Bio-environmental control of malaria in a tribal area of Mandla district, Madhya Pradesh, India.

Bizadandi block of District Mandla was selected for demonstration of bio-environmental control of malaria. The project presently covers 80 experimental villages and 12 control villages. In this area, because of indifferent surveillance and spraying in the past (from 1978-86) the API was reported low and the parasite reservoir in the community had built up over the years. At the outset of the study the malaria prevalence was high with preponderance of P. falciparum. Densities of A. culicifacies were very high and A. fluviatilis was also present. P. falciparum predominated in both experimental and control area during 1988 than in 1987. Annual blood examination rate (ABER) was 73.6 and 57.5 and annual parasite incidence (API) was 114.7 and 228.0 in experimental and control villages in 1987, while in 1988, ABER and API was 63 and 73 and 112 and 316 in experimental and control, respectively. There was constant stabilization of Pf in neighbouring blocks in 1988 while in experimental areas Pf percentage has come down appreciably during March to June. It is very alarming to note that the parasite reservoir in control villages was sufficient to maintain active transmission even when antimalarial activities are at a peak. The application of residual insecticides like DDT and HCH has no tangible impact on the reduction in vector densities and the transmission of malaria. Even if a replacement insecticide like malathion is used it may produce very limited impact on vector densities in such forested zones. Thus, there is an urgent need to intensify integrated malaria control operations in the area on long term basis.