The use of permethrin-impregnated bednets for malaria control in coastal Tanzania: preliminary entomological impact on vectors

A community-based malaria control programme, using permethrin-impregnated mosquito nets (IMNs) was carried out in the Bagamoyo District, coastal Tanzania. One of the aims of the programme was to determine whether sufficient protection could be achieved to reduce malaria transmission. We report on the relevant entomological aspects before and after intervention. The study was conducted in an area with high malaria transmission, with estimated entomological inoculation rates (EIR) of 300 infective bites per person per annum. After two and a half years of using IMNs, mosquito densities were not affected but there was a significant reduction in enzyme linked immunosorbent assay (ELISA) sporozoite rates. This led to a reduction of the EIR by 76% in intervention villages and is mainly due to individual protection. Reduction in EIR was 86% for Anopheles funestus Giles (Diptera: Culicidae) compared to 66% for An.gambiae s.l.Giles (P