title: Is K-O Tab 1-2-3((R)) long lasting on non-polyester mosquito nets?
abstract: Many societies use locally sourced mosquito nets made from a variety of materials. For protecting against malaria these require regular re-treatment with insecticide. K-O Tab 1-2-3 is a 'dip-it-yourself' long-lasting formulation with time-limited interim recommendation from WHO for treatment of washed white and coloured polyester nets for up to 15 washes. To determine wash-resistance on different fabrics, nets made of polyester, polyethylene, cotton or nylon were treated with K-O Tab 1-2-3 and washed up to 20 times using standard WHO washing procedures. Efficacy was assessed using cone and cylinder bioassays and tunnel tests, and deltamethrin content using high-pressure liquid chromatography. Polyethylene and cotton nets treated with K-O Tab 1-2-3 and washed 20 times achieved the WHO threshold of >80% mortality in tunnel tests. Polyethylene matched the performance of polyester in all bioassays in contrast to cotton and nylon which produced low mortality and knock-down in cone and cylinder bioassays. After 20 washes 16.5% of the loading dose of deltamethrin remained on the polyester nets compared with 28.7% on polyethylene, 38.9% on cotton and 2.2% on nylon. Cotton nets retained a high concentration of insecticide but the relatively poor performance in terms of knock-down and mortality suggest most insecticide is bound within the cotton fibres rather than on the surface. K-O Tab 1-2-3 renders insecticide wash fast on polyethylene nets, less so on cotton and nylon. Nets made from polyethylene can be treated in the home to render the insecticide long lasting.
authors.affiliation: London School of Hygiene and Tropical Medicine, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Oxborough
authors.forename: V
authors.initials: V
authors.lastname: Weir
authors.forename: S
authors.initials: S
authors.lastname: Irish
authors.forename: H
authors.initials: H
authors.lastname: Kaur
authors.forename: R
authors.initials: R
authors.lastname: N'Guessan
authors.forename: P
authors.initials: P
authors.lastname: Boko
authors.forename: A
authors.initials: A
authors.lastname: Odjo
authors.forename: C
authors.initials: C
authors.lastname: Metonnou
authors.forename: A
authors.initials: A
authors.lastname: Yates
authors.forename: M
authors.initials: M
authors.lastname: Akogbeto
authors.forename: M W
authors.initials: MW
authors.lastname: Rowland
mesh_terms: D000818:Animals; D009033:Culicidae / Q000187:drug effects*; D004355:Drug Stability; D005260:Female; D006796:Household Work; D007306:Insecticides / Q000494:pharmacology*; D009032:Mosquito Control / Q000379:methods*; D009570:Nitriles / Q000494:pharmacology*; D011482:Protective Devices; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin