title: Reduced susceptibility of Anopheles gambiae to permethrin associated with the use of permethrin-impregnated bednets and curtains in Kenya.
abstract: Susceptibility of the malaria vector Anopheles gambiae to permethrin decreased following the installation of mosquito nets impregnated with 0.5 g permethrin per square metre in four villages near Kisumu, Kenya. During the first year that permethrin-impregnated bednets and curtains were in place, the exposure time to 50% mortality (LT50) increased 2.5-fold from 13 to 33 min, while the LT50 for An.gambiae was unchanged in two other villages where no intervention measures were used. Two years after permethrin-impregnated mosquito nets were distributed the LT50s for An.gambiae were 28, 28 and 16 min, respectively, in the villages with bednets, curtains and with no such intervention. Using a colony of An.gambiae derived from females collected in the villages using permethrin-impregnated mosquito nets, we lengthened the LT50 from 28 to 41 min in two generations by exposing all females to permethrin-treated papers for 60 min and rearing offspring of the survivors. Permethrin-impregnated bednets and curtains are intended to reduce vectorial capacity. Reduced susceptibility to permethrin could counter this beneficial effect.
authors.affiliation: Research Centre, Kenya Medical Research Institute, Nairobi, Kenya.
authors.forename: J M
authors.initials: JM
authors.lastname: Vulule
authors.forename: R F
authors.initials: RF
authors.lastname: Beach
authors.forename: F K
authors.initials: FK
authors.lastname: Atieli
authors.forename: J M
authors.initials: JM
authors.lastname: Roberts
authors.forename: D L
authors.initials: DL
authors.lastname: Mount
authors.forename: R W
authors.initials: RW
authors.lastname: Mwangi
mesh_terms: D000818:Animals; D000852:Anopheles; D001513:Beds; D006801:Humans; D007306:Insecticides / Q000633:toxicity*; D007630:Kenya; D009032:Mosquito Control / Q000379:methods*; D026023:Permethrin; D011722:Pyrethrins / Q000633:toxicity*; D012424:Rural Population; D013997:Time Factors
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D026023:Permethrin