Final report covering period June 1991-June 1995 : ELISA using a species specific monoclonal antibody to detect infective larvae of Brugia malayi in vector mosquitoes

The average number of infective larvae of B. malayi to which inhabitants of two villages in Central Sulawesi (Indonesia) are exposed every year, the Annual Transmission Potential (ATP), was determined before treating the members of one of the villages with the filaricide drug diethylcarbamazine (DEC). Inhabitants of the other village were treated initially with a placebo. By the end of the third year, all participants were treated with DEC. The expectation was that the ATP in the village where people were treated would diminish, it was hoped to a negligible value. The potential social and economic impact of such a result would be enormous, since it is easier and less expensive to administer DEC chemotherapy in selected villages than to implement widespread mosquito control programs. To aid in determining the ATP, the investigators used an immunological assay (supplied by Tulane University) based on a monoclonal antibody which can distinguish between the animal parasites Brugia pahangi and B. malayi, the two species of filariae that live together in the study area (infective larvae from these two parasite species cannot be distinguished from one another by their shape). In the village whose inhabitants were treated with DEC (Walatana), the ATP decreased from 3,280 in 1991-1992 to 96 in 1993-1994, a decrease of 97%. In the control village, the ATP also decreased, but much less, from 1,602 in 1991-1992, to 584 in 1993-1994 (67%). These results are encouraging. Although it was not possible to completely interrupt the transmission of B. malayi by chemotherapy alone, it was possible to diminish transmission very significantly. (Author abstract, modified)