The effect of pyrethroid impregnated mosquito nets on field malaria vector populations in experimental huts and in individual local houses.

Studies were carried out in Tak Province, northwest Thailand to determine repellency and killing effects of four commercially available pyrethroids etofenprox, deltamethrin, lambdacyhalothrin and permethrin treated mosquito nets on field malaria vector populations in experimental huts and local houses. The studies reveal that all four test pyrethroids have a highly repellency effect. Repellency ratio between lifted and torn nets also showed some different among the four pyrethroids. Mosquito net treated with 0.3 g/m2 permethrin was most toxic to mosquito followed by 0.02 g/m2 deltamathrin, etofenprox 0.3 g/m2 and 0.02 g/m2 lambdacyhalothrin. However, careful consideration for future use should also include problem of cross-resistance, persistence of chemicals and also type of mosquito net material.