LARGE-SCALE SPRAYING OF BEDNETS TO CONTROL MOSQUITO VECTORS AND MALARIA IN SICHUAN, CHINA

Since 1987, up to 2.42 million bednets owned by rural householders in over 40 counties in seven prefectures of Sichuan Province, China, have been sprayed annually with deltamethrin at a dose of about 10 mg/m(2) . Data for the years 1987-89 indicate that there were marked reduction s in the biting populations and survival of the two vector species Ano pheles anthropophagus and A. sinensis. Extensive tests in 1992 in area s where bednet spraying had been carried out for 5 years showed that m ortality was 100% with the WHO-recommended discriminating dose of delt amethrin, i.e., there was no indication of resistance. Malaria data ob tained by passive surveillance of reported cases, mass blood surveys o f schoolchildren, and active surveillance of blood slides from fever c ases all indicated marked reductions after introduction of the net spr aying. In contrast, in the control areas, where the nets were not trea ted the situation remained static or deteriorated slightly.