title: Impact of permethrin-treated bednets on malaria transmission by the Anopheles gambiae complex in The Gambia.
abstract: Malaria vector mosquitoes belonging to the Anopheles gambiae complex were studied in four hamlets in The Gambia. All inhabitants were given bednets treated either with a placebo (milk) in two hamlets or with the pyrethroid insecticide permethrin (500 mg/m2) in two other hamlets. Malaria transmission occurred mainly during a few weeks of the rainy season, in September and October 1987. The indoor resting densities of mosquitoes in permethrin-treated hamlets were reduced, and we estimated over 90% reduction in biting on man by An. gambiae Giles sensu stricto in these hamlets. No mosquitoes were found under permethrin-treated bednets compared with eighty-one recovered from placebo-treated bednets. Mosquitoes exited more readily from rooms where permethrin-treated bednets were used than from rooms with placebo-treated nets. The annual mean probability that a child would receive an infective bite was estimated to be 0.09 in hamlets with insecticide-treated bednets, compared with 1.9 where placebo-treated bednets were used. Permethrin-treated bednets are therefore recommended as a means of effectively reducing the risk of exposure to malaria transmission, particularly in areas of low seasonal transmission.
authors.affiliation: Medical Research Council Laboratories, Fajara, The Gambia.
authors.forename: S W
authors.initials: SW
authors.lastname: Lindsay
authors.forename: R W
authors.initials: RW
authors.lastname: Snow
authors.forename: G L
authors.initials: GL
authors.lastname: Broomfield
authors.forename: M S
authors.initials: MS
authors.lastname: Janneh
authors.forename: R A
authors.initials: RA
authors.lastname: Wirtz
authors.forename: B M
authors.initials: BM
authors.lastname: Greenwood
mesh_terms: D000818:Animals; D000852:Anopheles; D001512:Bedding and Linens; D005714:Gambia; D006801:Humans; D007299:Insect Bites and Stings / Q000517:prevention & control; D007303:Insect Vectors; D007306:Insecticides; D008288:Malaria / Q000517:prevention & control*; D009032:Mosquito Control / Q000379:methods; D026023:Permethrin; D011722:Pyrethrins
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D026023:Permethrin