RESUMO
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.
RESUMO
Aims: The aim of the study was to evaluate the field performance of insecticide-treated mosquito nets (ITNs) in north-western Burkina Faso. Study design: Cross-sectional survey. Place and Duration: The study took place between September and November 2008 (end of rainy season) in rural north-western Burkina Faso. Methodology: Standard WHO bioassays were performed on field-collected ITNs from three areas of different insecticide pressure: semi-urban Nouna town, three villages with cotton agriculture, and three villages without cotton agriculture. Data on age and washing frequency of ITNs was collected, and deltamethrin content was determind by HPLC. Results: The mean age of field-collected ITNs was 2.1 years. The mosquito mortality rate (Anopheles gambiae sl.) after 24 hours was 4% for the negative controls, 90% for the positive controls, and 73% for field-used ITNs. Differences in mosquito mortality between sub-areas disappeared after controlling for confounding variables. Conclusion: This study demonstrates that under real life conditions, deltamethrin still shows some level of effectiveness despite ongoing insecticide pressure. However, deltamethrin resistance has been observed in other parts of the country and thus close surveillance of ITN efficacy is needed. More frequent replacement of ITNs is also recommended.