Field efficacy of a new mosaic long-lasting mosquito net (PermaNet(® )3.0) against pyrethroid-resistant malaria vectors: a multi centre study in Western and Central Africa

BACKGROUND: Due to the spread of pyrethroid-resistance in malaria vectors in Africa, new strategies and tools are urgently needed to better control malaria transmission. The aim of this study was to evaluate the performances of a new mosaic long-lasting insecticidal net (LLIN), i.e. PermaNet(® )3.0, against wild pyrethroid-resistant Anopheles gambiae s.l. in West and Central Africa. METHODS: A multi centre experimental hut trial was conducted in Malanville (Benin), Vallée du Kou (Burkina Faso) and Pitoa (Cameroon) to investigate the exophily, blood feeding inhibition and mortality induced by PermaNet(® )3.0 (i.e. a mosaic net containing piperonyl butoxide and deltamethrin on the roof) comparatively to the WHO recommended PermaNet(® )2.0 (unwashed and washed 20-times) and a conventionally deltamethrin-treated net (CTN). RESULTS: The personal protection and insecticidal activity of PermaNet 3.0 and PermaNet(® )2.0 were excellent (>80%) in the "pyrethroid-tolerant" area of Malanville. In the pyrethroid-resistance areas of Pitoa (metabolic resistance) and Vallée du Kou (presence of the L1014F kdr mutation), PermaNet(® )3.0 showed equal or better performances than PermaNet(® )2.0. It should be noted however that the deltamethrin content on PermaNet(® )3.0 was up to twice higher than that of PermaNet(® )2.0. Significant reduction of efficacy of both LLIN was noted after 20 washes although PermaNet(® )3.0 still fulfilled the WHO requirement for LLIN. CONCLUSION: The use of combination nets for malaria control offers promising prospects. However, further investigations are needed to demonstrate the benefits of using PermaNet(® )3.0 for the control of pyrethroid resistant mosquito populations in Africa.