Combined field and laboratory evaluation of a long-term impregnated bednet, PermaNet®

For how long does the insecticidal effect of long-lasting nets achieve high Anopheles mortality? Four PermaNets tested previously in Colombia for wash resistance were bioassayed again after 3 years of use and 23 washes. The tests were done both in Colombia and a reference laboratory in Indonesia. Additionally the residual. concentration of deltamethrin on the nets was chemically analysed. The results showed high Anopheles mortality and a mean dettamethrin concentration of 9.6 mg/m(2). Discrepancies with other studies are discussed. (C) 2003 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.