ALPHAMETHRIN-IMPREGNATED BED NETS FOR MALARIA AND MOSQUITO-CONTROL INCHINA

A community-based intervention trial was carried out to evaluate the e ffectiveness of alphamethrin-impregnated bed nets for control of Plasm odium vivax malaria and its vector in an area of moderate endemicity i n southern Henan province, central China in 1990. Malaria incidence wa s significantly lower in the intervention group than in the comparison group (2.03 vs. 3.57 per 100 person-years at risk). The protective ef ficacy for malaria incidence was 43%. The prevalence of malaria parasi taemia among children under 10 years old in the intervention group was about one-quarter of that in the comparison group (0.93% vs. 3.25% an d 0.71% vs. 1.96% after one and 4 months use of impregnated nets, resp ectively). Alphamethrin-impregnated bed nets had a mass killing effect on vector mosquitoes. The outdoor person-biting density of Anopheles anthropophagus and A, sinensis decreased by 70.3% and 29.3% respective ly. The density of these 2 mosquito species found resting inside treat ed nets was close to zero. No side effect was found among users of imp regnated bed nets. Impregnation with alphamethrin was more effective o n polyester than on cotton netting and residual effects lasted at leas t one year. Use of alphamethrin is less expensive than permethrin and deltamethrin.