in large ones (>6 members). Crude proportion ratios comparing possession and levels of intra-household saturation with ITNs varied between 1.5 (small households) and 7.8 (large households). The proportions of households with ITNs for every two members that were correctly hung or in very good physical condition ranged from 0% to 6.5% in large households and 27.8% to 40.7% in small ones. ITN use to protect under-five children was lower in large households; it was significantly higher when there was at least one ITN for every two members. In large households, it was significantly higher when a child had experienced an episode of any illness in the previous two weeks and when the mother had taken actions to control vector proliferation. In small households, ITN use was significantly higher in families with agricultural land and children aged 12-23 months. Ownership rates were high, but real access to bed nets remained limited. The allocation process disadvantages large families. Real access to bed

Insecticide resistance in the West African malaria vector Anopheles gambiae and investigation of alternative tools for its delay

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N'Guessan, R.

2009-01-01

There is a current policy to eliminate malaria in the African continent. Pyrethroid-incorporated Long Lasting Insecticidal Nets (LLINs) and/or Indoor Residual Spraying (IRS) are the chemical weapons being deployed to achieve that goal. Rather worryingly, resistance to pyrethroids is well documented

The importance of considering community-level effects when selecting insecticidal malaria vector products

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Coosemans Marc

2011-08-01

Full Text Available Abstract Background Insecticide treatment of nets, curtains or walls and ceilings of houses represent the primary means for malaria prevention worldwide. Direct personal protection of individuals and households arises from deterrent and insecticidal activities which divert or kill mosquitoes before they can feed. However, at high coverage, community-level reductions of mosquito density and survival prevent more transmission exposure than the personal protection acquired by using a net or living in a sprayed house. Methods A process-explicit simulation of malaria transmission was applied to results of 4 recent Phase II experimental hut trials comparing a new mosaic long-lasting insecticidal net (LLIN which combines deltamethrin and piperonyl butoxide with another LLIN product by the same manufacturer relying on deltamethrin alone. Results Direct estimates of mean personal protection against insecticide-resistant vectors in Vietnam, Cameroon, Burkina Faso and Benin revealed no clear advantage for combination LLINs over deltamethrin-only LLINs (P = 0.973 unless both types of nets were extensively washed (Relative mean entomologic inoculation rate (EIR ± standard error of the mean (SEM for users of combination nets compared to users of deltamethrin only nets = 0.853 ± 0.056, P = 0.008. However, simulations of impact at high coverage (80% use predicted consistently better impact for the combination net across all four sites (Relative mean EIR ± SEM in communities with combination nets, compared with those using deltamethrin only nets = 0.613 ± 0.076, P Conclusion Process-explicit simulations of community-level protection, parameterized using locally-relevant experimental hut studies, should be explicitly considered when choosing vector control products for large-scale epidemiological trials or public health programme procurement, particularly as growing insecticide resistance necessitates the use of multiple active ingredients.

Public-private delivery of insecticide-treated nets: a voucher scheme in Volta Region, Ghana

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Taylor Ian

2007-02-01

Full Text Available Abstract Background Coverage of vulnerable groups with insecticide-treated nets (ITNs in Ghana, as in the majority of countries of sub-Saharan Africa is currently low. A voucher scheme was introduced in Volta Region as a possible sustainable delivery system for increasing this coverage through scale-up to other regions. Successful scale-up of public health interventions depends upon optimal delivery processes but operational research for delivery processes in large-scale implementation has been inadequate. Methods A simple tool was developed to monitor numbers of vouchers given to each health facility, numbers issued to pregnant women by the health staff, and numbers redeemed by the distributors back to the management agent. Three rounds of interviews were undertaken with health facility staff, retailers and pregnant women who had attended antenatal clinic (ANC. Results During the one year pilot 25,926 vouchers were issued to eligible women from clinics, which equates to 50.7% of the 51,658 ANC registrants during this time period. Of the vouchers issued 66.7% were redeemed by distributors back to the management agent. Initially, non-issuing of vouchers to pregnant women was mainly due to eligibility criteria imposed by the midwives; later in the year it was due to decisions of the pregnant women, and supply constraints. These in turn were heavily influenced by factors external to the programme: current household ownership of nets, competing ITN delivery strategies, and competition for the limited number of ITNs available in the country from major urban areas of other regions. Conclusion Both issuing and redemption of vouchers should be monitored as factors assumed to influence voucher redemption had an influence on issuing, and vice versa. More evidence is needed on how specific contextual factors influence the success of voucher schemes and other models of delivery of ITNs. Such an evidence base will facilitate optimal strategic decision making

Demand and willingness-to-pay for bed nets in Tanzania: results from a choice experiment.

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Gingrich, Chris D; Ricotta, Emily; Kahwa, Amos; Kahabuka, Catherine; Koenker, Hannah

2017-07-14

Universal coverage campaigns for long-lasting insecticide-treated nets do not always reach the goal of one net for every two household members, and even when ownership of at least one net per household is high, many households may not own enough nets. The retail market provides these households options for replacing or increasing the number of nets they own with products that best fit their needs since a variety of net shapes, sizes, and colours are available. Hence, it is important to understand the factors affecting private net demand. This study explores private demand for nets in Tanzania using a discrete choice experiment. The experiment provides participants the option to buy nets with their own money, and thus should prove more accurate than a hypothetical survey of net preferences. Nearly 800 participants sampled in two regions showed an overall strong demand for nets, with 40% choosing to buy a net across all seven combinations of net prices and characteristics such as size, shape, and insecticide treatment. Only 8% of all participants chose not to buy a single net. A key factor influencing demand was whether a participant's household currently owned sufficient nets for all members, with rural participants showing lower net coverage and greater demand than urban participants. Both poor and less poor households showed strong evidence of making purchase decisions based on more than price alone. Mean willingness-to-pay values for a net started at US$1.10 and grew by US$0.50-1.40 for various attributes such as rectangular shape, large size, and insecticide treatment. The impact of price on demand was negative but small, with elasticity values between -0.25 and -0.45. The results suggest that private demand for nets in Tanzania could potentially supplement future coverage campaigns. Net manufacturers and retailers should advertise and promote consumers' preferred net attributes to improve sales and further expand net access and coverage. To overcome household

Community-wide effects of permethrin-treated bed nets on child mortality and malaria morbidity in western Kenya

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Hawley, William A.; Phillips-Howard, Penelope A.; ter Kuile, Feiko O.; Terlouw, Dianne J.; Vulule, John M.; Ombok, Maurice; Nahlen, Bernard L.; Gimnig, John E.; Kariuki, Simon K.; Kolczak, Margarette S.; Hightower, Allen W.

2003-01-01

Spatial analyses of the effect of insecticide (permethrin)-treated bed nets (ITNs) on nearby households both with and without ITNs was performed in the context of a large-scale, group-randomized, controlled mortality trial in Asembo, western Kenya. Results illustrate a protective effect of ITNs on

Country-level operational implementation of the Global Plan for Insecticide Resistance Management.

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Hemingway, Janet; Vontas, John; Poupardin, Rodolphe; Raman, Jaishree; Lines, Jo; Schwabe, Chris; Matias, Abrahan; Kleinschmidt, Immo

2013-06-04

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs.

Subsidized sales of insecticide-treated nets in Afghan refugee camps demonstrate the feasibility of a transition from humanitarian aid towards sustainability

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Kolaczinski Jan H

2004-06-01

Full Text Available Abstract Background Introducing sustainability and self-reliance is essential in chronic humanitarian emergencies before financial assistance is phased out. In Pakistan-based Afghan refugee camps, this was attempted through shifting from indoor residual spraying (IRS to the subsidized sale of insecticide-treated nets (ITNs for prevention of malaria and anthroponotic cutaneous leishmaniasis (ACL. Here we outline the strategy and document the progress to provide guidance for replication of similar approaches in other chronic refugee situations. Methods The operational monitoring data presented were collected through: (i two surveys of knowledge, attitude and practice (KAP; (ii routine sales reporting of health-care providers; (iii records completed during field visits; and (iv registers used during annual re-treatment campaigns. Results From 2000 until 2003, subsidized ITN sales expanded from 17 to 44 camps. Based on 2003 sales records, maximum coverage from subsidized sales exceeded 50% in 13 camps and 20% in an additional 14 camps. Free annual treatment campaigns showed that many refugees were in possession of non-programme nets, which were either locally-made or had leaked from an ITN programme in Afghanistan. Estimated re-treatment coverage of sold and existing nets through annual campaigns exceeded 43% in all camps and was above 70% in the majority. Conclusion Subsidized sales of ITNs have effectively introduced the components of sustainability and self-reliance to the prevention of malaria and ACL in Afghan refugee camps. Similar approaches should be investigated in other chronic refugee situations to discourage expectations of continuing humanitarian donations that cannot be fulfilled.

Experimental hut evaluation of bednets treated with an organophosphate (chlorpyrifos-methyl or a pyrethroid (lambdacyhalothrin alone and in combination against insecticide-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes

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Corbel Vincent

2005-05-01

Full Text Available Abstract Background Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. Methods Comparative studies of chlorpyrifos-methyl (CM, an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L, a pyrethroid, were conducted in experimental huts in Côte d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1R. Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. Results and Conclusion All of the treatments were effective in reducing blood feeding from sleepers under the nets and in killing both species of mosquito, despite the presence of the kdr and Ace.1R genes at high frequency. In most cases, the effects of the various treatments did not differ significantly. Five washes of the nets in soap solution did not reduce the impact of the insecticides on A. gambiae mortality, but did lead to an increase in blood feeding. The three combinations performed no differently from the single insecticide treatments, but the low dose mixture performed encouragingly well indicating that such combinations might be used for controlling insecticide resistant mosquitoes. Mortality of mosquitoes that carried both Ace.1R and Ace.1S genes did not differ significantly from mosquitoes that carried only Ace.1S genes on any of the treated nets, indicating that the Ace.1R allele does not confer effective resistance to chlorpyrifos-methyl under the realistic conditions of an experimental hut.

Use of insecticide-treated mosquito nets for children under five years in an urban area of Lagos State, Nigeria.

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Okafor, I P; Odeyemi, K A

2012-01-01

Insecticide-treated nets (ITNs) have proven to be one of the most effective means of reducing malaria morbidity and mortality in children and pregnant women. This study is carried out to determine the practice and determinants of ITN use for children under five years among care givers in an urban area of Lagos State. A community-based, cross sectional study was carried out in Lagos State in April 2007 among three hundred and forty (340) care givers primarily responsible for child care at home. They were selected by a multi-stage sampling method using a pre-tested, interviewer-administered, structured questionnaire. ITN use rate for under-fives was high (61.8%) and this was significantly determined by care giver's marital status (P level of care giver and occupation of head of the household were not significant determinants. There is need for health campaigns on ITNs targeted at unmarried care givers of young children. In addition, we also recommend social marketing of modern family planning methods to reduce family size, thereby increasing chances of ITN use among children less than five years to reduce malaria burden.

Evaluating the efficacy of biological and conventional insecticides with the new 'MCD bottle' bioassay.

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Sternberg, Eleanore D; Waite, Jessica L; Thomas, Matthew B

2014-12-16

Control of mosquitoes requires the ability to evaluate new insecticides and to monitor resistance to existing insecticides. Monitoring tools should be flexible and low cost so that they can be deployed in remote, resource poor areas. Ideally, a bioassay should be able to simulate transient contact between mosquitoes and insecticides, and it should allow for excito-repellency and avoidance behaviour in mosquitoes. Presented here is a new bioassay, which has been designed to meet these criteria. This bioassay was developed as part of the Mosquito Contamination Device (MCD) project and, therefore, is referred to as the MCD bottle bioassay. Presented here are two experiments that serve as a proof-of-concept for the MCD bottle bioassay. The experiments used four insecticide products, ranging from fast-acting, permethrin-treated, long-lasting insecticide nets (LLINs) that are already widely used for malaria vector control, to the slower acting entomopathogenic fungus, Beauveria bassiana, that is currently being evaluated as a prospective biological insecticide. The first experiment used the MCD bottle to test the effect of four different insecticides on Anopheles stephensi with a range of exposure times (1 minute, 3 minutes, 1 hour). The second experiment is a direct comparison of the MCD bottle and World Health Organization (WHO) cone bioassay that tests a subset of the insecticides (a piece of LLIN and a piece of netting coated with B. bassiana spores) and a further reduced exposure time (5 seconds) against both An. stephensi and Anopheles gambiae. Immediate knockdown and mortality after 24 hours were assessed using logistic regression and daily survival was assessed using Cox proportional hazards models. Across both experiments, fungus performed much more consistently than the chemical insecticides but measuring the effect of fungus required monitoring of mosquito mortality over several days to a week. Qualitatively, the MCD bottle and WHO cone performed comparably

Knowledge of malaria influences the use of insecticide treated nets but not intermittent presumptive treatment by pregnant women in Tanzania

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Nganda Rhoida Y

2004-11-01

Full Text Available Abstract Background To reduce the intolerable burden of malaria in pregnancy, the Ministry of Health in Tanzania has recently adopted a policy of intermittent presumptive treatment for pregnant women using sulphadoxine-pyrimethamine (IPTp-SP. In addition, there is strong national commitment to increase distribution of insecticide treated nets (ITNs among pregnant women. This study explores the determinants of uptake for both ITNs and IPTp-SP by pregnant women and the role that individual knowledge and socio-economic status has to play for each. Methods 293 women were recruited post-partum at Kibaha District Hospital on the East African coast. The haemoglobin level of each woman was measured and a questionnaire administered. Results Use of both interventions was associated with a reduced risk of severe anaemia (Hb Conclusion Individual knowledge of malaria was an important factor for ITN uptake, but not for IPTp-SP use, which was reliant on delivery of information by MCH systems. When both these interventions were used, severe anaemia postpartum was reduced by 69% compared to use of neither, thus providing evidence of effectiveness of these interventions when used in combination.

Explaining variation in adult Anopheles indoor resting abundance: the relative effects of larval habitat proximity and insecticide-treated bed net use.

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McCann, Robert S; Messina, Joseph P; MacFarlane, David W; Bayoh, M Nabie; Gimnig, John E; Giorgi, Emanuele; Walker, Edward D

2017-07-17

Spatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people's houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density. 525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified. Vector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85-0.89; 0.84, 0.82-0.86; 0.38, 0.37-0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48-0.50; 0.39, 0.39-0.40; 0.60, 0.58-0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house

Knowledge, access and utilization of bed-nets among stable and seasonal migrants in an artemisinin resistance containment area of Myanmar.

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Phyo Than, Wint; Oo, Tin; Wai, Khin Thet; Thi, Aung; Owiti, Philip; Kumar, Binay; Deepak Shewade, Hemant; Zachariah, Rony

2017-09-14

Myanmar lies in the Greater Mekong sub-region of South-East Asia faced with the challenge of emerging resistance to artemisinin combination therapies (ACT). Migrant populations are more likely than others to spread ACT resistance. A vital intervention to reduce malaria transmission, resistance spread and eliminate malaria is the use of bed nets. Among seasonal and stable migrants in an artemisinin resistance containment region of Myanmar, we compared a) their household characteristics, b) contact with health workers and information material, and c) household knowledge, access and utilization of bed nets. Secondary data from community-based surveys on 2484 migrant workers (2013 and 2014, Bago Region) were analyzed of which 37% were seasonal migrants. Bed net access and utilization were assessed using a) availability of at least one bed net per household, and b) one bed net per two persons, and c) proportion of household members who slept under abed net during the previous night (Indicator targets = 100%). Over 70% of all migrants were from unstable work settings with short transitory stays. Average household size was five (range 1-25) and almost half of all households had children under-five years. Roughly 10 % of migrants were night-time workers. Less than 40% of households had contact with health workers and less than 30% had exposure to information education and communication (IEC) materials, the latter being significantly lower among seasonal migrants. About 70% of households were aware of the importance of insecticide-treated bed-nets/long-lasting insecticidal nets (ITNs/LLINs), but knowledge on insecticide impregnation and retreatment of ITNs was poor (Myanmar. Possible ways forward include frequent distribution campaigns to compensate for short transitory stays, matching household distributions to household size, enhanced information campaigns and introducing legislation to make mosquito repellents available for night-time workers at plantations and farms

Longevity and efficacy of bifenthrin treatment on desert-pattern U.S. military camouflage netting against mosquitoes in a hot-arid environment

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Personnel deployed in support of US military operations will benefit from additions to the current Department of Defense pest management system. A recent study showed that residual insecticide treatment of woodland pattern US military camouflage netting was long lasting and effective at reducing mos...

Communal prevalence of malaria parasite and evaluation of Long ...

African Journals Online (AJOL)

This study investigates the prevalence of malaria and evaluates Long Lasting Insecticide Nets (LLINs) utilization for malaria control in Ikenne LGA, Ogun State, Nigeria. A cross-sectional survey was conducted in five major communities in Ikenne Local Government Area (LGA) namely: Ilisan, Ikenne, Iperu, Ogere and Irolu.

Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala

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Rizzo Nidia

2012-10-01

Full Text Available Abstract Background In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. Methods The study was conducted as a cluster randomized community trial using “reduction of the vector population” as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.. The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. Results At baseline (during the dry season a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae. After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed in 970 study

Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala.

Science.gov (United States)

Rizzo, Nidia; Gramajo, Rodrigo; Escobar, Maria Cabrera; Arana, Byron; Kroeger, Axel; Manrique-Saide, Pablo; Petzold, Max

2012-10-30

In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs) alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. The study was conducted as a cluster randomized community trial using "reduction of the vector population" as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods) and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices) at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material) and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.). The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. At baseline (during the dry season) a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae). After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed) in 970 study households, tropical rains occurred in the area and

Mathematical evaluation of community level impact of combining bed nets and indoor residual spraying upon malaria transmission in areas where the main vectors are Anopheles arabiensis mosquitoes

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Okumu Fredros O

2013-01-01

Full Text Available Abstract Background Indoor residual insecticide spraying (IRS and long-lasting insecticide treated nets (LLINs are commonly used together even though evidence that such combinations confer greater protection against malaria than either method alone is inconsistent. Methods A deterministic model of mosquito life cycle processes was adapted to allow parameterization with results from experimental hut trials of various combinations of untreated nets or LLINs (Olyset®, PermaNet 2.0®, Icon Life® nets with IRS (pirimiphos methyl, lambda cyhalothrin, DDT, in a setting where vector populations are dominated by Anopheles arabiensis, so that community level impact upon malaria transmission at high coverage could be predicted. Results Intact untreated nets alone provide equivalent personal protection to all three LLINs. Relative to IRS plus untreated nets, community level protection is slightly higher when Olyset® or PermaNet 2.0® nets are added onto IRS with pirimiphos methyl or lambda cyhalothrin but not DDT, and when Icon Life® nets supplement any of the IRS insecticides. Adding IRS onto any net modestly enhances communal protection when pirimiphos methyl is sprayed, while spraying lambda cyhalothrin enhances protection for untreated nets but not LLINs. Addition of DDT reduces communal protection when added to LLINs. Conclusions Where transmission is mediated primarily by An. arabiensis, adding IRS to high LLIN coverage provides only modest incremental benefit (e.g. when an organophosphate like pirimiphos methyl is used, but can be redundant (e.g. when a pyrethroid like lambda cyhalothin is used or even regressive (e.g. when DDT is used for the IRS. Relative to IRS plus untreated nets, supplementing IRS with LLINs will only modestly improve community protection. Beyond the physical protection that intact nets provide, additional protection against transmission by An. arabiensis conferred by insecticides will be remarkably small, regardless of

The effectiveness of non-pyrethroid insecticide-treated durable wall lining to control malaria in rural Tanzania: study protocol for a two-armed cluster randomized trial

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George Mtove

2016-07-01

Full Text Available Abstract Background Despite considerable reductions in malaria achieved by scaling-up long-lasting insecticidal nets (LLINs and indoor residual spraying (IRS, maintaining sustained community protection remains operationally challenging. Increasing insecticide resistance also threatens to jeopardize the future of both strategies. Non-pyrethroid insecticide­treated wall lining (ITWL may represent an alternate or complementary control method and a potential tool to manage insecticide resistance. To date no study has demonstrated whether ITWL can reduce malaria transmission nor provide additional protection beyond the current best practice of universal coverage (UC of LLINs and prompt case management. Methods/design A two-arm cluster randomized controlled trial will be conducted in rural Tanzania to assess whether non-pyrethroid ITWL and UC of LLINs provide added protection against malaria infection in children, compared to UC of LLINs alone. Stratified randomization based on malaria prevalence will be used to select 22 village clusters per arm. All 44 clusters will receive LLINs and half will also have ITWL installed on interior house walls. Study children, aged 6 months to 11 years old, will be enrolled from each cluster and followed monthly to estimate cumulative incidence of malaria parasitaemia (primary endpoint, time to first malaria episode and prevalence of anaemia before and after intervention. Entomological inoculation rate will be estimated using indoor CDC light traps and outdoor tent traps followed by detection of Anopheles gambiae species, sporozoite infection, insecticide resistance and blood meal source. ITWL bioefficacy and durability will be monitored using WHO cone bioassays and household surveys, respectively. Social and cultural factors influencing community and household ITWL acceptability will be explored through focus-group discussions and in-depth interviews. Cost-effectiveness, compared between study arms, will be

Can universal insecticide-treated net campaigns achieve equity in coverage and use? the case of northern Nigeria

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Ye Yazoume

2012-02-01

Full Text Available Abstract Background Insecticide-treated nets (ITNs are effective tools for malaria prevention and can significantly reduce severe disease and mortality due to malaria, especially among children under five in endemic areas. However, ITN coverage and use remain low and inequitable among different socio-economic groups in sub-Saharan Africa, particularly in Nigeria. Several strategies have been proposed to increase coverage and use and reduce inequity in Nigeria, including free distribution campaigns recently conducted by the Nigerian federal government. Using data from the first post-campaign survey, the authors investigated the effect of the mass free distribution campaigns in achieving equity in household ownership and use of ITNs. Methods A post-campaign survey was undertaken in November 2009 in northern Nigeria to assess the effect of the campaigns in addressing equity across different socio-economic groups. The survey included 987 households randomly selected from 60 clusters in Kano state. Using logistic regression and the Lorenz concentration curve and index, the authors assessed equity in ITN coverage and use. Results ITN ownership coverage increased from 10% before the campaigns to 70%-a more than fivefold increase. The campaigns reduced the ownership coverage gap by 75%, effectively reaching parity among wealth quintiles (Concentration index 0.02, 95% CI (-0.02 ; 0.05 versus 0.21 95%CI (0.08 ; 0.34 before the campaigns. ITN use (individuals reporting having slept under an ITN the night before the survey visit among individuals from households owning at least one ITN, was 53.1% with no statistically significant difference between the lowest, second, third and fourth wealth quintiles and the highest wealth quintile (lowest: odds ratio (OR 0.87, 95% confidence interval (CI (0.67 ; 1.13; second: OR 0.85, 95% CI (0.66 ; 1.24; third: OR 1.10 95% CI (0.86 ; 1.4 and fourth OR 0.91 95% CI (0.72 ; 1.15. Conclusion The campaign had a significant

Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam

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Tsunoda Takashi

2013-01-01

Full Text Available Abstract Background Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae. Methods We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets, while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti. Results The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old

Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam.

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Tsunoda, Takashi; Kawada, Hitoshi; Huynh, Trang T T; Luu, Loan Le; Le, San Hoang; Tran, Huu Ngoc; Vu, Huong Thi Que; Le, Hieu Minh; Hasebe, Futoshi; Tsuzuki, Ataru; Takagi, Masahiro

2013-01-11

Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs) form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae. We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets), while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti. The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old children when compared to older children and adults in

1 Scepticism towards insecticide treated mosquito nets for malaria ...

African Journals Online (AJOL)

Abstract: Despite existence of effective tools for malaria control, malaria ... breaks from traditional approach that tend to study low uptake of health ... Key words: scepticism, low uptake, mosquito nets, malaria, social marketing, Tanzania.

Malaria transmission in Bissau, Guinea-Bissau between 1995 and 2012

DEFF Research Database (Denmark)

Ursing, Johan; Rombo, Lars; Rodrigues, Amabelia

2014-01-01

of insecticide treated bed nets (ITN) amongst children chloroquine treatment regime was routinely used until artemisinin based combination therapy (ACT) was introduced in 2008. Long lasting insecticide treated bed nets (LLIN) were distributed in 2011. By 2012 there was 1 net...... (1995-2012) were considered incident cases. The mean annual malaria incidence per thousand children in 1995-1997, 1999-2003, 2007, 2011, 2012 were as follows; age use...... per 2 people and 97% usage. All-cause mortality decreased from post-war peaks in 1999 until 2012 in all age groups and was not negatively affected by malaria resurgence. CONCLUSION: The cause of decreasing malaria incidence (1995-2007) was probably multifactorial and coincident with the use...

Gender and willingness to pay for insecticides treated bed nets in a poor rural area in Tanzania.

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Mujinja, P G M; Makwaya, C K; Sauerborn, R

2004-12-01

To examine socio-economic and malaria related differences between males and females that may cause gender differences in willingness to pay (WTP) for insecticide treated bed nets in a poor rural area. A two-week-interval (test re-test) cross-sectional study. Kisarawe District in coastal Tanzania. Two hundred and fifty one males and two hundred dollars females were interviewed. Females had about 50% of the males' income. The monthly average income was about US dollars 10.50 for females and US dollars 20.20 for males. The proportion of respondents willing to pay for an ITN, for both males and females, declined as the ITN prices increased (Pdifference between men and women, between both rounds were not statistically significant (p>0.05). Male respondents reported a higher mean number of own underfives living in the household compared to women, the difference was not statistically significant (P>0.8). Willingness to pay for ITN was found to be independent of having an under five child with recent history of malaria. Among both males and females, there was an association between a recent experience with malaria episode and WTP, p=0.05 and p=0.02 respectively. Among females, the proportion of those willing to pay for another person, at the lowest ITN price, was significantly higher in those with under five children in their households than in those with no underfives. This was not the case among the male respondents as the association was not statistically significant. Contrary to expectations were was no statistically significant difference in WTP for an ITN between females and males. Further studies that link willingness and ability to pay are required in rural poor population, such studies may be valuable inputs to government policy on and planning of ITN interventions in the public and private sector.

The impact of pyrethroid resistance on the efficacy of insecticide-treated bed nets against African anopheline mosquitoes: systematic review and meta-analysis.

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Clare Strode

2014-03-01

Full Text Available Pyrethroid insecticide-treated bed nets (ITNs help contribute to reducing malaria deaths in Africa, but their efficacy is threatened by insecticide resistance in some malaria mosquito vectors. We therefore assessed the evidence that resistance is attenuating the effect of ITNs on entomological outcomes.We included laboratory and field studies of African malaria vectors that measured resistance at the time of the study and used World Health Organization-recommended impregnation regimens. We reported mosquito mortality, blood feeding, induced exophily (premature exit of mosquitoes from the hut, deterrence, time to 50% or 95% knock-down, and percentage knock-down at 60 min. Publications were searched from 1 January 1980 to 31 December 2013 using MEDLINE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, Social Sciences Citation Index, African Index Medicus, and CAB Abstracts. We stratified studies into three levels of insecticide resistance, and ITNs were compared with untreated bed nets (UTNs using the risk difference (RD. Heterogeneity was explored visually and statistically. Included were 36 laboratory and 24 field studies, reported in 25 records. Studies tested and reported resistance inconsistently. Based on the meta-analytic results, the difference in mosquito mortality risk for ITNs compared to UTNs was lower in higher resistance categories. However, mortality risk was significantly higher for ITNs compared to UTNs regardless of resistance. For cone tests: low resistance, risk difference (RD 0.86 (95% CI 0.72 to 1.01; moderate resistance, RD 0.71 (95% CI 0.53 to 0.88; high resistance, RD 0.56 (95% CI 0.17 to 0.95. For tunnel tests: low resistance, RD 0.74 (95% CI 0.61 to 0.87; moderate resistance, RD 0.50 (95% CI 0.40 to 0.60; high resistance, RD 0.39 (95% CI 0.24 to 0.54. For hut studies: low resistance, RD 0.56 (95% CI 0.43 to 0.68; moderate resistance, RD 0.39 (95% CI 0.16 to 0.61; high resistance, RD 0

Knowledge and perceptions about indoor residual spray for malaria ...

African Journals Online (AJOL)

Background: Malaria control and intervention tools usage and coverage in community depend on community acceptability and compliance. Indoor residual spray (IRS) and long lasting insecticide treated nets (LLINs) are the preferred and recommended intervention tools. This study assessed the knowledge and perceptions ...

Net Gain: A New Method for Preventing Malaria Deaths | CRDI ...

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

A finely spun net could prevent as many as one-third of all child deaths in Africa, reports IDRC's new publication, Net Gain. Studies conducted in Gambia, Ghana, and Kenya show that the insecticide-treated mosquito net reduced the mortality rate of children under 5 years of age by up to 63 percent. Net Gain reviews and ...

Impact of permethrin-treated bed nets on malaria, anemia, and growth in infants in an area of intense perennial malaria transmission in western Kenya

NARCIS (Netherlands)

ter Kuile, Feiko O.; Terlouw, Dianne J.; Kariuki, Simon K.; Phillips-Howard, Penelope A.; Mirel, Lisa B.; Hawley, William A.; Friedman, Jennifer F.; Shi, Ya Ping; Kolczak, Margarette S.; Lal, Altaf A.; Vulule, John M.; Nahlen, Bernard L.

2003-01-01

As part of a community-based, group-randomized, controlled trial of insecticide-treated bed nets (ITNs) in an area with intense malaria transmission in western Kenya, a birth cohort (n = 833) was followed monthly until the age of 24 months to determine the potential beneficial and adverse effects of

Significant decline in lymphatic filariasis associated with nationwide scale-up of insecticide-treated nets in Zambia

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M. Nsakashalo-Senkwe

2017-11-01

Full Text Available Lymphatic filariasis (LF is a mosquito-borne disease, broadly endemic in Zambia, and is targeted for elimination by mass drug administration (MDA of albendazole and diethylcarbamazine citrate (DEC to at-risk populations. Anopheline mosquitoes are primary vectors of LF in Africa, and it is possible that the significant scale-up of malaria vector control over the past decade may have also impacted LF transmission, and contributed to a decrease in prevalence in Zambia. We therefore aimed to examine the putative association between decreasing LF prevalence and increasing coverage of insecticide-treated mosquito nets (ITNs for malaria vector control, by comparing LF mapping data collected between 2003–2005 and 2009–2011 to LF sentinel site prevalence data collected between 2012 and 2014, before any anti-LF MDA was started. The coverage of ITNs for malaria was quantified and compared for each site in relation to the dynamics of LF. We found a significant decrease in LF prevalence from the years 2003–2005 (11.5% CI95 6.6; 16.4 to 2012–2014 (0.6% CI95 0.03; 1.1; at the same time, there was a significant scale-up of ITNs across the country from 0.2% (CI95 0.0; 0.3 to 76.1% (CI95 71.4; 80.7 respectively. The creation and comparison of two linear models demonstrated that the geographical and temporal variation in ITN coverage was a better predictor of LF prevalence than year alone. Whilst a causal relationship between LF prevalence and ITN coverage cannot be proved, we propose that the scale-up of ITNs has helped to control Anopheles mosquito populations, which have in turn impacted on LF transmission significantly before the scale-up of MDA. This putative synergy with vector control has helped to put Zambia on track to meet national and global goals of LF elimination by 2020.

Multi-country comparison of delivery strategies for mass campaigns to achieve universal coverage with insecticide-treated nets: what works best?

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Zegers de Beyl, Celine; Koenker, Hannah; Acosta, Angela; Onyefunafoa, Emmanuel Obi; Adegbe, Emmanuel; McCartney-Melstad, Anna; Selby, Richmond Ato; Kilian, Albert

2016-02-03

The use of insecticide-treated nets (ITNs) is widely recognized as one of the main interventions to prevent malaria. High ITN coverage is needed to reduce transmission. Mass distribution campaigns are the fastest way to rapidly scale up ITN coverage. However, the best strategy to distribute ITNs to ensure household coverage targets are met is still under debate. This paper presents results from 14 post-campaign surveys in five African countries to assess whether the campaign strategy used had any effect on distribution outcome. Data from 13,901 households and 14 campaigns from Ghana, Nigeria, Senegal, South Sudan and Uganda, were obtained through representative cross-sectional questionnaire surveys, conducted three to 16 months after ITN distribution. All evaluations used a multi-stage sampling approach and similar methods for data collection. Key outcomes examined were the proportion of households having received a net from the campaign and the proportion of households with one net for every two people. Household registration rates proved to be the most important determinant of a household receiving any net from the campaign (adjusted odds ratio [OR] 74.8; 95 % confidence interval [CI]: 55.3-101.1) or had enough ITNs for all household members (adjusted OR 19.1; 95 % CI: 55.34-101.05). Factors that positively influenced registration were larger household size (adjusted OR 1.7; 95 % CI: 1.5-2.1) and families with children under five (adjusted OR 1.4; 95 % CI: 1.2-1.6). Urban residence was negatively associated with receipt of a net from the campaign (adjusted OR 0.73; 95 % CI: 0.58-0.92). Registration was equitable in most campaigns except for Uganda and South Sudan, where the poorest wealth quintiles were less likely to have been reached. After adjusting for other factors, delivery strategy (house-to-house vs. fixed point) and distribution approach (integrated versus stand-alone) did not show a systematic impact on registration or owning any ITN. Campaigns that

The use of insecticide-treated nets for reducing malaria morbidity among children aged 6-59 months, in an area of high malaria transmission in central Côte d'Ivoire

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Nsanzabana Christian

2010-09-01

Full Text Available Abstract Background Long-lasting insecticidal nets (LLINs are an important tool for controlling malaria. Much attention has been devoted to determine both the effect of LLINs on the reduction of Plasmodium infection rate and on clinically-confirmed malaria cases in sub-Saharan Africa. We carried out an epidemiological study to investigate whether LLINs impact on Plasmodium prevalence rate and the proportion of clinically-confirmed malaria cases, in five villages in the district of Toumodi, central Côte d'Ivoire. Methods From April 2007 to November 2008, a community-based malaria control programme was implemented in the study villages, which involved large-scale distribution of LLINs, and training and sensitization activities within the community. We determined the effect of this programme on Plasmodium prevalence rate, clinically-confirmed malaria cases and proportion of high parasitaemia rates in children aged 6-59 months through a series of cross-sectional surveys starting in April 2007 and repeated once every 6 months. Results We observed a significant decrease in the mean P. falciparum prevalence rate from April 2007 to April 2008 (p = 0.029. An opposite trend was observed from November 2007 to November 2008 when P. falciparum prevalence rate increased significantly (p = 0.003. Highly significant decreases in the proportions of clinical malaria cases were observed between April 2007 and April 2008 (p Conclusions Large-scale distribution of LLINs, accompanied by training and sensitization activities, significantly reduced Plasmodium prevalence rates among young children in the first year of the project, whereas overall clinical malaria rates dropped over the entire 18-month project period. A decrease in community motivation to sleep under bed nets, perhaps along with changing patterns of malaria transmission, might explain the observed increase in the Plasmodium prevalence rate between November 2007 and November 2008.

Effectiveness and equity of the Tanzania National Voucher Scheme for mosquito nets over 10 years of implementation.

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Kramer, Karen; Mandike, Renata; Nathan, Rose; Mohamed, Ally; Lynch, Matthew; Brown, Nick; Mnzava, Ally; Rimisho, Wilhelmina; Lengeler, Christian

2017-06-15

The Tanzania National Voucher Scheme (TNVS) was a public private partnership managed by the Ministry of Health that provided pregnant women and infants with highly subsidized (long-lasting) insecticide-treated nets between 2004 and 2014. It was implemented in the context of the National Insecticide Treated Nets (NATNETS) Programme and was the main keep up strategy for vulnerable populations. The programme design was adjusted considerably over time to incorporate new evidence, shifting public health policies, and changing donor priorities. Three TNVS models can be distinguished: (1) the fixed discount; (2) the fixed top-up; (3) the hybrid voucher model. The changes improved equity and effectiveness, but also had a profound effect on how the programme was managed and implemented. The TNVS reached the majority of beneficiaries with vouchers, and significantly increased household ownership and use of LLINs. While two mass distribution campaigns implemented between 2009 and 2011 achieved universal coverage and equity, the TNVS ensured continuous protection of the vulnerable populations before, during and after the campaigns. The TNVS stimulated and maintained a large national retail network which managed the LLIN supply chain. The effectiveness of the TNVS was a function of several interdependent factors, including the supply chain of vouchers through the public health system; the supply chain of nets in the commercial sector; the demand for nets from voucher recipients; management and risk mitigation measures; and the influence of global and donor objectives. The TNVS was a highly innovative and globally influential programme, which stimulated the thinking around effectively and equitably distributing ITNs, and contributed directly to the evolution of global policy. It was a fundamental component of the NATNETS programme which protected a malaria-vulnerable population for over a decade.

The effect of deltamethrin-treated net fencing around cattle enclosures on outdoor-biting mosquitoes in Kumasi, Ghana.

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Marta Ferreira Maia

Full Text Available Classic vector control strategies target mosquitoes indoors as the main transmitters of malaria are indoor-biting and -resting mosquitoes. However, the intensive use of insecticide-treated bed-nets (ITNs and indoor residual spraying have put selective pressure on mosquitoes to adapt in order to obtain human blood meals. Thus, early-evening and outdoor vector activity is becoming an increasing concern. This study assessed the effect of a deltamethrin-treated net (100 mg/m(2 attached to a one-meter high fence around outdoor cattle enclosures on the number of mosquitoes landing on humans. Mosquitoes were collected from four cattle enclosures: Pen A - with cattle and no net; B - with cattle and protected by an untreated net; C - with cattle and protected by a deltamethrin-treated net; D - no cattle and no net. A total of 3217 culicines and 1017 anophelines were collected, of which 388 were Anopheles gambiae and 629 An. ziemanni. In the absence of cattle nearly 3 times more An. gambiae (p<0.0001 landed on humans. The deltamethrin-treated net significantly reduced (nearly three-fold, p<0.0001 culicine landings inside enclosures. The sporozoite rate of the zoophilic An. ziemanni, known to be a secondary malaria vector, was as high as that of the most competent vector An. gambiae; raising the potential of zoophilic species as secondary malaria vectors. After deployment of the ITNs a deltamethrin persistence of 9 months was observed despite exposure to African weather conditions. The outdoor use of ITNs resulted in a significant reduction of host-seeking culicines inside enclosures. Further studies investigating the effectiveness and spatial repellence of ITNs around other outdoor sites, such as bars and cooking areas, as well as their direct effect on vector-borne disease transmission are needed to evaluate its potential as an appropriate outdoor vector control tool for rural Africa.

Resistance to DDT and pyrethroids and increased kdr mutation frequency in An. gambiae after the implementation of permethrin-treated nets in Senegal.

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Mamadou O Ndiath

Full Text Available The aim of this study was to evaluate the susceptibility to insecticides of An. gambiae mosquitoes sampled in Dielmo (Senegal, in 2010, 2 years after the implementation of Long Lasting Insecticide-treated Nets (LLINs and to report the evolution of kdr mutation frequency from 2006 to 2010.WHO bioassay susceptibility tests to 6 insecticides were performed on adults F0, issuing from immature stages of An. gambiae s.l., sampled in August 2010. Species and molecular forms as well as the presence of L1014F and L1014S kdr mutations were assessed by PCR. Longitudinal study of kdr mutations was performed on adult mosquitoes sampled monthly by night landing catches from 2006 to 2010.No specimen studied presented the L1014S mutation. During the longitudinal study, L1014F allelic frequency rose from 2.4% in year before the implementation of LLINs to 4.6% 0-12 months after and 18.7% 13-30 months after. In 2010, An. gambiae were resistant to DDT, Lambda-cyhalothrin, Deltamethrin and Permethrin (mortality rates ranging from 46 to 63% but highly susceptible to Fenitrothion and Bendiocarb (100% mortality. There was significantly more RR genotype among An. gambiae surviving exposure to DDT or Pyrethroids. An. arabiensis represented 3.7% of the sampled mosquitoes (11/300 with no kdr resistance allele detected. An. gambiae molecular form M represented 29.7% of the mosquitoes with, among them, kdr genotypes SR (18% and SS (82%. An. gambiae molecular form S represented 66% of the population with, among them, kdr genotype SS (33.3%, SR (55.6% and RR (11.1%. Only 2 MS hybrid mosquitoes were sampled and presented SS kdr genotype.Biological evidence of resistance to DDT and pyrethroids was detected among An. gambiae mosquitoes in Dielmo (Senegal within 24 months of community use of LLINs. Molecular identification of L1014F mutation indicated that target site resistance increased after the implementation of LLINs.

Efficacy of permethrin-treated bed nets in the prevention of mortality in young children in an area of high perennial malaria transmission in western Kenya

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Phillips-Howard, Penelope A.; Nahlen, Bernard L.; Kolczak, Margarette S.; Hightower, Allen W.; ter Kuile, Feiko O.; Alaii, Jane A.; Gimnig, John E.; Arudo, John; Vulule, John M.; Odhacha, Amos; Kachur, S. Patrick; Schoute, Erik; Rosen, Daniel H.; Sexton, John D.; Oloo, Aggrey J.; Hawley, William A.

2003-01-01

A group-randomized controlled trial of insecticide (permethrin)-treated bed nets (ITNs) was conducted in an area of high perennial malaria transmission in western Kenya to test the effect of ITNs on all-cause mortality in children 1-59 months of age. Child deaths were monitored over a two-year

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African Journals Online (AJOL)

Factors affecting utilization of long lasting insecticide treated nets. Abstract PDF · Vol 2, No 4 (2014) - Original Article Integrated disesase surveillance and response reporting: effects of training on primary healthcare workers in plateau state, Nigeria Abstract PDF. ISSN: 2467-8252. AJOL African Journals Online. HOW TO ...

An elaborated feeding cycle model for reductions in vectorial capacity of night-biting mosquitoes by insecticide-treated nets.

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Le Menach, Arnaud; Takala, Shannon; McKenzie, F Ellis; Perisse, Andre; Harris, Anthony; Flahault, Antoine; Smith, David L

2007-01-25

Insecticide Treated Nets (ITNs) are an important tool for malaria control. ITNs are effective because they work on several parts of the mosquito feeding cycle, including both adult killing and repelling effects. Using an elaborated description of the classic feeding cycle model, simple formulas have been derived to describe how ITNs change mosquito behaviour and the intensity of malaria transmission, as summarized by vectorial capacity and EIR. The predicted changes are illustrated as a function of the frequency of ITN use for four different vector populations using parameter estimates from the literature. The model demonstrates that ITNs simultaneously reduce mosquitoes' lifespans, lengthen the feeding cycle, and by discouraging human biting divert more bites onto non-human hosts. ITNs can substantially reduce vectorial capacity through small changes to all of these quantities. The total reductions in vectorial capacity differ, moreover, depending on baseline behavior in the absence of ITNs. Reductions in lifespan and vectorial capacity are strongest for vector species with high baseline survival. Anthropophilic and zoophilic species are affected differently by ITNs; the feeding cycle is lengthened more for anthrophilic species, and the proportion of bites that are diverted onto non-human hosts is higher for zoophilic species. This model suggests that the efficacy of ITNs should be measured as a total reduction in transmission intensity, and that the quantitative effects will differ by species and by transmission intensity. At very high rates of ITN use, ITNs can generate large reductions in transmission intensity that could provide very large reductions in transmission intensity, and effective malaria control in some areas, especially when used in combination with other control measures. At high EIR, ITNs will probably not substantially reduce the parasite rate, but when transmission intensity is low, reductions in vectorial capacity combine with reductions in

Socio-economic inequity in demand for insecticide-treated nets, in-door residual house spraying, larviciding and fogging in Sudan

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Mustafa Sara

2005-12-01

Full Text Available Abstract Background In order to optimally prioritize and use public and private budgets for equitable malaria vector control, there is a need to determine the level and determinants of consumer demand for different vector control tools. Objectives To determine the demand from people of different socio-economic groups for indoor residual house-spraying (IRHS, insecticide-treated nets (ITNs, larviciding with chemicals (LWC, and space spraying/fogging (SS and the disease control implications of the result. Methods Ratings and levels of willingness-to-pay (WTP for the vector control tools were determined using a random cross-sectional sample of 720 householdes drawn from two states. WTP was elicited using the bidding game. An asset-based socio-economic status (SES index was used to explore whether WTP was related to SES of the respondents. Results IRHS received the highest proportion of highest preferred rating (41.0% followed by ITNs (23.1%. However, ITNs had the highest mean WTP followed by IRHS, while LWC had the least. The regression analysis showed that SES was positively and statistically significantly related to WTP across the four vector control tools and that the respondents' rating of IRHS and ITNs significantly explained their levels of WTP for the two tools. Conclusion People were willing to pay for all the vector-control tools, but the demand for the vector control tools was related to the SES of the respondents. Hence, it is vital that there are public policies and financing mechanisms to ensure equitable provision and utilisation of vector control tools, as well as protecting the poor from cost-sharing arrangements.

Use of Insecticide-Treated Mosquito Net among Pregnant Women and Guardians of Children under Five in the Democratic Republic of the Congo

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Joseph N. Inungu

2017-01-01

Full Text Available Background. Insecticide-treated mosquito nets (ITNs are one of the most effective tools for preventing malaria in sub-Saharan Africa. Objective. This study examined knowledge, attitude, and practice on the use of ITNs in the prevention of malaria among pregnant women and guardians of children under five in the Democratic Republic of the Congo. Methods. A total of 5,138 pregnant women and guardians of children under five were interviewed. Results. The majority of participants (>80% knew the signs and symptoms of malaria; 81.6% reported having an ITN in the household, but 78.4% reported using it the night before the interview. Only 71.4% of pregnant women used ITN the night compared to 68.2% of children under five. In the Logistic Regression model, women who believed that it is normal to use ITNs were 1.9 times more likely to use it than those who did not (OR: 1.930; women who were confident in their abilities to use ITNs were 1.9 times more likely than those who were not confident (OR: 1.915; and women who had a good attitude towards ITNs were also more likely to use ITNs compared to those who did not (OR: 1.529. Conclusion. New and innovative evidence-based behavior change interventions are needed to increase the utilization of ITNs among vulnerable groups.

Universal coverage with insecticide-treated nets - applying the revised indicators for ownership and use to the Nigeria 2010 malaria indicator survey data.

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Kilian, Albert; Koenker, Hannah; Baba, Ebenezer; Onyefunafoa, Emmanuel O; Selby, Richmond A; Lokko, Kojo; Lynch, Matthew

2013-09-10

Until recently only two indicators were used to evaluate malaria prevention with insecticide-treated nets (ITN): "proportion of households with any ITN" and "proportion of the population using an ITN last night". This study explores the potential of the expanded set of indicators recommended by the Roll Back Malaria Monitoring and Evaluation Reference Group (MERG) for comprehensive analysis of universal coverage with ITN by applying them to the Nigeria 2010 Malaria Indicator Survey data. The two additional indicators of "proportion of households with at least one ITN for every two people" and "proportion of population with access to an ITN within the household" were calculated as recommended by MERG. Based on the estimates for each of the four ITN indicators three gaps were calculated: i) households with no ITN, ii) households with any but not enough ITN, iii) population with access to ITN not using it. In addition, coverage with at least one ITN at community level was explored by applying Lot Quality Assurance Sampling (LQAS) decision rules to the cluster level of the data. All outcomes were analysed by household background characteristics and whether an ITN campaign had recently been done. While the proportion of households with any ITN was only 42% overall, it was 75% in areas with a recent mass campaign and in these areas 66% of communities had coverage of 80% or better. However, the campaigns left a considerable intra-household ownership gap with 66% of households with any ITN not having enough for every family member. In contrast, the analysis comparing actual against potential use showed that ITN utilization was good overall with only 19% of people with access not using the ITN, but with a significant difference between the North, where use was excellent (use gap 11%), and the South (use gap 36%) indicating the need for enhanced behaviour change communication. The expanded ITN indicators to assess universal coverage provide strong tools for a comprehensive

Dynamics of forest malaria transmission in Balaghat district, Madhya Pradesh, India.

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Neeru Singh

Full Text Available BACKGROUND: An epidemiological and entomological study was carried out in Balaghat district, Madhya Pradesh, India to understand the dynamics of forest malaria transmission in a difficult and hard to reach area where indoor residual spray and insecticide treated nets were used for vector control. METHODS: This community based cross-sectional study was undertaken from January 2010 to December 2012 in Baihar and Birsa Community Health Centres of district Balaghat for screening malaria cases. Entomological surveillance included indoor resting collections, pyrethrum spray catches and light trap catches. Anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite protein. FINDINGS: Plasmodium falciparum infection accounted for >80% of all infections. P. vivax 16.5%, P. malariae 0.75% and remaining were mixed infections of P. falciparum, P. vivax and P. malariae. More than, 30% infections were found in infants under 6 months of age. Overall, an increasing trend in malaria positivity was observed from 2010 to 2012 (chi-square for trend  =  663.55; P<0.0001. Twenty five Anopheles culicifacies (sibling species C, D and E were positive for circumsporozoite protein of P. falciparum (44% and P. vivax (56%. Additionally, 2 An. fluviatilis, were found positive for P. falciparum and 1 for P. vivax (sibling species S and T. An. fluviatilis sibling species T was found as vector in forest villages for the first time in India. CONCLUSION: These results showed that the study villages are experiencing almost perennial malaria transmission inspite of indoor residual spray and insecticide treated nets. Therefore, there is a need for new indoor residual insecticides which has longer residual life or complete coverage of population with long lasting insecticide treated nets or both indoor residual spray and long lasting bed nets for effective vector control. There is a need to undertake a well designed case control study to evaluate the efficacy

Comparative cost analysis of insecticide-treated net delivery strategies: sales supported by social marketing and free distribution through antenatal care.

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De Allegri, Manuela; Marschall, Paul; Flessa, Steffen; Tiendrebéogo, Justin; Kouyaté, Bocar; Jahn, Albrecht; Müller, Olaf

2010-01-01

Insecticide-treated nets (ITNs) are effective in substantially reducing malaria transmission. Still, ITN coverage in sub-Saharan Africa (SSA) remains extremely low. Policy makers are concerned with identifying the most suitable delivery mechanism to achieve rapid yet sustainable increases in ITN coverage. Little is known, however, on the comparative costs of alternative ITN distribution strategies. This paper aimed to fill this gap in knowledge by developing such a comparative cost analysis, looking at the cost per ITN distributed for two alternative interventions: subsidized sales supported by social marketing and free distribution to pregnant women through antenatal care (ANC). The study was conducted in rural Burkina Faso, where the two interventions were carried out alongside one another in 2006/07. Cost information was collected prospectively to derive both a financial analysis adopting a provider's perspective and an economic analysis adopting a societal perspective. The average financial cost per ITN distributed was US$8.08 and US$7.21 for sales supported by social marketing and free distribution through ANC, respectively. The average economic cost per ITN distributed was US$4.81 for both interventions. Contrary to common belief, costs did not differ substantially between the two interventions. Due to the district's ability to rely fully on the use of existing resources, financial costs associated with free ITN distribution through ANC were in fact even lower than those associated with the social marketing campaign. This represents an encouraging finding for SSA governments and points to the possibility to invest in programmes to favour free ITN distribution through existing health facilities. Given restricted budgets, however, free distribution programmes are unlikely to be feasible.

Long-Lasting Insecticidal Hammocks for controlling forest malaria: a community-based trial in a rural area of central Vietnam.

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Ngo Duc Thang

2009-10-01

Full Text Available In Vietnam, malaria remains a problem in some remote areas located along its international borders and in the central highlands, partly due to the bionomics of the local vector, mainly found in forested areas and less vulnerable to standard control measures. Long Lasting Insecticidal Hammocks (LLIH, a tailored and user-friendly tool for forest workers, may further contribute in reducing the malaria burden. Their effectiveness was tested in a large community-based intervention trial carried out in Ninh Thuan province in Central Vietnam.Thirty villages (population 18,646 were assembled in 20 clusters (1,000 individuals per cluster that were randomly allocated to either the intervention or control group (no LLIH after stratification according to the pre-intervention P. falciparum antibody prevalence ( or =30%. LLIH were distributed to the intervention group in December 2004. For the following 2 years, the incidence of clinical malaria and the prevalence of infection were determined by passive case detection at community level and by bi-annual malariometric surveys. A 2-fold larger effect on malaria incidence in the intervention as compared to the control group was observed. Similarly, malaria prevalence decreased more substantially in the intervention (1.6-fold greater reduction than in the control group. Both for incidence and prevalence, a stronger and earlier effect of the intervention was observed in the high endemicity stratum. The number of malaria cases and infections averted by the intervention overall was estimated at 10.5 per 1,000 persons and 5.6/100 individuals, respectively, for the last half of 2006. In the high endemicity stratum, the impact was much higher, i.e. 29/1000 malaria cases and 15.7 infections/100 individuals averted.LLIH reduced malaria incidence and prevalence in this remote and forested area of Central Vietnam. As the targets of the newly-launched Global Malaria Action Plan include the 75% reduction of the global

Population preference of net texture prior to bed net trial in Kala-Azar-endemic areas.

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Murari L Das

Full Text Available Prior to a community-based efficacy trial of long-lasting insecticidal nets (LLINs in the prevention of visceral leishmaniasis (VL; also called kala-azar, a pilot study on preference of tools was held in endemic areas of India and Nepal in September 2005.LLINs made of polyester and polyethylene were distributed to 60 participants, who used the nets sequentially for 7 d. Acceptability and preference were evaluated via indirect indicators through questionnaires at three defined time points before and after use of the LLINs and through focus group discussions (FGDs. In the latter, preferences for color and size were also assessed. Untreated bed nets were owned by 87% of the households prior to the study. All users liked textures of both LLIN types after 7 d of use, but had a slight preference for those made of polyester if they were to recommend a LLIN to relatives or friends (p<0.05, mainly because of their relatively greater softness in comparison to polyethylene LLINs. Users reported that both net types reduced mosquito bites and number of insects, including sand fly (bhusana; genus Phlebotomus, inside the house. Side effects were minor and disappeared quickly.The large-scale intervention trial considered the preferences of the study population to decide on the best tool of intervention--light-blue, rectangular, polyester LLINs of different sizes.

Assessing healthcare providers' knowledge and practices relating to insecticide-treated nets and the prevention of malaria in Ghana, Laos, Senegal and Tanzania.

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Hoffman, Steven J; Guindon, G Emmanuel; Lavis, John N; Ndossi, Godwin D; Osei, Eric J A; Sidibe, Mintou Fall; Boupha, Boungnong

2011-12-13

Research evidence is not always being disseminated to healthcare providers who need it to inform their clinical practice. This can result in the provision of ineffective services and an inefficient use of resources, the implications of which might be felt particularly acutely in low- and middle-income countries. Malaria prevention is a particularly compelling domain to study evidence/practice gaps given the proven efficacy, cost-effectiveness and disappointing utilization of insecticide-treated nets (ITNs). This study compares what is known about ITNs to the related knowledge and practices of healthcare providers in four low- and middle-income countries. A new questionnaire was developed, pilot tested, translated and administered to 497 healthcare providers in Ghana (140), Laos (136), Senegal (100) and Tanzania (121). Ten questions tested participants' knowledge and clinical practice related to malaria prevention. Additional questions addressed their individual characteristics, working context and research-related activities. Ordinal logistic regressions with knowledge and practices as the dependent variable were conducted in addition to descriptive statistics. The survey achieved a 75% response rate (372/497) across Ghana (107/140), Laos (136/136), Senegal (51/100) and Tanzania (78/121). Few participating healthcare providers correctly answered all five knowledge questions about ITNs (13%) or self-reported performing all five clinical practices according to established evidence (2%). Statistically significant factors associated with higher knowledge within each country included: 1) training in acquiring systematic reviews through the Cochrane Library (OR 2.48, 95% CI 1.30-4.73); and 2) ability to read and write English well or very well (OR 1.69, 95% CI 1.05-2.70). Statistically significant factors associated with better clinical practices within each country include: 1) reading scientific journals from their own country (OR 1.67, 95% CI 1.10-2.54); 2) working

Utilization, retention and bio-efficacy studies of PermaNet® in selected villages in Buie and Fentalie districts of Ethiopia

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Balkew Meshesha

2009-05-01

Full Text Available Abstract Background Malaria remains a major public health problem in Ethiopia. Pyrethroid-treated mosquito nets are one of the major tools available for the prevention and control of malaria transmission. PermaNet® is a long-lasting insecticide-treated net (LLIN recommended by WHO for malaria control. Objective The objective of the study was to assess utilization and retention of PermaNet® nets distributed for malaria control in Buie and Fentalie districts and monitor the bio-efficacy of the nets using the WHO cone bioassay test procedures. Methods A cross sectional study was carried out by interviewing household heads or their representative in Buie and Fentalie districts. The two districts were selected based on a priori knowledge of variations on ethnic background and housing construction. Clusters of houses were chosen within each of the study villages for selection of households. 20 households that had received one or more PermaNet® nets were chosen randomly from the clusters in each village. A total of eight used PermaNet® nets were collected for the bio-efficacy test. The bio-efficacy of PermaNet® nets was monitored according to the standard WHO procedures using a susceptible colony of Anopheles arabiensis to deltamethrin. Results A total of 119 household heads were interviewed during the study. The retention rate of nets that were distributed in 2005 and 2006 season was 72%. A total of 62.2% of the interviewees claimed children under five years of age slept under LLIN, while only 50.7% of the nets were observed to be hanged inside houses when used as a proxy indicator of usage of LLIN. For the bio-efficacy test the mean knock-down was 94% and 100%, while the mean mortality rate observed after 24 hr holding period was 72.2% and 67% for Buie and Fentalie districts respectively. Conclusion The study revealed a moderately high retention of PermaNet® in the study villages and effectiveness of the nets when tested according to the

Access and Use of Interventions to Prevent and Treat Malaria among Pregnant Women in Kenya and Mali: A Qualitative Study

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Hill, Jenny; Kayentao, Kassoum; Achieng, Florence; Diarra, Samba; Dellicour, Stephanie; Diawara, Sory I.; Hamel, Mary J.; Ouma, Peter; Desai, Meghna; Doumbo, Ogobara K.; ter Kuile, Feiko O.; Webster, Jayne

2015-01-01

Background Coverage of malaria in pregnancy interventions in sub-Saharan Africa is suboptimal. We undertook a systematic examination of the operational, socio-economic and cultural constraints to pregnant women's access to intermittent preventive treatment (IPTp), long-lasting insecticide-treated

Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America.

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Kroeger, Axel; Aviñna, Ana; Ordoñnez-Gonzalez, José; Escandon, Celia

2002-11-15

Insecticide-treated materials (ITMs) are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets) were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico) and by an academic institution (the Colombian Institute of Tropical Medicine) along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a) support by health services, b) smaller size, c) lesser desire for quick returns and d) lower ITM unit costs. ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving and maintaining high impregnation rates.

Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America

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Ordoñnez-Gonzalez José

2002-11-01

Full Text Available Abstract Background and objectives Insecticide-treated materials (ITMs are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico and by an academic institution (the Colombian Institute of Tropical Medicine along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. Methods The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Results Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a support by health services, b smaller size, c lesser desire for quick returns and d lower ITM unit costs. Conclusions ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving

Access to and use of long-lasting insecticidal nets and factors associated with non-use among communities in malaria-endemic areas of Al Hudaydah governorate in the Tihama region, west of Yemen.

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Al-Eryani, Samira M A; Mahdy, Mohammed A K; Al-Mekhlafi, Abdulsalam M; Abdul-Ghani, Rashad

2017-06-09

Universal coverage of the targeted malaria-endemic areas with long-lasting insecticidal nets (LLINs) is implemented as one of the key interventions for malaria control and elimination in Yemen. In 2013, through a mass campaign, LLINs were distributed to the targeted communities in Al Hudaydah governorate. This study aimed to assess the ownership of, access to, and use of LLINs. It also aimed to identify factors associated with not using LLINs in malaria-endemic areas of Al Hudaydah in the Tihama region, west of Yemen. A cross-sectional survey was conducted in four districts (Ad Durayhimi, Al Marawi'ah, Al Mansuriyah and Bayt Al Faqiah) in Al Hudaydah during February 2016. A total of 701 households were included in this study. Data on socio-demographic characteristics and availability of LLINs were collected by interview and observation. Four indicators for malaria prevention using LLINs; proportion of households with at least one LLIN, proportion of households with at least one LLIN for every two people, proportion of population with access to LLINs in the surveyed households and proportion of population who slept under LLINs the previous night of the survey were calculated as indicated by Roll Back Malaria Monitoring and Evaluation Reference Group. Use to access ratio was assessed. Factors associated with not using LLINs among people with access were also investigated. Of 701 households with 4900 de facto population, ownership of at least one LLIN was 90.6%, while 24.1% owned at least one for every two people during the survey in 2016. The overall proportion of people with access to LLINs was 51.5% (95% CI 50.1-52.9). Only 19.0% (95% CI 17.9-20.1) slept under LLINs the night before the survey and the overall use to access ratio was 0.37. The proportions of children under 5 years of age with access to and use of LLINs were 13.7 and 42.5%, respectively. On the other hand, the proportions of pregnant women with access to and use of LLINs were 16.4 and 20

Use of antenatal care, maternity services, intermittent presumptive treatment and insecticide treated bed nets by pregnant women in Luwero district, Uganda

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Mufubenga Patrobas

2008-03-01

Full Text Available Abstract Background To reduce the intolerable burden of malaria in pregnancy, the Ministry of Health in Uganda improved the antenatal care package by including a strong commitment to increase distribution of insecticide-treated nets (ITNs and introduction of intermittent preventive treatment with sulphadoxine-pyrimethamine for pregnant women (IPTp-SP as a national policy in 2000. This study assessed uptake of both ITNs and IPTp-SP by pregnant women as well as antenatal and maternity care use with the aim of optimizing their delivery. Methods 769 post-partum women were recruited from a rural area of central Uganda with perennial malaria transmission through a cross-sectional, community-based household survey in May 2005. Results Of the 769 women interviewed, antenatal clinic (ANC attendance was high (94.4%; 417 (57.7% visiting initially during the 2nd trimester, 242 (33.5% during the 3rd trimester and 266 (37.1% reporting ≥ 4 ANC visits. About 537 (71% and 272 (35.8% received one or ≥ 2 IPTp-SP doses respectively. Only 85 (15.8% received the first dose of IPTp-SP in the 3rd trimester. ITNs were used by 239 (31.3% of women during pregnancy and 314 (40.8% delivered their most recent pregnancy outside a health facility. Post-partum women who lacked post-primary education were more likely not to have attended four or more ANC visits (odds ratio [OR] 3.3, 95% confidence interval [CI] 1.2–9.3. Conclusion These findings illustrate the need to strengthen capacity of the district to further improve antenatal care and maternity services utilization and IPTp-SP uptake. More specific and effective community health strategies to improve effective ANC, maternity services utilization and IPTp-SP uptake in rural communities should be undertaken.

Insecticidal and sterilizing effect of Olyset Duo®, a permethrin and pyriproxyfen mixture net against pyrethroid-susceptible and -resistant strains of Anopheles gambiae s.s.: a release-recapture assay in experimental huts

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Djènontin Armel

2015-01-01

Full Text Available In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN, Olyset® Duo, incorporating a mixture of permethrin (PER and the insect growth regulator (IGR, pyri-proxyfen (PPF. An LN containing PPF alone and a classic Olyset® Net were tested in parallel as positive controls. The effect of progressive number of holes (6, 30, or 150 that may accrue in nets over time was simulated. We used two laboratory Anopheles gambiae s.s. strains: the susceptible Kisumu strain and the pyrethroid-resistant VK-Per strain having solely kdr as resistance mechanism. The effect of these nets on the reproductive success of blood-fed females that survived the different LNs conditions was recorded. Regardless of the mosquito strain, the LNs containing PPF alone with as many as 30 holes drastically reduced the number of eggs laid by females succeeding in feeding, i.e. fecundity by 98% and egg hatching rate (fertility by 93% relative to untreated control net. Very few of the resistant females blood fed and survived under the Olyset® Duo with similar number of holes (up to 30 but of these few, the inhibition of reproductive success was 100%. There was no evidence that the Olyset® Duo LN with 150 holes impacted fecundity or fertility of the resistant colony. The efficacy of Olyset® Duo is encouraging and clearly illustrates that this new net might be a promising tool for malaria transmission control and resistance management.

Insecticidal and sterilizing effect of Olyset Duo®, a permethrin and pyriproxyfen mixture net against pyrethroid-susceptible and -resistant strains of Anopheles gambiae s.s.: a release-recapture assay in experimental huts.

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Djènontin, Armel; Ahoua Alou, Ludovic P; Koffi, Alphonsine; Zogo, Barnabas; Duarte, Elves; N'Guessan, Raphael; Moiroux, Nicolas; Pennetier, Cédric

2015-01-01

In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN), Olyset® Duo, incorporating a mixture of permethrin (PER) and the insect growth regulator (IGR), pyri-proxyfen (PPF). An LN containing PPF alone and a classic Olyset® Net were tested in parallel as positive controls. The effect of progressive number of holes (6, 30, or 150) that may accrue in nets over time was simulated. We used two laboratory Anopheles gambiae s.s. strains: the susceptible Kisumu strain and the pyrethroid-resistant VK-Per strain having solely kdr as resistance mechanism. The effect of these nets on the reproductive success of blood-fed females that survived the different LNs conditions was recorded. Regardless of the mosquito strain, the LNs containing PPF alone with as many as 30 holes drastically reduced the number of eggs laid by females succeeding in feeding, i.e. fecundity by 98% and egg hatching rate (fertility) by 93% relative to untreated control net. Very few of the resistant females blood fed and survived under the Olyset® Duo with similar number of holes (up to 30) but of these few, the inhibition of reproductive success was 100%. There was no evidence that the Olyset® Duo LN with 150 holes impacted fecundity or fertility of the resistant colony. The efficacy of Olyset® Duo is encouraging and clearly illustrates that this new net might be a promising tool for malaria transmission control and resistance management. © A. Djènontin et al., published by EDP Sciences, 2015.

Status of insecticide resistance in high-risk malaria provinces in Afghanistan.

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Ahmad, Mushtaq; Buhler, Cyril; Pignatelli, Patricia; Ranson, Hilary; Nahzat, Sami Mohammad; Naseem, Mohammad; Sabawoon, Muhammad Farooq; Siddiqi, Abdul Majeed; Vink, Martijn

2016-02-18

Insecticide resistance seriously threatens the efficacy of vector control interventions in malaria endemic countries. In Afghanistan, the status of insecticide resistance is largely unknown while distribution of long-lasting insecticidal nets has intensified in recent years. The main objective of this study was thus to measure the level of resistance to four classes of insecticides in provinces with medium to high risk of malaria transmission. Adult female mosquitoes were reared from larvae successively collected in the provinces of Nangarhar, Kunar, Badakhshan, Ghazni and Laghman from August to October 2014. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), bendiocarb (0.1 %), permethrin (0.75 %) and deltamethrin (0.05 %). In addition, the presence of kdr mutations was investigated in deltamethrin resistant and susceptible Anopheles stephensi mosquitoes collected in the eastern provinces of Nangarhar and Kunar. Analyses of mortality rates revealed emerging resistance against all four classes of insecticides in the provinces located east and south of the Hindu Kush mountain range. Resistance is observed in both An. stephensi and Anopheles culicifacies, the two dominant malaria vectors in these provinces. Anopheles superpictus in the northern province of Badakhshan shows a different pattern of susceptibility with suspected resistance observed only for deltamethrin and bendiocarb. Genotype analysis of knock down resistance (kdr) mutations at the voltage-gated channel gene from An. stephensi mosquitoes shows the presence of the known resistant alleles L1014S and L1014F. However, a significant fraction of deltamethrin-resistant mosquitoes were homozygous for the 1014L wild type allele indicating that other mechanisms must be considered to account for the observed pyrethroid resistance. This study confirms the importance of monitoring insecticide resistance for the development of an integrated vector management in Afghanistan. The

Characterizing the insecticide resistance of Anopheles gambiae in Mali.

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Cisse, Moussa B M; Keita, Chitan; Dicko, Abdourhamane; Dengela, Dereje; Coleman, Jane; Lucas, Bradford; Mihigo, Jules; Sadou, Aboubacar; Belemvire, Allison; George, Kristen; Fornadel, Christen; Beach, Raymond

2015-08-22

The impact of indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs), key components of the national malaria control strategy of Mali, is threatened by vector insecticide resistance. The objective of this study was to assess the level of insecticide resistance in Anopheles gambiae sensu lato populations from Mali against four classes of insecticide recommended for IRS: organochlorines (OCs), pyrethroids (PYs), carbamates (CAs) and organophosphates (OPs). Characterization of resistance was done in 13 sites across southern Mali and assessed presence and distribution of physiological mechanisms that included target-site modifications: knockdown resistance (kdr) and altered acetycholinesterase (AChE), and/or metabolic mechanisms: elevated esterases, glutathione S-transferases (GSTs), and monooxygenases. The World Health Organization (WHO) tube test was used to determine phenotypic resistance of An. gambiae s.l. to: dichlorodiphenyltrichloroethane (DDT) (OC), deltamethrin (PY), lambda-cyhalothrin (PY), bendiocarb (CA), and fenitrothion (OP). Identification of sibling species and presence of the ace-1 (R) and Leu-Phe kdr, resistance-associated mutations, were determined using polymerase chain reaction (PCR) technology. Biochemical assays were conducted to detect increased activity of GSTs, oxidases and esterases. Populations tested showed high levels of resistance to DDT in all 13 sites, as well as increased resistance to deltamethrin and lambda-cyhalothrin in 12 out of 13 sites. Resistance to fenitrothion and bendiocarb was detected in 1 and 4 out of 13 sites, respectively. Anopheles coluzzii, An. gambiae sensu stricto and Anopheles arabiensis were identified with high allelic frequencies of kdr in all sites where each of the species were found (13, 12 and 10 sites, respectively). Relatively low allelic frequencies of ace-1 (R) were detected in four sites where this assessment was conducted. Evidence of elevated insecticide metabolism, based on oxidase

Synthetic sex pheromone in a long-lasting lure attracts the visceral leishmaniasis vector, Lutzomyia longipalpis, for up to 12 weeks in Brazil.

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Daniel P Bray

2014-03-01

Full Text Available Current control methodologies have not prevented the spread of visceral leishmaniasis (VL across Brazil. Here, we describe the development of a new tool for controlling the sand fly vector of the disease: a long-lasting lure, which releases a synthetic male sex pheromone, attractive to both sexes of Lutzomyia longipalpis. This device could be used to improve the effectiveness of residual insecticide spraying as a means of sand fly control, attracting L. longipalpis to insecticide-treated animal houses, where they could be killed in potentially large numbers over a number of weeks. Different lure designs releasing the synthetic pheromone (±-9-methylgermacrene-B (CAS 183158-38-5 were field-tested in Araçatuba, São Paulo (SP. Experiments compared numbers of sand flies caught overnight in experimental chicken sheds with pheromone lures, to numbers caught in control sheds without pheromone. Prototype lures, designed to last one night, were first used to confirm the attractiveness of the pheromone in SP, and shown to attract significantly more flies to test sheds than controls. Longer-lasting lures were tested when new, and at fortnightly intervals. Lures loaded with 1 mg of pheromone did not attract sand flies for more than two weeks. However, lures loaded with 10 mg of pheromone, with a releasing surface of 15 cm2 or 7.5 cm2, attracted female L. longipalpis for up to ten weeks, and males for up to twelve weeks. Approximately five times more sand flies were caught with 7.5 cm2 10 mg lures when first used than occurred naturally in non-experimental chicken resting sites. These results demonstrate that these lures are suitably long-lasting and attractive for use in sand fly control programmes in SP. To our knowledge, this is the first sex pheromone-based technology targeting an insect vector of a neglected human disease. Further studies should explore the general applicability of this approach for combating other insect-borne diseases.

Assessing healthcare providers' knowledge and practices relating to insecticide-treated nets and the prevention of malaria in Ghana, Laos, Senegal and Tanzania

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Hoffman Steven J

2011-12-01

Full Text Available Abstract Background Research evidence is not always being disseminated to healthcare providers who need it to inform their clinical practice. This can result in the provision of ineffective services and an inefficient use of resources, the implications of which might be felt particularly acutely in low- and middle-income countries. Malaria prevention is a particularly compelling domain to study evidence/practice gaps given the proven efficacy, cost-effectiveness and disappointing utilization of insecticide-treated nets (ITNs. Methods This study compares what is known about ITNs to the related knowledge and practices of healthcare providers in four low- and middle-income countries. A new questionnaire was developed, pilot tested, translated and administered to 497 healthcare providers in Ghana (140, Laos (136, Senegal (100 and Tanzania (121. Ten questions tested participants' knowledge and clinical practice related to malaria prevention. Additional questions addressed their individual characteristics, working context and research-related activities. Ordinal logistic regressions with knowledge and practices as the dependent variable were conducted in addition to descriptive statistics. Results The survey achieved a 75% response rate (372/497 across Ghana (107/140, Laos (136/136, Senegal (51/100 and Tanzania (78/121. Few participating healthcare providers correctly answered all five knowledge questions about ITNs (13% or self-reported performing all five clinical practices according to established evidence (2%. Statistically significant factors associated with higher knowledge within each country included: 1 training in acquiring systematic reviews through the Cochrane Library (OR 2.48, 95% CI 1.30-4.73; and 2 ability to read and write English well or very well (OR 1.69, 95% CI 1.05-2.70. Statistically significant factors associated with better clinical practices within each country include: 1 reading scientific journals from their own country (OR

Indoor application of attractive toxic sugar bait (ATSB in combination with mosquito nets for control of pyrethroid-resistant mosquitoes.

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Zachary P Stewart

Full Text Available BACKGROUND: Attractive toxic sugar bait (ATSB sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases. METHODS: Insecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. RESULTS: In feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (p<0.05. Mortality rates with ATSB were comparable to those with long lasting insecticidal nets previously tested against the same species in this area. CONCLUSIONS: Indoor ATSB shows promise as a supplement to mosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor

The importance of education to increase the use of bed nets in villages outside of Kinshasa, Democratic Republic of the Congo

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Ndjinga Julie K

2010-10-01

Full Text Available Abstract Background Malaria is the most prominent disease in the Democratic Republic of the Congo (DRC, and long-lasting insecticide-treated nets (LLINs have been distributed free of charge since 2006 to combat the disease. However, the success of this bed net campaign depends on sufficient bed net use in all age groups. This study was designed to examine the factors affecting bed net use in villages outside of Kinshasa. Methods Two villages along the Congo River, totalling 142 households with 640 residents, were surveyed using a standard questionnaire. The interview determined the number, ages, and sexes of family members; the education level of the family head; the number, colour, and type of nets owned; and the number of nets used in the previous night. The size of house was also measured, and numbers of rooms and beds were recorded. These variables were examined to reveal important factors that affect bed net use. Results A total of 469 nets were counted, and nearly all nets were white LLINs. Of these nets, 229 (48.8% nets were used by 284 (44.4% residents. Bed nets were used by over 90% of children 5 to 15 years of age, whereas less than 50% of the residents in other age groups used bed nets. The important variables affecting bed net use were numbers of beds and rooms in the house and the education level of the family head of household. Conclusion Education was the most important factor affecting bed net use in the villages outside Kinshasa. Development of an educational programme, particularly one directed toward parents, is necessary to reduce misconceptions and increase prevalence of bed net use among all age groups.

Sublethal effects of some synthetic and botanical insecticides on Bemisia tabaci (Hemiptera: Aleyrodidae

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Esmaeily Saeideh

2014-07-01

Full Text Available In addition to direct mortality caused by insecticides, some biological traits of insects may also be affected by sublethal insecticide doses. In this study, we used the age-stage, two-sex life table method to evaluate the sublethal effects of the four synthetic insecticides: abamectin, imidacloprid, diazinon, and pymetrozin as well as the botanical insecticide taken from Calotropis procera (Asclepiadaceae extract, on eggs of the cotton whitefly, Bemisia tabaci (Hem.: Aleyrodidae. The lowest and highest survival rates and oviposition periods were observed in whiteflies treated by diazinon and imidacloprid, respectively. We found significant differences in the net reproductive rate (R0, the intrinsic rate of increase (r, the finite rate of increase (?, and the gross reproductive rate (GRR among different insecticides. Altogether, our results showed that pymetrozin and C. procera induced the most sublethal effects, thus they may be suitable candidates for use in integrated pest management programs of B. tabaci.

Non-target toxicity of synthetic insecticides on the biological performance and population growth of Bracon hebetor Say.

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Muslim, Mohammad; Ansari, M Shafiq; Hasan, Fazil

2018-05-24

Bracon hebetor Say (Hymenoptera: Braconidae) is an important biological control agent of various species of order Lepidoptera and extensively used in biological control program worldwide. Present study evaluated the lethal and sublethal effects of insecticides on B. hebetor using demographic and population growth parameters. Doses of all the tested insecticides were within a maximum range of their recommended field dosages and adults were treated using residual glass vials method. For control experiments adults were treated with distilled water. Among the tested insecticides, the survivorship of various stages of B. hebetor was considerably prolonged on cyantraniliprole followed by chlorantraniliprole and shortest on chlorpyrifos and profenofos treated group. Total immature development time was prolonged in chlorpyrifos and profenofos treated group. Population growth parameters like intrinsic rate of natural increase (r m ), net reproductive rate (R 0 ), finite rate of increase (λ) and mean generation time (T c ) were considerably reduced in B. hebetor groups treated with chlorpyrifos and profenofos. However, B. hebetor groups treated with chlorantraniliprole and cyantraniliprole showed a little or no much difference in population growth parameters when compared with untreated group. It was also observed that chlorpyrifos and profenofos modified the sex ratio, thereby female emergence get reduced. On the basis of present findings it can be concluded that all tested insecticides caused considerable ecotoxic effects on B. hebetor compared to control. However, comparisons among the tested insecticides on the basis of IOBC criteria showed that chlorantraniliprol and cyntraniliprol was less toxic as compared to other insecticides tested on this biological control agent.

Use of insecticide-treated house screens to reduce infestations of dengue virus vectors, Mexico.

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Manrique-Saide, Pablo; Che-Mendoza, Azael; Barrera-Perez, Mario; Guillermo-May, Guillermo; Herrera-Bojorquez, Josue; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Lenhart, Audrey; Vazquez-Prokopec, Gonzalo; Sommerfeld, Johannes; McCall, Philip J; Kroeger, Axel; Arredondo-Jimenez, Juan I

2015-02-01

Dengue prevention efforts rely on control of virus vectors. We investigated use of insecticide-treated screens permanently affixed to windows and doors in Mexico and found that the screens significantly reduced infestations of Aedes aegypti mosquitoes in treated houses. Our findings demonstrate the value of this method for dengue virus vector control.

Mapping insecticide resistance in Anopheles gambiae (s.l.) from Côte d'Ivoire.

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Camara, Soromane; Koffi, Alphonsine A; Ahoua Alou, Ludovic P; Koffi, Kouakou; Kabran, Jean-Paul K; Koné, Aboubacar; Koffi, Mathieu F; N'Guessan, Raphaël; Pennetier, Cédric

2018-01-08

Insecticide resistance in malaria vectors is an increasing threat to vector control tools currently deployed in endemic countries. Resistance management must be an integral part of National Malaria Control Programmes' (NMCPs) next strategic plans to alleviate the risk of control failure. This obviously will require a clear database on insecticide resistance to support the development of such a plan. The present work gathers original data on insecticide resistance between 2009 and 2015 across Côte d'Ivoire in West Africa. Two approaches were adopted to build or update the resistance data in the country. Resistance monitoring was conducted between 2013 and 2015 in 35 sentinel sites across the country using the WHO standard procedure of susceptibility test on adult mosquitoes. Four insecticide families (pyrethroids, organochlorides, carbamates and organophosphates) were tested. In addition to this survey, we also reviewed the literature to assemble existing data on resistance between 2009 and 2015. High resistance levels to pyrethroids, organochlorides and carbamates were widespread in all study sites whereas some Anopheles populations remained susceptible to organophosphates. Three resistance mechanisms were identified, involving high allelic frequencies of kdr L1014F mutation (range = 0.46-1), relatively low frequencies of ace-1 R (below 0.5) and elevated activity of insecticide detoxifying enzymes, mainly mixed function oxidases (MFO), esterase and glutathione S-transferase (GST) in almost all study sites. This detailed map of resistance highlights the urgent need to develop new vector control tools to complement current long-lasting insecticidal nets (LLINs) although it is yet unclear whether these resistance mechanisms will impact malaria transmission control. Researchers, industry, WHO and stakeholders must urgently join forces to develop alternative tools. By then, NMCPs must strive to develop effective tactics or plans to manage resistance keeping in mind

Can the collection of expired long-lasting insecticidal nets reduce their coverage and use? Sociocultural aspects related to LLIN life cycle management and use in four districts in Madagascar.

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Ramanantsoa, Ambinina; Wilson-Barthes, Marta; Rahenintsoa, Rindra; Hoibak, Sarah; Ranaivoharimina, Harilala; Rahelimalala, Martha Delphine; Rakotomanga, Avotiana; Finlay, Alyssa; Muela Ribera, Joan; Peeters Grietens, Koen

2017-10-10

There is growing awareness of the likely impact increased numbers of LLINs will have on the environment, if not disposed of or recycled appropriately. As part of a World Health Organization (WHO) and United Nations Environment Programme (UNEP) pilot study to assess environmentally-sound and cost-effective LLIN recycling strategies, the USAID-Deliver Project collected 22,559 used bed nets in Madagascar. A social science study was conducted to provide data on socio-cultural factors related to collection and replacement of LLINs, including impact on primary and other net uses. Ethnographic exploratory research was carried out following the pilot USAID-Deliver net collection and recycling campaign in Betioky, Tsihombe, Fenerive Est and Ambanja districts of Madagascar, triangulating participant observation, interviewing and group discussions. Sampling was theoretical and data analysis was a continuous and iterative process concurrent to data collection. Final analysis was conducted using NVivo10. The following themes emerged as contributing to the success of collecting expired LLINs in the community for recycling purposes: (i) net adequacy and preference: characteristic differences between collected and newly distributed nets lead to communities' reticence to relinquish old nets before confirming new nets were appropriate for intended use. Where newly distributed nets failed to meet local requirements, this was expected to increase alternative uses and decrease household turn over. (ii) Net collection strategies: the net collection campaign brought net use out of the private sphere and into the public arena. Net owners reported feeling ashamed when presenting damaged nets in public for collection, leading to reduced net relinquishment. (iii) Net lifecycle: communities perceived nets as being individually owned and economic value was attributed both to good-condition nets for sleeping and to worn nets for alternative/secondary purposes. Collecting nets at the stage of

The cost of routine Aedes aegypti control and of insecticide-treated curtain implementation.

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Baly, Alberto; Flessa, Steffen; Cote, Marilys; Thiramanus, Thirapong; Vanlerberghe, Veerle; Villegas, Elci; Jirarojwatana, Somchai; Van der Stuyft, Patrick

2011-05-01

Insecticide-treated curtains (ITCs) are promoted for controlling the Dengue vector Aedes aegypti. We assessed the cost of the routine Aedes control program (RACP) and the cost of ITC implementation through the RACP and health committees in Venezuela and through health volunteers in Thailand. The yearly cost of the RACP per household amounted to US$2.14 and $1.89, respectively. The ITC implementation cost over three times more, depending on the channel used. In Venezuela the RACP was the most efficient implementation-channel. It spent US$1.90 (95% confidence interval [CI]: 1.83; 1.97) per curtain distributed, of which 76.9% for the curtain itself. Implementation by health committees cost significantly (P = 0.02) more: US$2.32 (95% CI: 1.93; 2.61) of which 63% for the curtain. For ITC implementation to be at least as cost-effective as the RACP, at equal effectiveness and actual ITC prices, the attained curtain coverage and the adulticiding effect should last for 3 years.

Posesión, retención y uso de mosquiteros tratados con insecticidas de larga duración luego de un año de su distribución en Loreto, Perú Long-lasting insecticide - treated bednet ownership, retention and usage one year after their distribution in Loreto, Peru

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Angel Rosas-Aguirre

2011-06-01

Full Text Available Objetivos. Evaluar la posesión, retención y uso de mosquiteros tratados con insecticida de larga duración (MTILD luego de un año de su distribución en Loreto, Perú. Materiales y métodos. De julio a septiembre de 2007 se distribuyeron 26 185 MTILD Olyset Net® en 194 comunidades objetivo de Loreto, que protegieron a 45 331 personas. Posteriormente, se realizaron visitas de monitoreo (primera en diciembre de 2007 y segunda en julio de 2008 a los hogares de una muestra de 60 comunidades objetivo (30,9% del total, colectándose mediante un cuestionario semiestructurado los datos necesarios para el cálculo de indicadores de posesión, retención y uso de los MTILD. Resultados. En ambas visitas, la posesión de MTILD en hogares fue elevada (99,9% y 98,7%, respectivamente. La razón MTILD/persona disminuyó de 0,58 al momento de la distribución a 0,51 en la segunda visita, estimándose una retención al año de MTILD de 87%. En la primera visita, 99,0% de los niños Objectives. To assess long-lasting insecticide - treated bednet (LLITN ownership, retention and usage one year after their distribution in Loreto, Peru. Materials and methods. From July to September 2007, 26,185 LLITNs Olyset Net ® were delivered in 194 targeted communities in the Peruvian Amazon region, covering 45,331 people. Two cross-sectional community-based surveys in December 2007 and July 2008 were undertaken in a sample of 60 targeted communities (30.9% out of the total. A semi-structured questionnaire was used to collect necessary data to calculate LLITN ownership, retention and usage indicators. Results. High LLITN household ownership was showed in both surveys (99.9% and 98.7%, respectively. LLITN/ person ratio decreased from 0.58 at the end of the LLITN delivery to 0.51 in the second survey, estimating LLITN retention of 87% after 1 year of intervention. In the first survey, 99.0% of all children <5 years and 96,0% of pregnant women slept under a LLITN the previous

Rural households at risk of malaria did not own sufficient insecticide treated nets at Dabat HDSS site: evidence from a cross sectional re-census.

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Muchie, Kindie Fentahun; Alemu, Kassahun; Tariku, Amare; Tsegaye, Adino Tesfahun; Abebe, Solomon Mekonnen; Yitayal, Mezgebu; Awoke, Tadesse; Biks, Gashaw Andargie

2017-11-21

Malaria is the leading cause of disease burden across the world, especially in African countries. Ethiopia has designed a five year (2011-2015) plan to cover 100% of the households in malarious areas with one insecticide treated net (ITN) for every two persons, and to raise consistent ITN utilization to at least 80%. However, evidence on ownership of ITN among malarious rural households in northwest Ethiopia is quite limited. Hence, the present study aimed at assessing ownership of ITN and associated factors among rural households at risk of malaria at Dabat Health and Demographic Surveillance System site, northwest Ethiopia. A cross sectional re-census was carried out in Dabat Health and Demographic Surveillance System site during peak malaria seasons from October to December, 2014. Data for 15,088 households at Dabat Health and Demographic Surveillance System site were used for the analysis. Descriptive measures and binary logistic regression were carried out. Among those who owned at least one ITN, 53.4% were living at an altitude >2500 m above sea level. However, out of households living at an altitude ownership of ITN. Rural households at risk of malaria did not own a sufficient number of ITN though the utilization is promising. Moreover, prioritizing children and pregnant women to sleep under ITN remains public health problems. Programmers, partners and implementers should consider tailored intervention strategy stratified by altitude in distributing ITN. ITN distribution should also be accompanied by using exhaustive promotion strategies that consider people without access to any source of information, and educating households to prioritize pregnant and under five children to sleep under ITN.

Malaria control under the Taliban regime: insecticide-treated net purchasing, coverage, and usage among men and women in eastern Afghanistan

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2010-01-01

Background Scaling up insecticide-treated mosquito net (ITN) coverage is a key malaria control strategy even in conflict-affected countries [1,2]. Socio-economic factors influence access to ITNs whether subsidized or provided free to users. This study examines reported ITN purchasing, coverage, and usage in eastern Afghanistan and explores women's access to health information during the Taliban regime (1996-2001). This strengthens the knowledge base on household-level health choices in complex-emergency settings. Methods Fifteen focus group discussions (FGDs) and thirty in-depth interviews were conducted with men and women from ITN-owning and non-owning households. FGDs included rank ordering, pile sorting and focused discussion of malaria knowledge and ITN purchasing. Interviews explored general health issues, prevention and treatment practices, and women's malaria knowledge and concerns. Seven key informant interviews with health-related workers and a concurrent survey of 200 ITN-owning and 214 non-owning households were used to clarify or quantify findings. Results Malaria knowledge was similar among men and women and ITN owners and non-owners. Women reported obtaining health information through a variety of sources including clinic staff, their husbands who had easier access to information, and particularly female peers. Most participants considered ITNs very desirable, though not usually household necessities. ITN owners reported more household assets than non-owners. Male ITN owners and non-owners ranked rugs and ITNs as most desired, while women ranked personal assets such as jewellery highest. While men were primarily responsible for household decision-making and purchasing, older women exerted considerable influence. Widow-led and landless households reported most difficulties purchasing ITNs. Most participants wanted to buy ITNs only if they could cover all household members. When not possible, preferential usage was given to women and children

A good night's sleep and the habit of net use: perceptions of risk and reasons for bed net use in Bukoba and Zanzibar.

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Koenker, Hannah M; Loll, Dana; Rweyemamu, Datius; Ali, Abdullah S

2013-06-13

Intensive malaria control interventions in the United Republic of Tanzania have contributed to reductions in malaria prevalence. Given that malaria control remains reliant upon continued use of long-lasting insecticidal bed nets (LLINs) even when the threat of malaria has been reduced, this qualitative study sought to understand how changes in perceived risk influence LLIN usage, and to explore in more detail the benefits of net use that are unrelated to malaria. Eleven focus group discussions were conducted in Bukoba Rural district and in Zanzibar Urban West district in late 2011. Participants were males aged 18 and over, females between the ages of 18 and 49, and females at least 50 years old. The perceived risk of malaria had decreased among the respondents, and malaria control interventions were credited for the decline. Participants cited reductions in both the severity of malaria and in their perceived susceptibility to malaria. However, malaria was still considered a significant threat. Participants' conceptualization of risk appeared to be an important consideration for net use. At the same time, comfort and aspects of comfort (getting a good night's sleep, avoiding biting pests) appeared to play a large role in personal decisions to use nets consistently or not. Barriers to comfort (feeling uncomfortable or trapped; perceived difficulty breathing, or itching/rashes) were frequently cited as reasons not to use a net consistently. While it was apparent that participants acknowledged the malaria-prevention benefits of net use, the exploration of the risk and comfort determinants of net use provides a richer understanding of net use behaviours, particularly in a setting where transmission has fallen and yet consistent net use is still crucial to maintaining those gains. Future behaviour change communication campaigns should capitalize on the non-malaria benefits of net use that provide a long-term rationale for consistent use even when the immediate threat of

First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions

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2011-01-01

Background Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant malaria vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. Methods This study used the fungus Beauveria bassiana to infect the insecticide-resistant malaria vector Anopheles gambiae s.s (Diptera: Culicidae) VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of B. bassiana conidia was measured after up to 20 days exposure to field conditions. Results The results show that B. bassiana infection caused significantly increased mortality with the daily risk of dying being increased by 2.5× for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the B. bassiana conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but the viability of control

Comparative performance of three experimental hut designs for measuring malaria vector responses to insecticides in Tanzania.

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Massue, Dennis J; Kisinza, William N; Malongo, Bernard B; Mgaya, Charles S; Bradley, John; Moore, Jason D; Tenu, Filemoni F; Moore, Sarah J

2016-03-15

Experimental huts are simplified, standardized representations of human habitations that provide model systems to evaluate insecticides used in indoor residual spray (IRS) and long-lasting insecticidal nets (LLINs) to kill disease vectors. Hut volume, construction materials and size of entry points impact mosquito entry and exposure to insecticides. The performance of three standard experimental hut designs was compared to evaluate insecticide used in LLINs. Field studies were conducted at the World Health Organization Pesticide Evaluation Scheme (WHOPES) testing site in Muheza, Tanzania. Three East African huts, three West African huts, and three Ifakara huts were compared using Olyset(®) and Permanet 2.0(®) versus untreated nets as a control. Outcomes measured were mortality, induced exophily (exit rate), blood feeding inhibition and deterrence (entry rate). Data were analysed using linear mixed effect regression and Bland-Altman comparison of paired differences. A total of 613 mosquitoes were collected in 36 nights, of which 13.5% were Anopheles gambiae sensu lato, 21% Anopheles funestus sensu stricto, 38% Mansonia species and 28% Culex species. Ifakara huts caught three times more mosquitoes than the East African and West African huts, while the West African huts caught significantly fewer mosquitoes than the other hut types. Mosquito densities were low, very little mosquito exit was measured in any of the huts with no measurable exophily caused by the use of either Olyset or Permanet. When the huts were directly compared, the West African huts measured greater exophily than other huts. As unholed nets were used in the experiments and few mosquitoes were captured, it was not possible to measure difference in feeding success either between treatments or hut types. In each of the hut types there was increased mortality when Permanet or Olyset were present inside the huts compared to the control, however this did not vary between the hut types. Both East African

Efficacy, Safety and Cost of Insecticide Treated Wall Lining, Insecticide Treated Bed Nets and Indoor Wall Wash with Lime for Visceral Leishmaniasis Vector Control in the Indian Sub-continent: A Multi-country Cluster Randomized Controlled Trial

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Das, Pradeep; Ghosh, Debashis; Priyanka, Jyoti; Matlashewski, Greg; Kroeger, Axel; Upfill-Brown, Alexander

2016-01-01

Background We investigated the efficacy, safety and cost of lime wash of household walls plus treatment of sand fly breeding places with bleach (i.e. environmental management or EM), insecticide impregnated durable wall lining (DWL), and bed net impregnation with slow release insecticide (ITN) for sand fly control in the Indian sub-continent. Methods This multi-country cluster randomized controlled trial had 24 clusters in each three sites with eight clusters per high, medium or low sand fly density stratum. Every cluster included 45–50 households. Five households from each cluster were randomly selected for entomological measurements including sand fly density and mortality at one, three, nine and twelve months post intervention. Household interviews were conducted for socioeconomic information and intervention acceptability assessment. Cost for each intervention was calculated. There was a control group without intervention. Findings Sand fly mortality [mean and 95%CI] ranged from 84% (81%-87%) at one month to 74% (71%-78%) at 12 months for DWL, 75% (71%-79%) at one month to 49% (43%-55%) at twelve months for ITN, and 44% (34%-53%) at one month to 22% (14%-29%) at twelve months for EM. Adjusted intervention effect on sand fly density measured by incidence rate ratio ranged from 0.28 (0.23–0.34) at one month to 0.62 (0.51–0.75) at 12 months for DWL; 0.72 (0.62–0.85) at one month to 1.02 (0.86–1.22) at 12 months for ITN; and 0.89 (0.76–1.03) at one months to 1.49 (1.26–1.74) at 12 months for EM. Household acceptance of EM was 74% compared to 94% for both DWL and ITN. Operational cost per household in USD was about 5, 8, and 2 for EM, DWL and ITN, respectively. Minimal adverse reactions were reported for EM and ITN while 36% of households with DWL reported transient itching. Interpretation DWL is the most effective, durable and acceptable control method followed by ITN. The Visceral Leishmaniasis (VL) Elimination Program in the Indian sub

The effect of small solar powered 'Bͻkͻͻ' net fans on mosquito net use: results from a randomized controlled cross-over trial in southern Ghana.

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Briët, Olivier J T; Yukich, Joshua O; Pfeiffer, Constanze; Miller, William; Jaeger, Mulako S; Khanna, Nitin; Oppong, Samuel; Nardini, Peter; Ahorlu, Collins K; Keating, Joseph

2017-01-03

Long-lasting insecticidal nets (LLINs) are ineffective malaria transmission prevention tools if they are unused. Discomfort due to heat is the most commonly reported reason for not using nets, but this problem is largely unaddressed. With increasing rural electrification and the dropping price of solar power, fans could improve comfort inside nets and be affordable to populations in malaria endemic areas. Here, results are presented from a pilot randomized controlled cross-over study testing the effect of fans on LLIN use. Eighty-three households from two rural communities in Greater Accra, Ghana, randomized into three groups, participated in a 10-month cross-over trial. After a screening survey to identify eligible households, all households received new LLINs. Bͻkͻͻ net fan systems (one fan per member) were given to households in Group 1 and water filters were given to households in Group 2. At mid-point, Group 1 and 2 crossed over interventions. Households in Group 1 and 2 participated in fortnightly surveys on households' practices related to nets, fans and water filters, while households in Group 3 were surveyed only at screening, mid-point and study end. Entomological and weather data were collected throughout the study. Analysis took both 'per protocol' (PP) and 'intention to treat' (ITT) approaches. The mid- and end-point survey data from Group 1 and 2 were analysed using Firth logistic regressions. Fortnightly survey data from all groups were analysed using logistic regressions with random effects. Provision of fans to households appeared to increase net use in this study. Although the increase in net use explained by fans was not significant in the primary analyses (ITT odds ratio 3.24, p > 0.01; PP odds ratio = 1.17, p > 0.01), it was significant in secondary PP analysis (odds ratio = 1.95, p Fan use was 90-100% depending on the fortnightly visit. This pilot study could not provide definitive evidence that fans increase net use. A larger

Insecticide Treated Camouflage Sceening Reduces Sand Fly Numbers in Leishmania-Endemic Regions in Kenya

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Current U.S. military operations in deserts face persistent threats from sand flies that transmit human Leishmania. In this study we investigated the efficacy of artificial barriers treated with residual insecticide to potentially reduce the risk of human infection from leishmaniasis by reducing the...

Use of insecticide-treated school uniforms for prevention of dengue in schoolchildren: a cost-effectiveness analysis.

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Tozan, Yesim; Ratanawong, Pitcha; Louis, Valérie R; Kittayapong, Pattamaporn; Wilder-Smith, Annelies

2014-01-01

Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a "do-nothing" alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440) in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER$16,440). Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention.

Determinants of household demand for bed nets in a rural area of southern Mozambique.

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Chase, Claire; Sicuri, Elisa; Sacoor, Charfudin; Nhalungo, Delino; Nhacolo, Ariel; Alonso, Pedro L; Menéndez, Clara

2009-06-15

A key to making insecticide-treated nets (ITNs) a long-term, sustainable solution to the spread of malaria is understanding what drives their purchase and use. Few studies have analysed the determinants of demand for bed nets for malaria prevention at the household level, and in particular, how demand for nets compares with demand for other mosquito prevention methods. This study uses a household survey to assess the determinants of demand for bed nets in an area of endemic malaria transmission in rural, southern Mozambique. The study looks at willingness to pay (WTP) for bed nets, net ownership, usage, and past purchase behaviour, alongside expenditure and frequency of use of alternate methods for malaria prevention. While overall net ownership in the sample is low, the evidence fails to suggest that poorer households are less likely to own bed nets, when controlling for covariates, nor does the likelihood of receiving a free net depend on socioeconomic status (SES). Formal schooling and market knowledge seem to indicate higher average willingness to pay, while use of alternate methods for malaria prevention, and receipt of Indoor Residual Spraying (IRS) are found to decrease demand for bed nets. For long-term sustainability of ITNs to be realized, results suggest that either full or partial subsidies may be necessary in some contexts to encourage households to obtain and use nets. Given the possible substitution effects of combined malaria control interventions, and the danger of not taking into consideration household preferences for malaria prevention, successful malaria control campaigns should invest a portion of their funds towards educating recipients of IRS and users of other preventive methods on the importance of net use even in the absence of mosquitoes.

Determinants of household demand for bed nets in a rural area of southern Mozambique

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Nhacolo Ariel

2009-06-01

Full Text Available Abstract Background A key to making insecticide-treated nets (ITNs a long-term, sustainable solution to the spread of malaria is understanding what drives their purchase and use. Few studies have analysed the determinants of demand for bed nets for malaria prevention at the household level, and in particular, how demand for nets compares with demand for other mosquito prevention methods. Methods This study uses a household survey to assess the determinants of demand for bed nets in an area of endemic malaria transmission in rural, southern Mozambique. The study looks at willingness to pay (WTP for bed nets, net ownership, usage, and past purchase behaviour, alongside expenditure and frequency of use of alternate methods for malaria prevention. Results While overall net ownership in the sample is low, the evidence fails to suggest that poorer households are less likely to own bed nets, when controlling for covariates, nor does the likelihood of receiving a free net depend on socioeconomic status (SES. Formal schooling and market knowledge seem to indicate higher average willingness to pay, while use of alternate methods for malaria prevention, and receipt of Indoor Residual Spraying (IRS are found to decrease demand for bed nets. Conclusion For long-term sustainability of ITNs to be realized, results suggest that either full or partial subsidies may be necessary in some contexts to encourage households to obtain and use nets. Given the possible substitution effects of combined malaria control interventions, and the danger of not taking into consideration household preferences for malaria prevention, successful malaria control campaigns should invest a portion of their funds towards educating recipients of IRS and users of other preventive methods on the importance of net use even in the absence of mosquitoes.

Use of bed nets and factors that influence bed net use among Jinuo Ethnic Minority in southern China.

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Xu, Jian-wei; Liao, Yuan-mei; Liu, Hui; Nie, Ren-hua; Havumaki, Joshua

2014-01-01

Insecticide-treated nets (ITNs) are an integral part of vector control recommendations for malaria elimination in China. This study investigated the extent to which bed nets were used and which factors influence bed net use among Jinuo Ethnic Minority in China-Myanmar-Laos border areas. This study combined a quantitative household questionnaire survey and qualitative semi-structured in-depth interviews (SDI). Questionnaires were administered to 352 heads of households. SDIs were given to 20 key informants. The bed net to person ratio was 1∶2.1 (i.e., nearly one net for every two people), however only 169 (48.0%) households owned at least one net and 623 (47.2%) residents slept under bed nets the prior night. The percentages of residents who regularly slept under nets (RSUN) and slept under nets the prior night (SUNPN) were similar (48.0% vs. 47.2%, P>0.05), however the percentage correct use of nets (CUN) was significantly lower (34.5%, Pcash income per person (ACIP) was an independent factor that influenced bed net use (PHigh bed net availability does not necessarily mean higher coverage or bed net use. Household income, house type and knowledge of the ability of bed nets to prevent malaria are all independent factors that influence bed net use among Jinuo Ethnic Minority.

Reduced risk insecticides to control scale insects and protect natural enemies in the production and maintenance of urban landscape plants.

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Frank, Steven D

2012-04-01

Armored scale insects are among the most difficult to manage and economically important arthropod pests in the production and maintenance of urban landscape plants. This is because of morphological traits that protect them from contact insecticides. I compared initial and season-long control of euonymus scale, Unaspis euonymi Comstock (Hemiptera: Diaspidae), by reduced-risk insecticides (insect growth regulators [IGRs], neonicotinoids, spirotetramat) to determine if they controlled scale as well as more toxic insecticides such as the organophosphate, acephate, and pyrethroid, bifenthrin. I also evaluated how these insecticides affected natural enemy abundance on experimental plants and survival when exposed to insecticide residue. All insecticides tested reduced first generation euonymus scale abundance. In 2009, reinfestation by second generation euonymus scale was highest on plants treated with acetamiprid and granular dinotefuran. In 2010, systemic neonicotinoids and spirotetramat prevented cottony cushion scale infestation 133 d after treatment whereas scale readily infested plants treated with bifenthrin and horticultural oil. Encarsia spp. and Cybocephalus spp. abundance was related to scale abundance. These natural enemies were generally less abundant than predicted by scale abundance on granular dinotefuran treated plants and more abundant on granular thiamethoxam treated plants. Bifenthrin residue killed 90-100% of O. insidiosus and E. citrina within 24 h. My results indicate that reduced risk insecticides can provide season-long scale control with less impact on natural enemies than conventional insecticides. This could have economic and environmental benefits by reducing the number of applications necessary to protect nursery and landscape plants from scale.

Protective effect and economic impact of insecticide application methods on barley

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Alfred Stoetzer

2014-03-01

Full Text Available The objective of this work was to evaluate the protective effect of different forms of insecticide application on the transmission of yellow dwarf disease in barley cultivars, as well as to determine the production costs and the net profit of these managements. The experiments were carried out during 2011 and 2012 growing seasons, using the following managements at main plots: T1, seed treatment with insecticide (ST + insecticide on shoots at 15-day interval; T2, just ST; T3, insecticide applied on shoots, when aphid control level (CL was reached; T4, without insecticide; and T5, ST + insecticide on shoots when CL was reached. Different barley cultivars - BRS Cauê, BRS Brau and MN 6021 - were arranged in the subplots. Insecticides lambda cyhalothrin (pyrethroid and thiamethoxam (neonicotinoid were used. There were differences on yellow dwarf disease index in both seasons for the different treatments, while damage to grain yield was influenced by year and aphid population. Production costs and net profit were different among treatments. Seed treatment with insecticide is sufficient to reduce the transmission of yellow dwarf disease in years with low aphid population pressure, while in years with larger populations, the application of insecticide on shoots is also required.

Perceptions on the effect of small electric fans on comfort inside bed nets in southern Ghana: a qualitative study.

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Jaeger, Mulako S; Briët, Olivier J T; Keating, Joseph; Ahorlu, Collins K; Yukich, Joshua O; Oppong, Samuel; Nardini, Peter; Pfeiffer, Constanze

2016-12-01

Long-lasting insecticidal nets (LLINs) are known to be highly effective in reducing malaria transmission, morbidity and mortality. However, among those owning an LLIN, use rates are often suboptimal. A reported barrier to bed net use is discomfort due to heat. This qualitative study was part of a larger evaluation conducted in communities without electricity in rural Ghana to assess whether 0.8 W solar powered net fans can increase net use. Twenty-three key informant interviews with household heads in the study communities in Shai-Osudoku District, southern Ghana, were conducted from July to August 2015. The purpose of the interviews was to obtain insight into perceptions of participants about the net fan system in relation to LLIN use. While all study participants reported using LLINs, with mosquito nuisance prevention as the prime motivation, heat was also mentioned as a key barrier to net use. Respondents appreciated the net fans because they improved comfort inside bed nets. The LED light on the fan stand became the main source of light at night and positively influenced the perception of the intervention as a whole. The general acceptance of the net fan system by the study participants highlights the potential of the intervention to improve comfort inside mosquito nets. This, therefore, has a potential to increase bed net use in areas with low access to electricity.

Lethal and Sub-lethal Effects of Four Insecticides on the Aphidophagous Coccinellid Adalia bipunctata (Coleoptera: Coccinellidae).

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Depalo, Laura; Lanzoni, Alberto; Masetti, Antonio; Pasqualini, Edison; Burgio, Giovanni

2017-12-05

Conventional insecticide assays, which measure the effects of insecticide exposure on short-term mortality, overlook important traits, including persistence of toxicity or sub-lethal effects. Therefore, such approaches are especially inadequate for prediction of the overall impact of insecticides on beneficial arthropods. In this study, the side effects of four modern insecticides (chlorantraniliprole, emamectin benzoate, spinosad, and spirotetramat) on Adalia bipunctata (L.) (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by exposition on treated potted plants. In addition to investigation of acute toxicity and persistence of harmful activity in both larvae and adults of A. bipunctata, demographic parameters were evaluated, to provide a comprehensive picture of the nontarget effects of these products. Field doses of the four insecticides caused detrimental effects to A. bipunctata; but in different ways. Overall, spinosad showed the best toxicological profile among the products tested. Emamectin benzoate could be considered a low-risk insecticide, but had high persistence. Chlorantraniliprole exhibited lethal effects on early instar larvae and adults, along with a long-lasting activity, instead spirotetramat showed a low impact on larval and adult mortality and can be considered a short-lived insecticide. However, demographic analysis demonstrated that chlorantraniliprole and spirotetramat caused sub-lethal effects. Our findings highlight that sole assessment of mortality can lead to underestimation of the full impact of pesticides on nontarget insects. Demographic analysis was demonstrated to be a sensitive method for detection of the sub-lethal effects of insecticides on A. bipunctata, and this approach should be considered for evaluation of insecticide selectivity. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Which family members use the best nets? An analysis of the condition of mosquito nets and their distribution within households in Tanzania

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Lines Jo

2010-07-01

Full Text Available Abstract Background Household ownership of insecticide-treated mosquito nets (ITNs is increasing, and coverage targets have been revised to address universal coverage with ITNs. However, many households do not have enough nets to cover everyone, and the nets available vary in physical condition and insecticide treatment status. Since 2004, the Government of Tanzania has been implementing the Tanzania National Voucher Scheme (TNVS, which distributes vouchers for ITNs through antenatal clinics to target pregnant women and their infants. This analysis aimed to determine the following: (1 coverage patterns of bed nets within households according to physical condition and treatment status; (2 who might be at risk if mosquitoes were diverted from occupants of untreated nets to those not using nets? (3 the degree to which those at highest risk of malaria use the most protective nets. Methods Data from the 2006 TNVS household survey were analysed to assess within-household distribution of net use. The associations between net characteristics and net user were also evaluated. Multivariate analysis was applied to the relationship between the number of holes per net and user characteristics while adjusting for confounders. Results In households with a net:person ratio better than 1:4 (one net for every four household members, more than 80% of the people in such households reported using a net the previous night. ITNs were most likely to be used by infants, young children (1-4 y, and women of childbearing age; they were least likely to be used by older women (≥50 y, older children (5-14 y, and adult men. The nets used by infants and women of childbearing age were in better-than-average physical condition; the nets used by older women and older children were in worse-than-average condition; while young children and adult men used nets in intermediate (average condition. When adjusted for confounders, the nets used by young and older children had more holes

Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns.

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Jonathan L Larson

Full Text Available Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees.

Assessing Insecticide Hazard to Bumble Bees Foraging on Flowering Weeds in Treated Lawns

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Larson, Jonathan L.; Redmond, Carl T.; Potter, Daniel A.

2013-01-01

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees. PMID:23776667

Use of insecticide-treated school uniforms for prevention of dengue in schoolchildren: a cost-effectiveness analysis.

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Yesim Tozan

Full Text Available BACKGROUND: Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. METHODS: Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a "do-nothing" alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. RESULTS: At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440 in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER$16,440. CONCLUSIONS: Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention.

Rice Production without Insecticide in Smallholder Farmer's Field

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M. P. Ali

2017-05-01

Full Text Available Highlights:Use of perching, sweeping, and need based insecticide (IPM technique useage produce at par yields compared to prophylactic insecticide useage in rice fields.There exists a technique that can reduce 75% of insecticide useage in rice field.The results were obtained in cooperation between smallholder rice farmers and researchers of Bangladesh.Currently rice protection from insect pests solely depends on chemical pesticides which have tremendous impact on biodiversity, environment, animal, and human health. To reduce their impact from our society we need to cut pesticide use from agricultural practices. To address this issue, we did an experiment to identify realistic solutions that could help farmers build sustainable crop protection systems and minimize useage of insecticides and thus reduce the impact of pesticides in the environment. Innovations developed jointly by farmers and researchers and evaluated for their potential to be adopted by more farmers. In this paper we tested four management practices jointly with smallholder farmer fields in order to select the best one. Four management practices were used namely, T1 = Prophylactic use of insecticide where insecticide was applied in rice field at every 15 days interval without judging the infestation level; T2 = Perching (that is, placing roosting (perching sites for insectivorous birds within the rice field and concurrent sweep net samples along with need-based insecticide application; T3 = Perching only; and T4 = Farmer's own practices. The results revealed that routine application of insecticides for crop protection is not mandatory which is commonly found at use in rice farmers. In our experiment, where prophylactic method or farmers used 3–4 times insecticides without judging the insect pests infestation level, the similar pest population was found when compared to the field where insecticide was not applied. Our management system reduced by 75% the use of insecticides even

Olyset Duo® (a pyriproxyfen and permethrin mixture net: an experimental hut trial against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus in Southern Benin.

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Corine Ngufor

Full Text Available Alternative compounds which can complement pyrethroids on long-lasting insecticidal nets (LN in the control of pyrethroid resistant malaria vectors are urgently needed. Pyriproxyfen (PPF, an insect growth regulator, reduces the fecundity and fertility of adult female mosquitoes. LNs containing a mixture of pyriproxyfen and pyrethroid could provide personal protection through the pyrethroid component and reduce vector abundance in the next generation through the sterilizing effect of pyriproxyfen.The efficacy of Olyset Duo, a newly developed mixture LN containing pyriproxyfen and permethrin, was evaluated in experimental huts in southern Benin against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus. Comparison was made with Olyset Net® (permethrin alone and a LN with pyriproxyfen alone (PPF LN. Laboratory tunnel tests were performed to substantiate the findings in the experimental huts.Overall mortality of wild pyrethroid resistant An. gambiae s.s. was significantly higher with Olyset Duo than with Olyset Net (50% vs. 27%, P = 0.01. Olyset DUO was more protective than Olyset Net (71% vs. 3%, P<0.001. The oviposition rate of surviving blood-fed An. gambiae from the control hut was 37% whereas none of those from Olyset Duo and PPF LN huts laid eggs. The tunnel test results were consistent with the experimental hut results. Olyset Duo was more protective than Olyset Net in the huts against wild pyrethroid resistant Cx. quinquefasciatus although mortality rates of this species did not differ significantly between Olyset Net and Olyset Duo. There was no sterilizing effect on surviving blood-fed Cx. quinquefasciatus with the PPF-treated nets.Olyset Duo was superior to Olyset Net in terms of personal protection and killing of pyrethroid resistant An. gambiae, and sterilized surviving blood-fed mosquitoes. Mixing pyrethroid and pyriproxyfen on a LN shows potential for malaria control and management of pyrethroid resistant vectors by

ANABOLIC STEROIDS HAVE LONG-LASTING EFFECTS ON MALE SOCIAL BEHAVIORS

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Salas-Ramirez, Kaliris Y.; Montalto, Pamela R.; Sisk, Cheryl L.

2010-01-01

Anabolic androgenic steroids (AAS) use by adolescents is steadily increasing. Adolescence involves remodeling of steroid-sensitive neural circuits that mediate social behaviors, and previous studies using animal models document effects of AAS on male social behaviors. The present experiments tested whether AAS have persistent and more pronounced behavioral consequences when drug exposure occurs during adolescence as compared to exposure in adulthood. Male Syrian hamsters were injected daily for 14 days with either vehicle or an AAS cocktail containing testosterone cypionate (2 mg/kg), nandrolone decanoate (2 mg/kg), and boldenone undecylenate (1 mg/kg), either during adolescence (27-41 days of age) or adulthood (63-77 days of age). As adults, subjects were tested two or four weeks after the last injection for either sexual behavior with a receptive female or male-male agonistic behavior in a resident-intruder test. Compared with vehicle-treated males, AAS-treated males, regardless of age of treatment, displayed fewer long intromissions and a significant increase in latency to the first long intromission, indicative of reduced potential to reach sexual satiety. Increased aggression was observed in males exposed to AAS compared with males treated with vehicle, independently of age of AAS treatment. However, unlike hamsters exposed to AAS in adulthood, hamsters exposed to AAS during adolescence did not display any submissive or risk-assessment behaviors up to 4 weeks after discontinuation of AAS treatment. Thus, AAS have long-lasting effects on male sexual and agonistic behaviors, with AAS exposure during adolescence resulting in a more pronounced reduction in submissive behavior compared to AAS exposure in adulthood. PMID:20036695

The underlying reasons for very high levels of bed net use, and higher malaria infection prevalence among bed net users than non-users in the Tanzanian city of Dar es Salaam: a qualitative study.

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Msellemu, Daniel; Shemdoe, Aloysia; Makungu, Christina; Mlacha, Yeromini; Kannady, Khadija; Dongus, Stefan; Killeen, Gerry F; Dillip, Angel

2017-10-23

Bed nets reduce malaria-related illness and deaths, by forming a protective barrier around people sleeping under them. When impregnated with long-lasting insecticide formulations they also repel or kill mosquitoes attempting to feed upon sleeping humans, and can even suppress entire populations of malaria vectors that feed predominantly upon humans. Nevertheless, an epidemiological study in 2012 demonstrated higher malaria prevalence among bed net users than non-users in urban Dar es Salaam, Tanzania. Focus group discussions were conducted with women from four selected wards of Dar es Salaam city, focusing on four major themes relating to bed net use behaviours: (1) reasons for bed net use, (2) reasons for not using bed nets, (3) stimuli or reminders for people to use a bed net (4) perceived reasons for catching malaria while using a bed net. An analytical method by framework grouping of relevant themes was used address key issues of relevance to the study objectives. Codes were reviewed and grouped into categories and themes. All groups said the main reason for bed net use was protection against malaria. Houses with well-screened windows, with doors that shut properly, and that use insecticidal sprays against mosquitoes, were said not to use bed nets, while frequent attacks from malaria was the main stimulus for people to use bed nets. Various reasons were mentioned as potential reasons that compromise bed net efficacy, the most common of which were: (1) bed net sharing by two or more people, especially if one occupant tends to come to bed late at night, and does not tuck in the net 71%; (2) one person shares the bed but does not use the net, moving it away from the side on which s/he sleeps 68%; (3) ineffective usage habits, called ulalavi, in which a sprawling sleeper either touches the net while sleeping up against it or leaves a limb hanging outside of it 68%. Less common reasons mentioned included: (1) Small bed nets which become un-tucked at night (31%); (2

Multiple causes of an unexpected malaria outbreak in a high-transmission area in Madagascar.

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Kesteman, Thomas; Rafalimanantsoa, Solofoniaina A; Razafimandimby, Harimahefa; Rasamimanana, Heriniaina H; Raharimanga, Vaomalala; Ramarosandratana, Benjamin; Ratsimbasoa, Arsene; Ratovonjato, Jocelyn; Elissa, Nohal; Randrianasolo, Laurence; Finlay, Alyssa; Rogier, Christophe; Randrianarivelojosia, Milijaona

2016-02-02

pyrethroids. Two years after distribution, nearly all LLINs collected showed a loss of physical integrity and insecticide activity, Increased rainfall, decreasing use and reduced insecticide activity of long-lasting insecticide-treated nets, and drug shortages may have been responsible for, or contributed to, the outbreak observed in South-Eastern Madagascar in 2011-2012. Control interventions for malaria elimination must be sustained at the risk of triggering harmful epidemics, even in zones of high transmission.

Net Gain

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

Describing the effect of tax incentives for import, production, and sale of nets and insecticides; and ..... So far, China is the only country where a system for the routine treatment of ...... 1993), and the trials in Ecuador and Peru (Kroeger et al.

Insecticide-Treated Nets Utilization and Associated Factors among under-5 Years Old Children in Mirab-Abaya District, Gamo-Gofa Zone, Ethiopia.

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Admasie, Amha; Zemba, Amanuel; Paulos, Wondimagegn

2018-01-01

Malaria can be prevented using cost-effective interventions. It can be prevented at large via the use of insecticide-treated mosquito nets (ITNs). The use of ITNs decreases malaria mortality rates by 55% in under-5 years old children in Africa, Ethiopia, realizing the effectiveness, scaling up distribution and utilization of ITNs to cover 100% of children less than 5 years of age. However, little is known about ITNs utilization and factors associated with the utilization in under-5 years old children in the study area yet. The purpose of this study was to assess the level and associated factors of ITNs utilization in under-5 years old children among households with under-5 years old children of Mirab Abaya District, Gamo Gofa Zone, Ethiopia. A community-based cross-sectional study was conducted during August-September, 2016. Six study Kebeles were identified by simple random sampling technique and 398 households with at least one under-5 years old children were selected by random sampling technique using computer generated random numbers from health post family folders. Structured, interviewer questionnaire was administered to mothers or care givers of the children. Data were entered to Epi Info Version 3.5 and analyzed in SPSS version 21 statistical software. Bivariate and multivariate logistic regression analysis was done. P -value used for the determination of associations between dependent and predictor variables. Results were presented in narrations, tables, and graph. Among 398 under-5 years old children assessed, the majority, 362 (91.0%) of them had access to ITN, but only 137 (37.2%) of the child had ITNs utilization during the previous night prior to the survey. Households with age of mothers or caretakers 31-44 years, AOR = 0.03, 95% CI (0.01-0.07) and ≥45 years of age; AOR = 0.05, 95% CI (0.01-0.58); households with family size ≤5 members, AOR = 11.23, 95% CI (4.31-29.24); and households with sleeping space ≥2, AOR�

Markets, voucher subsidies and free nets combine to achieve high bed net coverage in rural Tanzania

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Gerrets Rene PM

2008-06-01

Full Text Available Abstract Background Tanzania has a well-developed network of commercial ITN retailers. In 2004, the government introduced a voucher subsidy for pregnant women and, in mid 2005, helped distribute free nets to under-fives in small number of districts, including Rufiji on the southern coast, during a child health campaign. Contributions of these multiple insecticide-treated net delivery strategies existing at the same time and place to coverage in a poor rural community were assessed. Methods Cross-sectional household survey in 6,331 members of randomly selected 1,752 households of 31 rural villages of Demographic Surveillance System in Rufiji district, Southern Tanzania was conducted in 2006. A questionnaire was administered to every consenting respondent about net use, treatment status and delivery mechanism. Findings Net use was 62.7% overall, 87.2% amongst infants (0 to1 year, 81.8% amongst young children (>1 to 5 years, 54.5% amongst older children (6 to 15 years and 59.6% amongst adults (>15 years. 30.2% of all nets had been treated six months prior to interview. The biggest source of nets used by infants was purchase from the private sector with a voucher subsidy (41.8%. Half of nets used by young children (50.0% and over a third of those used by older children (37.2% were obtained free of charge through the vaccination campaign. The largest source of nets amongst the population overall was commercial purchase (45.1% use and was the primary means for protecting adults (60.2% use. All delivery mechanisms, especially sale of nets at full market price, under-served the poorest but no difference in equity was observed between voucher-subsidized and freely distributed nets. Conclusion All three delivery strategies enabled a poor rural community to achieve net coverage high enough to yield both personal and community level protection for the entire population. Each of them reached their relevant target group and free nets only temporarily

The impact of a hybrid social marketing intervention on inequities in access, ownership and use of insecticide-treated nets

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Stallworthy Guy

2007-01-01

Full Text Available Abstract Background An ITN intervention was initiated in three predominantly rural districts of Eastern Province, Zambia, that lacked commercial distribution and communication infrastructures. Social marketing techniques were used for product and message development. Public sector clinics and village-based volunteers promoted and distributed subsidized ITNs priced at $2.5 per net. A study was conducted to assess the effects of the intervention on inequities in knowledge, access, ownership and use of ITNs. Methods A post-test only quasi-experimental study design was used to compare intervention and comparison districts. A total of 2,986 respondents were interviewed. Survey respondents were grouped into four socio-economic (SES categories: low, medium-low, medium and high. Knowledge, access, ownership and use indicators are compared. Concentration index scores are calculated. Interactions between intervention status and SES help determine how different SES groups benefited from the intervention. Results Although overall use of nets remained relatively low, post-test data show that knowledge, access, ownership and use of mosquito nets was higher in intervention districts. A decline in SES inequity in access to nets occurred in intervention districts, resulting from a disproportionately greater increase in access among the low SES group. Declines in SES inequities in net ownership and use of nets were associated with the intervention. The largest increases in net ownership and use occurred among medium and high SES categories. Conclusion Increasing access to nets among the poorest respondents in rural areas may not lead to increases in net use unless the price of nets is no longer a barrier to their purchase.

The impact of a hybrid social marketing intervention on inequities in access, ownership and use of insecticide-treated nets.

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Agha, Sohail; Van Rossem, Ronan; Stallworthy, Guy; Kusanthan, Thankian

2007-01-29

An ITN intervention was initiated in three predominantly rural districts of Eastern Province, Zambia, that lacked commercial distribution and communication infrastructures. Social marketing techniques were used for product and message development. Public sector clinics and village-based volunteers promoted and distributed subsidized ITNs priced at 2.5 dollars per net. A study was conducted to assess the effects of the intervention on inequities in knowledge, access, ownership and use of ITNs. A post-test only quasi-experimental study design was used to compare intervention and comparison districts. A total of 2,986 respondents were interviewed. Survey respondents were grouped into four socio-economic (SES) categories: low, medium-low, medium and high. Knowledge, access, ownership and use indicators are compared. Concentration index scores are calculated. Interactions between intervention status and SES help determine how different SES groups benefited from the intervention. Although overall use of nets remained relatively low, post-test data show that knowledge, access, ownership and use of mosquito nets was higher in intervention districts. A decline in SES inequity in access to nets occurred in intervention districts, resulting from a disproportionately greater increase in access among the low SES group. Declines in SES inequities in net ownership and use of nets were associated with the intervention. The largest increases in net ownership and use occurred among medium and high SES categories. Increasing access to nets among the poorest respondents in rural areas may not lead to increases in net use unless the price of nets is no longer a barrier to their purchase.

Anopheles coluzzii larval habitat and insecticide resistance in the island area of Manoka, Cameroon.

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Etang, Josiane; Mbida Mbida, Arthur; Ntonga Akono, Patrick; Binyang, Jerome; Eboumbou Moukoko, Carole Else; Lehman, Leopold Gustave; Awono-Ambene, Parfait; Talipouo, Abdou; Ekoko Eyisab, Wolfgang; Tagne, Darus; Tchoffo, Romeo; Manga, Lucien; Mimpfoundi, Remy

2016-05-20

The effectiveness of Long-Lasting Insecticidal Nets and Indoor Residual Spraying in malaria vector control is threatened by vector resistance to insecticides. Knowledge of mosquito habitats and patterns of insecticide resistance would facilitate the development of appropriate vector control strategies. Therefore, we investigated An. coluzzii larval habitats and resistance to insecticides in the Manoka rural island area compared with the Youpwe suburban inland area, in Douala VI and II districts respectively. Anopheline larvae and pupae were collected from open water bodies in December 2013 and April 2014 and reared until adult emergence. Two to four day old emerging females were morphologically identified as belonging to the An. gambiae complex and used for WHO susceptibility tests with 4 % DDT, 0.75 % permethrin, and 0.05 % deltamethrin, with or without piperonyl butoxide (PBO) synergist. Control and surviving specimens were identified down to the species using a PCR-RFLP method. Survivors were genotyped for kdr L1014 mutations using Hot Oligonucleotide Ligation Assay. In both study sites, ponds, residual puddles, boats, and drains were identified as the major An. gambiae s.l. larval habitats. A total of 1397 females, including 784 specimens from Manoka and 613 from Youpwe, were used for resistance testing. The two mosquito populations displayed resistance to DDT, permethrin and deltamethrin, with variable mortality rates from 1 % to 90 %. The knock-down times were also significantly increased (at least 2.8 fold). Pre-exposure of mosquitoes to PBO did not impact on their mortality to DDT, conversely the mortality rates to permethrin and deltamethrin were significantly increased (7.56 ≤ X(2) ≤ 48.63, df = 1, p habitats have been identified, larval source management strategies may be trialed in this area as complementary vector control interventions.

Quantifying behavioural interactions between humans and mosquitoes: Evaluating the protective efficacy of insecticidal nets against malaria transmission in rural Tanzania

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Mathenge Evan

2006-11-01

Full Text Available Abstract Background African malaria vectors bite predominantly indoors at night so sleeping under an Insecticide-Treated Net (ITN can greatly reduce malaria risk. Behavioural adaptation by mosquitoes to increasing ITN coverage could allow vector mosquitoes to bite outside of peak sleeping hours and undermine efficacy of this key malaria prevention measure. Methods High coverage with largely untreated nets has been achieved in the Kilombero Valley, southern Tanzania through social marketing programmes. Direct surveys of nightly biting activity by An. gambiae Giles were conducted in the area before (1997 and after (2004 implementation of ITN promotion. A novel analytical model was applied to estimate the effective protection provided by an ITN, based on published experimental hut trials combined with questionnaire surveys of human sleeping behaviour and recorded mosquito biting patterns. Results An. gambiae was predominantly endophagic and nocturnal in both surveys: Approximately 90% and 80% of exposure occurred indoors and during peak sleeping hours, respectively. ITNs consistently conferred >70% protection against exposure to malaria transmission for users relative to non-users. Conclusion As ITN coverage increases, behavioural adaptation by mosquitoes remains a future possibility. The approach described allows comparison of mosquito biting patterns and ITN efficacy at multiple study sites and times. Initial results indicate ITNs remain highly effective and should remain a top-priority intervention. Combined with recently developed transmission models, this approach allows rapid, informative and cost-effective preliminary comparison of diverse control strategies in terms of protection against exposure before more costly and intensive clinical trials.

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba.

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Dennis Pérez

2018-01-01

Full Text Available Within the context of a field trial conducted by the Cuban vector control program (AaCP, we assessed acceptability of insecticide-treated curtains (ITCs and residual insecticide treatment (RIT with deltamethrin by the community. We also assessed the potential influence of interviewees' risk perceptions for getting dengue and disease severity.We embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38 were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT.Acceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement.

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba.

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Pérez, Dennis; Van der Stuyft, Patrick; Toledo, María Eugenia; Ceballos, Enrique; Fabré, Francisco; Lefèvre, Pierre

2018-01-01

Within the context of a field trial conducted by the Cuban vector control program (AaCP), we assessed acceptability of insecticide-treated curtains (ITCs) and residual insecticide treatment (RIT) with deltamethrin by the community. We also assessed the potential influence of interviewees' risk perceptions for getting dengue and disease severity. We embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT) testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38) were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT. Acceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement.

Decline in frequency of the 2La chromosomal inversion in Anopheles gambiae (s.s.) in Western Kenya: correlation with increase in ownership of insecticide-treated bed nets.

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Matoke-Muhia, Damaris; Gimnig, John E; Kamau, Luna; Shililu, Josephat; Bayoh, M Nabie; Walker, Edward D

2016-06-10

The 2La chromosomal inversion, a genetic polymorphism in An. gambiae (sensu stricto) (s.s.), is associated with adaptation to microclimatic differences in humidity and desiccation resistance and mosquito behaviors. Ownership of insecticide-treated bed nets (ITNs) for malaria control has increased markedly in western Kenya in the last 20 years. An increase in the frequency of ITNs indoors could select against house entering or indoor resting of Anopheles mosquitoes. Thus, the frequency of the 2La inversion is postulated to change in An. gambiae (s.s.) with the increase of ITN ownership over time. Anopheles gambiae mosquitoes were sampled between 1994 and 2011 using pyrethrum knockdown, bednet traps and human landing catches (HLC) from Asembo and Seme, western Kenya. The 2La inversion was detected by a PCR assay with primers designed for proximal breakpoints of the 2La/a and 2L+(a)/+(a) chromosomal conformation. Mosquitoes were tested for malaria parasite infection by sporozoite ELISA. The frequency of the 2La chromosomal inversion declined from 100 % of all chromosomes in 1994 to 17 % in 2005 and remained low through 2011 (21 %). ITN ownership increased from 0 to > 90 % of houses in the study area during this interval. The decline in the frequency of the 2La chromosomal inversion was significantly, negatively correlated with year (r = -0.93) and with increase in ITN ownership (r = -0.96). The frequency of the homo- and heterokaryotypes departed significantly from Hardy-Weinberg equilibrium, suggesting that 2La/a karyotype was under selection, earlier in its favor and later, against it. Precipitation and maximum monthly temperature did not vary over time, therefore there was no trend in climate that could account for the decline. There was no significant difference in frequency of the 2La inversion in An. gambiae (s.s.) females sampled indoors or outdoors in HCL in 2011, nor was there an association between the 2La inversion and infection with Plasmodium

Impact of PermaNet 3.0 on entomological indices in an area of pyrethroid resistant Anopheles gambiae in south-western Nigeria

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2014-01-01

Background PermaNet® 3.0 is an insecticide synergist-combination long-lasting insecticidal net designed to have increased efficacy against malaria vectors with metabolic resistance, even when combined with kdr. The current study reports on the impact of this improved tool on entomological indices in an area with pyrethroid-resistant malaria vectors in Nigeria. Methods Baseline entomological indices across eight villages in Remo North LGA of Ogun State provided the basis for selection of three villages (Ilara, Irolu and Ijesa) for comparing the efficacy of PermaNet® 3.0 (PN3.0), PermaNet® 2.0 (PN2.0) and untreated polyester nets as a control (UTC). In each case, nets were distributed to cover all sleeping spaces and were evaluated for insecticidal activity on a 3-monthly basis. Collection of mosquitoes was conducted monthly via window traps and indoor resting catches. The arithmetic means of mosquito catches per house, entomological inoculation rates before and during the intervention were compared as well as three other outcome parameters: the mean mosquito blood feeding rate, mean mortality and mean parity rates. Results Anopheles gambiae s.l. was the main malaria vector in the three villages, accounting for >98% of the Anopheles population and found in appreciable numbers for 6–7 months. Deltamethrin, permethrin and lambdacyhalothrin resistance were confirmed at Ilara, Irolu and Ijesa. The kdr mutation was the sole resistance mechanism at Ilara, whereas kdr plus P450-based metabolic mechanisms were detected at Irolu and Ijesa. Bioassays repeated on domestically used PN 2.0 and PN 3.0 showed persistent optimal (100%) bio-efficacy for both net types after the 3rd, 6th, 9th and 12th month following net distribution. The use of PN 3.0 significantly reduced mosquito densities with a ‘mass killing’ effect inside houses. Households with PN 3.0 also showed reduced blood feeding as well as lower mosquito parity and sporozoite rates compared to the PN 2.0 and the

Impact of reduced-risk insecticides on soybean aphid and associated natural enemies.

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Ohnesorg, Wayne J; Johnson, Kevin D; O'Neal, Matthew E

2009-10-01

Insect predators in North America suppress Aphis glycines Matsumura (Hemiptera: Aphididae) populations; however, insecticides are required when populations reach economically damaging levels. Currently, insecticides used to manage A. glycines are broad-spectrum (pyrethroids and organophosphates), and probably reduce beneficial insect abundance in soybean, Glycine max (L.) Merr. Our goal was to determine whether insecticides considered reduced-risk by the Environmental Protection Agency could protect soybean yield from A. glycines herbivory while having a limited impact on the aphid's natural enemies. We compared three insecticides (imidacloprid, thiamethoxam, and pymetrozine,) to a broad-spectrum insecticide (lamda-cyhalothrin) and an untreated control using two application methods. We applied neonicotinoid insecticides to seeds (imidacloprid and thiamethoxam) as well as foliage (imidacloprid); pymetrozine and lamda-cyhalothrin were applied only to foliage. Foliage-applied insecticides had lower A. glycines populations and higher yields than the seed-applied insecticides. Among foliage-applied insecticides, pymetrozine and imidacloprid had an intermediate level of A. glycines population and yield protection compared with lamda-cyhalothrin and the untreated control. We monitored natural enemies with yellow sticky cards, sweep-nets, and direct observation. Before foliar insecticides were applied (i.e., before aphid populations developed) seed treatments had no observable effect on the abundance of natural enemies. After foliar insecticides were applied, differences in natural enemy abundance were observed when sampled with sweep-nets and direct observation but not with yellow sticky cards. Based on the first two sampling methods, pymetrozine and the foliage-applied imidacloprid had intermediate abundances of natural enemies compared with the untreated control and lamda-cyhalothrin.

Which nets are being used: factors associated with mosquito net use in Amhara, Oromia and Southern Nations, Nationalities and Peoples' Regions of Ethiopia.

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Ngondi, Jeremiah M; Graves, Patricia M; Gebre, Teshome; Mosher, Aryc W; Shargie, Estifanos B; Emerson, Paul M; Richards, Frank O

2011-04-17

There has been recent large scale-up of malaria control interventions in Ethiopia where transmission is unstable. While household ownership of long-lasting insecticidal nets (LLIN) has increased greatly, there are concerns about inadequate net use. This study aimed to investigate factors associated with net use at two time points, before and after mass distribution of nets. Two cross sectional surveys were carried out in 2006 and 2007 in Amhara, Oromia and SNNP regions. The latter was a sub-sample of the national Malaria Indicator Survey (MIS 3R). Each survey wave used multi-stage cluster random sampling with 25 households per cluster (224 clusters with 5,730 households in Baseline 2006 and 245 clusters with 5,910 households in MIS 3R 2007). Net ownership was assessed by visual inspection while net utilization was reported as use of the net the previous night. This net level analysis was restricted to households owning at least one net of any type. Logistic regression models of association between net use and explanatory variables including net type, age, condition, cost and other household characteristics were undertaken using generalized linear latent and mixed models (GLLAMM). A total of 3,784 nets in 2,430 households were included in the baseline 2006 analysis while the MIS 3R 2007 analysis comprised 5,413 nets in 3,328 households. The proportion of nets used the previous night decreased from 85.1% to 56.0% between baseline 2006 and MIS 3R 2007, respectively. Factors independently associated with increased proportion of nets used were: LLIN net type (at baseline 2006); indoor residual spraying (at MIS 3R 2007); and increasing wealth index at both surveys. At both baseline 2006 and MIS 3R 2007, reduced proportion of nets used was independently associated with increasing net age, increasing damage of nets, increasing household net density, and increasing altitude (>2,000 m). This study identified modifiable factors affecting use of nets that were consistent

Which nets are being used: factors associated with mosquito net use in Amhara, Oromia and Southern Nations, Nationalities and Peoples' Regions of Ethiopia

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Mosher Aryc W

2011-04-01

Full Text Available Abstract Background There has been recent large scale-up of malaria control interventions in Ethiopia where transmission is unstable. While household ownership of long-lasting insecticidal nets (LLIN has increased greatly, there are concerns about inadequate net use. This study aimed to investigate factors associated with net use at two time points, before and after mass distribution of nets. Methods Two cross sectional surveys were carried out in 2006 and 2007 in Amhara, Oromia and SNNP regions. The latter was a sub-sample of the national Malaria Indicator Survey (MIS 3R. Each survey wave used multi-stage cluster random sampling with 25 households per cluster (224 clusters with 5,730 households in Baseline 2006 and 245 clusters with 5,910 households in MIS 3R 2007. Net ownership was assessed by visual inspection while net utilization was reported as use of the net the previous night. This net level analysis was restricted to households owning at least one net of any type. Logistic regression models of association between net use and explanatory variables including net type, age, condition, cost and other household characteristics were undertaken using generalized linear latent and mixed models (GLLAMM. Results A total of 3,784 nets in 2,430 households were included in the baseline 2006 analysis while the MIS 3R 2007 analysis comprised 5,413 nets in 3,328 households. The proportion of nets used the previous night decreased from 85.1% to 56.0% between baseline 2006 and MIS 3R 2007, respectively. Factors independently associated with increased proportion of nets used were: LLIN net type (at baseline 2006; indoor residual spraying (at MIS 3R 2007; and increasing wealth index at both surveys. At both baseline 2006 and MIS 3R 2007, reduced proportion of nets used was independently associated with increasing net age, increasing damage of nets, increasing household net density, and increasing altitude (>2,000 m. Conclusion This study identified

Comparison of exclusion and imidacloprid for reduction of oviposition damage to young trees by periodical cicadas (Hemiptera: Cicadidae).

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Ahern, Robert G; Frank, Steven D; Raupp, Michael J

2005-12-01

Insecticides are traditionally used to control periodical cicadas (Homoptera: Cicadidae) and to reduce associated injury caused by oviposition. However, research has shown that conventional insecticides have low or variable season-long efficacy in reducing injury caused by cicadas. New systemic neonicotinoid insecticides provide excellent levels of control against a variety of sucking insects. We compared the efficacy of a neonicotinoid insecticide, imidacloprid, and a nonchemical control measure, netting, to reduce cicada injury. Netted trees sustained very little injury, whereas unprotected trees were heavily damaged. Fewer eggnests, scars, and flags were observed on trees treated with imidacloprid compared with unprotected trees; however, the hatching of cicada eggs was unaffected by imidacloprid.

Genetic variation associated with increased insecticide resistance in the malaria mosquito, Anopheles coluzzii.

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Main, Bradley J; Everitt, Amanda; Cornel, Anthony J; Hormozdiari, Fereydoun; Lanzaro, Gregory C

2018-04-04

Malaria mortality rates in sub-Saharan Africa have declined significantly in recent years as a result of increased insecticide-treated bed net (ITN) usage. A major challenge to further progress is the emergence and spread of insecticide resistance alleles in the Anopheles mosquito vectors, like An. coluzzii. A non-synonymous mutation in the para voltage-gated sodium channel gene reduces pyrethroid-binding affinity, resulting in knockdown resistance (kdr). Metabolic mechanisms of insecticide resistance involving detoxification genes like cytochrome P450 genes, carboxylesterases, and glutathione S-transferases are also important. As some gene activity is tissue-specific and/or environmentally induced, gene regulatory variation may be overlooked when comparing expression from whole mosquito bodies under standard rearing conditions. We detected complex insecticide resistance in a 2014 An. coluzzii colony from southern Mali using bottle bioassays. Additional bioassays involving recombinant genotypes from a cross with a relatively susceptible 1995 An. coluzzii colony from Mali confirmed the importance of kdr and associated increased permethrin resistance to the CYP9K1 locus on the X chromosome. Significant differential expression of CYP9K1 was not observed among these colonies in Malpighian tubules. However, the P450 gene CYP6Z1 was overexpressed in resistant individuals following sublethal permethrin exposure and the carboxylesterase gene COEAE5G was constitutively overexpressed. The significant P450-related insecticide resistance observed in the 2014 An. coluzzii colony indicates that ITNs treated with the P450 inhibitor piperonyl butoxide (PBO) would be more effective in this region. The known insecticide resistance gene CYP6Z1 was differentially expressed exclusively in the context of sublethal permethrin exposure, highlighting the importance of tissue-specificity and environmental conditions in gene expression studies. The increased activity of the carboxylesterase

Willingness to pay for small solar powered bed net fans: results of a Becker-DeGroot-Marschak auction in Ghana.

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Yukich, Joshua O; Briët, Olivier J T; Ahorlu, Collins K; Nardini, Peter; Keating, Joseph

2017-08-07

Long-lasting insecticidal nets (LLINs) are one of the main interventions recommended by the World Health Organization for malaria vector control. LLINs are ineffective if they are not being used. Subsequent to the completion of a cluster randomized cross over trial conducted in rural Greater Accra where participants were provided with the 'Bɔkɔɔ System'-a set of solar powered net fan and light consoles with a solar panel and battery-or alternative household water filters, all trial participants were invited to participate in a Becker-DeGroot-Marschak auction to determine the mean willingness to pay (WTP) for the fan and light consoles and to estimate the demand curve for the units. Results demonstraed a mean WTP of approximately 55 Cedis (~13 USD). Demand results suggested that at a price which would support full manufacturing cost recovery, a majority of households in the area would be willing to purchase at least one such unit.

Insecticide susceptibility of Phlebotomus argentipes & assessment of vector control in two districts of West Bengal, India.

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Kumar, Vijay; Shankar, Lokesh; Kesari, Shreekant; Bhunia, Gouri Shankar; Dinesh, Diwakar Singh; Mandal, Rakesh; Das, Pradeep

2015-08-01

Kala-azar or visceral leishmanisis (VL) is known to be endemic in several States of India including West Bengal (WB). Only meager information is available on the vector dynamics of its vector species, Phlebotomus argentipes particularly in relation to control measure from this State. Hence, a pilot study was undertaken to assess the control strategy and its impact on vector in two endemic districts of WB, India. Two villages each from the two districts, Maldah and Burdwan, were selected for the study. Seasonal variation of sandflies was observed during pre-monsoon, post-monsoon and winter seasons. Susceptibility test of P. argentipes against DDT and bioassay on DDT sprayed wall and on long lasting insecticide nets (LN) Perma Net [®] 2.0 were conducted as per the WHO standard methods. P. argentipes density was high during March to October. Susceptibility status of P. argentipes ranged from 40 to 61.54 per cent. Bioassay test showed 57.89 per cent mortality against LN PermaNet [®] -2.0. and 50 per cent against DDT on wall within 30 min of exposure. Despite the integrated vector management approach, the sandfly population was high in the study area. The reason could be development of resistance in P. argentipes against DDT and low effectiveness of LN PermaNet [®] -2.0. The more pragmatic step will be to conduct large studies to monitor the susceptibility level in P. argentipes against DDT.

Factors influencing the use of topical repellents: implications for the effectiveness of malaria elimination strategies

NARCIS (Netherlands)

Gryseels, C.; Uk, S.; Sluydts, V.; Durnez, L.; Phoeuk, P.; Suon, S.; Set, S.; Heng, S.; Siv, S.; Gerrets, R.; Tho, S.; Coosemans, M.; Peeters Grietens, K.

2015-01-01

In Cambodia, despite an impressive decline in prevalence over the last 10 years, malaria is still a public health problem in some parts of the country. This is partly due to vectors that bite early and outdoors reducing the effectiveness of measures such as Long-Lasting Insecticidal Nets. Repellents

Ownership and usage of mosquito nets after four years of large-scale free distribution in Papua New Guinea

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Hetzel Manuel W

2012-06-01

Full Text Available Abstract Background Papua New Guinea (PNG is a highly malaria endemic country in the South-West Pacific with a population of approximately 6.6 million (2009. In 2004, the country intensified its malaria control activities with support from the Global Fund. With the aim of achieving 80% ownership and usage, a country-wide campaign distributed two million free long-lasting insecticide-treated nets (LLINs. Methods In order to evaluate outcomes of the campaign against programme targets, a country-wide household survey based on stratified multi-stage random sampling was carried out in 17 of the 20 provinces after the campaign in 2008/09. In addition, a before-after assessment was carried out in six purposively selected sentinel sites. A structured questionnaire was administered to the heads of sampled households to elicit net ownership and usage information. Results After the campaign, 64.6% of households owned a LLIN, 80.1% any type of mosquito net. Overall usage by household members amounted to 32.5% for LLINs and 44.3% for nets in general. Amongst children under five years, 39.5% used a LLIN and 51.8% any type of net, whereas 41.3% of pregnant women used a LLIN and 56.1% any net. Accessibility of villages was the key determinant of net ownership, while usage was mainly determined by ownership. Most (99.5% of the household members who did not sleep under a net did not have access to a (unused net in their household. In the sentinel sites, LLIN ownership increased from 9.4% to 88.7%, ownership of any net from 52.7% to 94.1%. Usage of LLINs increased from 5.5% to 55.1%, usage of any net from 37.3% to 66.7%. Among children under five years, usage of LLINs and of nets in general increased from 8.2% to 67.0% and from 44.6% to 76.1%, respectively (all p ≤ 0.001. Conclusions While a single round of free distribution of LLINs significantly increased net ownership, an insufficient number of nets coupled with a heterogeneous distribution led to overall

Rural households at risk of malaria did not own sufficient insecticide treated nets at Dabat HDSS site: evidence from a cross sectional re-census

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Kindie Fentahun Muchie

2017-11-01

Full Text Available Abstract Background Malaria is the leading cause of disease burden across the world, especially in African countries. Ethiopia has designed a five year (2011–2015 plan to cover 100% of the households in malarious areas with one insecticide treated net (ITN for every two persons, and to raise consistent ITN utilization to at least 80%. However, evidence on ownership of ITN among malarious rural households in northwest Ethiopia is quite limited. Hence, the present study aimed at assessing ownership of ITN and associated factors among rural households at risk of malaria at Dabat Health and Demographic Surveillance System site, northwest Ethiopia. Methods A cross sectional re-census was carried out in Dabat Health and Demographic Surveillance System site during peak malaria seasons from October to December, 2014. Data for 15,088 households at Dabat Health and Demographic Surveillance System site were used for the analysis. Descriptive measures and binary logistic regression were carried out. Results Among those who owned at least one ITN, 53.4% were living at an altitude >2500 m above sea level. However, out of households living at an altitude <2000 m above sea level, 15.8% (95% CI 14.4%, 17.3% owned ITN at an average of 4.3 ± 2.1 persons per ITN. Of these, 69.5% (95% CI 64.7%, 74.1% used the ITN. Among utilizing households at malarious areas, 23.7% prioritized pregnant women and 31.4% children to use ITN. The availability of radio receiver/mobile (AOR 1.60, 95%CI 1.08, 2.35 and secondary/above educational status of household member (AOR 1.54, 95%CI 1.19, 2.04 were predictors of ownership of ITN. Conclusion Rural households at risk of malaria did not own a sufficient number of ITN though the utilization is promising. Moreover, prioritizing children and pregnant women to sleep under ITN remains public health problems. Programmers, partners and implementers should consider tailored intervention strategy stratified by altitude in distributing

Social marketing and the fight against malaria in Africa: population services international (PSI) and insecticide treated nets (ITNS).

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Omona, Julius

2009-12-01

This textual analyses on Social marketing, Insecticide Treated Nets (ITNs) and Population Services International (PSI) were undertaken to achieve two objectives: (a) to contribute to the continuing debate and search for a better strategy for combating malaria in sub-Saharan Africa; and (b) to contribute to theory building on social marketing. The analyses revealed that Malaria has reached an epidemic proportion and despite major inroads by PSI in combating malaria on the principles of social marketing, the strategies of pricing and segmentation of the clients are not appropriate for Sub-Saharan African countries that are mired in absolute poverty where majority of the rural communities eke a living on less than a dollar per day and the health sector does not receive priority attention from policy makers and politicians. The descriptive statistics and a one sample t test for the sampled countries suggest that sub-Saharan countries have not even met the hypothesized 5% investment of their GDP on health, compared to their counterparts, the developed countries, who are all above this figure. The null hypothesis that there is no significant different between the population and the sample means of both developed and a developing country in their investments in the health sector was also tested and rejected. Though the elements in some of the existent models and theories of social marketing such as Health Belief Model, Theory of Reasoned Action, Social Cognitive Theory and Trans-theoretical Models all attempt to advocate for elimination of constraints and barriers to effective access to a service or product, PSI is adamant to these and try to generalize these principles in all contexts, including in Sub-Saharan Africa. The African scenario, where about 90% of Malaria related deaths cases in the world occur, demands more than what these theories present. Accordingly, it was concluded that however good intentioned social marketing is, in the case of ITNs in this region, it

Decrease of insecticide resistance over generations without exposure to insecticides in Nilaparvata lugens (Hemipteran: Delphacidae).

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Yang, Yajun; Dong, Biqin; Xu, Hongxing; Zheng, Xusong; Tian, Junce; Heong, Kongleun; Lu, Zhongxian

2014-08-01

The brown planthopper, Nilaparvata lugens (Stål), is one of the most important insect pests on paddy rice in tropical and temperate Asia. Overuse and misuse of insecticides have resulted in the development of high resistance to many different insecticides in this pest. Studies were conducted to evaluate the change of resistance level to four insecticides over 15 generations without any exposure to insecticides in brown planthopper. After 15 generations' rearing without exposure to insecticide, brown planthopper could reverse the resistance to imidacloprid, chlorpyrifos, fipronil, and fenobucarb. The range and style of resistance reversal of brown planthopper differed when treated with four different insecticides. To monitor potential changes in insect physiological responses, we measured the activity of each of the three selected enzymes, including acetylcholinesterases (AChE), general esterases (EST), and glutathione S-transferases. After multiple generations' rearing without exposure to insecticide, AChE and EST activities of brown planthopper declined with the increased generations, suggesting that the brown planthopper population adjusted activities of EST and AChE to adapt to the non-insecticide environment. These findings suggest that the reducing, temporary stop, or rotation of insecticide application could be incorporated into the brown planthopper management.

Insecticide Exposures on Commercial Aircraft: A Literature Review and Screening Level Assessment

Energy Technology Data Exchange (ETDEWEB)

Maddalena, Randy I.; McKone, Thomas E.

2008-10-01

on a thin-film polymer-coated glass design, was developed specifically for deployment in the airliner ventilation system for long-term unattended monitoring of insecticide loading in the aircraft. Because access was not available for either treated aircraft or treatment records during the course of this study, the development and calibration of the passive samplers was halted prior to completion. Continued development of a field ready passive sampler for insecticides in aircraft would require collaboration with the airline industry to finalize the method for deployment and calibration conditions for the sampler. The Task 3 screening level modeling assessment used a dynamic two-box mass balance model that includes treated surfaces and air to explore the time-concentration history of insecticides in the cabin. The model was parameterized using information gathered during the literature review and run for several different insecticide use scenarios. Chemical degradation or sequestration in the surface compartment and mass transfer from the surface to the air limit the rate at which insecticides are removed from the system. This rate limiting process can result in an accumulation of insecticide in the airliner cabin following repeated applications. The extent of accumulation is a function of the overall persistence of the chemical in the system and the amount of chemical applied during each treatment.

"Tazomoka Is Not a Problem". Local Perspectives on Malaria, Fever Case Management and Bed Net Use in Madagascar.

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Mattern, Chiarella; Pourette, Dolorès; Raboanary, Emma; Kesteman, Thomas; Piola, Patrice; Randrianarivelojosia, Milijaona; Rogier, Christophe

2016-01-01

Although its incidence has been decreasing during the last decade, malaria is still a major public health issue in Madagascar. The use of Long Lasting Insecticidal Nets (LLIN) remains a key malaria control intervention strategy in Madagascar, however, it encounters some obstacles. The present study aimed to explore the local terminology related to malaria, information channels about malaria, attitude towards bed nets, and health care seeking practices in case of fever. This article presents novel qualitative findings about malaria. Until now, no such data has been published for Madagascar. A comparative qualitative study was carried out at four sites in Madagascar, each differing by malaria epidemiology and socio-cultural background of the populations. Seventy-one semi-structured interviews were conducted with biomedical and traditional caregivers, and members of the local population. In addition, observations of the living conditions and the uses of bed net were conducted. Due to the differences between local and biomedical perspectives on malaria, official messages did not have the expected impact on population in terms of prevention and care seeking behaviors. Rather, most information retained about malaria was spread through informal information circulation channels. Most interviewees perceived malaria as a disease that is simple to treat. Tazomoka ("mosquito fever"), the Malagasy biomedical word for malaria, was not used by populations. Tazo ("fever") and tazomahery ("strong fever") were the terms more commonly used by members of the local population to refer to malaria related symptoms. According to local perceptions in all areas, tazo and tazomahery were not caused by mosquitos. Each of these symptoms required specific health recourse. The usual fever management strategies consisted of self-medication or recourse to traditional and biomedical caregivers. Usage of bed nets was intermittent and was not directly linked to protection against malaria in the eyes

Insecticides suppress natural enemies and increase pest damage in cabbage.

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Bommarco, Riccardo; Miranda, Freddy; Bylund, Helena; Björkman, Christer

2011-06-01

Intensive use of pesticides is common and increasing despite a growing and historically well documented awareness of the costs and hazards. The benefits from pesticides of increased yields from sufficient pest control may be outweighed by developed resistance in pests and killing of beneficial natural enemies. Other negative effects are human health problems and lower prices because of consumers' desire to buy organic products. Few studies have examined these trade-offs in the field. Here, we demonstrate that Nicaraguan cabbage (Brassica spp.) farmers may suffer economically by using insecticides as they get more damage by the main pest diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), at the same time as they spend economic resources on insecticides. Replicated similarly sized cabbage fields cultivated in a standardized manner were either treated with insecticides according common practice or not treated with insecticides over two seasons. Fields treated with insecticides suffered, compared with nontreated fields, equal or, at least in some periods of the seasons, higher diamondback moth pest attacks. These fields also had increased leaf damage on the harvested cabbage heads. Weight and size of the heads were not affected. The farmers received the same price on the local market irrespective of insecticide use. Rates of parasitized diamondback moth were consistently lower in the treated fields. Negative effects of using insecticides against diamondback moth were found for the density of parasitoids and generalist predatory wasps, and tended to affect spiders negatively. The observed increased leaf damages in insecticide-treated fields may be a combined consequence of insecticide resistance in the pest, and of lower predation and parasitization rates from naturally occurring predators that are suppressed by the insecticide applications. The results indicate biological control as a viable and economic alternative pest management strategy

Forty years of erratic insecticide resistance evolution in the mosquito Culex pipiens.

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Pierrick Labbé

2007-11-01

Full Text Available One view of adaptation is that it proceeds by the slow and steady accumulation of beneficial mutations with small effects. It is difficult to test this model, since in most cases the genetic basis of adaptation can only be studied a posteriori with traits that have evolved for a long period of time through an unknown sequence of steps. In this paper, we show how ace-1, a gene involved in resistance to organophosphorous insecticide in the mosquito Culex pipiens, has evolved during 40 years of an insecticide control program. Initially, a major resistance allele with strong deleterious side effects spread through the population. Later, a duplication combining a susceptible and a resistance ace-1 allele began to spread but did not replace the original resistance allele, as it is sublethal when homozygous. Last, a second duplication, (also sublethal when homozygous began to spread because heterozygotes for the two duplications do not exhibit deleterious pleiotropic effects. Double overdominance now maintains these four alleles across treated and nontreated areas. Thus, ace-1 evolution does not proceed via the steady accumulation of beneficial mutations. Instead, resistance evolution has been an erratic combination of mutation, positive selection, and the rearrangement of existing variation leading to complex genetic architecture.

Laboratory evaluation of lambda-cyhalothrin a microencapsulated formulation on mosquito nets for control of vector mosquitos.

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Vythilingam, I; Zainal, A R; Hamidah, T

1999-03-01

Two formulations of lambda-cyhalothrin (EC-Emulsion concentrate and MC-Microencapsulated) were impregnated into bednets made of polyethylene and polyester. The nets were treated at a dosage of 15 mg/m2. For bioassay of insecticidal efficacy, female Anopheles maculatus and Aedes aegypti were exposed to the nets for two minutes and mortality was scored 24 hours later. The nets were also tested after repeated washings with water and with soap and water. Microencapsulated (2.5CS) formulation was more effective than emulsion concentrate (2.5EC) formulation on both net materials--polyethylene and polyester. Repeated washing with water and soap reduces the efficacy of all bednet treatment combinations. Microencapsulated formulation on polyethylene gave best results; it could sustain up to five washes with water and two with soap and water.

Insecticide-induced hormesis and arthropod pest management.

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Guedes, Raul Narciso C; Cutler, G Christopher

2014-05-01

Ecological backlashes such as insecticide resistance, resurgence and secondary pest outbreaks are frequent problems associated with insecticide use against arthropod pest species. The last two have been particularly important in sparking interest in the phenomenon of insecticide-induced hormesis within entomology and acarology. Hormesis describes a biphasic dose-response relationship that is characterized by a reversal of response between low and high doses of a stressor (e.g. insecticides). Although the concept of insecticide-induced hormesis often does not receive sufficient attention, or has been subject to semantic confusion, it has been reported in many arthropod pest species and natural enemies, and has been linked to pest outbreaks and potential problems with insecticide resistance. The study of hormesis remains largely neglected in entomology and acarology. Here, we examined the concept of insecticide-induced hormesis in arthropods, its functional basis and potential fitness consequences, and its importance in arthropod pest management and other areas. © 2013 Society of Chemical Industry.

Factors impeding the acceptability and use of malaria preventive measures: implications for malaria elimination in eastern Rwanda

NARCIS (Netherlands)

Ingabire, Chantal Marie; Rulisa, Alexis; van Kempen, Luuk; Muvunyi, Claude; Koenraadt, Constantianus J. M.; van Vugt, Michele; Mutesa, Leon; van den Borne, Bart; Alaii, Jane

2015-01-01

Long-lasting insecticidal nets (LLIN), indoor residual spraying (IRS) and malaria case treatment with artemisinin-based combination therapy (ACT) have been proven to significantly reduce malaria, but may not necessarily lead to malaria elimination. This study explored factors hindering the

Value of Neonicotinoid Insecticide Seed Treatments in Mid-South Corn (Zea mays) Production Systems.

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North, J H; Gore, J; Catchot, A L; Stewart, S D; Lorenz, G M; Musser, F R; Cook, D R; Kerns, D L; Leonard, B R; Dodds, D M

2018-02-09

Neonicotinoid seed treatments are one of several effective control options used in corn, Zea mays L., production in the Mid-South for early season insect pests. An analysis was performed on 91 insecticide seed treatment trials from Arkansas, Louisiana, Mississippi, and Tennessee to determine the value of neonicotinoids in corn production systems. The analysis compared neonicotinoid insecticide treated seed plus a fungicide to seed only with the same fungicide. When analyzed by state, corn yields were significantly higher when neonicotinoid seed treatments were used compared to fungicide only treated seed in Louisiana and Mississippi. Corn seed treated with neonicotinoid seed treatments yielded 111, 1,093, 416, and 140 kg/ha, higher than fungicide only treatments for Arkansas, Louisiana, Mississippi, and Tennessee, respectively. Across all states, neonicotinoid seed treatments resulted in a 700 kg/ha advantage compared to fungicide only treated corn seed. Net returns for corn treated with neonicotinoid seed treatment were $1,446/ha compared with $1,390/ha for fungicide only treated corn seed across the Mid-South. Economic returns for neonicotinoid seed treated corn were significantly greater than fungicide-only-treated corn seed in 8 out of 14 yr. When analyzed by state, economic returns for neonicotinoid seed treatments were significantly greater than fungicide-only-treated seed in Louisiana. In some areas, dependent on year, neonicotinoid seed treatments provide significant yield and economic benefits in Mid-South corn. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Temporo-spatial distribution of insecticide-resistance in Indian malaria vectors in the last quarter-century: Need for regular resistance monitoring and management.

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Raghavendra, Kamaraju; Velamuri, Poonam Sharma; Verma, Vaishali; Elamathi, Natarajan; Barik, Tapan Kumar; Bhatt, Rajendra Mohan; Dash, Aditya Prasad

2017-01-01

The Indian vector control programme similar to other programmes in the world is still reliant on chemical insecticides. Anopheles culicifacies is the major vector out of six primary malaria vectors in India and alone contributes about 2/3 malaria cases annually; and per se its control is actually control of malaria in India. For effective management of vectors, current information on their susceptibility status to different insecticides is essential. In this review, an attempt was made to compile and present the available data on the susceptibility status of different malaria vector species in India from the last 2.5 decades. Literature search was conducted by different means mainly web and library search; susceptibility data was collated from 62 sources for the nine malaria vector species from 145 districts in 21 states and two union territories between 1991 and 2016. Interpretation of the susceptibility/resistance status was made on basis of the recent WHO criteria. Comprehensive analysis of the data indicated that An. culicifacies, a major vector species was resistant to at least one insecticide in 70% (101/145) of the districts. It was reported mostly resistant to DDT and malathion whereas, its resistant status against deltamethrin varied across the districts. The major threat for the malaria control programmes is multiple-insecticide-resistance in An. culicifacies which needs immediate attention for resistance management in order to sustain the gains achieved so far, as the programmes have targeted malaria elimination by 2030.

Activity of Selected Formulated Biorational and Synthetic Insecticides Against Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae).

Science.gov (United States)

Vivan, L M; Torres, J B; Fernandes, P L S

2017-02-01

This work studied 17 insecticides belonging to nucleopolyhedrovirus (NPV), Bacillus thuringiensis (Bt kurstaki and Bt aizawai), benzoylureas (insect growth regulators [IGRs]), carbamates, organophosphates, spinosyns, and diamides against larvae of Helicoverpa armigera (Hübner), invasive species in the South American continent. Larvae of different instars were fed for 7 d with untreated or insecticide-treated diets. Mortality was recorded daily for 7 d, and surviving larvae were individually weighed on the seventh day. The NPV and Bt insecticides caused 100% mortality of first-instar larvae and first-instar and second-instar larvae, respectively. However, both NPV and Bt-based products caused low mortality of third-instar larvae and did not kill older larvae. The IGR lufenuron was highly effective against all three ages of larvae tested, whereas teflubenzuron and triflumuron produced maximum 60% mortality of second-instar larvae and lower than 50% to older larvae. Thiodicarb, chlorantraniliprole, indoxacarb, chlorpyrifos, and chlorfenapyr, irrespective of tested age, caused 100% mortality of larvae, with the last two insecticides reaching 100% mortality within 2 d of feeding on the treated diet. Flubendiamide caused lower mortality but significantly affected the weight of surviving larvae, whereas neither spinosad nor methomyl produced significant mortality or affected the weight of larvae. Based on the results, the age of H. armigera larvae plays an important role in the recommendation of NPV and Bt insecticides. Furthermore, there are potential options between biological and synthetic insecticides tested against H. armigera, and recording larval size during monitoring, in addition to the infestation level, should be considered when recommending biological-based insecticides to control this pest. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Posttreatment Feeding Affects Mortality of Bed Bugs (Hemiptera: Cimicidae) Exposed to Insecticides.

Science.gov (United States)

Singh, Narinderpal; Wang, Changlu; Cooper, Richard

2016-02-01

Insecticide sprays and dusts are used for controlling bed bugs, Cimex lectularius L. In natural environments, bed bugs have daily access to hosts after they are exposed to insecticides. The established laboratory insecticide bioassay protocols do not provide feeding after insecticide treatments, which can result in inflated mortality compared with what would be encountered in the field. We evaluated the effect of posttreatment feeding on mortality of bed bugs treated with different insecticides. None of the insecticides tested had a significant effect on the amount of blood consumed and percent feeding. The effect of posttreatment feeding on bed bug mortality varied among different insecticides. Feeding significantly reduced mortality in bed bugs exposed to deltamethrin spray, an essential oil mixture (Bed Bug Fix) spray, and diatomaceous earth dust. Feeding increased the mean survival time for bed bugs treated with chlorfenapyr spray and a spray containing an essential oil mixture (Ecoraider), but did not affect the final mortality. First instars hatched from eggs treated with chlorfenapyr liquid spray had reduced feeding compared with nymphs hatched from nontreated eggs. Those nymphs hatched from eggs treated with chlorfenapyr liquid spray and successfully fed had reduced mortality and a higher mean survival time than those without feeding. We conclude that the availability of a bloodmeal after insecticide exposure has a significant effect on bed bug mortality. Protocols for insecticide efficacy testing should consider offering a bloodmeal to the treated bed bugs within 1 to 3 d after treatment. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Effect of Indoor Residual Spraying on the Prevalence of Malaria Parasite Infection, Clinical Malaria and Anemia in an Area of Perennial Transmission and Moderate Coverage of Insecticide Treated Nets in Western Kenya.

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John E Gimnig

Full Text Available Insecticide treated nets (ITNs and indoor residual spraying (IRS have been scaled up for malaria prevention in sub-Saharan Africa. However, there are few studies on the benefit of implementing IRS in areas with moderate to high coverage of ITNs. We evaluated the impact of an IRS program on malaria related outcomes in western Kenya, an area of intense perennial malaria transmission and moderate ITN coverage (55-65% use of any net the previous night.The Kenya Division of Malaria Control, with support from the US President's Malaria Initiative, conducted IRS in one lowland endemic district with moderate coverage of ITNs. Surveys were conducted in the IRS district and a neighboring district before IRS, after one round of IRS in July-Sept 2008 and after a second round of IRS in April-May 2009. IRS was conducted with pyrethroid insecticides. At each survey, 30 clusters were selected for sampling and within each cluster, 12 compounds were randomly selected. The primary outcomes measured in all residents of selected compounds included malaria parasitemia, clinical malaria (P. falciparum infection plus history of fever and anemia (Hb<8 of all residents in randomly selected compounds. At each survey round, individuals from the IRS district were matched to those from the non-IRS district using propensity scores and multivariate logistic regression models were constructed based on the matched dataset.At baseline and after one round of IRS, there were no differences between the two districts in the prevalence of malaria parasitemia, clinical malaria or anemia. After two rounds of IRS, the prevalence of malaria parasitemia was 6.4% in the IRS district compared to 16.7% in the comparison district (OR = 0.36, 95% CI = 0.22-0.59, p<0.001. The prevalence of clinical malaria was also lower in the IRS district (1.8% vs. 4.9%, OR = 0.37, 95% CI = 0.20-0.68, p = 0.001. The prevalence of anemia was lower in the IRS district but only in children under 5 years of age (2

An epidemiological overview of malaria in Bangladesh.

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Islam, Nazrul; Bonovas, Stefanos; Nikolopoulos, Georgios K

2013-01-01

Bangladesh is one of the four major malaria-endemic countries in South-East Asia having approximately 34% of its population at risk of malaria. This paper aims at providing an overview of the malaria situation in this country. Relevant information was retrieved from published articles and reports in PubMed and Google Scholar. Malaria in Bangladesh is concentrated in 13 districts with a prevalence ranging between 3.1% and 36%, and is mostly caused by Plasmodium falciparum. Geographical conditions pose a potential risk for Plasmodium knowlesi malaria. Resistance to a number of drugs previously recommended for treatment has been reported. Low socio-economic status, poor schooling and close proximity to water bodies and forest areas comprise important risk factors. Despite the significant steps in Long Lasting Insecticide Net (LLIN)/Insecticide Treated Net (ITN) coverage in Bangladesh, there are still many challenges including the extension of malaria support to the remote areas of Bangladesh, where malaria prevalence is higher, and further improvements in the field of referral system and treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Use of insecticide-treated clothes for personal protection against malaria: a community trial

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Kuria Isabel W

2006-07-01

Full Text Available Abstract Background The study sought to determine the effect of using insecticide-treated clothes (ITCs on personal protection against malaria infection. The specific objectives were to determine the effect of using ITCs on the rate of infection with malaria parasites and the effect on indoor mosquito density. Methods This study was done in Dadaab refugee camps, North Eastern Province Kenya between April and August 2002, and involved a total of 198 participants, all refugees of Somali origin. The participants were selected through multi-stage cluster sampling. Half of the participants (treatment group had their personal clothes worn on a daily basis (Diras, Saris, Jalbaabs, Ma'awis and shirts and their bedding (sheets and blankets treated with insecticide (permethrin. The other half (comparison group had their clothes treated with placebo (plain water. Indoor mosquito density was determined from twelve households belonging to the participants; six in the treatment block and six in the comparison block. During pre-test and post-test, laboratory analysis of blood samples was done, indoor mosquito density determined and questionnaires administered. Using STATA statistical package, tests for significant difference between the two groups were conducted. Results Use of ITCs reduced both malaria infection rates and indoor mosquito density significantly. The odds of malaria infection in the intervention group were reduced by about 70 percent. The idea of using ITCs for malaria infection control was easily accepted among the refugees and they considered it beneficial. No side effects related to use of the ITCs were observed from the participants. Conclusion The use of ITCs reduces malaria infection rate and has potential as an appropriate method of malaria control. It is recommended, therefore, that this strategy be considered for use among poor communities like slum dwellers and other underprivileged communities, such as street children and refugees

Insecticide resistance in Anopheles gambiae from south-western Chad, Central Africa

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Etang Josiane

2008-09-01

Full Text Available Abstract Background Indoor residual spraying and insecticide-treated nets (ITN are essential components of malaria vector control in Africa. Pyrethroids are the only recommended compounds for nets treatment because they are fast-acting insecticides with low mammalian toxicity. However, there is growing concern that pyrethroid resistance may threaten the sustainability of ITN scaling-up programmes. Here, insecticide susceptibility was investigated in Anopheles gambiae sensu lato from an area of large scale ITN distribution programme in south-western Chad. Methods Susceptibility to 4% DDT, 0.05% deltamethrin, 0.75% permethrin, 0.1% bendiocarb and 5% malathion was assessed using the WHO standard procedures for adult mosquitoes. Tests were carried out with two to four days-old, non-engorged female mosquitoes. The An. gambiae Kisumu strain was used as a reference. Knockdown effect was recorded every 5 min and mortality scored 24 h after exposure. Mosquitoes were identified to species and molecular form by PCR-RFLP and genotypes at the kdr locus were determined in surviving specimens by Hot Oligonucleotide Ligation Assay (HOLA. Results During this survey, full susceptibility to malathion was recorded in all samples. Reduced susceptibility to bendiocarb (mortality rate of 96.1% was found in one sample out of nine assayed. Increased tolerance to pyrethroids was detected in most samples (8/9 with mortality rates ranging from 70.2 to 96.6% for deltamethrin and from 26.7 to 96.3% for permethrin. Pyrethroid tolerance was not associated with a significant increase of knock-down times. Anopheles arabiensis was the predominant species of the An. gambiae complex in the study area, representing 75 to 100% of the samples. Screening for kdr mutations detected the L1014F mutation in 88.6% (N = 35 of surviving An. gambiae sensu stricto S form mosquitoes. All surviving An. arabiensis (N = 49 and M form An. gambiae s.s. (N = 1 carried the susceptible allele

Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis to experimental chicken sheds treated with insecticide

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Brazil Reginaldo P

2010-03-01

Full Text Available Abstract Background Current strategies for controlling American visceral leishmaniasis (AVL have been unable to prevent the spread of the disease across Brazil. With no effective vaccine and culling of infected dogs an unpopular and unsuccessful alternative, new tools are urgently needed to manage populations of the sand fly vector, Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae. Here, we test two potential strategies for improving L. longipalpis control using the synthetic sand fly pheromone (±-9-methylgermacrene-B: the first in conjunction with spraying of animal houses with insecticide, the second using coloured sticky traps. Results Addition of synthetic pheromone resulted in greater numbers of male and female sand flies being caught and killed at experimental chicken sheds sprayed with insecticide, compared to pheromone-less controls. Furthermore, a ten-fold increase in the amount of sex pheromone released from test sheds increased the number of females attracted and subsequently killed. Treating sheds with insecticide alone resulted in a significant decrease in numbers of males attracted to sheds (compared to pre-spraying levels, and a near significant decrease in numbers of females. However, this effect was reversed through addition of synthetic pheromone at the time of insecticide spraying, leading to an increase in number of flies attracted post-treatment. In field trials of commercially available different coloured sticky traps, yellow traps caught more males than blue traps when placed in chicken sheds. In addition, yellow traps fitted with 10 pheromone lures caught significantly more males than pheromone-less controls. However, while female sand flies showed a preference for both blue and yellow pheromone traps sticky traps over white traps in the laboratory, neither colour caught significant numbers of females in chicken sheds, either with or without pheromone. Conclusions We conclude that synthetic pheromone could

factors influencing utilisation of insecticide treated nets

African Journals Online (AJOL)

2010-12-12

Dec 12, 2010 ... in the prevention of Malaria to children under five years. Design: A descriptive ... Malaria prevention and liking to use ITN. Insignificant ... pregnant women by 2005 (6). .... mothers were in their teenage who were the targeted.

Combining fungal biopesticides and insecticide-treated bednets to enhance malaria control.

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Hancock, Penelope A

2009-10-01

In developing strategies to control malaria vectors, there is increased interest in biological methods that do not cause instant vector mortality, but have sublethal and lethal effects at different ages and stages in the mosquito life cycle. These techniques, particularly if integrated with other vector control interventions, may produce substantial reductions in malaria transmission due to the total effect of alterations to multiple life history parameters at relevant points in the life-cycle and transmission-cycle of the vector. To quantify this effect, an analytically tractable gonotrophic cycle model of mosquito-malaria interactions is developed that unites existing continuous and discrete feeding cycle approaches. As a case study, the combined use of fungal biopesticides and insecticide treated bednets (ITNs) is considered. Low values of the equilibrium EIR and human prevalence were obtained when fungal biopesticides and ITNs were combined, even for scenarios where each intervention acting alone had relatively little impact. The effect of the combined interventions on the equilibrium EIR was at least as strong as the multiplicative effect of both interventions. For scenarios representing difficult conditions for malaria control, due to high transmission intensity and widespread insecticide resistance, the effect of the combined interventions on the equilibrium EIR was greater than the multiplicative effect, as a result of synergistic interactions between the interventions. Fungal biopesticide application was found to be most effective when ITN coverage was high, producing significant reductions in equilibrium prevalence for low levels of biopesticide coverage. By incorporating biological mechanisms relevant to vectorial capacity, continuous-time vector population models can increase their applicability to integrated vector management.

Impact of promoting longer-lasting insecticide treatment of bed nets upon malaria transmission in a rural Tanzanian setting with pre-existing high coverage of untreated nets

NARCIS (Netherlands)

Russell, T.L.; Lwetoijera, D.W.; Maliti, D.; Chipwaza, B.; Kihonda, J.; Charlwood, J.D.; Smith, T.A.; Lengeler, C.; Mwanyangala, M.A.; Nathan, R.; Knols, B.G.J.; Takken, W.; Killeen, G.F.

2010-01-01

Background The communities of Namawala and Idete villages in southern Tanzania experienced extremely high malaria transmission in the 1990s. By 2001-03, following high usage rates (75% of all age groups) of untreated bed nets, a 4.2-fold reduction in malaria transmission intensity was achieved.

Long lasting decontamination foam

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Demmer, Ricky L.; Peterman, Dean R.; Tripp, Julia L.; Cooper, David C.; Wright, Karen E.

2010-12-07

Compositions and methods for decontaminating surfaces are disclosed. More specifically, compositions and methods for decontamination using a composition capable of generating a long lasting foam are disclosed. Compositions may include a surfactant and gelatin and have a pH of less than about 6. Such compositions may further include affinity-shifting chemicals. Methods may include decontaminating a contaminated surface with a composition or a foam that may include a surfactant and gelatin and have a pH of less than about 6.

The effect of insecticide applications to melon crop on melon aphid and its natural enemies

International Nuclear Information System (INIS)

Guerra, J.; Gonzalez, J.E.; Ceballos, J.; Checa, B.

1999-01-01

Melons are an important export crop for Panama and are cultivated on more than 1000 ha of land. Long growing season, extending well into January, allows several generations and build up of heavy populations of an important insect pest, Aphis gossypii, the melon aphid. Growers find it difficult to cultivate melons without several applications of insecticides. Although the insecticide applications control the aphids, they may also have adverse effects on the natural enemies of the aphid, in particular the two predatory insects Cycloneda sanguinea and Chrysoperla carnea. The purpose of this research was to evaluate the impact of insecticide applications on these insects and on the yield of melons, and to estimate residues of the applied insecticides in soil. The insecticides were applied as four different type of treatments to melon crop. The treatments were (i) three periodic applications of endosulfan (Thiodan 35EC), each at 0.52 kg a.i./ha, (ii) three applications of fenitrothion (Sumithion 50WP), each at 0.35 kg a.i./ha, (iii) two applications of fenitrothion and one of endosulfan, and (iv) grower's treatment, which included applications of six different insecticides. The effect of the insecticide applications was evaluated by estimating numbers of each of the three type of insects before and within 72 hours after the applications and estimating yield of melons. All insecticide treatments reduced the populations of Aphis gossypii, but they also reduced the numbers of the benificial insects. Endosulfan was somewhat less toxic to C. carnea than the other insecticides were, since greater number of C. carnea were recorded from the plots treated with endosulfan than the other treated plots. The best yield of melons was recorded in the plots which were sprayed with fenitrothion, followed by the plots sprayed with endosulfan. and then those with grower's insecticides. Soon after the application of endosulfan the residue in the soil was 0.2 mg/kg, but it declined to less

Targeted application of an organophosphate-based paint applied on windows and doors against Anopheles coluzzii resistant to pyrethroids under real life conditions in Vallée du Kou, Burkina Faso (West Africa).

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Poda, Serge B; Soma, Dieudonné D; Hien, Aristide; Namountougou, Moussa; Gnankiné, Olivier; Diabaté, Abdoulaye; Fournet, Florence; Baldet, Thierry; Mas-Coma, Santiago; Mosqueira, Beatriz; Dabiré, Roch K

2018-04-02

A novel strategy applying an organophosphate-based insecticide paint on doors and windows in combination with long-lasting insecticide-treated nets (LLINs) was tested for the control of pyrethroid-resistant malaria vectors in a village setting in Vallée du Kou, a rice-growing area west of Burkina Faso. Insecticide Paint Inesfly 5A IGR™, comprised of two organophosphates and an insect growth regulator, was applied to doors and windows and tested in combination with pyrethroid-treated LLINs. The killing effect was monitored for 5 months by early morning collections of anophelines and other culicids. The residual efficacy was evaluated monthly by WHO bioassays using Anopheles gambiae 'Kisumu' and local populations of Anopheles coluzzii resistant to pyrethroids. The spatial mortality efficacy (SME) at distances of 1 m was also assessed against pyrethroid-susceptible and -resistant malaria vectors. The frequency of L1014F kdr and Ace-1 R G119S mutations was, respectively, reported throughout the study. The Insecticide Paint Inesfly 5A IGR had been tested in past studies yielding a long-term mortality rate of 80% over 12 months against An. coluzzii, the local pyrethroid-resistant malaria vector. The purpose of the present study is to test if treating smaller, targeted surfaces (e.g. doors and windows) was also efficient in killing malaria vectors. Treating windows and doors alone yielded a killing efficacy of 100% for 1 month against An. coluzzii resistant to pyrethroids, but efficacy reduced quickly afterwards. Likewise, WHO cone bioassays yielded mortalities of 80-100% for 2 months but declined to 90 and 40% 2 and 3 months after treatment, respectively. Mosquitoes exposed to insecticide paint-treated surfaces at distances of 1 m, yielded mortality rates of about 90-80% against local pyrethroids-resistant An. coluzzii during the first 2 months, but decreased to 30% afterwards. Anopheles coluzzii was reported to be exclusively the local malaria vector and

Effect of malaria transmission reduction by insecticide-treated bed nets (ITNs) on the genetic diversity of Plasmodium falciparum merozoite surface protein (MSP-1) and circumsporozoite (CSP) in western Kenya.

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Kariuki, Simon K; Njunge, James; Muia, Ann; Muluvi, Geofrey; Gatei, Wangeci; Ter Kuile, Feiko; Terlouw, Dianne J; Hawley, William A; Phillips-Howard, Penelope A; Nahlen, Bernard L; Lindblade, Kim A; Hamel, Mary J; Slutsker, Laurence; Shi, Ya Ping

2013-08-27

Although several studies have investigated the impact of reduced malaria transmission due to insecticide-treated bed nets (ITNs) on the patterns of morbidity and mortality, there is limited information on their effect on parasite diversity. Sequencing was used to investigate the effect of ITNs on polymorphisms in two genes encoding leading Plasmodium falciparum vaccine candidate antigens, the 19 kilodalton blood stage merozoite surface protein-1 (MSP-1(19kDa)) and the Th2R and Th3R T-cell epitopes of the pre-erythrocytic stage circumsporozoite protein (CSP) in a large community-based ITN trial site in western Kenya. The number and frequency of haplotypes as well as nucleotide and haplotype diversity were compared among parasites obtained from children diversity of > 0.7. No MSP-1(19kDa) 3D7 sequence-types were detected in 1996 and the frequency was less than 4% in 2001. The CSP Th2R and Th3R domains were highly polymorphic with a total of 26 and 14 haplotypes, respectively detected in 1996 and 34 and 13 haplotypes in 2001, with an overall haplotype diversity of > 0.9 and 0.75 respectively. The frequency of the most predominant Th2R and Th3R haplotypes was 14 and 36%, respectively. The frequency of Th2R and Th3R haplotypes corresponding to the 3D7 parasite strain was less than 4% at both time points. There was no significant difference in nucleotide and haplotype diversity in parasite isolates collected at both time points. High diversity in these two genes has been maintained overtime despite marked reductions in malaria transmission due to ITNs use. The frequency of 3D7 sequence-types was very low in this area. These findings provide information that could be useful in the design of future malaria vaccines for deployment in endemic areas with high ITN coverage and in interpretation of efficacy data for malaria vaccines based on 3D7 parasite strains.

Bed net use and associated factors in a rice farming community in Central Kenya

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Kabuage Lucy

2009-04-01

Full Text Available Abstract Background Use of insecticide-treated nets (ITNs continues to offer potential strategy for malaria prevention in endemic areas. However their effectiveness, sustainability and massive scale up remain a factor of socio-economic and cultural variables of the local community which are indispensable during design and implementation stages. Methods An ethnographic household survey was conducted in four study villages which were purposefully selected to represent socio-economic and geographical diversity. In total, 400 households were randomly selected from the four study villages. Quantitative and qualitative information of the respondents were collected by use of semi-structured questionnaires and focus group discussions. Results Malaria was reported the most frequently occurring disease in the area (93% and its aetiology was attributed to other non-biomedical causes like stagnant water (16%, and long rains (13%. Factors which significantly caused variation in bed net use were occupant relationship to household head (χ2 = 105.705; df 14; P = 0.000, Age (χ2 = 74.483; df 14; P = 0.000, village (χ2 = 150.325; df 6; P = 0.000, occupation (χ2 = 7.955; df 3; P = 0.047, gender (χ2 = 4.254; df 1; P = 0.039 and education levels of the household head or spouse (χ2 = 33.622; df 6; P = 0.000. The same variables determined access and conditions of bed nets at household level. Protection against mosquito bite (95% was the main reason cited for using bed nets in most households while protection against malaria came second (54%. Colour, shape and affordability were some of the key potential factors which determined choice, use and acceptance of bed nets in the study area. Conclusion The study highlights potential social and economic variables important for effective and sustainable implementation of bed nets-related programmes in Sub-Saharan Africa.

Evaluation of the efficacy of insecticidal coatings based on teflutrin and chlorpyrifos against Rhynchophorus ferrugineus.

Science.gov (United States)

Pugliese, Massimo; Rettori, Andrea Alberto; Martinis, Roberto; Al-Rohily, Khalid; Velate, Suresh; Moideen, Mohamed Ashraf; Al-Maashi, Ali

2017-08-01

The date palm (Phoenix dactylifera L.), an important economic resource for many nations worldwide, has recently been threatened by the presence of different insect pests, like the red palm weevil (RPW) Rhynchophorus ferrugineus. Two products, a glue (polyvinyl acetate) and an oil (raw linseed oil) were used as coatings and applied together with a repellent and two insecticides (teflutrin and chlorpyrifos) at different dosages on two species of palm (P. dactylifera and P. canariensis). Phytotoxic effects of the treatments were evaluated in a greenhouse on 260 potted palms (130 P. dactylifera and 130 P. canariensis) and no negative effects were observed. Afterwards, a trial lasting 400 days was carried out in a nursery located in Sicily (south Italy), treating 572 potted palm trees (286 P. dactylifera and 286 P. canariensis) with an average diameter at the base of 18-20 cm. After 400 days, 48% of the untreated palms were infested, while only 3% of date palms and 7% of Canary palms treated with insecticide at lower dosages were infested. The application of an insecticide-based coating is a good strategy to control and prevent the red palm weevil infestation, in particular on date palms. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

A renaissance for botanical insecticides?

Science.gov (United States)

Isman, Murray B

2015-12-01

Botanical insecticides continue to be a subject of keen interest among the international research community, reflected in the steady growth in scientific publications devoted to the subject. Until very recently though, the translation of that theory to practice, i.e. the commercialisation and adoption of new botanical insecticides in the marketplace, has seriously lagged behind. Strict regulatory regimes, long the bane of small pesticide producers, are beginning to relax some of the data requirements for 'low-risk' pesticide products, facilitating movement of more botanicals into the commercial arena. In this paper I discuss some of the jurisdictions where botanicals are increasingly finding favour, some of the newer botanical insecticides in the plant and animal health arsenal and some of the specific sectors where botanicals are most likely to compete effectively with other types of insecticidal product. © 2015 Society of Chemical Industry.

The effect of household heads training about the use of treated bed nets on the burden of malaria and anaemia in under-five children: a cluster randomized trial in Ethiopia

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Deribew Amare

2012-01-01

Full Text Available Abstract Background Long-lasting insecticide-treated bed nets (LLITN have demonstrated a significant effect in reducing malaria-related morbidity and mortality. However, barriers on the utilization of LLITN have hampered the desired outcomes. The aim of this study was to assess the effect of community empowerment on the burden of malaria and anaemia in under-five children in Ethiopia. Methods A cluster randomized trial was done in 22 (11 intervention and 11 control villages in south-west Ethiopia. The intervention consisted of tailored training of household heads about the proper use of LLITN and community network system. The burden of malaria and anaemia in under-five children was determined through mass blood investigation at baseline, six and 12 months of the project period. Cases of malaria and anaemia were treated based on the national protocol. The burden of malaria and anaemia between the intervention and control villages was compared using the complex logistic regression model by taking into account the clustering effect. Eight Focus group discussions were conducted to complement the quantitative findings. Results A total of 2,105 household heads received the intervention and the prevalence of malaria and anaemia was assessed among 2410, 2037 and 2612 under-five children at baseline, six and 12 months of the project period respectively. During the high transmission/epidemic season, children in the intervention arm were less likely to have malaria as compared to children in the control arm (OR = 0.42; 95%CI: 0.32, 0.57. Symptomatic malaria also steadily declined in the intervention villages compared to the control villages in the follow up periods. Children in the intervention arm were less likely to be anaemic compared to those in the control arm both at the high (OR = 0.84; 95%CI: 0.71, 0.99 and low (OR = 0.73; 95%CI: 0.60, 0.89 transmission seasons. Conclusion Training of household heads on the utilization of LLITN significantly

Long-Term Efficacy of Various Natural or "Green" Insecticides against Bed Bugs: A Double-Blind Study.

Science.gov (United States)

Goddard, Jerome

2014-11-28

Bed bugs are resurging throughout the world, and, thus, effective pest control strategies are constantly needed. A few studies have evaluated 25(b) and other natural, or so-called "green" products, as well as over-the-counter insecticides for bed bugs, but additional studies are needed to determine efficacy of bed bug control products. This double-blinded research project was initiated to examine long-term effectiveness of six commercially available natural or "green" insecticides against bed bugs and to compare them with three known traditional residual products. Water was used as a control. Products were evaluated against both susceptible and resistant strains of bed bugs (1200 bugs each), and two different substrates were used. Temprid(®) (Bayer Corporation, Monheim, Germany), Transport(®) (FMC Corp., Philadelphia, PA, USA), Invader(®) (FMC Corporation, Philadelphia, PA USA), Cimexa(®) (Rockwell Laboratories, Kansas City, MO, USA), and BBT-2000(®) (Swepe-Tite LLC, Tupelo, MS, USA) were the only products which showed any substantial (>40%) bed bug control upon exposure to treated substrates after the six-month waiting period, although results with the resistant bed bug strain were much reduced. Alpine dust(®) (BASF Corporation, Florham Park, NJ, USA) killed 27% of bed bugs or less, depending on strain and substrate. EcoRaider(®) (North Bergen, NJ, USA) and Mother Earth D(®) (Whitmire Microgen, Florham Park, NJ, USA) (diatomaceous earth) produced 11% control or less. Cimi-Shield Protect(®) (Pest Barrier, Carson, CA, USA) showed no activity against bed bugs in this study. Analysis using SAS software showed a three-way interaction between treatment, substrate, and bed bug strain (Numerator DF 9; Denominator DF 80; F = 4.90; p < 0.0001).

Characterization of the metabolic phenotype of rapamycin-treated CD8+ T cells with augmented ability to generate long-lasting memory cells.

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Shan He

Full Text Available BACKGROUND: Cellular metabolism plays a critical role in regulating T cell responses and the development of memory T cells with long-term protections. However, the metabolic phenotype of antigen-activated T cells that are responsible for the generation of long-lived memory cells has not been characterized. DESIGN AND METHODS: Using lymphocytic choriomeningitis virus (LCMV peptide gp33-specific CD8(+ T cells derived from T cell receptor transgenic mice, we characterized the metabolic phenotype of proliferating T cells that were activated and expanded in vitro in the presence or absence of rapamycin, and determined the capability of these rapamycin-treated T cells to generate long-lived memory cells in vivo. RESULTS: Antigen-activated CD8(+ T cells treated with rapamycin gave rise to 5-fold more long-lived memory T cells in vivo than untreated control T cells. In contrast to that control T cells only increased glycolysis, rapamycin-treated T cells upregulated both glycolysis and oxidative phosphorylation (OXPHOS. These rapamycin-treated T cells had greater ability than control T cells to survive withdrawal of either glucose or growth factors. Inhibition of OXPHOS by oligomycin significantly reduced the ability of rapamycin-treated T cells to survive growth factor withdrawal. This effect of OXPHOS inhibition was accompanied with mitochondrial hyperpolarization and elevation of reactive oxygen species that are known to be toxic to cells. CONCLUSIONS: Our findings indicate that these rapamycin-treated T cells may represent a unique cell model for identifying nutrients and signals critical to regulating metabolism in both effector and memory T cells, and for the development of new methods to improve the efficacy of adoptive T cell cancer therapy.

Selective insecticide-induced stimulation on fecundity and biochemical changes in Tryporyza incertulas (Lepidoptera: Pyralidae).

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Wang, Ai-Hua; Wu, Jin-Cai; Yu, Yue-Shu; Liu, Jing-Lan; Yue, Jiang-Fei; Wang, Mei-Yue

2005-08-01

The use of selective insecticides in rice, Oryza sativa L., fields often causes resurgence of nontarget pest insects. This study was conducted to investigate the effect of two selective insecticides, buprofezin and imidacloprid, on Tryporyza incertulas (Walker), a nontarget pest. After larval feeding on rice plants treated with each insecticide, fecundity, ovary protein content, and titer of juvenile hormone III (JHIII) in the resulting female moths were determined with 'Xiushui 63' rice susceptible to T. incertulas and 'Zhendao 2' moderately resistant to T. incertulas. The fecundity of females developed from larvae that fed on the insecticide-treated Xiushui 63 plants was stimulated compared with that of moths from larvae that fed on rice plants that were not treated with either insecticide. There was no stimulating effect in females from larvae that fed on insecticide-treated Zhendao 2 plants. The weight of fourth instars (final instars) that fed on the insecticide-treated Xiushui 63 rice plants was significantly greater than that of control, increasing by 50.3 and 46.7% for 60 and 112.5 g (AI) ha(-1) buprofezin, and by 23.7 and 19.5% for 15 and 37.5 g (AI) ha(-1) imidacloprid treatments, respectively. Ovary protein content in adult females developed from larvae that fed on the rice treated with the high dose of buprofezin was significantly higher than that in control. For the high and low doses of imidacloprid during the second instar, and the low dose of imidacloprid during the fourth instar, JHIII titers in female adults were also significantly higher than that in control, increasing by 152.81, 90.52, and 114.19%, respectively.

Field evaluation of non-synthetic insecticides for the management of ...

African Journals Online (AJOL)

/l and B.thurigiensis was applied at the rate 1.0 g/l of water. Actellic 25 EC, a synthetic insecticide, was applied at the rate of 2 ml/l as standard check. Arthropod fauna on okra were sampled using traps, sweep nets, aspirators and handpicking.

Long-Lasting Sound-Evoked Afterdischarge in the Auditory Midbrain.

Science.gov (United States)

Ono, Munenori; Bishop, Deborah C; Oliver, Douglas L

2016-02-12

Different forms of plasticity are known to play a critical role in the processing of information about sound. Here, we report a novel neural plastic response in the inferior colliculus, an auditory center in the midbrain of the auditory pathway. A vigorous, long-lasting sound-evoked afterdischarge (LSA) is seen in a subpopulation of both glutamatergic and GABAergic neurons in the central nucleus of the inferior colliculus of normal hearing mice. These neurons were identified with single unit recordings and optogenetics in vivo. The LSA can continue for up to several minutes after the offset of the sound. LSA is induced by long-lasting, or repetitive short-duration, innocuous sounds. Neurons with LSA showed less adaptation than the neurons without LSA. The mechanisms that cause this neural behavior are unknown but may be a function of intrinsic mechanisms or the microcircuitry of the inferior colliculus. Since LSA produces long-lasting firing in the absence of sound, it may be relevant to temporary or chronic tinnitus or to some other aftereffect of long-duration sound.

Net savings and the Japanese long-term interest rate

NARCIS (Netherlands)

Jansen, P.W.

2011-01-01

This article discusses why the interest rate on Japanese government bonds is so low in comparison with other industrialized countries with a better credit rating, after correcting for inflation differences. We find that the net savings surplus has kept the long-term interest rate low. Japanese

The Effect of Early Mosquito Insecticides Exposure on Spraque Dawley Rat Testis: A Histopathological Feature Towards Malignancy?

Science.gov (United States)

Indah Winarni, Tri; Auzan Aziman, Milzam; Abshar Andar, Anindyo; Pawitra, Ika

2017-02-01

The incidence of health problems associated with endocrine-disruption have increased. Many studies suggesting that endocrine disruptor chemicals (EDC) do contribute to cancer through estrogen-related receptors. Many chemicals have EDCs properties including insecticides. Early life exposure to EDCs can increased the risk of testicular cancer have been reported in the last decade. This study was aimed to determine the effect of insecticides exposure on histopathological tumor cell development of germ and Leydig cell. True experiment research design with posttest only control group design was applied. Sprague Dawley (SD) rat (n = 25) were randomly divided into 5 groups (control group, 25 mg β estradiol 3-benzoate, spiral mosquito coil repellent, 3 ml of liquid mosquito repellent, and 4 ml of liquid mosquito repellent). The exposure were administered for 20 days started at aged 3 days. At the age of 100 days (older adult), testis was stained using Hematoxyllin Eosin (HE) and histological features predicting malignancy were observed. The number of tumor cell development in both testicular germ cells and Leydig cells significantly increased in all treated group compared to those of control and the changes towards malignancy were also observed in all treated group. Exposure to mosquito insecticides causes significant changes in testicular germ and Leydig cell histological features that leads to malignancy.

Insecticide-treated nets usage and malaria episodes among ...

African Journals Online (AJOL)

... is urgent need on the part of all the three tiers of Government for public health awareness campaigns through information, education and communication (IEC) to create positive ITN culture and usage. It is also suggested that ITN usage among boarding school pupils should be incorporated into school health service.

Providing insecticide treated bed nets in antiretroviral treatment ...

African Journals Online (AJOL)

HIV-replication.5-13 Mathematical models show that repeated ... antiretroviral treatment clinics in Malawi: a pilot ... related disease or AIDS.3 In addition, there are between 300 - ... and growing evidence of interactive pathology.1,2. HIV ..... by the HIV Unit and its partners. ... procurement and supply chain systems developed.

Insecticide-treated nets usage and malaria episodes among ...

African Journals Online (AJOL)

2009-10-05

Oct 5, 2009 ... Background: Despite malaria being the largest public health problem in Africa South of Sahara with over one million associated deaths each year, there has been little progress in its prevention/control during the past decades. Therefore, this study was conducted to determine the knowledge, attitude, use of ...

Assessing bed net damage: comparisons of three measurement methods for estimating the size, shape, and distribution of holes on bed nets.

Science.gov (United States)

Vanden Eng, Jodi L; Mathanga, Don P; Landman, Keren; Mwandama, Dyson; Minta, Anna A; Shah, Monica; Sutcliffe, James; Chisaka, Joseph; Lindblade, Kim A; Steinhardt, Laura

2017-10-10

Measuring the physical condition of long-lasting insecticidal nets (LLINs) under field conditions is of great importance for malaria control programmes to guide decisions on how frequently to replace LLINs. Current guidelines by the World Health Organization Pesticide Evaluation Scheme (WHOPES) propose a proportionate hole index (pHI) for assessing LLIN condition by counting the number of holes the size of a thumb, fist, head, and larger than a head. However, this method does not account for irregular hole shapes or exact hole sizes which could result in inaccurate decisions about when to replace LLINs. LLINs were collected during a 2013 health facility-based malaria case control study in Machinga District, Malawi. To evaluate the accuracy of the pHI, the physical condition of 277 LLINs was estimated by the WHOPES method and then compared with two more thorough measurement methods: image analysis of digital photographs of each LLIN side; and for 10 nets, ruler measurements of the length, width, and location of each hole. Total hole counts and areas per net were estimated by each method, and detailed results of hole shapes and composite pictures of hole locations were generated using image analysis. The WHOPES method and image analysis resulted in similar estimates of total hole counts, each with a median of 10 (inter-quartile range (IQR) 4-24 and 4-23, respectively; p = 0.004); however, estimated hole areas were significantly larger using the WHOPES method (median 162 cm 2 , IQR 28-793) than image analysis (median 13 cm 2 , IQR 3-101; p holes than image analysis did (p = 0.002) in 10 LLINs; however, total hole area was not significantly different (p = 0.16). Most holes were not circular but roughly 2-5 times longer in one direction. The lower quarter of LLIN sides was found to have the most holes. The WHOPES method overestimated total hole area, likely because holes are elongated rather than circular, suggesting further adjustments to the pHI formula may be

31 CFR 356.13 - When must I report my net long position and how do I calculate it?

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false When must I report my net long position and how do I calculate it? 356.13 Section 356.13 Money and Finance: Treasury Regulations Relating... net long position and how do I calculate it? (a) Net long position reporting threshold. (1) If you are...

Is Apis mellifera more sensitive to insecticides than other insects?

Science.gov (United States)

Hardstone, Melissa C; Scott, Jeffrey G

2010-11-01

Honey bees (Apis mellifera L.) are among the most important pollinators in natural and agricultural settings. They commonly encounter insecticides, and the effects of insecticides on honey bees have been frequently noted. It has been suggested that honey bees may be (as a species) uniquely sensitive to insecticides, although no comparative toxicology study has been undertaken to examine this claim. An extensive literature review was conducted, using data in which adult insects were topically treated with insecticides. The goal of this review was to summarize insecticide toxicity data between A. mellifera and other insects to determine the relative sensitivity of honey bees to insecticides. It was found that, in general, honey bees were no more sensitive than other insect species across the 62 insecticides examined. In addition, honey bees were not more sensitive to any of the six classes of insecticides (carbamates, nicotinoids, organochlorines, organophosphates, pyrethroids and miscellaneous) examined. While honey bees can be sensitive to individual insecticides, they are not a highly sensitive species to insecticides overall, or even to specific classes of insecticides. However, all pesticides should be used in a way that minimizes honey bee exposure, so as to minimize possible declines in the number of bees and/or honey contamination. Copyright © 2010 Society of Chemical Industry.

Joint malaria surveys lead towards improved cross-border cooperation between Savannakhet province, Laos and Quang Tri province, Vietnam

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Pongvongsa Tiengkham

2012-08-01

Full Text Available Abstract Background In Savannakhet province, Laos and Quang Tri province, Vietnam, malaria is still an important health problem and most cases are found in the mountainous, forested border areas where ethnic minority groups live. The objectives of this study were to obtain a better joint understanding of the malaria situation along the border and, on the basis of that, improve malaria control methods through better cooperation between the two countries. Methods Fourteen villages in Savannakhet and 22 villages in Quang Tri were randomly selected within 5 km from the border where a blood survey for microscopic diagnosis (n = 1256 and n = 1803, respectively, household interviews (n = 400, both sides and vector surveys were conducted between August and October 2010. Satellite images were used to examine the forest density around the study villages. Results Malaria prevalence was significantly higher in Laos (5.2% than in Vietnam (1.8% and many other differences were found over the short distance across the border. Bed net coverage was high (> 90% in both Laos and Vietnam but, while in Laos more than 60% of the nets were long-lasting insecticide-treated, Vietnam used indoor residual spraying in this area and the nets were untreated. Anopheles mosquitoes were more abundant in Laos than in Vietnam, especially many Anopheles dirus were captured in indoor light traps while none were collected in Vietnam. The forest cover was higher around the Lao than the Vietnamese villages. After this study routine exchange of malaria surveillance data was institutionalized and for the first time indoor residual spraying was applied in some Lao villages. Conclusions The abundance of indoor-collected An. dirus on the Laos side raises doubts about the effectiveness of a sole reliance on long-lasting insecticide-treated nets in this area. Next to strengthening the early detection, correct diagnosis and prompt, adequate treatment of malaria infections, it is

Long-lasting desynchronization in rat hippocampal slice induced by coordinated reset stimulation

International Nuclear Information System (INIS)

Tass, P. A.; Barnikol, U. B.; Silchenko, A. N.; Hauptmann, C.; Speckmann, E.-J.

2009-01-01

In computational models it has been shown that appropriate stimulation protocols may reshape the connectivity pattern of neural or oscillator networks with synaptic plasticity in a way that the network learns or unlearns strong synchronization. The underlying mechanism is that a network is shifted from one attractor to another, so that long-lasting stimulation effects are caused which persist after the cessation of stimulation. Here we study long-lasting effects of multisite electrical stimulation in a rat hippocampal slice rendered epileptic by magnesium withdrawal. We show that desynchronizing coordinated reset stimulation causes a long-lasting desynchronization between hippocampal neuronal populations together with a widespread decrease in the amplitude of the epileptiform activity. In contrast, periodic stimulation induces a long-lasting increase in both synchronization and amplitude.

Effects of various insecticides on the development of the egg parasitoid Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae).

Science.gov (United States)

Takada, Y; Kawamura, S; Tanaka, T

2001-12-01

The toxicity of six insecticides, acephate, methomyl, ethofenprox, cartap, chlorfluazuron, and Bacillus thuringiensis (Bt) was tested on different developmental stages of the egg parasitoid, Trichogramma dendrolimi (Matsumura). Each of the insecticides tested showed different degrees of toxicity to the parasitoid, Ethofenprox showed the highest toxicity and cartap showed relatively higher toxicity compared with the other insecticides. The development of the parasitoids treated with these two insecticides was normal, similar to that of the control group. Only the emergence of adult wasps from host eggs was disturbed. Emergence of the host, Mamestra brassicae larva was reduced following treatment with ethofenprox, cartap and methomyl. However, adult female wasps, which emerged from host eggs treated with the insecticides had the ability to oviposit normally.

Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

Directory of Open Access Journals (Sweden)

Carnevale Pierre

2010-11-01

Full Text Available Abstract Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs, chlorpyrifos and diazinon, and insect growth regulator (IGR, pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2 on different commonly used surfaces: porous (cement and stucco and non-porous (softwood and hard plastic. Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100% even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p -3. A reduction in fecundity was still observed nine months after treatment at both doses (p -3 and adult emergence was reduced at the higher dose (p -3. Conclusions High mortality rates were observed against laboratory strains of the pest mosquito Cx. quinquefasciatus susceptible and resistant to insecticides. Long-term killing remained equally important on non-porous surfaces regardless the resistance status for over 12 months. The paint's effect on fecundity, fertility and

Household possession, use and non-use of treated or untreated mosquito nets in two ecologically diverse regions of Nigeria – Niger Delta and Sahel Savannah

Directory of Open Access Journals (Sweden)

Otsemobor Peju

2009-02-01

Full Text Available Abstract Background Current use of treated mosquito nets for the prevention of malaria falls short of what is expected in sub-Saharan Africa (SSA, though research within the continent has indicated that the use of these commodities can reduce malaria morbidity by 50% and malaria mortality by 20%. Governments in sub-Sahara Africa are investing substantially in scaling-up treated mosquito net coverage for impact. However, certain significant factors still prevent the use of the treated mosquito nets, even among those who possess them. This survey examines household ownership as well as use and non-use of treated mosquito nets in Sahel Savannah and Niger Delta regions of Nigeria. Methodology This survey employed cross-sectional survey to collect data from households on coverage and use of mosquito nets, whether treated or not. Fever episodes in previous two weeks among children under the age of five were also recorded. The study took place in August 1 – 14 2007, just five months after the March distribution of treated mosquito nets, coinciding with the second raining period of the year and a time of high malaria transmission during the wet season. EPI INFO version 2003 was used in data analysis. Results The survey covered 439 households with 2,521 persons including 739 under-fives, 585 women in reproductive age and 78 pregnant women in Niger Delta Region and Sahel Savannah Region. Of the 439 HHs, 232 had any mosquito nets. Significantly higher proportion of households in the Niger Delta Region had any treated or untreated mosquito nets than those in the Sahel Savannah Region. In the Niger Delta Region, the proportion of under-fives that had slept under treated nets the night before the survey exceeded those that slept under treated nets in the Sahel Savannah Region. Children under the age of five years in the Niger Delta Region were four times more likely to sleep under treated nets than those in the Sahel Savannah Region. Conclusion This study

Comparing ownership and use of bed nets at two sites with differential malaria transmission in western Kenya.

Science.gov (United States)

Ernst, Kacey C; Hayden, Mary H; Olsen, Heather; Cavanaugh, Jamie L; Ruberto, Irene; Agawo, Maurice; Munga, Stephen

2016-04-14

Challenges persist in ensuring access to and optimal use of long-lasting, insecticidal bed nets (LLINs). Factors associated with ownership and use may differ depending on the history of malaria and prevention control efforts in a specific region. Understanding how the cultural and social-environmental context of bed net use may differ between high- and low-risk regions is important when identifying solutions to improve uptake and appropriate use. Community forums and a household, cross-sectional survey were used to collect information on factors related to bed net ownership and use in western Kenya. Sites with disparate levels of transmission were selected, including an endemic lowland area, Miwani, and a highland epidemic-prone area, Kapkangani. Analysis of ownership was stratified by site. A combined site analysis was conducted to examine factors associated with use of all available bed nets. Logistic regression modelling was used to determine factors associated with ownership and use of owned bed nets. Access to bed nets as the leading barrier to their use was identified in community forums and cross-sectional surveys. While disuse of available bed nets was discussed in the forums, it was a relatively rare occurrence in both sites. Factors associated with ownership varied by site. Education, perceived risk of malaria and knowledge of individuals who had died of malaria were associated with higher bed net ownership in the highlands, while in the lowlands individuals reporting it was easy to get a bed net were more likely to own one. A combined site analysis indicated that not using an available bed net was associated with the attitudes that taking malaria drugs is easier than using a bed net and that use of a bed net will not prevent malaria. In addition, individuals with an unused bed net in the household were more likely to indicate that bed nets are difficult to use, that purchased bed nets are better than freely distributed ones, and that bed nets should only

Performance of honey bee colonies under a long-lasting dietary exposure to sublethal concentrations of the neonicotinoid insecticide thiacloprid.

Science.gov (United States)

Siede, Reinhold; Faust, Lena; Meixner, Marina D; Maus, Christian; Grünewald, Bernd; Büchler, Ralph

2017-07-01

Substantial honey bee colony losses have occurred periodically in the last decades. The drivers for these losses are not fully understood. The influence of pests and pathogens are beyond dispute, but in addition, chronic exposure to sublethal concentrations of pesticides has been suggested to affect the performance of honey bee colonies. This study aims to elucidate the potential effects of a chronic exposure to sublethal concentrations (one realistic worst-case concentration) of the neonicotinoid thiacloprid to honey bee colonies in a three year replicated colony feeding study. Thiacloprid did not significantly affect the colony strength. No differences between treatment and control were observed for the mortality of bees, the infestation with the parasitic mite Varroa destructor and the infection levels of viruses. No colony losses occurred during the overwintering seasons. Furthermore, thiacloprid did not influence the constitutive expression of the immunity-related hymenoptaecin gene. However, upregulation of hymenoptaecin expression as a response to bacterial challenge was less pronounced in exposed bees than in control bees. Under field conditions, bee colonies are not adversely affected by a long-lasting exposure to sublethal concentrations of thiacloprid. No indications were found that field-realistic and higher doses exerted a biologically significant effect on colony performance. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Long lasting insecticidal bed nets ownership, access and use in a high malaria transmission setting before and after a mass distribution campaign in Uganda.

Science.gov (United States)

Wanzira, Humphrey; Eganyu, Thomas; Mulebeke, Ronald; Bukenya, Fred; Echodu, Dorothy; Adoke, Yeka

2018-01-01

Uganda is conducting a second mass LLIN distribution campaign and Katakwi district recently received LLINs as part of this activity. This study was conducted to measure the success of the campaign in this setting, an area of high transmission, with the objectives to estimate LLIN ownership, access and use pre and post campaign implementation. Two identical cross sectional surveys, based on the Malaria Indicator Survey methodology, were conducted in three sub-counties in this district (Kapujan, Magoro and Toroma), six months apart, one before and another after the mass distribution campaign. Data on three main LLIN indicators including; household LLIN ownership, population with access to an LLIN and use were collected using a household and a women's questionnaire identical to the Malaria Indicator Survey. A total of 601 and 607 households were randomly selected in survey one and two respectively. At baseline, 60.57% (56.53-64.50) of households owned at least one net for every two persons who stayed in the household the night before the survey which significantly increased to 70.35% (66.54-73.96) after the campaign (p = 0.001). Similarly, the percentage of the household population with access to an LLIN significantly increased from 84.76% (82.99-86.52) to 91.57% (90.33-92.81), p = 0.001 and the percentage of household population that slept under an LLIN the night before the survey also significantly increased from 56.85% (55.06-58.82) to 81.72% (76.75-83.21), p = 0.001. The LLIN mass campaign successfully achieved the national target of over eighty-five percent of the population with access to an LLIN in this setting, however, universal household coverage and use were fourteen and three percent points less than the national target respectively. This is useful for malaria programs to consider during the planning of future campaigns by tailoring efforts around deficient areas like mechanisms to increase universal coverage and behavior change communication.

Mechanisms of translation control underlying long-lasting synaptic plasticity and the consolidation of long-term memory.

Science.gov (United States)

Santini, Emanuela; Huynh, Thu N; Klann, Eric

2014-01-01

The complexity of memory formation and its persistence is a phenomenon that has been studied intensely for centuries. Memory exists in many forms and is stored in various brain regions. Generally speaking, memories are reorganized into broadly distributed cortical networks over time through systems level consolidation. At the cellular level, storage of information is believed to initially occur via altered synaptic strength by processes such as long-term potentiation. New protein synthesis is required for long-lasting synaptic plasticity as well as for the formation of long-term memory. The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of cap-dependent protein synthesis and is required for numerous forms of long-lasting synaptic plasticity and long-term memory. As such, the study of mTORC1 and protein factors that control translation initiation and elongation has enhanced our understanding of how the process of protein synthesis is regulated during memory formation. Herein we discuss the molecular mechanisms that regulate protein synthesis as well as pharmacological and genetic manipulations that demonstrate the requirement for proper translational control in long-lasting synaptic plasticity and long-term memory formation. © 2014 Elsevier Inc. All rights reserved.

Allelic Variation of Cytochrome P450s Drives Resistance to Bednet Insecticides in a Major Malaria Vector.

Science.gov (United States)

Ibrahim, Sulaiman S; Riveron, Jacob M; Bibby, Jaclyn; Irving, Helen; Yunta, Cristina; Paine, Mark J I; Wondji, Charles S

2015-10-01

Scale up of Long Lasting Insecticide Nets (LLINs) has massively contributed to reduce malaria mortality across Africa. However, resistance to pyrethroid insecticides in malaria vectors threatens its continued effectiveness. Deciphering the detailed molecular basis of such resistance and designing diagnostic tools is critical to implement suitable resistance management strategies. Here, we demonstrated that allelic variation in two cytochrome P450 genes is the most important driver of pyrethroid resistance in the major African malaria vector Anopheles funestus and detected key mutations controlling this resistance. An Africa-wide polymorphism analysis of the duplicated genes CYP6P9a and CYP6P9b revealed that both genes are directionally selected with alleles segregating according to resistance phenotypes. Modelling and docking simulations predicted that resistant alleles were better metabolizers of pyrethroids than susceptible alleles. Metabolism assays performed with recombinant enzymes of various alleles confirmed that alleles from resistant mosquitoes had significantly higher activities toward pyrethroids. Additionally, transgenic expression in Drosophila showed that flies expressing resistant alleles of both genes were significantly more resistant to pyrethroids compared with those expressing the susceptible alleles, indicating that allelic variation is the key resistance mechanism. Furthermore, site-directed mutagenesis and functional analyses demonstrated that three amino acid changes (Val109Ile, Asp335Glu and Asn384Ser) from the resistant allele of CYP6P9b were key pyrethroid resistance mutations inducing high metabolic efficiency. The detection of these first DNA markers of metabolic resistance to pyrethroids allows the design of DNA-based diagnostic tools to detect and track resistance associated with bednets scale up, which will improve the design of evidence-based resistance management strategies.

The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand.

Science.gov (United States)

Wilder-Smith, Annelies; Byass, Peter; Olanratmanee, Phanthip; Maskhao, Pongsri; Sringernyuang, Luechai; Logan, James G; Lindsay, Steve W; Banks, Sarah; Gubler, Duane; Louis, Valérie R; Tozan, Yesim; Kittayapong, Pattamaporn

2012-11-15

There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7-18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. clinicaltrial.gov. NCT01563640.

How many holes is too many? A prototype tool for estimating mosquito entry risk into damaged bed nets.

Science.gov (United States)

Sutcliffe, James; Ji, Xin; Yin, Shaoman

2017-08-01

Insecticide-treated bed nets (ITNs) have played an integral role in malaria reduction but how insecticide depletion and accumulating physical damage affect ITN performance is poorly understood. More accurate methods are needed to assess damage to bed nets so that they can be designed, deployed and replaced optimally. Video recordings of female Anopheles gambiae in near approach (1-½ cm) to occupied untreated rectangular bed nets in a laboratory study were used to quantify the amount of mosquito activity (appearances over time) around different parts of the net, the per-appearance probability of a mosquito coming close to holes of different sizes (hole encounter) and the per-encounter probability of mosquitoes passing through holes of different sizes (hole passage). Appearance frequency on different parts of the net reflected previously reported patterns: the area of the net under greatest mosquito pressure was the roof, followed by the bottom 30 cm of the sides, followed by the 30 cm area immediately above this, followed by the upper two-thirds of the sides. The ratio of activity in these areas was (respectively) 250:33:5:1. Per-appearance probability of hole encounter on all parts of the net was strongly predicted by a factor combining hole perimeter and area. Per-encounter probability of hole passage, in turn, was strongly predicted by hole width. For a given width, there was a 20% greater risk of passage through holes on the roof than holes on the sides. Appearance, encounter and passage predictors correspond to various mosquito behaviours that have previously been described and are combined into a prototype mosquito entry risk tool that predicts mosquito entry rates for nets with various amounts of damage. Scenarios that use the entry risk tool to test the recommendations of the WHOPES proportionate hole index (pHI) suggest that the pHI hole size categories and failure to account for hole location likely sometimes lead to incorrect conclusions about net

The benefits of cholinergic enhancement during perceptual learning are long-lasting

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Ariel eRokem

2013-05-01

Full Text Available The neurotransmitter acetylcholine (ACh regulates many aspects of cognition, including attention and memory. Previous research in animal models has shown that plasticity in sensory systems often depends on the behavioral relevance of a stimulus and/or task. However, experimentally increasing ACh release in the cortex can result in experience-dependent plasticity, even in the absence of behavioral relevance. In humans, the pharmacological enhancement of ACh transmission by administration of the cholinesterase inhibitor donepezil during performance of a perceptual task increases the magnitude of perceptual learning (PL and its specificity to physical parameters of the stimuli used for training. Behavioral effects of PL have previously been shown to persist for many months. In the present study, we tested whether enhancement of PL by donepezil is also long-lasting. Healthy human subjects were trained on a motion direction discrimination task during cholinergic enhancement, and follow-up testing was performed 5-15 months after the end of training and without additional drug administration. Increases in performance associated with training under donepezil were evident in follow-up retesting, indicating that cholinergic enhancement has beneficial long-term effects on PL. These findings suggest that cholinergic enhancement of training procedures used to treat clinical disorders should improve long-term outcomes of these procedures.

Design and Optimization of Die Preforming Process for Long Last-stage Blade of Nuclear Power

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He Xiaomao

2017-01-01

Full Text Available The long last-stage blade is a key component of the steam turbine of nuclear conventional island. The die preforming process for a new technology that provides billets for near-net-shape roll-forging process was designed, the effects of the forging temperature, friction coefficient, flash land’s height and die’s outer fillet radius on the die forging force and forging energy were studied by using the orthogonal experiment method, the primary and secondary order of the four factors were analysed by using range analysis method, and the optimal combination of the factors was obtained. By means of numerical simulation and physical experiment, the die preforming process that can provide qualified billets for the subsequent roll-forging process was verified, and the PZS1120f electric screw press can meet the requirements of the die preforming process.

SELECTIVITY OF INSECTICIDES USED IN PEACH FARMING TO LARVAE OF Chrysoperla externa (NEUROPTERA: CHRYSOPIDAE IN SEMI-FIELD CONDITIONS

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RODOLFO VARGAS CASTILHOS

2017-01-01

Full Text Available The selectivity of five insecticides, regularly used in peach farming, was assessed for larvae of the predator Chrysoperla externa (Hagen (Neuroptera: Chrysopidae by means of bioassay in semi-field conditions. The bioassay was based on the counting of captured larvae after release in peach trees treated with the insecticides (% of active ingredient in spray liquid: deltamethrin (0.001, fenthion (0.050, phosmet (0.100, lufenuron (0.005 and malathion (0.200. Bait-cards with eggs of Anagasta kuehniella (Zeller (Lepidoptera: Pyralidae were used to capture larvae from treated plants; five of them were fixed in plant canopy and five others left on the soil around stem. A protective barrier made up of galvanized steel sheet was used for each plant to avoid loss of larvae. The number of larvae feeding on the bait-cards was measured for four days. According to the number of captured larvae, each insecticide effect was estimated and classified into toxicity categories as stated by the International Organization for Biological and Integratec Control of Noxious Animals and Plants (IOBC. Based on observations, the insect growth regulator lufenuron was harmless, while the neurotoxins deltamethrin and malathion were slightly harmful; and lastly, fenthion and phosmet were moderately harmful to C. externa larvae in semi-field conditions. Thus, lufenuron should be recommended for integrated pest management, since it would preserve this predator species in peach orchards.

Mechanistic modeling of insecticide risks to breeding birds in ...

Science.gov (United States)

Insecticide usage in the United States is ubiquitous in urban, suburban, and rural environments. In evaluating data for an insecticide registration application and for registration review, scientists at the United States Environmental Protection Agency (USEPA) assess the fate of the insecticide and the risk the insecticide poses to the environment and non-target wildlife. At the present time, current USEPA risk assessments do not include population-level endpoints. In this paper, we present a new mechanistic model, which allows risk assessors to estimate the effects of insecticide exposure on the survival and seasonal productivity of birds known to use agricultural fields during their breeding season. The new model was created from two existing USEPA avian risk assessment models, the Terrestrial Investigation Model (TIM v.3.0) and the Markov Chain Nest Productivity model (MCnest). The integrated TIM/MCnest model has been applied to assess the relative risk of 12 insecticides used to control corn pests on a suite of 31 avian species known to use cornfields in midwestern agroecosystems. The 12 insecticides that were assessed in this study are all used to treat major pests of corn (corn root worm borer, cutworm, and armyworm). After running the integrated TIM/MCnest model, we found extensive differences in risk to birds among insecticides, with chlorpyrifos and malathion (organophosphates) generally posing the greatest risk, and bifenthrin and ë-cyhalothrin (

Insecticide exposure affects DNA and antioxidant enzymes activity in honey bee species Apis florea and A. dorsata: Evidence from Punjab, Pakistan.

Science.gov (United States)

Hayat, Khizar; Afzal, Muhammad; Aqueel, Muhammad Anjum; Ali, Sajjad; Saeed, Muhammad Farhan; Khan, Qaiser M; Ashfaq, Muhammad; Damalas, Christos A

2018-04-23

Insecticide exposure can affect honey bees in agro-ecosystems, posing behavioral stresses that can lead to population decline. In this study, insecticide incidence, DNA damage, and antioxidant enzyme activity were studied in Apis florea and A. dorsata honey bee samples collected from insecticide-treated and insecticide-free areas of Punjab, Pakistan. Seven insecticides: chlorpyrifos, dimethoate, imidacloprid, phorate, emamectin, chlorfenapyr, and acetamiprid were detected in seven samples of A. florea and five samples of A. dorsata. In total, 12 samples (22.2%) of honey bees were found positive to insecticide presence out of 54 samples. The most frequently detected insecticide was chlorpyrifos, which was found in four samples (7.4%), with a concentration ranging from 0.01 to 0.05 μg/g and an average concentration 0.03 μg/g. The comet assay or single cell gel electrophoresis assay, a simple way to measure DNA strand breaks in eukaryotic cells, was used to microscopically find damage of DNA at the level of a single cell. Comet tail lengths of DNA in A. florea and A. dorsata samples from insecticide-treated areas were significantly higher (P honey bee samples from insecticide-treated and insecticide-free areas, while glutathione S-transferase (GST) activity showed a significant reduction in response to insecticide exposure. Significant positive correlations were detected between enzyme activity and insecticide concentration in honey bee species from insecticide-treated areas compared with control groups. Toxicity from pesticide exposure at sub-lethal levels after application or from exposure to pesticide residues should not be underestimated in honey bees, as it may induce physiological impairment that can decline honey bees' health. Copyright © 2018. Published by Elsevier B.V.

The response of natural enemies to selective insecticides applied to soybean.

Science.gov (United States)

Varenhorst, A J; O'Neal, M E

2012-12-01

Natural enemies of the invasive pest Aphis glycines Matsumura can prevent its establishment and population growth. However, current A. glycines management practices include the application of broad-spectrum insecticides that affect pests and natural enemies that are present in the field at the time of application. An alternative is the use of selective insecticides that affect the targeted pest species, although having a reduced impact on the natural enemies. We tested the effects of esfenvalerate, spirotetramat, imidacloprid, and a combination of spirotetramat and imidacloprid on the natural enemies in soybean during the 2009 and 2010 field season. The natural enemy community that was tested differed significantly between 2009 and 2010 (F = 87.41; df = 1, 598; P natural enemy in 2009 was Harmonia axyridis (Pallas) (56.0%) and in 2010 was Orius insidiosus (Say) (41.0%). During 2009, the abundance of natural enemies did not vary between the broad-spectrum and selective insecticides; however, the abundance of natural enemies was reduced by all insecticide treatments when compared with the untreated control. In 2010, the selective insecticide imidacloprid had more natural enemies than the broad-spectrum insecticide. Although we did not observe a difference in the abundance of the total natural enemy community in 2009, we did observe more H. axyridis in plots treated with spirotetramat. In 2010, we observed more O. insidiosus in plots treated with imidacloprid. We suggest a couple of mechanisms to explain how the varying insecticides have different impacts on separate components of the natural enemy community.

Malaria and protective behaviours: is there a malaria trap?

Science.gov (United States)

Berthélemy, Jean-Claude; Thuilliez, Josselin; Doumbo, Ogobara; Gaudart, Jean

2013-06-13

In spite of massive efforts to generalize efficient prevention, such as insecticide-treated mosquito nets (ITN) or long-lasting insecticidal nets (LLINs), malaria remains prevalent in many countries and ITN/LLINs are still only used to a limited extent. This study proposes a new model for malaria economic analysis by combining economic epidemiology tools with the literature on poverty traps. A theoretical model of rational protective behaviour in response to malaria is designed, which includes endogenous externalities and disease characteristics. Survey data available for Uganda provide empirical support to the theory of prevalence-elastic protection behaviours, once endogeneity issues related to epidemiology and poverty are solved. Two important conclusions emerge from the model. First, agents increase their protective behaviour when malaria is more prevalent in a society. This is consistent with the literature on "prevalence-elastic behaviour". Second, a 'malaria trap' defined as the result of malaria reinforcing poverty while poverty reduces the ability to deal with malaria can theoretically exist and the conditions of existence of the malaria trap are identified. These results suggest the possible existence of malaria traps, which provides policy implications. Notably, providing ITN/LLINs at subsidized prices is not sufficient. To be efficient an ITN/LLINs dissemination campaigns should include incentive of the very poor for using ITN/LLINs.

Assessment of coverage of preventive treatment and insecticide-treated mosquito nets in pregnant women attending antenatal care services in 11 districts in Mozambique in 2011: the critical role of supply chain.

Science.gov (United States)

Salomão, Cristolde; Sacarlal, Jahit; Gudo, Eduardo Samo

2017-05-25

Malaria during pregnancy is associated with poor maternal and pregnancy outcome and the World Health Organization recommends the administration of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) and distribution of insecticide-treated mosquito nets (ITNs) to all pregnant women attending antenatal care (ANC) services. This study was conducted with the aim to assess the uptake of IPTp and ITNs in pregnant women attending ANC services and correlate with ANC attendance and frequency of stock-outs in 22 health facilities Mozambique. A cross-sectional study was conducted between July and December 2011 in 22 health units in 11 districts situated in 11 provinces in Mozambique. Two health facilities were selected per district (one urban and one rural). Data were collected by reviewing logbooks of antenatal consultations as well as from monthly district reports. During the period under investigation, a total of 23,524 pregnant women attended their 1st antenatal care visits, of which 12,775 (54.3%) and 7581 (32.2%) received one and two doses of IPTp, respectively. In regard to ITNs, a total of 16,436 (69.9%) pregnant women received ITNs. Uptake of IPTp and ITNs by pregnant women at ANC services was higher in southern Mozambique and lower in districts situated in the northern part of the country. Stock-outs of SP and ITNs were reported in 50.0% (11/22) and 54.5% (12/22) of the health facilities, respectively. Coverage of IPTp and ITN in health facilities with stock-outs of SP and ITNs was much lower as compared to health facilities with no stock-outs. Altogether, data from this study shows that coverage of the 2nd dose of IPTp, as well as ITNs, was low in pregnant women attending ANC services in Mozambique. In addition, this data also shows that stock-outs of SP and ITNs were frequent and led to lower coverage of IPTp and ITN, representing a serious barrier for the accomplishment of targets. In conclusion, this study recommends that

Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

Directory of Open Access Journals (Sweden)

Mariusz Cycoń

2015-01-01

Full Text Available The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB in soil using the denaturing gradient gel electrophoresis (DGGE approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S and the Shannon-Wiener index (H values for soil treated with the field rate (FR dosage of imidacloprid (1 mg/kg soil showed no changes in measured indices for the AOA and AOB community members. In turn, the 10*FR dosage of insecticide (10 mg/kg soil negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4+, known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

Insecticide solvents: interference with insecticidal action.

Science.gov (United States)

Brattsten, L B; Wilkinson, C F

1977-06-10

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

Insecticide resistance and glutathione S-transferases in mosquitoes ...

African Journals Online (AJOL)

Mosquito glutathione S-transferases (GSTs) have received considerable attention in the last 20 years because of their role in insecticide metabolism producing resistance. Many different compounds, including toxic xenobiotics and reactive products of intracellular processes such as lipid peroxidation, act as GST substrates.

Laboratory investigations of insecticide impregnated materials for the control of New World screwworm flies

International Nuclear Information System (INIS)

Harris, E.G.; Brown, M.; Smith, S.

1992-01-01

In laboratory tests, New World screwworm flies were found to be at least three orders of magnitude less susceptible to the insecticides deltamethrin, alphacypermethrin and cyfluthrin than are tsetse flies. Deltamethrin was the most toxic of the three insecticides to screwworm flies. For topical application, the LD50s for deltamethrin 20% suspension concentrate were 33 ng and 25 ng for male and female screwworm flies respectively, compared with 0.04 ng for tsetse, G.m. morsitans. In various tests simulating contact of screwworm flies with cloth or netting targets impregnated with insecticide, 100% kill was only achieved with 3.2% deltamethrin and contact times of at least 10 sec, although 100% knockdown for up to 24 hours was obtained with lower concentrations. No repellent effect was observed at the higher concentrations. Cloth targets impregnated with a high dose of insecticide and baited with an attractant could be effective against NWS flies, especially if after ''knockdown'' flies are removed by predators. 1 fig., 9 tabs

Household training vs. mass campaigns: a better method of health communication for preventing malaria.

Science.gov (United States)

Chourasia, Mehul Kumar; Abraham, Vinod J; John, Jacob

2014-10-01

Malaria is endemic in several states of India with high tribal population. Effective use of long-lasting insecticide treated bed nets (LLITNs) can reduce the burden of malaria in these settings. This study assessed the knowledge and behaviour regarding malaria in a tribal population and compared two health education strategies for enhancing effective utilisation of bed nets. A community-based intervention study was carried out among 218 households in two villages. One community received household level training on effective utilisation of LLITNs while the others received training in a mass campaign and outcomes were measured after 2 months. The study showed that the proportion utilising LLITNs was significantly higher among those receiving household level training as compared to those who received the mass campaign. Household level training appears to be a more effective form of health education for improving knowledge and promoting use of LLITNs in these isolated community groups. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Insecticide-driven patterns of genetic variation in the dengue vector Aedes aegypti in Martinique Island.

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Sébastien Marcombe

Full Text Available Effective vector control is currently challenged worldwide by the evolution of resistance to all classes of chemical insecticides in mosquitoes. In Martinique, populations of the dengue vector Aedes aegypti have been intensively treated with temephos and deltamethrin insecticides over the last fifty years, resulting in heterogeneous levels of resistance across the island. Resistance spreading depends on standing genetic variation, selection intensity and gene flow among populations. To determine gene flow intensity, we first investigated neutral patterns of genetic variability in sixteen populations representative of the many environments found in Martinique and experiencing various levels of insecticide pressure, using 6 microsatellites. Allelic richness was lower in populations resistant to deltamethrin, and consanguinity was higher in populations resistant to temephos, consistent with a negative effect of insecticide pressure on neutral genetic diversity. The global genetic differentiation was low, suggesting high gene flow among populations, but significant structure was found, with a pattern of isolation-by-distance at the global scale. Then, we investigated adaptive patterns of divergence in six out of the 16 populations using 319 single nucleotide polymorphisms (SNPs. Five SNP outliers displaying levels of genetic differentiation out of neutral expectations were detected, including the kdr-V1016I mutation in the voltage-gated sodium channel gene. Association tests revealed a total of seven SNPs associated with deltamethrin resistance. Six other SNPs were associated with temephos resistance, including two non-synonymous substitutions in an alkaline phosphatase and in a sulfotransferase respectively. Altogether, both neutral and adaptive patterns of genetic variation in mosquito populations appear to be largely driven by insecticide pressure in Martinique.

Residual Acute Toxicity of Some Modern Insecticides Toward Two Mirid Predators of Tomato Pests.

Science.gov (United States)

Wanumen, Andrea C; Carvalho, Geraldo A; Medina, Pilar; Viñuela, Elisa; Adán, Ángeles

2016-03-31

The successful integration of chemical and biological control strategies for crop pests depends on a thorough evaluation of the effects of pesticides on the natural enemies of pests. A case-by-case review is difficult to achieve because of the many combinations of pests, natural enemies, and crops that need to be tested. Within this framework, we tested and compared seven insecticides representative of four different modes of action (MoAs) groups on closely related predators (Miridae): flubendiamide, spirotetramat, metaflumizone, and sulfoxaflor onNesidiocoris tenuisReuter and flubendiamide, spiromesifen, indoxacarb, and imidacloprid onMacrolophus basicornis(Stal). We follow the standardized methodology of the International Organization for Biological Control, a sequential testing exposure scheme. The lethal effect of each insecticide was evaluated in adults after three days of contact with treated surfaces in the laboratory, extended laboratory, and semifield tests (inert substrate, tomato leaves, and tomato plant as the treated surface, respectively). Flubendiamide, spiromesifen, and spirotetramat were classified as harmless (class 1), metaflumizone was slightly harmful (class 2) but persistent, indoxacarb was harmless (class 1), and sulfoxaflor and imidacloprid were toxic (class 4) and exhibited a long residual activity. Our results suggest similarities in the acute toxicities of insecticides from the same MoA group on related species of natural enemies. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand

Directory of Open Access Journals (Sweden)

Wilder-Smith Annelies

2012-11-01

Full Text Available Abstract Background There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. Methods A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7–18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Discussion Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. Trial registration clinicaltrial.gov. Registration number: NCT01563640

Ipilimumab in advanced melanoma: reports of long-lasting responses.

Science.gov (United States)

Farolfi, Alberto; Ridolfi, Laura; Guidoboni, Massimo; Nicoletti, Stefania Vittoria Luisa; Piciucchi, Sara; Valmorri, Linda; Costantini, Matteo; Scarpi, Emanuela; Amadori, Dino; Ridolfi, Ruggero

2012-06-01

Patients with metastatic melanoma have a poor prognosis; the results of chemotherapy remain unsatisfactory. Ipilimumab, an anticytotoxic T lymphocyte-associated antigen-4 antibody, has shown promising results in several clinical trials. In this report, advanced melanoma patients receiving ipilimumab were scored according to novel immune-related response criteria (irRC) in an attempt to capture additional response patterns and to avoid premature treatment cessation. Thirty-six heavily pretreated metastatic melanoma patients recieved ipilimumab within five international clinical trials at our Institution from May 2006 to August 2008. Disease progression was defined as an increase in tumor burden by at least 25% compared with the nadir, irrespective of any initial increase in baseline lesions or the appearance of new lesions. We report unusually long-lasting responses in patients treated with ipilimumab 10 mg/kg. An overall response was observed in six out of 30 patients (20%), a complete response in three (10%), and disease control in 11 (37%), which seemed to be of a long duration (median of 16 months; complete response 36+, 34+, and 41+ months). All irRC patterns seemed to be strongly associated with an improvement in overall survival. Interestingly, we found a correlation between the presence of a grade 3/4 immune-related adverse event and responses, time to progression, and overall survival. Ipilimumab therapy resulted in clinically meaningful responses in advanced melanoma patients, supporting the need for further irRC validation.

Reduced ultraviolet light transmission increases insecticide longevity in protected culture raspberry production.

Science.gov (United States)

Leach, Heather; Wise, John C; Isaacs, Rufus

2017-12-01

High tunnels are large protective structures used for season extension of many crops, including raspberries. These structures are often covered in plastic films to reduce and diffuse ultraviolet light transmission for pest and disease control, but this may also affect the photodegradation and efficacy of pesticides applied under these tunnels. We compared the residue levels of ten insecticides under three tunnel plastics with varying levels of UV transmission and open field conditions. Raspberry plants placed in research-scale tunnels were treated with insecticides and residues on fruit and foliage were monitored for one or two weeks in early 2015 and early and late 2016. Plastics that reduce UV transmission resulted in 50% greater residues of some insecticides compared to transparent plastics, and 60% compared to uncovered tunnels. This increased persistence of residues was evident within 1 day and remained consistently higher for up to 14 days. This pattern was demonstrated for multiple insecticides, including bifenthrin, esfenvalerate, imidacloprid, thiamethoxam, and spinosad. In contrast, the insecticide malathion degraded rapidly regardless of the plastic treatment, indicating less sensitivity to photodegradation. Bioassays using insecticide-treated leaves that were under UV-blocking plastic revealed higher mortality of the invasive fruit pest, Drosophila suzukii, compared to leaves that were uncovered. This indicates that the activity of pesticides under high tunnels covered in UV-reducing plastics may be prolonged, allowing for fewer insecticide applications and longer intervals between sprays. This information can be used to help optimize pest control in protected culture berry production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk Factors of Developing Long-Lasting Breast Pain After Breast Cancer Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Lundstedt, Dan, E-mail: dan.lundstedt@vgregion.se [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg (Sweden); Department of Oncology, Sahlgrenska University Hospital, Gothenburg (Sweden); Gustafsson, Magnus [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg (Sweden); Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Steineck, Gunnar [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, the Karolinska Institute, Stockholm (Sweden); Malmstroem, Per [Skane Department of Oncology, Skane University Hospital, Lund (Sweden); Alsadius, David [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg (Sweden); Department of Oncology, Sahlgrenska University Hospital, Gothenburg (Sweden); Sundberg, Agnetha [Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Wilderaeng, Ulrica [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg (Sweden); Holmberg, Erik [Oncologic Centre, Sahlgrenska University Hospital, Gothenburg (Sweden); Johansson, Karl-Axel [Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Karlsson, Per [Department of Oncology, Sahlgrenska University Hospital, Gothenburg (Sweden)

2012-05-01

Purpose: Postoperative radiotherapy decreases breast cancer mortality. However, studies have revealed a long-lasting breast pain among some women after radiotherapy. The purpose of this study was to identify risk factors that contribute to breast pain after breast cancer radiotherapy. Methods and Materials: We identified 1,027 recurrence-free women in two cohorts of Swedish women treated for breast cancer. The women had breast-conserving surgery and postoperative radiotherapy, the breast was treated to 48 Gy in 2.4-Gy fractions or to 50 Gy in 2.0-Gy fractions. Young women received a boost of up to 16 Gy. Women with more than three lymph node metastases had locoregional radiotherapy. Systemic treatments were given according to health-care guidelines. Three to 17 years after radiotherapy, we collected data using a study-specific questionnaire. We investigated the relation between breast pain and potential risk modifiers: age at treatment, time since treatment, chemotherapy, photon energy, fractionation size, boost, loco-regional radiotherapy, axillary surgery, overweight, and smoking. Results: Eight hundred seventy-seven women (85%) returned the questionnaires. Among women up to 39 years of age at treatment, 23.1% had breast pain, compared with 8.7% among women older than 60 years (RR 2.66; 95% CI 1.33-5.36). Higher age at treatment (RR 0.96; 95% CI 0.94-0.98, annual decrease) and longer time since treatment (RR 0.93; 95% CI 0.88-0.98, annual decrease) were related to a lower occurrence of breast pain. Chemotherapy increased the occurrence of breast pain (RR 1.72; 95% CI 1.19-2.47). In the multivariable model only age and time since treatment were statistically significantly related to the occurrence of breast pain. We found no statistically significant relation between breast pain and the other potential risk modifiers. Conclusions: Younger women having undergone breast-conserving surgery with postoperative radiotherapy report a higher occurrence of long-lasting

Effect of insecticides and Plutella xylostella (Lepidoptera: Plutellidae) genotype on a predator and parasitoid and implications for the evolution of insecticide resistance.

Science.gov (United States)

Liu, Xiaoxia; Chen, Mao; Collins, Hilda L; Onstad, David; Roush, Rick; Zhang, Qingwen; Shelton, Anthony M

2012-04-01

In the laboratory and in cages in the greenhouse, we evaluated the toxicity of two insecticides (lambda-cyhalothrin and spinosad) on the parasitoid, Diadegma insulare (Cresson), and the predator, Coleomegilla maculate (DeGeer), both natural enemies of the diamondback moth, Plutella xylostella (L.). Lambda-cyhalothrin was very toxic to both natural enemies. Spinosad was less toxic to C. maculata adults and larvae, and slightly toxic to D. insulare. Both natural enemies suppressed P. xylostella populations in cages with 80% spinosad-treated and 20% nontreated plants; such suppression was not seen when lambda-cyhalothrin was used. Using broccoli, Brassica oleracea L. variety italica, a common host for P. xylostella, we also studied direct and indirect effects of both natural enemies in the presence and absence of the two insecticides and to different P. xylostella genotypes: resistant to the insecticide, susceptible, or heterozygous. Neither natural enemy could distinguish host genotype if P. xylostella were feeding on nontreated plants. They could also not distinguish between larvae feeding on spinosad-treated plants and nontreated plants, but D. insulare could distinguish between larvae feeding on lambda-cyhalothrin treated and nontreated plants. Our studies suggest that lambda-cyhalothrin has direct toxicity to these two natural enemies, can affect their host foraging and acceptance of P. xylostella and consequently would not be compatible in conserving these natural enemies in a program for suppression of P. xylostella. In contrast, our studies suggest that treatment with spinosad has much less effect on these natural enemies and would allow them to help suppress populations of P. xylostella. These findings are discussed in relation to the evolution of insecticide resistance and suppression of the pest populations.

Long-Term Results for Trigeminal Schwannomas Treated With Gamma Knife Surgery

Energy Technology Data Exchange (ETDEWEB)

Hasegawa, Toshinori, E-mail: h-toshi@komakihp.gr.jp; Kato, Takenori; Iizuka, Hiroshi; Kida, Yoshihisa

2013-12-01

Purpose: Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS). Methods and Materials: Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm{sup 3}. The median maximum and marginal doses were 28 Gy and 14 Gy, respectively. Results: The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect. Conclusions: GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then

Long Term RadNet Quality Data

Data.gov (United States)

U.S. Environmental Protection Agency — This RadNet Quality Data Asset includes all data since initiation and when ERAMS was expanded to become RadNet, name changed to reflect new mission. This includes...

Utilization of insecticide treated nets among pregnant women and ...

African Journals Online (AJOL)

Malaria is mostly endemic in tropical environments and has caused several still births and deaths particularly among children. ... The possibility of provision of steady light supply through the use of solar power in the homes by those who can afford it can be explored as a remedy for promoting consistent use of ITN by ...

Ownership and utilization of insecticide-treated nets (ITNs) for ...

African Journals Online (AJOL)

Though ITNs are the most prominent measure for large-scale deployment in highly endemic areas their compliance in terms of ownership and usage needs attention. The aim of this study was therefore to ... included from malarious areas. Data were collected by using structured questionnaires and observational checklist.

Benefit incidence analysis of free insecticide treated nets distribution ...

African Journals Online (AJOL)

2013-09-05

Sep 5, 2013 ... Student's t-test and Chi-square were used for comparison where ... Results: The respondents' mean monthly expenditures on food utilities and anti-malarials in the ..... free ITNs as compared to those who would have to travel.

Management of glioblastoma at safety-net hospitals.

Science.gov (United States)

Brandel, Michael G; Rennert, Robert C; Lopez Ramos, Christian; Santiago-Dieppa, David R; Steinberg, Jeffrey A; Sarkar, Reith R; Wali, Arvin R; Pannell, J Scott; Murphy, James D; Khalessi, Alexander A

2018-04-24

Safety-net hospitals (SNHs) provide disproportionate care for underserved patients. Prior studies have identified poor outcomes, increased costs, and reduced access to certain complex, elective surgeries at SNHs. However, it is unknown whether similar patterns exist for the management of glioblastoma (GBM). We sought to determine if patients treated at HBHs receive equitable care for GBM, and if safety-net burden status impacts post-treatment survival. The National Cancer Database was queried for GBM patients diagnosed between 2010 and 2015. Safety-net burden was defined as the proportion of Medicaid and uninsured patients treated at each hospital, and stratified as low (LBH), medium (MBH), and high-burden (HBH) hospitals. The impact of safety-net burden on the receipt of any treatment, trimodality therapy, gross total resection (GTR), radiation, or chemotherapy was investigated. Secondary outcomes included post-treatment 30-day mortality, 90-day mortality, and overall survival. Univariate and multivariate analyses were utilized. Overall, 40,082 GBM patients at 1202 hospitals (352 LBHs, 553 MBHs, and 297 HBHs) were identified. Patients treated at HBHs were significantly less likely to receive trimodality therapy (OR = 0.75, p < 0.001), GTR (OR = 0.84, p < 0.001), radiation (OR = 0.73, p < 0.001), and chemotherapy (OR = 0.78, p < 0.001) than those treated at LBHs. Patients treated at HBHs had significantly increased 30-day (OR = 1.25, p = 0.031) and 90-day mortality (OR = 1.24, p = 0.001), and reduced overall survival (HR = 1.05, p = 0.039). GBM patients treated at SNHs are less likely to receive standard-of-care therapies and have increased short- and long-term mortality. Additional research is needed to evaluate barriers to providing equitable care for GBM patients at SNHs.

The influence of long term climate change on net infiltration at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Flint, A.L.; Hevesi, J.A.; Flint, L.E.

1993-01-01

Net infiltration and recharge at Yucca Mountain, Nevada, a potential site for a high level nuclear waste repository, are determined both by the rock properties and past and future changes in climate. A 1-dimensional model was constructed to represent a borehole being drilled through the unsaturated zone. The rock properties were matched to the lithologies expected to be encountered in the borehole. As current paleoclimate theory assumes that 18 O increases with wetter and cooler global climates, a past climate scenario, built on depletion of 18 O from ocean sediments was used as a basis for climate change over the past 700,000 years. The climate change was simulated by assigning net infiltration values as a linear function of 18 O. Assuming the rock properties, lithologies, and climate scenarios are correct, simulations indicated that Yucca Mountain is not in steady state equilibrium at the surface ( 250 meters. Based on the cyclic climate inputs, the near surface is currently in a long term drying trend (for the last 3,000 years) yet recharge into the water table is continuing to occur at an average rate equivalent to the average input rate of the climate model, indicating that conditions at depth are damped out over very long time periods. The Paintbrush Tuff nonwelded units, positioned between the Tiva Canyon and Topopah Spring welded tuff Members, do not appear to act as a capillary barrier and therefore would not perch water. The low porosity vitric caprock and basal vitrophyre of the Topopah Spring Member, however, act as restrictive layers. The higher porosity rock directly above the caprock reduces the potential for the caprock to perch water leaving the basal vitrophyre as the most likely location for perched water to develop

The mode of action of spatial repellents and their impact on vectorial capacity of Anopheles gambiae sensu stricto.

Science.gov (United States)

Ogoma, Sheila B; Ngonyani, Hassan; Simfukwe, Emmanuel T; Mseka, Antony; Moore, Jason; Maia, Marta F; Moore, Sarah J; Lorenz, Lena M

2014-01-01

Malaria vector control relies on toxicity of insecticides used in long lasting insecticide treated nets and indoor residual spraying. This is despite evidence that sub-lethal insecticides reduce human-vector contact and malaria transmission. The impact of sub-lethal insecticides on host seeking and blood feeding of mosquitoes was measured. Taxis boxes distinguished between repellency and attraction inhibition of mosquitoes by measuring response of mosquitoes towards or away from Transfluthrin coils and humans. Protective effective distance of coils and long-term effects on blood feeding were measured in the semi-field tunnel and in a Peet Grady chamber. Laboratory reared pyrethroid susceptible Anopheles gambiae sensu stricto mosquitoes were used. In the taxis boxes, a higher proportion of mosquitoes (67%-82%) were activated and flew towards the human in the presence of Transfluthrin coils. Coils did not hinder attraction of mosquitoes to the human. In the semi-field Tunnel, coils placed 0.3 m from the human reduced feeding by 86% (95% CI [0.66; 0.95]) when used as a "bubble" compared to 65% (95% CI [0.51; 0.76]) when used as a "point source". Mosquitoes exposed to coils inside a Peet Grady chamber were delayed from feeding normally for 12 hours but there was no effect on free flying and caged mosquitoes exposed in the semi-field tunnel. These findings indicate that airborne pyrethroids minimize human-vector contact through reduced and delayed blood feeding. This information is useful for the development of target product profiles of spatial repellent products that can be used to complement mainstream malaria vector control tools.

Degradation analysis of some synthetic and bio-insecticides sprayed on okra crop using HPLC

International Nuclear Information System (INIS)

Abar, M.F.; Haq, M.A.; Yasmin, N.; Khan, M.F.U.

2012-01-01

This study aimed to find out the degradation of three conventional and two bio-insecticides sprayed on okra crop. Imidacloprid, Endosulfan and Profenofos were selected as convectional and biosal and spinosad as bioinsecticide. The insecticides were sprayed at the rates of 49.4, 642.2, 988, 35.5 and 158 g. a. i. ha/sup -1/ respectively. The insecticide residues were analyzed in the leaf and fruit after 0, 1, 3 and 7 days using high performance liquid chromatography. First order degradation kinetics was fitted on this data and degradation rate constants and half life were calculated. Conventional insecticides were found to be more persistent in the crop (Average half life: 1.95, 2.42 and 1.57 days for imidacloprid, endosulfan and profenofos respectively) than bioinsecticides (Average half life 1.25 and 0.27 days for spinosad and biosal respectively). Residues of all tested insecticides were compared with codex and EU MRLs and found both the bio-insecticides treated crops safe for human consumption even after few hours of spray. Endosulfan and profenofos treated crops were not found to be fit for consumption even after 7 days of application. Imidacloprid being biorational (low risk) was also safe for consumption on the next day of application. (author)

Log bioassay of residual effectiveness of insecticides against bark beetles

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Richard H. Smith

1982-01-01

Residual effectiveness of nine insecticides applied to bark was tested against western, mountain, and Jeffrey pine beetles. Ponderosa and Jeffrey pine trees were treated and logs cut from them 2 to 13 months later, and bioassayed with the three beetles. The insecticides were sprayed at the rate of 1 gal (3.8 l) per 40- or 80-ft² (3.6 or 7.2 m²) bark surface at varying...

Long lasting protein synthesis- and activity-dependent spine shrinkage and elimination after synaptic depression.

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Yazmín Ramiro-Cortés

Full Text Available Neuronal circuits modify their response to synaptic inputs in an experience-dependent fashion. Increases in synaptic weights are accompanied by structural modifications, and activity dependent, long lasting growth of dendritic spines requires new protein synthesis. When multiple spines are potentiated within a dendritic domain, they show dynamic structural plasticity changes, indicating that spines can undergo bidirectional physical modifications. However, it is unclear whether protein synthesis dependent synaptic depression leads to long lasting structural changes. Here, we investigate the structural correlates of protein synthesis dependent long-term depression (LTD mediated by metabotropic glutamate receptors (mGluRs through two-photon imaging of dendritic spines on hippocampal pyramidal neurons. We find that induction of mGluR-LTD leads to robust and long lasting spine shrinkage and elimination that lasts for up to 24 hours. These effects depend on signaling through group I mGluRs, require protein synthesis, and activity. These data reveal a mechanism for long lasting remodeling of synaptic inputs, and offer potential insights into mental retardation.

The Effects of Some Botanical Insecticides and Pymetrozine on Life Table Parameters of Silver Leaf Whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae

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Reihaneh Barati

2013-01-01

Full Text Available The objective of this research was to assess the effects of extracts of two medicinalplant species: Allium sativum (Linn and Calotropis procera (Aiton, and a formulation containingazadirachtin on life table parameters of silver leaf whitefly (SLW, Bemisia tabaci biotypeB (Gennadius (Hemiptera: Aleyrodidae, grown on greenhouse tomato plants. Theeffects were compared to that of pymetrozine, a synthetic insecticide. Bioassays were carriedout in a greenhouse under controlled conditions of 27 ± 2°C, R.H. of 55 ± 5% and 16:8h (L:D photo period.All treatments significantly affected the survivorship and fertility of SLW female adults,reducing the net reproduction rate, mean generation time and intrinsic rate of increase ofthis insect.The net reproductive rate [R0] values for the populations treated with garlic extract,milkweed extract, pymetrozine, azadirachtin, control for extracts (ethanol + distilled waterand control for pesticides (distilled water were 23.58, 19.32, 10.78, 8.23, 49.66, 57.55; theintrinsic rate of increases [rm] were 0.134, 0.139, 0.110, 0.090, 0.177, 0.178; the mean generationtimes [T] were 23.49, 21.23, 21.66, 23.50, 22.06, 22.69; the doubling times [DT] were 5.14,4.95, 6.27, 7.56, 3.91, 3.87, and the finite rates of increase [λ] were 1.144, 1.149, 1.116, 1.094, 1.193,1.195, respectively. Azadirachtin had the highest effect on the life table parameters of SLW.Our findings indicated that, although herbal extracts were not effective as much asthe chemical insecticides, they can be effective in pest control. Therefore, they are suitablechoices for replacing chemical insecticides and for alternative use with azadirachtin inSLW IPM program.

Impact of permethrin-treated bed nets on entomologic indices in an area of intense year-round malaria transmission.

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Gimnig, John E; Vulule, John M; Lo, Terrence Q; Kamau, Luna; Kolczak, Margarette S; Phillips-Howard, Penelope A; Mathenge, Evan M; ter Kuile, Feiko O; Nahlen, Bernard L; Hightower, Allen W; Hawley, William A

2003-04-01

The effect of permethrin-treated bed nets (ITNs) on malaria vectors was studied as part of a large-scale, randomized, controlled trial in western Kenya. Indoor resting densities of fed Anopheles gambiae s.l. and An. funestus in intervention houses were 58.5% (P = 0.010) and 94.5% (P = 0.001) lower, respectively, compared with control houses. The sporozoite infection rate in An. gambiae s.l. was 0.8% in intervention areas compared with 3.4% (P = 0.026) in control areas, while the sporozoite infection rates in An. funestus were not significantly different between the two areas. We estimated the overall transmission of Plasmodium falciparum in intervention areas to be 90% lower than in control areas. Permethrin resistance was not detected during the study period. As measured by densities of An. gambiae s.l., the efficacy of bed nets decreased if one or more residents did not sleep under a net or if bed nets had not been re-treated within six months. These results indicate that ITNs are optimally effective if used every night and if permethrin is reapplied at least biannually.

Toxicity of Insecticides on Various Life Stages of Two Tortricid Pests of Cranberries and on a Non-Target Predator.

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Rodriguez-Saona, Cesar; Wanumen, Andrea Carolina; Salamanca, Jordano; Holdcraft, Robert; Kyryczenko-Roth, Vera

2016-04-15

Laboratory and extended laboratory bioassays were conducted to determine the residual toxicities of various insecticides against two key pests of cranberries, Sparganothis sulfureana and Choristoneura parallela (Lepidoptera: Tortricidae), and their non-target effects on the predatory Orius insidiosus (Hemiptera: Anthocoridae). The effects of nine insecticides with different modes of action on S. sulfureana and Ch. parallela eggs, larvae, and adults were tested in the laboratory, while the efficacy of a post-bloom application on larval mortality and mass of these pests and on adult O. insidiosus was evaluated in extended laboratory experiments. The organophosphate chlorpyrifos and the spinosyn spinetoram provided long-lasting (seven-day) control against all stages of both pests. The growth regulator methoxyfenozide and the diamides chlorantraniliprole and cyantraniliprole had strong (1-7 days) larvicidal, particularly on young larvae, and growth inhibitory activity, but only the diamides were adulticidal. Among neonicotinoids, acetamiprid had stronger ovicidal and adulticidal activity than thiamethoxam, showing within-insecticide class differences in toxicities; however, both were weak on larvae. Lethality of novaluron and indoxacarb was inconsistent, varying depending on species and stage. Chlorpyrifos was most toxic to O. insidiosus. These results show species- and stage-specific toxicities, and greater compatibility with biological control, of the newer reduced-risk classes of insecticides than older chemistries.

Toxicity of Insecticides on Various Life Stages of Two Tortricid Pests of Cranberries and on a Non-Target Predator

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Cesar Rodriguez-Saona

2016-04-01

Full Text Available Laboratory and extended laboratory bioassays were conducted to determine the residual toxicities of various insecticides against two key pests of cranberries, Sparganothis sulfureana and Choristoneura parallela (Lepidoptera: Tortricidae, and their non-target effects on the predatory Orius insidiosus (Hemiptera: Anthocoridae. The effects of nine insecticides with different modes of action on S. sulfureana and Ch. parallela eggs, larvae, and adults were tested in the laboratory, while the efficacy of a post-bloom application on larval mortality and mass of these pests and on adult O. insidiosus was evaluated in extended laboratory experiments. The organophosphate chlorpyrifos and the spinosyn spinetoram provided long-lasting (seven-day control against all stages of both pests. The growth regulator methoxyfenozide and the diamides chlorantraniliprole and cyantraniliprole had strong (1–7 days larvicidal, particularly on young larvae, and growth inhibitory activity, but only the diamides were adulticidal. Among neonicotinoids, acetamiprid had stronger ovicidal and adulticidal activity than thiamethoxam, showing within-insecticide class differences in toxicities; however, both were weak on larvae. Lethality of novaluron and indoxacarb was inconsistent, varying depending on species and stage. Chlorpyrifos was most toxic to O. insidiosus. These results show species- and stage-specific toxicities, and greater compatibility with biological control, of the newer reduced-risk classes of insecticides than older chemistries.

Insecticide susceptibility of Anopheles mosquitoes changes in response to variations in the larval environment.

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Owusu, Henry F; Chitnis, Nakul; Müller, Pie

2017-06-16

Insecticide resistance threatens the success achieved through vector control in reducing the burden of malaria. An understanding of insecticide resistance mechanisms would help to develop novel tools and strategies to restore the efficacy of insecticides. Although we have substantially improved our understanding of the genetic basis of insecticide resistance over the last decade, we still know little of how environmental variations influence the mosquito phenotype. Here, we measured how variations in larval rearing conditions change the insecticide susceptibility phenotype of adult Anopheles mosquitoes. Anopheles gambiae and A. stephensi larvae were bred under different combinations of temperature, population density and nutrition, and the emerging adults were exposed to permethrin. Mosquitoes bred under different conditions showed considerable changes in mortality rates and body weight, with nutrition being the major factor. Weight is a strong predictor of insecticide susceptibility and bigger mosquitoes are more likely to survive insecticide treatment. The changes can be substantial, such that the same mosquito colony may be considered fully susceptible or highly resistant when judged by World Health Organization discriminatory concentrations. The results shown here emphasise the importance of the environmental background in developing insecticide resistance phenotypes, and caution for the interpretation of data generated by insecticide susceptibility assays.

Clinical development of placental malaria vaccines and immunoassays harmonization

DEFF Research Database (Denmark)

Chêne, Arnaud; Houard, Sophie; Nielsen, Morten A

2016-01-01

Placental malaria caused by Plasmodium falciparum infection constitutes a major health problem manifesting as severe disease and anaemia in the mother, impaired fetal development, low birth weight or spontaneous abortion. Prevention of placental malaria currently relies on two key strategies...... that are losing efficacy due to spread of resistance: long-lasting insecticide-treated nets and intermittent preventive treatment during pregnancy. A placental malaria vaccine would be an attractive, cost-effective complement to the existing control tools. Two placental malaria vaccine candidates are currently...... in Phase Ia/b clinical trials. During two workshops hosted by the European Vaccine Initiative, one in Paris in April 2014 and the other in Brussels in November 2014, the main actors in placental malaria vaccine research discussed the harmonization of clinical development plans and of the immunoassays...

Household bed net ownership and use among under-5 children in Nigeria

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Osuorah DC

2013-07-01

Full Text Available D Chidiebere Osuorah,1,2 Chijioke Elias Ezeudu,2 Stanley Kenechi Onah,2 Obinna Tochukwu Anyabolu31Child Survival Unit, Medical Research Council UK, The Gambia Unit, Banjul, The Gambia; 2Department of Pediatrics, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra, Nigeria; 3School of Health and Social Care, Oxford Brookes University, Oxford, UKBackground: Malaria remains the leading cause of morbidity and mortality in sub-Saharan Africa, with children under 5 years accounting for 86% of all malaria deaths. For effective control of malaria, WHO recommends rapid diagnosis and effective treatment, insecticide-treated bed nets, and indoor residual spraying. The use of insecticide-treated bed nets has been shown to be the most cost-effective strategy in preventing this infection. However, despite the Roll Back Malaria subsidized and free bed net distribution initiatives in some Africa countries, bed net uptake and usage still remains low in many households.Aim: This study aimed to investigate household characteristics and child factors that determine bed net ownership and use amongst under-5 children and the effect of its usage on malaria parasitemia in under-5 children in Nigeria.Methods: Data from a nationally representative sample of 5895 households was obtained from the 36 states and the Federal Capital Territory in the 2010 Nigeria demographic and health survey, with a minimum of 67 households enrolled per state. Appropriate statistical tools were used to identify the characteristics of households that owned a bed net and to examine the association between the households and child-level factors that predict the use of bed net and malaria prevalence among under-5 children within these households.Results: The rate of households bed net ownership in Nigeria is about 45.5%. About 48.5% of under-5 children in 33.9% of households surveyed, use a bed net during sleep. There was a strong correlation between households ownership and child

Chemical and environmental vector control as a contribution to the elimination of visceral leishmaniasis on the Indian subcontinent: cluster randomized controlled trials in Bangladesh, India and Nepal

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Das Pradeep

2009-10-01

Full Text Available Abstract Background Bangladesh, India and Nepal are working towards the elimination of visceral leishmaniasis (VL by 2015. In 2005 the World Health Organization/Training in Tropical Diseases launched an implementation research programme to support integrated vector management for the elimination of VL from Bangladesh, India and Nepal. The programme is conducted in different phases, from proof-of-concept to scaling up intervention. This study was designed in order to evaluate the efficacy of the three different interventions for VL vector management: indoor residual spraying (IRS; long-lasting insecticide treated nets (LLIN; and environmental modification (EVM through plastering of walls with lime or mud. Methods Using a cluster randomized controlled trial we compared three vector control interventions with a control arm in 96 clusters (hamlets or neighbourhoods in each of the 4 study sites: Bangladesh (one, India (one and Nepal (two. In each site four villages with high reported VL incidences were included. In each village six clusters and in each cluster five households were randomly selected for sand fly collection on two consecutive nights. Control and intervention clusters were matched with average pre-intervention vector densities. In each site six clusters were randomly assigned to each of the following interventions: indoor residual spraying (IRS; long-lasting insecticide treated nets (LLIN; environmental management (EVM or control. All the houses (50-100 in each intervention cluster underwent the intervention measures. A reduction of intra-domestic sand fly densities measured in the study households by overnight US Centres for Disease Prevention and Control light trap captures (that is the number of sand flies per trap per night was the main outcome measure. Results IRS, and to a lesser extent EVM and LLINs, significantly reduced sand fly densities for at least 5 months in the study households irrespective of type of walls or whether or

Insecticide control of vector-borne diseases: when is insecticide resistance a problem?

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Ana Rivero

Full Text Available Many of the most dangerous human diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector species have demonstrated the capacity to evolve resistance to insecticides. Insecticide resistance is generally considered to undermine control of vector-transmitted diseases because it increases the number of vectors that survive the insecticide treatment. Disease control failure, however, need not follow from vector control failure. Here, we review evidence that insecticide resistance may have an impact on the quality of vectors and, specifically, on three key determinants of parasite transmission: vector longevity, competence, and behaviour. We argue that, in some instances, insecticide resistance is likely to result in a decrease in vector longevity, a decrease in infectiousness, or in a change in behaviour, all of which will reduce the vectorial capacity of the insect. If this effect is sufficiently large, the impact of insecticide resistance on disease management may not be as detrimental as previously thought. In other instances, however, insecticide resistance may have the opposite effect, increasing the insect's vectorial capacity, which may lead to a dramatic increase in the transmission of the disease and even to a higher prevalence than in the absence of insecticides. Either way-and there may be no simple generality-the consequence of the evolution of insecticide resistance for disease ecology deserves additional attention.

Compatibility of endoparasitoid Hyposoter didymator (Hymenoptera: Ichneumonidae) protected stages with five selected insecticides.

Science.gov (United States)

Medina, P; Morales, J J; Budia, F; Adan, A; Del Estal, P; Viñuela, E

2007-12-01

Hyposoter didymator (Thunberg) (Hymenoptera: Ichneumonidae) is a koinobiont endoparasitoid that emerges from the parasitization of economically important noctuid pests. H. didymator also is considered one of the most important native biocontrol agents of noctuids in Spain. Side effects of five insecticides with very different modes of action (fipronil, imidacloprid, natural pyrethrins + piperonyl butoxide, pymetrozine, and triflumuron) at the maximum field recommended rate in Spain were evaluated on H. didymator parasitizing Spodoptera littoralis (Boisduval) larvae and pupae of the endoparasitoid. Parasitized larvae were topically treated or ingested treated artificial diet. Parasitoid cocoons were topically treated. Host mortality when parasitized larvae were treated, as well as further development of the parasitoid surviving (e.g., percentage of cocoons spun, adult emergence, hosts attacked, and numbered progeny) were determined. Toxicity after treatment of parasitized larvae differed depending on the mode of exposure and insecticide. Fipronil was always highly toxic; imidacloprid killed all host insects by ingestion, but it was less toxic to both host and parasitoids, when administered topically; natural pyrethrins + piperonyl butoxide and triflumuron showed differing degrees of toxicity, and pymetrozine was harmless. Parasitoid cocoons provided effective protection against all the insecticides, except fipronil.

Pyrethroid Resistance Alters the Blood-Feeding Behavior in Puerto Rican Aedes aegypti Mosquitoes Exposed to Treated Fabric

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Emerging insecticide resistance is a major issue for vector control; it decreases effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has b...

Prevention of anaemia in pregnancy using insecticide-treated bednets and sulfadoxine-pyrimethamine in a highly malarious area of Kenya: a randomized controlled trial.

Science.gov (United States)

Njagi, Joseph Kiambo; Magnussen, Pascal; Estambale, Benson; Ouma, John; Mugo, Benbolt

2003-01-01

To compare the effects of intermittent treatment with sulfadoxine-pyrimethamine (SP) given during the second and third trimester of pregnancy, the use of insecticide-treated nets (ITN), or the combination of both on haemoglobin (Hb) levels during pregnancy, a randomized, placebo-controlled intervention trial was conducted in a malaria-endemic area of western Kenya from July 1997 to September 1999. Primigravidae and secundigravidae were enrolled into the study and randomized into 4 intervention groups: (i) ITNs and SP, (ii) ITNs and placebo SP, (iii) SP alone, and (iv) placebo SP. All groups were offered case management and iron and folic acid supplementation. Seven hundred and fifty-two women were followed until delivery (53.2% were primigravidae and 46.8% secundigravidae). Among primigravidae in all the groups there was a significant improvement in Hb levels at delivery (107.6 g/L) compared with recruitment (101.9 g/L) (P anaemia was 55.8% (95% CI 30.6-71.8), of SP alone 50.9% (95% CI 22.2-69.0), and of ITNs 41.6% (95% CI 9.8-62.3). Among secundigravidae, Hb levels were slightly lower at delivery compared with recruitment (P = 0.03). It was concluded that malaria is a major cause of anaemia in primigravidae but that other causes play a more significant role in secundigravidae, and that intermittent treatment with SP or use of ITNs benefits primigravidae more than secundigravidae.

Transmitter-controlled properties of α-motoneurones causing long-lasting motor discharge to brief excitatory inputs

DEFF Research Database (Denmark)

Hounsgaard, J.; Hultborn, H.; Kiehn, O.

1986-01-01

Brief sensory inputs to intact conscious subjects commonly trigger complex long-lasting motor responses, in which higher cerebral mechanisms, or even voluntary action, may be integrative parts. However, long-lasting motor discharge following brief afferent stimulation is also observed in reduced ...... flipflops, which are set at one of two levels by short excitatory or inhibitory inputs. However, when the whole motoneuronal pool is considered, many different levels can be maintained by recruitment of new units.......Brief sensory inputs to intact conscious subjects commonly trigger complex long-lasting motor responses, in which higher cerebral mechanisms, or even voluntary action, may be integrative parts. However, long-lasting motor discharge following brief afferent stimulation is also observed in reduced...

Investigating molecular basis of lambda-cyhalothrin resistance in an Anopheles funestus population from Senegal.

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Samb, Badara; Konate, Lassana; Irving, Helen; Riveron, Jacob M; Dia, Ibrahima; Faye, Ousmane; Wondji, Charles S

2016-08-12

Anopheles funestus is one of the major malaria vectors in tropical Africa, notably in Senegal. The highly anthropophilic and endophilic behaviours of this mosquito make it a good target for vector control operations through the use of insecticide treated nets, long-lasting insecticide nets and indoor residual spraying. However, little is known about patterns of resistance to insecticides and the underlying resistance mechanisms in field populations of this vector in Senegal. Here, we assessed the susceptibility status of An. funestus populations from Gankette Balla, located in northern Senegal and investigated the potential resistance mechanisms. WHO bioassays indicated that An. funestus is resistant to lambda-cyhalothrin 0.05 % (74.64 % mortality), DDT 4 % (83.36 % mortality) and deltamethrin 0.05 % (88.53 % mortality). Suspected resistance was observed to permethrin 0.75 % (91.19 % mortality), bendiocarb 0.1 % (94.13 % mortality) and dieldrin 4 % (96.41 % mortality). However, this population is fully susceptible to malathion 5 % (100 % mortality) and fenitrothion 1 % (100 % mortality). The microarray and qRT-PCR analysis indicated that the lambda-cyhalothrin resistance in Gankette Balla is conferred by metabolic resistance mechanisms under the probable control of cytochrome P450 genes among which CYP6M7 is the most overexpressed. The absence of overexpression of the P450 gene, CYP6P9a, indicates that the resistance mechanism in Senegal is different to that observed in southern Africa. This study represents the first report of pyrethroid and DDT resistance in An. funestus from Senegal and shows that resistance to insecticides is not only confined to An. gambiae as previously thought. Therefore, urgent action should be taken to manage the resistance in this species to ensure the continued effectiveness of malaria control.

Toxicity and sublethal effects of six insecticides to last instar larvae and adults of the biocontrol agents Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and Adalia bipunctata (L.) (Coleoptera: Coccinellidae).

Science.gov (United States)

Garzón, A; Medina, P; Amor, F; Viñuela, E; Budia, F

2015-08-01

To further develop Integrated Pest Management (IPM) strategies against crop pests, it is important to evaluate the effects of insecticides on biological control agents. Therefore, we tested the toxicity and sublethal effects (fecundity and fertility) of flonicamid, flubendiamide, metaflumizone, spirotetramat, sulfoxaflor and deltamethrin on the natural enemies Chrysoperla carnea and Adalia bipunctata. The side effects of the active ingredients of the insecticides were evaluated with residual contact tests for the larvae and adults of these predators in the laboratory. Flonicamid, flubendiamide, metaflumizone and spirotetramat were innocuous to last instar larvae and adults of C. carnea and A. bipunctata. Sulfoxaflor was slightly toxic to adults of C. carnea and was highly toxic to the L4 larvae of A. bipunctata. For A. bipunctata, sulfoxaflor and deltamethrin were the most damaging compounds with a cumulative larval mortality of 100%. Deltamethrin was also the most toxic compound to larvae and adults of C. carnea. In accordance with the results obtained, the compounds flonicamid, flubendiamide, metaflumizone and spirotetramat might be incorporated into IPM programs in combination with these natural enemies for the control of particular greenhouse pests. Nevertheless, the use of sulfoxaflor and deltamethrin in IPM strategies should be taken into consideration when releasing either of these biological control agents, due to the toxic behavior observed under laboratory conditions. The need for developing sustainable approaches to combine the use of these insecticides and natural enemies within an IPM framework is discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa

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Howard Annabel FV

2010-09-01

Full Text Available Abstract Background Mosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show that entomopathogenic fungi can kill insecticide-resistant malaria vectors but this needs to be verified in the field. Methods The present study investigated whether these fungi will be effective at infecting, killing and/or modifying the behaviour of wild multi-insecticide-resistant West African mosquitoes. The entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were separately applied to white polyester window netting and used in combination with either a permethrin-treated or untreated bednet in an experimental hut trial. Untreated nets were used because we wanted to test the effect of fungus alone and in combination with an insecticide to examine any potential additive or synergistic effects. Results In total, 1125 female mosquitoes were collected during the hut trial, mainly Culex quinquefasciatus Say. Unfortunately, not enough wild Anopheles gambiae Giles were collected to allow the effect the fungi may have on this malaria vector to be analysed. None of the treatment combinations caused significantly increased mortality of Cx. quinquefasciatus when compared to the control hut. The only significant behaviour modification found was a reduction in blood feeding by Cx. quinquefasciatus, caused by the permethrin and B. bassiana treatments, although no additive effect was seen in the B. bassiana and permethrin combination treatment. Beauveria bassiana did not repel blood foraging mosquitoes either in the laboratory or field. Conclusions This is the first time that an entomopathogenic fungus has been shown to reduce blood feeding of wild mosquitoes. This behaviour modification indicates that B. bassiana could potentially be a new

Malaria prevalence, anemia and baseline intervention coverage prior to mass net distributions in Abia and Plateau States, Nigeria.

Science.gov (United States)

Noland, Gregory S; Graves, Patricia M; Sallau, Adamu; Eigege, Abel; Emukah, Emmanuel; Patterson, Amy E; Ajiji, Joseph; Okorofor, Iheanyichi; Oji, Oji Uka; Umar, Mary; Alphonsus, Kal; Damen, James; Ngondi, Jeremiah; Ozaki, Masayo; Cromwell, Elizabeth; Obiezu, Josephine; Eneiramo, Solomon; Okoro, Chinyere; McClintic-Doyle, Renn; Oresanya, Olusola; Miri, Emmanuel; Emerson, Paul M; Richards, Frank O

2014-03-26

Nigeria suffers the world's largest malaria burden, with approximately 51 million cases and 207,000 deaths annually. As part of the country's aim to reduce by 50% malaria-related morbidity and mortality by 2013, it embarked on mass distribution of free long-lasting insecticidal nets (LLINs). Prior to net distribution campaigns in Abia and Plateau States, Nigeria, a modified malaria indicator survey was conducted in September 2010 to determine baseline state-level estimates of Plasmodium prevalence, childhood anemia, indoor residual spraying (IRS) coverage and bednet ownership and utilization. Overall age-adjusted prevalence of Plasmodium infection by microscopy was similar between Abia (36.1%, 95% CI: 32.3%-40.1%; n = 2,936) and Plateau (36.6%, 95% CI: 31.3%-42.3%; n = 4,209), with prevalence highest among children 5-9 years. P. malariae accounted for 32.0% of infections in Abia, but only 1.4% of infections in Plateau. More than half of children ≤10 years were anemic, with anemia significantly higher in Abia (76.9%, 95% CI: 72.1%-81.0%) versus Plateau (57.1%, 95% CI: 50.6%-63.4%). Less than 1% of households in Abia (n = 1,305) or Plateau (n = 1,335) received IRS in the 12 months prior to survey. Household ownership of at least one bednet of any type was 10.1% (95% CI: 7.5%-13.4%) in Abia and 35.1% (95% CI: 29.2%-41.5%) in Plateau. Ownership of two or more bednets was 2.1% (95% CI: 1.2%-3.7%) in Abia and 14.5% (95% CI: 10.2%-20.3%) in Plateau. Overall reported net use the night before the survey among all individuals, children Abia and 14.7%, 19.1% and 21.0%, respectively in Plateau. Among households owning nets, 34.4% of children Abia used a net, compared to 52.6% of children and 62.7% of pregnant women in Plateau. These results reveal high Plasmodium prevalence and childhood anemia in both states, low baseline coverage of IRS and LLINs, and sub-optimal net use-especially among age groups with highest observed malaria burden.

The contribution of agricultural insecticide use to increasing insecticide resistance in African malaria vectors

OpenAIRE

Reid, Molly C.; McKenzie, F. Ellis

2016-01-01

The fight against malaria is increasingly threatened by failures in vector control due to growing insecticide resistance. This review examines the recent primary research that addresses the putative relationship between agricultural insecticide use and trends in insecticide resistance. To do so, descriptive evidence offered by the new research was categorized, and additional factors that impact the relationship between agricultural insecticide use and observed insecticide resistance in malari...

Factors affecting use of permethrin-treated bed nets during a randomized controlled trial in western Kenya

NARCIS (Netherlands)

Alaii, Jane A.; Hawley, William A.; Kolczak, Margarette S.; ter Kuile, Feiko O.; Gimnig, John E.; Vulule, John M.; Odhacha, Amos; Oloo, Aggrey J.; Nahlen, Bernard L.; Phillips-Howard, Penelope A.

2003-01-01

Adherence with permethrin-treated bed net (ITN) use and their proper deployment was directly observed in 2,178 individuals (784 households) participating in a large-scale trial of ITNs on child mortality in western Kenya. The ITNs were distributed free of charge to ensure high coverage, resulting in

The mode of action of spatial repellents and their impact on vectorial capacity of Anopheles gambiae sensu stricto.

Directory of Open Access Journals (Sweden)

Sheila B Ogoma

Full Text Available Malaria vector control relies on toxicity of insecticides used in long lasting insecticide treated nets and indoor residual spraying. This is despite evidence that sub-lethal insecticides reduce human-vector contact and malaria transmission. The impact of sub-lethal insecticides on host seeking and blood feeding of mosquitoes was measured. Taxis boxes distinguished between repellency and attraction inhibition of mosquitoes by measuring response of mosquitoes towards or away from Transfluthrin coils and humans. Protective effective distance of coils and long-term effects on blood feeding were measured in the semi-field tunnel and in a Peet Grady chamber. Laboratory reared pyrethroid susceptible Anopheles gambiae sensu stricto mosquitoes were used. In the taxis boxes, a higher proportion of mosquitoes (67%-82% were activated and flew towards the human in the presence of Transfluthrin coils. Coils did not hinder attraction of mosquitoes to the human. In the semi-field Tunnel, coils placed 0.3 m from the human reduced feeding by 86% (95% CI [0.66; 0.95] when used as a "bubble" compared to 65% (95% CI [0.51; 0.76] when used as a "point source". Mosquitoes exposed to coils inside a Peet Grady chamber were delayed from feeding normally for 12 hours but there was no effect on free flying and caged mosquitoes exposed in the semi-field tunnel. These findings indicate that airborne pyrethroids minimize human-vector contact through reduced and delayed blood feeding. This information is useful for the development of target product profiles of spatial repellent products that can be used to complement mainstream malaria vector control tools.

Resurgence of Malaria Following Discontinuation of Indoor Residual Spraying of Insecticide in an Area of Uganda With Previously High-Transmission Intensity.

Science.gov (United States)

Raouf, Saned; Mpimbaza, Arthur; Kigozi, Ruth; Sserwanga, Asadu; Rubahika, Denis; Katamba, Henry; Lindsay, Steve W; Kapella, Bryan K; Belay, Kassahun A; Kamya, Moses R; Staedke, Sarah G; Dorsey, Grant

2017-08-01

Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the primary tools for malaria prevention in Africa. It is not known whether reductions in malaria can be sustained after IRS is discontinued. Our aim in this study was to assess changes in malaria morbidity in an area of Uganda with historically high transmission where IRS was discontinued after a 4-year period followed by universal LLIN distribution. Individual-level malaria surveillance data were collected from 1 outpatient department and 1 inpatient setting in Apac District, Uganda, from July 2009 through November 2015. Rounds of IRS were delivered approximately every 6 months from February 2010 through May 2014 followed by universal LLIN distribution in June 2014. Temporal changes in the malaria test positivity rate (TPR) were estimated during and after IRS using interrupted time series analyses, controlling for age, rainfall, and autocorrelation. Data include 65 421 outpatient visits and 13 955 pediatric inpatient admissions for which a diagnostic test for malaria was performed. In outpatients aged malaria morbidity to pre-IRS levels. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com

Risk of long-lasting negative cognitive consequences after electroconvulsive therapy

DEFF Research Database (Denmark)

Svendsen, Anne Marie; Miskowiak, Kamilla; Vinberg, Maj

2013-01-01

This case study describes a patient who had a unipolar depression and experienced long-lasting cognitive problems after electroconvulsive therapy (ECT). Neuropsychological testing revealed lower scores on measures of learning, memory and sustained attention. These results stress the importance...

Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries.

Science.gov (United States)

Dengela, Dereje; Seyoum, Aklilu; Lucas, Bradford; Johns, Benjamin; George, Kristen; Belemvire, Allison; Caranci, Angela; Norris, Laura C; Fornadel, Christen M

2018-01-30

comparisons of mosquito mortality rates were then made to determine any significant differences when comparing insecticide formulation, country, year, surface type, and the source of the mosquitoes used in testing. The residual efficacy of alpha-cypermethrin ranged from 4 to 10 months (average = 6.4 months), with no reported incidents of underperformance when compared to the efficacy range provided in WHO guidelines. Deltamethrin residual efficacy results reported a range of 1 to 10 months (average = 4.9 months), with two instances of underperformance. The residual efficacy of bendiocarb ranged from 2 weeks to 7 months (average = 2.8 months) and failed to achieve proposed minimum efficacy on 14 occasions. Lastly, long-lasting pirimiphos-methyl efficacy ranged from 2 months to 9 months (average = 5.3 months), but reported 13 incidents of underperformance. Much of the data used to determine application rate and expected efficacy of insecticides approved for use in IRS programs are collected in controlled laboratory or pilot field studies. However, the generalizability of the results obtained under controlled conditions are limited and unlikely to account for variation in locally sourced housing materials, climate, and the myriad other factors that may influence the bio-efficacy of insecticides. Here, data are presented that confirm the variation in residual efficacy observed when monitoring household surfaces sprayed during PMI/USAID-supported IRS campaigns. All insecticides except alpha-cypermethrin showed evidence of failing to meet the minimum range of residual efficacy proposed in WHO criteria at least once. However, this initial effort in characterizing program-wide insecticide bio-efficacy indicates that some insecticides, such as bendiocarb and pirimiphos-methyl, may be vulnerable to variations in the local environment. Additionally, the comparative analysis performed in this study provides evidence that mosquito mortality rates differ with

The contribution of agricultural insecticide use to increasing insecticide resistance in African malaria vectors.

Science.gov (United States)

Reid, Molly C; McKenzie, F Ellis

2016-02-19

The fight against malaria is increasingly threatened by failures in vector control due to growing insecticide resistance. This review examines the recent primary research that addresses the putative relationship between agricultural insecticide use and trends in insecticide resistance. To do so, descriptive evidence offered by the new research was categorized, and additional factors that impact the relationship between agricultural insecticide use and observed insecticide resistance in malaria vectors were identified. In 23 of the 25 relevant recent publications from across Africa, higher resistance in mosquito populations was associated with agricultural insecticide use. This association appears to be affected by crop type, farm pest management strategy and urban development.

Implementing reduced-risk integrated pest management in fresh-market cabbage: improved net returns via scouting and timing of effective control.

Science.gov (United States)

Burkness, Eric C; Hutchison, W D

2008-04-01

During 1998-2001, field studies were done to assess the efficacy of an integrated pest management (IPM) program using an action threshold and "reduced-risk" insecticides. The IPM program was compared with a conventional grower-based program. Program performance was evaluated based on management of Trichoplusia ni (Hiibner), Pieris (=Artogeia) rapae (L.), and Plutella xylostella (L.), as well as the economic impact of each program on net returns. The action threshold used in the IPM program consisted of 10% plants infested with T. ni larvae, based on previous small-plot experiment station trials. In all years of the study, the IPM program resulted in significantly lower percentages of plants infested than the conventional program or untreated check. The mean reduction in insecticide applications for the IPM program compared with the conventional program was 23.5%, whereas, on average, the costs of the IPM program were 46.0% higher than the conventional program. Pest reduction in the IPM program resulted in an average of 10.5% higher marketable yields than the conventional program. Percentages of marketable heads in the IPM program ranged from 82 to 99% and from 63 to 96% in the conventional program. Mean net returns for the IPM program exceeded the conventional program by $984.20/ha. These results indicated that the IPM program reduced insecticide use overall, even though costs of the IPM program, with either spinosad or indoxacarb, were sometimes higher. Overall, net returns of the IPM program were higher due to active pest scouting, improved application timing, and increases in marketable yield. Given the potential decrease in insecticide applications and increases in net profit resulting from this IPM program, additional analyses should be conducted to quantify the economic risk, or consistency of the results, to fully evaluate the benefits of the IPM program compared with a conventional program.

Social and behavior change communication in the fight against malaria in Mozambique.

Science.gov (United States)

Arroz, Jorge Alexandre Harrison

2017-03-23

Long-lasting insecticide-treated nets and/or indoor residual spraying, associated with case management, are key interventions in the control of malaria in Africa. The objective of this study is to comment on the role of social and behavior change communication as a potential key intervention in the control of malaria in Mozambique. RESUMO As redes mosquiteiras impregnadas com insecticidade de longa duração e/ou pulverização intra-domiciliária, associada ao manejo de casos são intervenções-chave no controlo da malária em África. O objetivo deste estudo foi comentar o papel da comunicação para a mudança social e de comportamento como intervenção potencialmente chave no controlo da malária em Moçambique.

A short history of insecticides

Directory of Open Access Journals (Sweden)

Oberemok Volodymyr Volodymyrovych

2015-07-01

Full Text Available This review contains a brief history of the use of insecticides. The peculiarities, main advantages, and disadvantages of some modern insecticides are described. The names of the discoverers of some of the most popular insecticide preparations on the world market, are listed. The tendencies to find new insecticides to control the quantity of phytophagous insects are discussed. Special attention is paid to the perspective of creating preparations based on nucleic acids, in particular DNA insecticides. The use of insect-specific, short single-stranded DNA fragments as DNA insecticides, is paving the way in the field of “intellectual” insecticides that “think” before they act. It is worth noting, though, that in the near future, the quantity of produced insecticides will increase due to the challenges associated with food production for a rapidly growing population. It is concluded, that an agreeable interaction of scientists and manufacturers of insecticides should lead to the selection of the most optimal solutions for insect pest control, which would be safe, affordable, and effective at the same time.

Insecticide toxicity to Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) females and effect on descendant generation.

Science.gov (United States)

Vianna, Ulysses R; Pratissoli, Dirceu; Zanuncio, José C; Lima, Eraldo R; Brunner, Jay; Pereira, Fabrício F; Serrão, José E

2009-02-01

The effect of nine insecticides used in tomato production was evaluated on adults of two Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) populations from Rive and Afonso Cláudio, Espírito Santo State, Brazil. The experiment was developed in an acclimatized chamber at 25 +/- 1 degrees C, 70 +/- 10% relative humidity and 14 h photophase. Eggs of Anagasta kuehniella (Lepidoptera: Pyralidae), previously immersed in insecticides solutions were offered to females of both T. pretiosum populations. Bacillus thuringiensis, lufenuron and triflumuron had lowest negative effects on parasitism and viability of individuals of these populations; however, abamectin and pyrethroids (betacyflurin 50 and 125 g/l and esfenvalerate) insecticides reduced parasitism rates. T. pretiosum emerged from A. kuehniella eggs treated with esfenvalerate but were not able to parasitize non treated eggs of this host. B. thuringiensis, lufenuron and triflumuron may be used in integrated pest management programs to control tomato pests, because they have moderated negative effect on parasitoid wasps.

Efficacy of insecticide residues on adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) mortality and injury in apple and peach orchards.

Science.gov (United States)

Leskey, Tracy C; Short, Brent D; Lee, Doo-Hyung

2014-07-01

The primary threat from Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) originates from populations continuously dispersing from and among wild and cultivated hosts, so many individuals may not be directly sprayed with insecticides. Limited information exists regarding field-based residual activity of insecticides for management of H. halys in tree fruit. Thus, we conducted field-based bioassays in apple and peach orchards to evaluate residual activity of insecticides commonly applied against H. halys. Adults used in these trials were collected from wild and cultivated hosts less than one week prior to testing to more accurately reflect the susceptibility of wild H. halys populations in the field throughout the season. Significantly higher mortality rates of Halyomorpha halys were observed early in the growing season, when overwintered adults were prevalent, compared with populations present later in the growing season that included new generation adults. Significantly higher mortality was recorded for adults exposed to fresh insecticide applications compared with three- and seven-day old residues. Typically, the addition of an adjuvant did not enhance efficacy or residual activity of insecticides. Significantly fewer injury sites were recorded on apples treated with dinotefuran and fenpropathrin compared with the untreated apples for all residue ages. Overwintered Halyomorpha halys populations are easier to kill with insecticide applications than the first and second generation which are present in the field during the mid- to late-season. Residual activity of nearly all insecticides decreased significantly three days after application and adjuvants generally did not increase residual activity. These factors should be considered in developing season-long programs for management of this invasive species in tree fruit. © 2013 Society of Chemical Industry.

Properties of 13HMF steel welded joints after long-lasting service

International Nuclear Information System (INIS)

Zeman, M.

2002-01-01

Results are presented of research conducted on the 13HMF steel in the as-received condition after long-lasting service over 100000 hours. Simulation tests have been performed by means of modern research methods. The influence of thermal cycles on the microstructure (continuous cooling TTT diagrams), plastic properties (notch toughness and hardness) of simulated heat affected zones and reheat cracking resistance has been evaluated by using the thermal and strain cycle simulator. Susceptibility to thermal fatigue has been determined, the creep strength estimated and welding heat input was given, as well as the post weld heat treatment conditions of the 13HMF steel after service. properties of the welded joints made of 13HMF steel after long-lasting service are given. (author)

Efficacy of insecticides through contact and oral uptake towards four Agriotes wireworm species under controlled conditions

NARCIS (Netherlands)

Rozen, van K.; Huiting, H.F.; Wilhelm, R.; Heger, M.; Ester, A.

2013-01-01

Wireworms of Agriotes lineatus, A. obscurus, A. sputator and A. sordidus were exposed to insecticide treated soil using two different control methods. One method consisted of a spray application of insecticides at doses of 50, 100, 200, and 300 g a.i. per ha. The other method consisted of a bait

Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

Science.gov (United States)

Griffin, T W; Zapata, S D

2016-08-01

The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the

Activity of the Antioxidant Defense System in a Typical Bioinsecticide-and Synthetic Insecticide-treated Cowpea Storage Beetle F. (Coleoptera: Chrysomelidae

Directory of Open Access Journals (Sweden)

Ayodele O. Kolawole

2014-01-01

Full Text Available The non-enzymatic and enzymatic antioxidant defense systems play a major role in detoxification of pro-oxidant endobiotics and xenobiotics. The possible involvement of beetle non-enzymatic [α-tocopherol, glutathione (GSH, and ascorbic acid] and enzymatic [catalase (CAT, superoxide dismutase (SOD, peroxidase (POX, and polyphenol oxidase (PPO] antioxidant defense system on the insecticidal activity of synthetic insecticides (cypermethrin, 2,2-dicholorovinyl dimethyl phosphate, and λ-cyhalothrin and ethanolic plant extracts of Tithonia diversifolia, Cyperus rotundus, Hyptis suaveolens leaves , and Jatropha Curcas seeds was investigated. 2,2-Dicholorovinyl dimethyl phosphate (DDVP; 200 ppm, LC 50 = 13.24 ppm and T. diversifolia (20,000 ppm resulted in 100% beetle mortality at 96-hour post-treatment. The post-treatments significantly increased the beetle α-tocopherol and GSH contents. Activities of CAT, SOD, POX, and PPO were modulated by the synthetic insecticides and bioinsecticides to diminish the adverse effect of the chemical stresses. Quantitative and qualitative allelochemical compositions of bioinsecticides and chemical structure of synthetic insecticides possibly account and for modulation of their respective enzyme activities. Altogether, oxidative stress was enormous enough to cause maladaptation in insects. This study established that oxidative imbalance created could be the molecular basis of the efficacy of both insecticides and bio-insecticides. Two, there was development of functional but inadequate antioxidant defense mechanism in the beetle.

Investigation and control of a Plasmodium falciparum malaria outbreak in Shan Special Region II of Myanmar along the China-Myanmar Border from June to December 2014.

Science.gov (United States)

Liu, Hui; Xu, Jian-Wei; Yang, Heng-Lin; Li, Mei; Sun, Cheng-De; Yin, Yi-Jie; Zheng, Zhi-Liang; Zhang, Guang-Yun; Yu, Ai-Shui; Yang, Yong-Hui; Li, Chun-Hui; Ai, Shui

2016-04-25

From 2007 to 2013, intensive control measures reduced malaria burden by 90 % along the China-Myanmar border. However, despite these measures a P. falciparum malaria outbreak was reported in the Shan Special Region II of Myanmar in June of 2014. Epidemiological, parasitological and entomological investigations were performed. Dihydroartemisinin piperaquine (DAPQ) was immediately administered to treat parasite positive individuals. Long lasting insecticidal nets (LLIN), indoor residual spraying (IRS) with insecticides and behavior change communication (BCC) were also provided for outbreak control. An embedded efficacy study was conducted evaluating DP. Molecular genotyping via polymerase chain reaction (PCR) was performed on the Kelch gene on chromosome 13. All infections were identified as Plasmodium falciparum by RDT and microscopy. Two fatalities resulted from the outbreak. The attack rate was 72.8 % (67/92) and the incidence density rate was 14.2 per 100 person-weeks. The positive rate of rapid diagnostic test (RDT) was 72.2 % (65/90) and microscopically-determine parasite rate 42.2 % (38/90). Adjusted odds ratio (OR) of multivariate logistic regression analysis for aged Myanmar border, especially among special populations, needs further collaboration between China, Myanmar and international societies.

Knowledge and practice of the use of insecticide Treated Nets ...

African Journals Online (AJOL)

The level of awareness and utilization were low among mothers of children less than 5 years of age. Social mobilization and advocacy strategy in conjunction with existing social marketing would achieve considerable results as regards increasing awareness and utilization levels among mothers. NQJHM Vol. 14 (2) 2004: ...

Awareness, accessibility and use of insecticide treated nets: a cross ...

African Journals Online (AJOL)

Methodology: A cross-sectional study of 400 women attending ANC in Nnamdi Azikiwe University Teaching Hospital (NAUTH) Nnewi was done. Data was collected using pre-tested semi-structured interviewer administered questionnaires and analyzed using Epi-info version 3.5.1 software. Tests of statistical significance ...

Utilisation of insecticide treated nets among pregnant women in Gulu

African Journals Online (AJOL)

EB

Results: 35% of pregnant women (95% CI 31% - 38%) had utilised ITNs. Factors that promoted ... 0.050) and being single/widow/divorced (AOR 0.22, p-value 0.000). Conclusion: .... being engaged in business (OR = 1.56, 95% CI 1.08. - 2.26 ...

[Malaria: knowledge, behaviour and practices among a rural population of Gossas, Senegal].

Science.gov (United States)

Ndour, C T; Ba, O; Manga, N M; Fortes, M L; Nyamwasa, D; Sow, P S

2006-10-01

Malaria remains a major public health problem in Sub-Saharian Africa, in terms of morbidity and mortality rate. To assess the knowledge and behaviour of population regarding the transmission, the treatment and the prevention of malaria, we conducted a cluster sample household survey in Gossas, a rural District in Senegal, from May 2nd to May 6th 2005. A questionnaire that focused on socioeconomic conditions, beliefs, knowledge about and behavior toward antimalarial medication and the prevention means used was given to 480 household owners. Overall, 107 pregnant women and 1,201 children aged less than 5 years old lived within these household. More than a half of the household owners (51%) were illiterate and 25.2% ignored how malaria is transmitted. Fever was the most common symptom suggesting malaria (61%). In 46.1% of febrile cases, people did not seek for treatment from a physician. Home treatment of febrile episodes was based on paracetamol or aspirin (84%), chloroquine (13%) and cotrimoxazole (2.9%). Overall, the proportion of insecticide treated nets users were 22.7%. This percentage was 14.9% and 11.4% for pregnant women and children younger than 5 years old, respectively. People having radio sets, regular access to television, and people aware of the transmission route of malaria were more likely to use bed nets. In most cases, organic material burning was used as repellent against mosquitoes. The low prevalence of bed net use was most often explained by participants' limited accessibility to and by the high cost of insecticide-treated nets. Knowledge about malaria prevention and treatment is low in the rural district of Gossas. The rate of insecticide-treated-bed nets use in vulnerable people is very low, far from the Abuja meeting objective. A sensibilization program and a social marketing plan for insecticide-treated-bed nets could improve this situation.

miR-191 and miR-135 are required for long-lasting spine remodelling associated with synaptic long-term depression

Science.gov (United States)

Hu, Zhonghua; Yu, Danni; Gu, Qin-Hua; Yang, Yanqin; Tu, Kang; Zhu, Jun; Li, Zheng

2014-02-01

Activity-dependent modification of dendritic spines, subcellular compartments accommodating postsynaptic specializations in the brain, is an important cellular mechanism for brain development, cognition and synaptic pathology of brain disorders. NMDA receptor-dependent long-term depression (NMDAR-LTD), a prototypic form of synaptic plasticity, is accompanied by prolonged remodelling of spines. The mechanisms underlying long-lasting spine remodelling in NMDAR-LTD, however, are largely unclear. Here we show that LTD induction causes global changes in miRNA transcriptomes affecting many cellular activities. Specifically, we show that expression changes of miR-191 and miR-135 are required for maintenance but not induction of spine restructuring. Moreover, we find that actin depolymerization and AMPA receptor exocytosis are regulated for extended periods of time by miRNAs to support long-lasting spine plasticity. These findings reveal a miRNA-mediated mechanism and a role for AMPA receptor exocytosis in long-lasting spine plasticity, and identify a number of candidate miRNAs involved in LTD.

Can topical insect repellents reduce malaria? A cluster-randomised controlled trial of the insect repellent N,N-diethyl-m-toluamide (DEET in Lao PDR.

Directory of Open Access Journals (Sweden)

Vanessa Chen-Hussey

Full Text Available BACKGROUND: Mosquito vectors of malaria in Southeast Asia readily feed outdoors making malaria control through indoor insecticides such as long-lasting insecticidal nets (LLINs and indoor residual spraying more difficult. Topical insect repellents may be able to protect users from outdoor biting, thereby providing additional protection above the current best practice of LLINs. METHODS AND FINDINGS: A double blind, household randomised, placebo-controlled trial of insect repellent to reduce malaria was carried out in southern Lao PDR to determine whether the use of repellent and long-lasting insecticidal nets (LLINs could reduce malaria more than LLINs alone. A total of 1,597 households, including 7,979 participants, were recruited in June 2009 and April 2010. Equal group allocation, stratified by village, was used to randomise 795 households to a 15% DEET lotion and the remainder were given a placebo lotion. Participants, field staff and data analysts were blinded to the group assignment until data analysis had been completed. All households received new LLINs. Participants were asked to apply their lotion to exposed skin every evening and sleep under the LLINs each night. Plasmodium falciparum and P. vivax cases were actively identified by monthly rapid diagnostic tests. Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI: 0.99-1.01, p = 0.868. A higher socio-economic score was found to significantly decrease malaria risk (hazard ratio: 0.72, 95% CI: 0.58-0.90, p = 0.004. Women were also found to have a reduced risk of infection (hazard ratio: 0.59, 95% CI: 0.37-0.92, p = 0.020. According to protocol analysis which excluded participants using the lotions less than 90% of the time found similar results with no effect from the use of repellent. CONCLUSIONS: This randomised controlled trial suggests that topical repellents are not a suitable intervention in addition to

Genome-wide identification of long non-coding RNA genes and their association with insecticide resistance and metamorphosis in diamondback moth, Plutella xylostella.

Science.gov (United States)

Liu, Feiling; Guo, Dianhao; Yuan, Zhuting; Chen, Chen; Xiao, Huamei

2017-11-20

Long non-coding RNA (lncRNA) is a class of noncoding RNA >200 bp in length that has essential roles in regulating a variety of biological processes. Here, we constructed a computational pipeline to identify lncRNA genes in the diamondback moth (Plutella xylostella), a major insect pest of cruciferous vegetables. In total, 3,324 lncRNAs corresponding to 2,475 loci were identified from 13 RNA-Seq datasets, including samples from parasitized, insecticide-resistant strains and different developmental stages. The identified P. xylostella lncRNAs had shorter transcripts and fewer exons than protein-coding genes. Seven out of nine randomly selected lncRNAs were validated by strand-specific RT-PCR. In total, 54-172 lncRNAs were specifically expressed in the insecticide resistant strains, among which one lncRNA was located adjacent to the sodium channel gene. In addition, 63-135 lncRNAs were specifically expressed in different developmental stages, among which three lncRNAs overlapped or were located adjacent to the metamorphosis-associated genes. These lncRNAs were either strongly or weakly co-expressed with their overlapping or neighboring mRNA genes. In summary, we identified thousands of lncRNAs and presented evidence that lncRNAs might have key roles in conferring insecticide resistance and regulating the metamorphosis development in P. xylostella.

A potential target for organophosphate insecticides leading to spermatotoxicity.

Science.gov (United States)

Suzuki, Himiko; Tomizawa, Motohiro; Ito, Yuki; Abe, Keisuke; Noro, Yuki; Kamijima, Michihiro

2013-10-16

Organophosphate (OP) insecticides as an anticholinesterase also act on the diverse serine hydrolase targets, thereby revealing secondary or unexpected toxic effects including male reproductive toxicity. The present investigation detects a possible target molecule(s) for OP-induced spermatotoxicity (sperm deformity, underdevelopment, and reduced motility) from a chemical standpoint. The activity-based protein profiling (ABPP) approach with a phosphonofluoridate fluorescent probe pinpointed the molecular target for fenitrothion (FNT, a major OP insecticide) oxon (bioactive metabolite of FNT) in the mouse testicular membrane proteome, i.e., FNT oxon phosphorylates the fatty acid amide hydrolase (FAAH), which plays pivotal roles in spermatogenesis and sperm motility acquirement. Subsequently, mice were treated orally with vehicle or FNT for 10 days, and FAAH activity in testis or epididymis cauda was markedly reduced by the subacute exposure. ABPP analysis revealed that FAAH was selectively inhibited among the FNT-treated testicular membrane proteome. Accordingly, FAAH is a potential target for OP-elicited spermatotoxicity.

Net sulfur mineralization potential in Swedish arable soils in relation to long-term treatment history and soil properties

DEFF Research Database (Denmark)

Boye, Kristin; Nilsson, S Ingvar; Eriksen, Jørgen

2009-01-01

accumulated net S mineralization (SAccMin) and a number of soil physical and chemical properties were determined. Treatments and soil differences in SAccMin, as well as correlations with soil variables, were tested with single and multivariate analyses. Long-term FYM application resulted in a significantly (p......The long-term treatment effect (since 1957-1966) of farmyard manure (FYM) application compared with crop residue incorporation was investigated in five soils (sandy loam to silty clay) with regards to the net sulfur (S) mineralization potential. An open incubation technique was used to determine...... = 0.012) higher net S mineralization potential, although total amounts of C, N, and S were not significantly (p soils within this treatment. The measured soil variables were not significantly correlated...

Middle and long-term follow-up of intracranial aneurysms treated with Matrix detachable coils

International Nuclear Information System (INIS)

Wu Xi; Liu Jianmin; Huang Qinghai; Xu Yi

2008-01-01

Objective: This study was undertaken to evaluate the safety of the polyglycolic/polylactic acid (PGLA)-coated Matrix detachable coils (Matrix) and analyze factors which may relate to the recanalization rate of the Matrix coils in the treatment of intracranial aneurysms. Methods: 75 patients underwent 79 aneurysm treatments with Matrix coils from May 2003 to July 2005 were retrospectively investigated. Morphological changes were compared postoperatively with last-follow-up digital subtraction angiography (DSA) by using the Raymond scale. We defined incomplete recanalization or stable aneurysms as uncured, while those of progressive occlusion or complete occlusion aneurysms demonstrated on the last-follow-up imagings as cured. We also utilized Cox model for analyzing the relationships between factors including age, gender, degree of aneurysmal occlusion, stenting, aneurysm neck size, aneurysm maximum size and Matrix coils length (%) and the long-term angiographic follow-up results. Results: The correlative surgical complications rate with Matrix coils was 13.3%. The total rate of recanalization was 11.4%. Large aneurysms treated with combined stenting got 40% recanalization. No statistic relationships were shown between the factors forementioned and the recanalization rate, but progressive occlusion was observed in 11 (61%)incompletely treated aneurysms. Conclusions: Matrix detachable coil technique is safe for intracranial aneurysm and would further decrease the recurrence of large aneurysm with combination of stenting but long term efficacy needs further follow-up and large scale randomized control study. (authors)

Bed net ownership, use and perceptions among women seeking antenatal care in Kinshasa, Democratic Republic of the Congo (DRC: Opportunities for improved maternal and child health

Directory of Open Access Journals (Sweden)

Tabala Martine

2008-09-01

Full Text Available Abstract Background To describe malaria knowledge, attitudes toward malaria and bed net use, levels of ownership and use of bed nets, and factors associated with ownership and use among pregnant women attending their first antenatal care (ANC visit in Kinshasa, DRC. Methods Women attending their first ANC visit at one maternity in Kinshasa were recruited to take part in a study where they were given free insecticide treated bed nets (ITNs and then followed up at delivery and 6 months post delivery to assess ITN use. This study describes the baseline levels of bed net ownership and use, attitudes towards net use and factors associated with net use Results Among 351 women interviewed at baseline, 115 (33% already owned a bed net and 86 (25% reported to have slept under the net the previous night. Cost was reported as the reason for not owning a net by 48% of the 236 women who did not own one. In multivariable analyses, women who had secondary school or higher education were 3.4 times more likely to own a net (95% CI 1.6–7.3 and 2.8 times more likely to have used a net (95% CI 1.3–6.0 compared to women with less education Conclusion Distribution of ITNs in antenatal clinics in this setting is needed and feasible. The potential for ITN use by this target population is high.

A cluster randomized controlled cross-over bed net acceptability and preference trial in Solomon Islands: community participation in shaping policy for malaria elimination

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Appleyard Bridget

2009-12-01

Full Text Available Abstract Background A key component of the malaria elimination strategy in Solomon Islands (SI is widespread coverage of long-lasting insecticidal nets (LLINs. The success of this strategy is dependent on LLIN acceptability and compliance. There has been unresolved debate among policy makers and donors as to which type of LLIN would be most appropriate for large-scale distribution in SI, and anecdotal reports of a lack of acceptability of certain brands of LLINs. A cluster randomized controlled crossover bed net acceptability and preference trial was therefore carried out from July to September, 2008 to inform policy and to facilitate community engagement and participation in the selection of the most appropriate LLIN for use in SI. Method A three-stage sampling method was used to randomly select the study population from Malaita Province, SI. Three brands of LLINs were assessed in this study: Olyset®, PermaNet® and DuraNet®. Bed net acceptability and preference were evaluated through surveys at three defined time points after short and longer-term trial of each LLIN. Results The acceptability of PermaNet® after short-term use (96.5% was significantly greater than Olyset® (67.3%, p and DuraNet® (69.8%, p . The acceptability of DuraNet® and Olyset® after short-term use was not significantly different at the 5% level. LLINs that were perceived not to prevent mosquito bites were significantly less acceptable than LLINs that were perceived to prevent mosquito bites (OR 0.15; 95%CI 0.03 to 0.6. LLINs that allow a pleasant night's sleep (OR 6.3; 95%CI:3.3-12.3 and have a soft texture (OR 5.7; 95%CI:1.9-20.5 were considered more acceptable than those that did not. Olyset®'s acceptability decreased over time and this was due to net wrinkling/shrinkage after washing resulting in reduced efficiency in preventing mosquito bites. The increase in DuraNet® acceptability was a result of a reduction in minor adverse events following longer-term use

Malaria control. generating evidence from local to global level

OpenAIRE

Plüss, Bianca

2009-01-01

In addition of the provision of effective treatment to each case, malaria control is heavily relying on vector control with either insecticide treated mosquito nets (ITNs) or indoor residual spraying (IRS). The effectiveness of ITNs in controlling malaria in many different settings has already been comprehensively documented. On the other hand, while IRS has a long and distinguished history in malaria control, its health effects have never been properly quantified. The present thesis aimed...

The additional benefit of residual spraying and insecticide-treated curtains for dengue control over current best practice in Cuba: Evaluation of disease incidence in a cluster randomized trial in a low burden setting with intensive routine control.

Science.gov (United States)

Toledo, Maria Eugenia; Vanlerberghe, Veerle; Rosales, Julio Popa; Mirabal, Mayelin; Cabrera, Pedro; Fonseca, Viviana; Gómez Padrón, Tania; Pérez Menzies, Mirtha; Montada, Domingo; Van der Stuyft, Patrick

2017-11-01

Aedes control interventions are considered the cornerstone of dengue control programmes, but there is scarce evidence on their effect on disease. We set-up a cluster randomized controlled trial in Santiago de Cuba to evaluate the entomological and epidemiological effectiveness of periodical intra- and peri-domiciliary residual insecticide (deltamethrin) treatment (RIT) and long lasting insecticide treated curtains (ITC). Sixty three clusters (around 250 households each) were randomly allocated to two intervention (RIT and ITC) and one control arm. Routine Aedes control activities (entomological surveillance, source reduction, selective adulticiding, health education) were applied in the whole study area. The outcome measures were clinical dengue case incidence and immature Aedes infestation. Effectiveness of tools was evaluated using a generalized linear regression model with a negative binomial link function. Despite significant reduction in Aedes indices (Rate Ratio (RR) 0.54 (95%CI 0.32-0.89) in the first month after RIT, the effect faded out over time and dengue incidence was not reduced. Overall, in this setting there was no protective effect of RIT or ITC over routine in the 17months intervention period, with for house index RR of 1.16 (95%CI 0.96-1.40) and 1.25 (95%CI 1.03-1.50) and for dengue incidence RR of 1.43 (95%CI 1.08-1.90) and 0.96 (95%CI 0.72-1.28) respectively. The monthly dengue incidence rate (IR) at cluster level was best explained by epidemic periods (Incidence Rate Ratio (IRR) 5.50 (95%CI 4.14-7.31)), the IR in bordering houseblocks (IRR 1.03 (95%CI 1.02-1.04)) and the IR pre-intervention (IRR 1.02 (95%CI 1.00-1.04)). Adding RIT to an intensive routine Aedes control programme has a transient effect on the already moderate low entomological infestation levels, while ITC did not have any effect. For both interventions, we didn't evidence impact on disease incidence. Further studies are needed to evaluate impact in settings with high Aedes

Insecticide-mediated apparent displacement between two invasive species of leafminer fly.

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Yulin Gao

Full Text Available BACKGROUND: Closely related invasive species may often displace one another, but it is often difficult to determine mechanisms because of the historical nature of these events. The leafmining flies Liriomyza sativae and Liriomyza trifolii have become serious invasive agricultural pests throughout the world. Where both species have invaded the same region, one predominates over the other. Although L. sativae invaded Hainan Island of China first, it recently has been displaced by the newly invasive L. trifolii. We hypothesized that differential susceptibilities to insecticides could be causing this demographic shift. METHODOLOGY/PRINCIPAL FINDINGS: Avermectin and cyromazine are the most commonly used insecticides to manage leafminers, with laboratory bioassays demonstrating that L. trifolii is significantly less susceptible to these key insecticides than is L. sativae. In trials where similar numbers of larvae of both species infested plants, which subsequently were treated with the insecticides, the eclosing adults were predominately L. trifolii, yet similar numbers of adults of both species eclosed from control plants. The species composition was then surveyed in two regions where L. trifolii has just begun to invade and both species are still common. In field trials, both species occurred in similar proportions before insecticide treatments began. Following applications of avermectin and cyromazine, almost all eclosing adults were L. trifolii in those treatment plots. In control plots, similar numbers of adults of the two species eclosed, lending further credence to the hypothesis that differential insecticide susceptibilities could be driving the ongoing displacement of L. sativae by L. trifolii. CONCLUSIONS/SIGNIFICANCE: Our results show that differential insecticide susceptibility can lead to rapid shifts in the demographics of pest complexes. Thus, successful pest management requires the identification of pest species to understand the

Effect of intermittent glutamine supplementation on skeletal muscle is not long-lasting in very old rats.

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Meynial-Denis, D; Beaufrère, A-M; Mignon, M; Patureau Mirand, P

2013-01-01

Muscle is the major site for glutamine synthesis via glutamine synthetase (GS). This enzyme is increased 1.5-2 fold in 25-27-mo rats and may be a consequence of aging-induced stress. This stimulation is similar to the induction observed following a catabolic state such as glucocorticoid treatment (6 to 24 months). Although oral glutamine supply regulates the plasma glutamine level, nothing is known if this supplementation is interrupted before the experiment. Adult (8-mo) and very old (27-mo) female rats were exposed to intermittent glutamine supplementation for 50 % of their age lifetime. Treated rats received glutamine added to their drinking water and control rats water alone but the effect of glutamine supplementation was only studied 15 days after the last supplementation. Glutamine pretreatment discontinued 15 days before the experiment increased plasma glutamine to ~ 0.6 mM, a normal value in very old rats. However, it failed to decrease the up-regulated GS activity in skeletal muscle from very old rats. Our results suggest that long-term treatment with glutamine started before advanced age but discontinued 15 days before rat sacrifice is effective in increasing plasma glutamine to recover basal adult value and in maintaining plasma glutamine in very old rats, but has no long-lasting effect on the GS activity of skeletal muscle with advanced age.

Utilization Of Malaria Prophylaxes Amongst Nigerian Urban ...

African Journals Online (AJOL)

TNHJOURNALPH

utilization of a combination of interventions such as sleeping under insecticide treated nets (ITNs),. Intermittent Preventive Treatment in pregnancy (IPTp), insecticide room spraying (IRS) and effective case management and treatment. All these strategies have been adopted in Nigeria through a national policy on malaria.

Marmosets treated with oxytocin are more socially attractive to their long-term mate

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Jon eCavanaugh

2015-10-01

their long-term mate, as well as increase female interest in initiating and maintaining proximity with their long-term mate. Furthermore, these results support the notion that central OXT activity plays an important neuromodulatory role in the maintenance of long-lasting male-female relationships.

Insecticide resistance in vector Chagas disease: evolution, mechanisms and management.

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Mougabure-Cueto, Gastón; Picollo, María Inés

2015-09-01

Chagas disease is a chronic parasitic infection restricted to America. The disease is caused by the protozoa Trypanosoma cruzi, which is transmitted to human through the feces of infected triatomine insects. Because no treatment is available for the chronic forms of the disease, vector chemical control represents the best way to reduce the incidence of the disease. Chemical control has been based principally on spraying dwellings with insecticide formulations and led to the reduction of triatomine distribution and consequent interruption of disease transmission in several areas from endemic region. However, in the last decade it has been repeatedly reported the presence triatomnes, mainly Triatoma infestans, after spraying with pyrethroid insecticides, which was associated to evolution to insecticide resistance. In this paper the evolution of insecticide resistance in triatomines is reviewed. The insecticide resistance was detected in 1970s in Rhodnius prolixus and 1990s in R. prolixus and T. infestans, but not until the 2000s resistance to pyrthroids in T. infestans associated to control failures was described in Argentina and Bolivia. The main resistance mechanisms (i.e. enhanced metabolism, altered site of action and reduced penetration) were described in the T. infestans resistant to pyrethrods. Different resistant profiles were demonstrated suggesting independent origin of the different resistant foci of Argentina and Bolivia. The deltamethrin resistance in T. infestans was showed to be controlled by semi-dominant, autosomally inherited factors. Reproductive and developmental costs were also demonstrated for the resistant T. infestans. A discussion about resistance and tolerance concepts and the persistence of T. infestans in Gran Chaco region are presented. In addition, theoretical concepts related to toxicological, evolutionary and ecological aspects of insecticide resistance are discussed in order to understand the particular scenario of pyrethroid

Ecohealth Interventions Limit Triatomine Reinfestation following Insecticide Spraying in La Brea, Guatemala

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Lucero, David E.; Morrissey, Leslie A.; Rizzo, Donna M.; Rodas, Antonieta; Garnica, Roberto; Stevens, Lori; Bustamante, Dulce M.; Monroy, Maria Carlota

2013-01-01

In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory interventions focused on community awareness and low-cost home improvements using local materials to limit areas of refuge and alternative blood meals for the vector within the home, and potential shelter for the vector outside the home. As a result, domestic infestation was maintained at ≤ 3% and peridomestic infestation at ≤ 2% for 5 years beyond the last insecticide spraying, in sharp contrast to the rapid reinfestation experienced in earlier insecticide only interventions. PMID:23382173

Environmental risk assessment of registered insecticides in Iran using Environmental Impact Quotient (EIQ index

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S. Moinoddini

2016-05-01

Full Text Available In the last decades, pesticides have been used extensively, in order to control pests and plant diseases, but negative impacts of pesticides caused several environmental problems and put human health in danger. In order to decrease environmental hazards of pesticide, risk of pesticide application should be measured briefly and precisely. In this study environmental impacts of registered insecticides in Iran which applied in 2001-2002, 2003-2004, 2004-2005, are considered using environmental impact quotient (EIQ index. Results showed that among considered insecticides, Imidacloprid, Fipronil and Tiodicarb, potentially (EIQ were the most hazardous insecticides, respectively. Taking rate of application and active ingredient of insecticide in to account, environmental impact (practical toxicity per cultivated hectare (EIQ Field of each provinces were investigated. In this regard, among different province of Iran, Kerman, Mazandaran and Golestan were in danger more than the others, respectively. Besides, considering the amount of agricultural production in provinces, environmental impact per ton of production were calculated for each provinces which three northern provinces of Mazandaran, Golestan and Guilan, respectively endure the most environmental impact per ton of production. Eventually based on environmental impact quotient, results demonstrated that majority of environmental impacts of insecticide in Iran were due to inadequate knowledge and also overuse of a few number of insecticides. Therefore, by improving knowledge about environmental impact of pesticides and also developing environmental friendly and ecological based methods, negative environmental impacts of insecticides will be reduced significantly.

Efficacy of eco-smart insecticides against certain biological stages of jasmine moth, Palpita unionalis Hb.(Lepidoptera: Pyralidae

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Mahmoud Farag Mahmoud

2014-03-01

Full Text Available The efficacy of six eco-smart insecticides, Dipel 2x 6.4% WP (Bacillus thuringensis AI, Biofly 100% WP (Beauvaria bessiana AI, Radiant 12% SC (Saccharopolyspora spinosa AI, Mectin 1.8% EC (Streptomyces avermitilis AI, Nimbecidine 0.03% EC (Azadirachtin AI and Bio-Power 50% EC (Beauvaria bessiana AI, were tested against eggs, larvae and pupae of the jasmine moth, Palpita unionalis Hb. and its parasitoid Apanteles syleptae under laboratory conditions. Data indicated that all tested insecticides had ovicidal activity against P. unionalis. Mectin was the most toxic among the tested insecticides against the egg stage, followed by Radiant or Dipel 2x, and their respective values of LC50 were 0.005 cm/l, 0.006 cm/l and 0.055 g/l. Dipel 2x was the most toxic insecticide to the 1st instar larvae of P. unionalis, whereas Mectin was the most toxic to both the 3rd and 5th instar larvae. Also, the results revealed that Mectin was the most effective against the pupal stage, followed descendingly by Radiant and Dipel 2x. The toxicity index values showed a superior efficiency of Mectin at LC50 (100% against eggs, 3rd and 5th instar larvae, and pupal stage, whereas Dipel 2x showed such superior efficiency at LC50 (100% only against 1st instar larvae. The results showed that the percents of pupation and emergence of moths were significantly different in all treatments compared to control, while deformed pupae and malformed adults were insignificantly different when fifth instar larvae were treated with the tested insecticides. Moreover, the rate of P. unionalis adult emergence from treated pupae was concentration-dependent and significant differences were found between insecticide treatments and control. Generally, Mectin, Radiant and Dipel 2x caused the highest impacts on adult emergence and malformed adults percentages. Regarding the toxicity of insecticides to the endoparasitoid A. syleptae, the treated cocoons developed to adult stages with no significant

Botanical Insecticides in Plant Protection

OpenAIRE

Grdiša, Martina; Gršić, Kristina

2013-01-01

Botanical insecticides are natural compounds with insecticidal properties and their use in crop protection is as old as agricultural practice. Although they have been in use for over one hundred years, the advent of synthetic insecticides has unfortunately displaced their use today. Due to fast action, low cost, easy application and efficiency against a wide range of harmful species, synthetic insecticides have become an important part of pest management in modern agricultural systems....

Genome wide discovery of long intergenic non-coding RNAs in Diamondback moth (Plutella xylostella) and their expression in insecticide resistant strains

Science.gov (United States)

Etebari, Kayvan; Furlong, Michael J.; Asgari, Sassan

2015-01-01

Long non-coding RNAs (lncRNAs) play important roles in genomic imprinting, cancer, differentiation and regulation of gene expression. Here, we identified 3844 long intergenic ncRNAs (lincRNA) in Plutella xylostella, which is a notorious pest of cruciferous plants that has developed field resistance to all classes of insecticides, including Bacillus thuringiensis (Bt) endotoxins. Further, we found that some of those lincRNAs may potentially serve as precursors for the production of small ncRNAs. We found 280 and 350 lincRNAs that are differentially expressed in Chlorpyrifos and Fipronil resistant larvae. A survey on P. xylostella midgut transcriptome data from Bt-resistant populations revealed 59 altered lincRNA in two resistant strains compared with the susceptible population. We validated the transcript levels of a number of putative lincRNAs in deltamethrin-resistant larvae that were exposed to deltamethrin, which indicated that this group of lincRNAs might be involved in the response to xenobiotics in this insect. To functionally characterize DBM lincRNAs, gene ontology (GO) enrichment of their associated protein-coding genes was extracted and showed over representation of protein, DNA and RNA binding GO terms. The data presented here will facilitate future studies to unravel the function of lincRNAs in insecticide resistance or the response to xenobiotics of eukaryotic cells. PMID:26411386

Use of insecticide-impregnated mosquito nets and other impregnated materials for malaria control in the Americas Uso de mosquiteros y otros materiales impregnados para el control de la malaria en las Américas

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R. H. Zimmerman

1997-07-01

Full Text Available This article reviews the current status of the use of insecticide-impregnated mosquito nets and other impregnated materials in the Americas. Studies from Brazil, Colombia, Ecuador, Guatemala, Peru, Suriname, and Venezuela are examined. It is concluded that most studies have suffered from experimental design errors, short duration problems, and/or inadequate measurement of health indicators. The review brings out the great difficulty of conducting scientific studies that attempt to measure the impact of insecticide-treated materials on malaria incidence. In particular, the low incidence of malaria in the Americas, the high prevalences of P. vivax and relapsing cases, and the relationship between human activity patterns and the crepuscular biting patterns of certain malaria vectors stand in the way of easy experimental design and execution. The utilization of impregnated mosquito nets or other impregnated materials as a major component of an integrated malaria control program would be premature at this time. However, it is recommended that well-conceived large-scale trials and interventions be considered when they are based on a thorough understanding of the dynamics of malaria transmission in the area of study.En este artículo se revisa el uso actual en las Américas de mosquiteros y otros materiales impregnados con insecticida. Se examinan diversos estudios efectuados en el Brasil, Colombia, Ecuador, Guatemala, Perú, Suriname y Venezuela y se llega a la conclusión de que en su mayor parte estos estudios adolecen de graves deficiencias de diseño, problemas de excesiva brevedad, o de una medición inadecuada de los indicadores de salud. La revisión resalta la gran dificultad de llevar a cabo estudios que buscan medir el impacto de los materiales tratados con insecticidas sobre la incidencia de malaria. En particular, la baja incidencia de malaria en las Américas, las altas prevalencias de Plasmodium vivax y de casos recurrentes y la relaci

Effects of Soil Water Deficit on Insecticidal Protein Expression in Boll Shells of Transgenic Bt Cotton and the Mechanism

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Xiang Zhang

2017-12-01

Full Text Available This study was conducted to investigate the effects of soil water deficit on insecticidal protein expression in boll shells of cotton transgenic for a Bt gene. In 2014, Bt cotton cultivars Sikang 1 (a conventional cultivar and Sikang 3 (a hybrid cultivar were planted in pots and five soil water content treatments were imposed at peak boll stage: 15% (G1, 35% (G2, 40% (G3, 60% (G4, and 75% field capacity (CK, respectively. Four treatments (G2, G3, G4, and CK were repeated in 2015 in the field. Results showed that the insecticidal protein content of boll shells decreased with increasing water deficit. Compared with CK, boll shell insecticidal protein content decreased significantly when soil water content was below 60% of maximum water holding capacity for Sikang 1 and Sikang 3. However, increased Bt gene expression was observed when boll shell insecticidal protein content was significantly reduced. Activity assays of key enzymes in nitrogen metabolism showed that boll shell protease and peptidase increased but nitrogen reductase and glutamic-pyruvic transaminase (GPT decreased. Insecticidal protein content exhibited significant positive correlation with nitrogen reductase and GPT activities; and significant negative correlation with protease and peptidase activities. These findings suggest that the decrease of insecticidal protein content associated with increasing water deficit was a net result of decreased synthesis and increased decomposition.

Putting Petri nets to work in Industry

NARCIS (Netherlands)

Aalst, van der W.M.P.

1994-01-01

Petri nets exist for over 30 years. Especially in the last decade Petri nets have been put into practive extensively. Thanks to several useful extensions and the availability of computer tools, Petri nets have become a mature tool for modelling and analysing industrial systems. This paper describes

Pheromone-assisted techniques to improve the efficacy of insecticide sprays against Linepithema humile (Hymenoptera: Formicidae).

Science.gov (United States)

Choe, Dong-Hwan; Tsai, Kasumi; Lopez, Carlos M; Campbell, Kathleen

2014-02-01

Outdoor residual sprays are among the most common methods for targeting pestiferous ants in urban pest management programs. If impervious surfaces such as concrete are treated with these insecticides, the active ingredients can be washed from the surface by rain or irrigation. As a result, residual sprays with fipronil and pyrethroids are found in urban waterways and aquatic sediments. Given the amount of insecticides applied to urban settings for ant control and their possible impact on urban waterways, the development of alternative strategies is critical to decrease the overall amounts of insecticides applied, while still achieving effective control of target ant species. Herein we report a "pheromone-assisted technique" as an economically viable approach to maximize the efficacy of conventional sprays targeting the Argentine ant. By applying insecticide sprays supplemented with an attractive pheromone compound, (Z)-9-hexadecenal, Argentine ants were diverted from nearby trails and nest entrances and subsequently exposed to insecticide residues. Laboratory experiments with fipronil and bifenthrin sprays indicated that the overall kill of the insecticides on Argentine ant colonies was significantly improved (57-142% increase) by incorporating (Z)-9-hexadecenal in the insecticide sprays. This technique, once it is successfully implemented in practical pest management programs, has the potential of providing maximum control efficacy with reduced amount of insecticides applied in the environment.

Distributional learning has immediate and long-lasting effects.

Science.gov (United States)

Escudero, Paola; Williams, Daniel

2014-11-01

Evidence of distributional learning, a statistical learning mechanism centered on relative frequency of exposure to different tokens, has mainly come from short-term learning and therefore does not ostensibly address the development of important learning processes. The present longitudinal study examines both short- and long-term effects of distributional learning of phonetic categories on non-native sound discrimination over a 12-month period. Two groups of listeners were exposed to a two-minute distribution of auditory stimuli in which the most frequently presented tokens either approximated or exaggerated the natural production of the speech sounds, whereas a control group listened to a piece of classical music for the same length of time. Discrimination by listeners in the two distribution groups improved immediately after the short exposure, replicating previous results. Crucially, this improvement was maintained after six and 12 months, demonstrating that distributional learning has long-lasting effects. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of susceptibility of pest Euschistus servus and predator Podisus maculiventris (Heteroptera: Pentatomidae) to selected insecticides.

Science.gov (United States)

Tillman, P Glynn; Mullinix, Benjamin G

2004-06-01

Susceptibility of the brown stink bug, Euschistus serous (Say), and the spined soldier bug, Podisus maculiventris (Say), to acetamiprid, cyfluthrin, dicrotophos, indoxacarb, oxamyl, and thiamethoxam, was compared in residual and oral toxicity tests. Generally, susceptibility of P. maculiventris to insecticides was significantly greater than or not significantly different from that of E. servus. Cyfluthrin and oxamyl were more toxic to the predator than to E. servus in residual and feeding tests, respectively. Dicrotophos is the only compound that exhibited both good residual and oral activity against E. servus, but even this toxicant was more toxic to the predator than to the pest in oral toxicity tests. Feeding on indoxacarb-treated food caused high mortality for both nymphs and adults of P. maculiventris. In contrast, E. servus was unaffected by feeding on food treated with this compound. Insecticide selectivity to P. maculiventris was detected only with acetamiprid for adults in residual toxicity tests and for nymphs in oral toxicity tests. Because insecticide selectivity to P. maculiventris was limited, it is extremely important to conserve P. maculiventris in cotton fields by applying these insecticides for control of brown stink bugs only when the pest reaches economic threshold.

Development, oviposition, and mortality of Neoseiulus fallacis (Acari: Phytoseiidae) in response to reduced-risk insecticides.

Science.gov (United States)

Villanueva, Raul T; Walgenbach, James F

2005-12-01

Eight reduced-risk insecticides (acetamiprid, thiamethoxam, imidacloprid, thiacloprid, methoxyfenozide, pyriproxyfen, indoxacarb, and spinosad) and three conventional insecticides (azinphosmethyl, fenpropathrin, and esfenvalerate) were tested against Neoseiulus fallacis (Garman) (Acari: Phytoseiidae), the most abundant predacious mite in North Carolina apple (Malus spp.) orchards. To assess the effect of insecticides on development and mortality of N. fallacis immatures, 12-h-old eggs were individually placed on bean leaf disks previously dipped in insecticide solutions. Tetranychus urticae Koch (Acari: Tetranychidae) females were added as a food source. None of the reduced-risk insecticides significantly affected immature N. fallacis compared with the control; however, the pyrethroids esfenvalerate and fenpropathrin were highly toxic to immatures. To evaluate the effect of insecticides on mortality and oviposition of adult N. fallacis, 7- to 8-d-old females were confined on insecticide-treated bean leaves with Malephora crocea (Aizoaceae) pollen added as a food source. Spinosad resulted in the highest mortality, whereas azinphosmethyl, acetamiprid, fenpropathrin, and imidacloprid were moderately toxic, and mortality from esfenvalerate, indoxacarb, thiacloprid, methoxyfenozide, pyriproxyfen, and thiamethoxam did not differ significantly from the control. Oviposition was affected in a similar manner, with the exception of acetamiprid that did not affect oviposition, and thiamethoxam that reduced oviposition.

Hormonal enhancement of insecticide efficacy in Tribolium castaneum: oxidative stress and metabolic aspects.

Science.gov (United States)

Plavšin, Ivana; Stašková, Tereza; Šerý, Michal; Smýkal, Vlastimil; Hackenberger, Branimir K; Kodrík, Dalibor

2015-04-01

Insect anti-stress responses, including those induced by insecticides, are controlled by adipokinetic hormones (AKHs). We examined the physiological consequences of Pyrap-AKH application on Tribolium castaneum adults (AKH-normal and AKH-deficient prepared by the RNAi technique) treated by two insecticides, pirimiphos-methyl and deltamethrin. Co-application of pirimiphos-methyl and/or deltamethrin with AKH significantly increased beetle mortality compared with application of the insecticides alone. This co-treatment was accompanied by substantial stimulation of general metabolism, as monitored by carbon dioxide production. Further, the insecticide treatment alone affected some basic markers of oxidative stress: it lowered total antioxidative capacity as well as the activity of superoxide dismutase in the beetle body; in addition, it enhanced the activity of catalase and glutathione-S-transferase. However, these discrepancies in oxidative stress markers were eliminated/reduced by co-application with Pyrap-AKH. We suggest that the elevation of metabolism, which is probably accompanied with faster turnover of toxins, might be responsible for the higher mortality that results after AKH and insecticide co-application. Changes in oxidative stress markers are probably not included in the mechanisms responsible for increased mortality. Copyright © 2015 Elsevier Inc. All rights reserved.

Models of Disease Vector Control: When Can Aggressive Initial Intervention Lower Long-Term Cost?

Science.gov (United States)

Oduro, Bismark; Grijalva, Mario J; Just, Winfried

2018-04-01

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. As vectors may invade both from other infested houses and sylvatic areas and as the effectiveness of insecticide wears off over time, the dynamics of (re)infestations can be approximated by [Formula: see text]-type models with a reservoir, where housing units are treated as hosts, and insecticide spraying corresponds to removal of hosts. Here, we investigate three ODE-based models of this type. We describe a dual-rate effect where an initially very high spraying rate can push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels. We determine some sufficient and some necessary conditions under which this effect occurs and show that it is robust in models that incorporate some heterogeneity in the relevant properties of housing units.

Plant Essential Oils Synergize and Antagonize Toxicity of Different Conventional Insecticides against Myzus persicae (Hemiptera: Aphididae)

Science.gov (United States)

Faraone, Nicoletta; Hillier, N. Kirk; Cutler, G. Christopher

2015-01-01

Plant-derived products can play an important role in pest management programs. Essential oils from Lavandula angustifolia (lavender) and Thymus vulgaris (thyme) and their main constituents, linalool and thymol, respectively, were evaluated for insecticidal activity and synergistic action in combination with insecticides against green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The essential oils and their main constituents exerted similar insecticidal activity when aphids were exposed by direct sprays, but were non-toxic by exposure to treated leaf discs. In synergism experiments, the toxicity of imidacloprid was synergized 16- to 20-fold by L. angustifolia and T. vulgaris essential oils, but far less synergism occurred with linalool and thymol, indicating that secondary constituents of the oils were probably responsible for the observed synergism. In contrast to results with imidacloprid, the insecticidal activity of spirotetramat was antagonized by L. angustifolia and T. vulgaris essential oils, and linalool and thymol. Our results demonstrate the potential of plant essential oils as synergists of insecticides, but show that antagonistic action against certain insecticides may occur. PMID:26010088