Experimental hut evaluation of Fendona 6SC®-treated bednets and Interceptor® long-lasting nets against Anopheles gambiae s.l. in Burkina Faso.

Background & objectives: Malaria prevention relies heavily on insecticide-treated bednets. Even though the benefits of bednets have been proven that in most of the studies carried out in Africa, their efficacy remains dependent on local conditions. In this study, under field conditions, we evaluated the efficacy of two LLINs (PermaNet® vs Interceptor®) and two bednet treatment kits (K-O TAB® vs Fendona 6SC®) against Anopheles gambiae s.l. Methods: Bednets were evaluated using experimental huts in the village of Pissy located in the Saponé health district of Burkina Faso. Treatments and sleepers were randomly rotated between huts. Results are expressed in terms of induced exophily, mortality after 24 h and blood-feeding inhibition. Results: A total of 1392 An. gambiae s.l. mosquitoes were collected during 120 nights in the experimental huts. The overall mortality rates were 85.4% (CL: 79.7–91.4) and 77.5% (CL: 56.9–97.3) for PermaNet® and Interceptor®, respectively. For the conventionally treated bednets, the mortality was 78.2% (CL: 63.13–96.7) with the Fendona 6SC®-treated nets and 75.5% (CL: 61.2–93) with the K-O TAB®-treated nets. The proportion of blood-fed mosquitoes was significantly higher in the untreated bednet arm than in the treated one, as well as for long-lasting nets than for conventionally treated nets. The entry rate did not vary significantly according to the bednet type, but the treated bednets increased the level of exophily by at least 43%. Conclusion: In the field, the Fendona 6SC® kit and the Interceptor bednets showed comparable efficacy to the already used K-O TAB® kit and PermaNet® bednets. These results could help National Malaria Program managers to formulate appropriate policy for effective vector control.

Knowledge, Attitudes and Practices Relevant to Malaria Control in Remote Island Populations of Manus, Papua New Guinea

A community-based cross-sectional survey of 262 participants in four island communities of Manus, Papua New Guinea was conducted using a structured questionnaire to examine possible factors of malaria prevalence, including education experiences, knowledge, attitudes, and preventive behaviors, in relation to antimalarial antibody titers. Bivariate and multivariate analyses revealed that micro-environmental conditions caused inter-community differences in malaria prevalence. Ninety-nine percent of the subject villagers recognized mosquito bites as a cause of malaria transmission, which explains the high possession rate of bednets. There was a significant correlation between malaria education experience at schools and knowledge (<i>p</i> < 0.01) and between knowledge and bednet use (<i>p</i> < 0.05). However, regular bednet users were only 35% of the total, due primarily to feelings of discomfort, heat, and stuffiness inside the bednet. Villagers’ behavior of consulting an aid post orderly (APO) in case of high fever significantly lowered the titer level (<i>p</i> < 0.05), while their bednet use did not. This unexpected result was attributable to inappropriate bednet use and to daily living patterns, including both subsistence and social activities. We conclude that information regarding lifestyles and attitudes toward bednet use as well as malaria education experience at schools are particularly important for practical malaria prevention.

Aceptabilidad y eficacia de mosquiteros tratados con insecticida de larga duración Olyset® en un área endémica para malaria en Colombia / Acceptability and efficacy of long-lasting insecticidal nets Olyset® in a malaria endemic area of Colombia

En Colombia, el uso de mosquiteros es promovido por el Programa nacional de prevención y control de enfermedades transmitidas por vectores en áreas endémicas para malaria. A pesar de esto, son pocos los estudios realizados para evaluar su efectividad y en particular el grado de aceptabilidad por los usuarios lo cual es fundamental para mantener la adherencia a esta medida de control. En el presente estudio se evaluó, a pequeña escala, la aceptación de mosquiteros impregnados con insecticida de larga duración (Olyset®) y su efecto biológico en mosquitos, en una localidad de la región pacífica colombiana. Se instalaron 100 mosquiteros Olyset® en 30 viviendas con la recomendación, basados en una encuesta previa, de lavarlos mensualmente. Cuatro, ocho y doce meses después, se aplicó una encuesta en donde se determinó la aceptación teniendo en cuenta: el porcentaje de mosquiteros Olyset® en uso y la percepción de protección de los habitantes contra las picaduras de los mosquitos. Además, en la primera encuesta se indagó sobre los posibles efectos secundarios en la salud de los usuarios por el uso de estos mosquiteros. Grupos de hembras criadas en laboratorio de Anopheles albimanus Wiedemann y Culex quinquefasciatus Say fueron expuestos a los mosquiteros cada cuatro meses para determinar el efecto letal.

La proporción de mosquiteros Olyset® en uso fue disminuyendo en cada evaluación: 77,5%, 51,1% y 46,6% a los cuatro, ocho y doce meses, respectivamente. La misma tendencia fue observada en la percepción de protección contra la picadura de los mosquitos: 82,7%, 62% y 46%, respectivamente. La mortalidad de A. albimanus fue de 100%, 77,8%, 78,6% y 43,7% y la de C. quinquefasciatus de 100%, 42,3%, 74,1% y 5,7% a los cero, cuatro, ocho y doce meses de uso de los mosquiteros, respectivamente. Sólo un 5% de los usuarios manifestó irritación de la piel en los primeros días de uso de estos mosquiteros. En conclusión, durante el año de seguimiento se evidenció una disminución gradual en la aceptación de los mosquiteros Olyset®. Esto probablemente debido a que la notable reducción del efecto letal de los mosquiteros permitió un aumento en las tasas de picadura de los mosquitos que ocasionó la deserción de varios de los usuarios. Sin embargo, no se puede descartar que otras causas hayan contribuido a la reducción en la aceptación.

The use of bednets is promoted by the National Program of Promotion and Prevention of Diseases Transmitted by Vectors in malaria endemic areas of Colombia. This study estimated the acceptance and retention of long-lasting insecticide-treated nets (Olyset®). The study also measured the efficacy of the bednets after being washed once a month. Thirty dwellings were chosen in the village of Beté (Chocó department) to receive bednets. Interviews were administered in four month intervals to determine the frequency of bednet use and to assess the health outcomes. Among the recipients, nets were readily accepted and used at the beginning. However, usage began to decline: 77.5%, 51.1% and 46.6% after 4, 8 and 12 months of use respectively. In addition, 5% of recipients reported skin irritation after 15 days of continuous use. Anopheles albimanus and Culex quinquefasciatus females were exposed to used bednets every four months to estimate mortality and knock down rates. Bioassays revealed a decrease in efficacy over time. A. albimanus mortality was 77.8%, 78.6% and 43.7% after 4, 8 and 12 months of use, respectively. Mortality for C. quinquefasciatus was variable. A. albimanus mean knock down percent was above 80% at each sampling period. C. quinquefasciatus mean knock down percent was at a similar >80% at the 4 and 8 month sampling times, however, declined to 5.7% after 12 months of use. One year of use and monthly washings of bednets results in significantly less acceptance among recipients and a decrease in efficacy.

Evaluation of the effectiveness of Interceptor bed net on controlling disease vectors Aedes aegypti in Vietnam, 2007

Background: Using insecticides is considered as a temporary and rapid method for interrupting the disease transmission through disease vectors such as dengue. The insecticide Fendona, when absorbed into bed nets, is slowly released and rapidly knocks out, kills or repels mosquitoes as they come into contact with the bed net. Objectives: To evaluate the effectiveness of the Interceptor bed net (a unique textile-finishing product developed by BASF, Singapore PTE. LTD, that were coated with the Fendona insecticide) on controlling disease vector Aedes aegypti. Subjects and method: An experimental trial was carried out at the National Institute of Hygiene and Epidemiology and in the field of Hien Giang commune, Thuong Tin district, Ha Tay province. The changes of efficacy of Interceptor bed net were compared by not washing with washing at the different levels. Results: The unwashed bed nets can knock out and kill Aedes aegypti mosquitoes by 50% after 20 minutes of exposure on every trial. About 90-100% of total mosquitoes were killed after the first 30 minutes of exposure. Bed net\u2019s efficacy remains until 24 hours of the trial. The recovery rate of the mosquito is 0%. The same results were also observed after 90 days, 36 days and 18 days of bed nets being laundered. However, after 9 day of washing, the bed nets can only kill the mosquitoes up to about 90-95% of the total after the first 30 minutes of exposure. It also reached 100% of killing after 24 hours. However, its efficacy was conversely reduced with regard to the increase of laundry times. Conclusion: The density of adult mosquitoes and larvae for Aedes aegypti was significantly reduced in the intervention areas, even at zero level in comparison to the control sites. The insecticide had no side-effect or any stimulation to users, community, poultry, cattle and environment in the intervention sites.

Bioassay test of Responsar against Anopheles sinensis and Anopheles anthropophagus in lab / 中国血吸虫病防治杂志

ObjectiveTo observe the effectiveness of Responsar against Anopheles sinensis and Anopheles anthropophagus. MethodsThe cotton and nylon gauze absorbing Responsar solutions of 10,15 and 20 mg/m~2 (effective dosage) were used in the test. An. sinensis and An. anthropophagus raised in the lab were used as probational worms, having the knockdown power, lethiferous power and effective keeping observation. ResultsWith Responsar of 10,15 and 20 (mg/m~2) impregnating two different kinds of bednets, the KT_(50(s)) of An. sinensis and An. anthropophagus were between 3.98 and 7.30 min after touching the bednets. The knocked down mosquitoes were resumed breeding for 24 h, and the mortality was 100%. Touching nets 3 min, resuming breeding for 24 h, the mortality of mosquitoes was more than 90%. The nets hung for 180 d after impregnated with the insecticide and the knockdown power was still between 8.57 and 16.31 min for Anopheles vector, and resuming breeding for 24 h, the mortality was still 100%. ConclusionThere is strong deadly effect of Responsar to Anopheles sinensis and Anopheles anthropophagus, and the effect can keep more than 180 d.