| Summary: | <p>Abstract</p> <p>Background</p> <p>Recent field studies indicated that insecticide-treated bednets (ITNs) maintain their efficacy despite a high frequency of the knock-down resistance (<it>kdr</it>) gene in <it>Anopheles gambiae </it>populations. It was essential to evaluate ITNs efficacy in areas with metabolic-based resistance.</p> <p>Methods</p> <p>Bifenthrin was used in this experiment because it is considered a promising candidate for bednets impregnation. Nets were treated at 50 mg/m<sup>2</sup>, a dose that has high insecticidal activity on <it>kdr </it>mosquitoes and at 5 mg/m<sup>2</sup>, a dose that kills 95% of susceptible mosquitoes under laboratory conditions with 3 minutes exposure. Bednets were holed to mimic physical damage. The trial was conducted in three experimental huts from Pitoa, North-Cameroon where <it>Anopheles gambiae </it>displays metabolic resistance and cohabits with <it>An. funestus</it>.</p> <p>Results</p> <p>Bifenthrin at 50 mg/m<sup>2 </sup>significantly reduced anophelines' entry rate (>80%). This was not observed at 5 mg/m<sup>2</sup>. Both treatments increased exophily in <it>An. gambiae</it>, and to a lesser extent in <it>An. funestus</it>. With bifenthrin at high dosage, over 60% reduction in blood feeding and 75–90% mortality rates were observed in both vectors. Despite presence of holes, only a single <it>An. gambiae </it>and two <it>An. funestus </it>females were collected inside the treated net, and all were found dead. The same trends were observed with low dosage bifenthrin though in most cases, no significant difference was found with the untreated control net.</p> <p>Conclusion</p> <p>Bifenthrin-impregnated bednets at 50 mg/m<sup>2 </sup>were efficient in the reduction of human-vector contact in Pitoa. Considerable personal protection was gained against <it>An. funestus </it>and metabolic pyrethroid resistant <it>An. gambiae </it>populations.</p>
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