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 m osquito nets (IMNs) was carried out in the Bagamoyo District, coastal Tanza nia. One of the aims of the programme was to determine whether sufficient p rotection could be achieved to reduce malaria transmission. We report on th e relevant entomological aspects before and after intervention. The study w as conducted in an area with high malaria transmission, with estimated ento mological inoculation rates (EIR) of 300 infective bites per person per ann um. After two and a half years of using IMNs, mosquito densities were not a ffected but there was a significant reduction in enzyme linked immunosorben t assay (ELISA) sporozoite rates. This led to a reduction of the ETR by 76 % in intervention villages and is mainly due to individual protection. Redu ction in EIR was 86 % for Anopheles funestus Giles (Diptera: Culicidae) com pared to 66 % for An.gambiae s.l.Giles (P < 0.001). However, unprotected co mmunities are still at risk from malaria. To realize optimum community prot ection against malaria, extra effort should be made to maximize net coverag e in the community, encourage net use throughout the year and ensure regula r and timely re-impregnation of mosquito nets.