[Mosquito nets impregnated against malaria in Zaire]

On the Bateké plateau 60 km east of Kinshasa, Zaïre, where malaria is stable, three villages have been selected for a trial of malaria control using bednets impregnated with deltamethrin at 25 mg per square meter from February to November 1991. One village (3,000 inhabitants) has been provided 800 impregnated bednets and an other one (2,900 inhabitants) kept 800 non impregnated bednets. The third village (900 inhabitants) served as a control and has remained without nets. Anopheles gambiae was the main and nearly exclusive vector of malaria. Its biting density was reduced by 94% in the village protected by impregnated bednets and the inoculation rate dropped from 182 infective bites/man/year to 3.7 a decrease of 98%. The longevity of the vector expressed by its expectation of life decreased from 11.02 days to 3.64 days. In the village where inhabitants were protected by non impregnated nets, as well as in the control, the entomological indexes did not change. In the village protected with impregnated nets the malaria prevalence decreased by 50%, five months after the beginning of the experiment. The high parasitemia, above 10,000 and 20,000 parasites per mm3 decreased by 77% and 83% in the 0-7 year age group and by 67% and 65% in the 8-14 year group in the protected village. These high parasitemias are good markers of the clinical malaria risk. The experiment can be considered as very satisfactory on the point of view of public health.