MASS CHEMOTHERAPY WITH DIETHYLCARBAMAZINE FOR THE CONTROL OF BANCROFTIAN-FILARIASIS - A 12-YEAR FOLLOW-UP IN NORTHERN TRINIDAD, INCLUDING OBSERVATIONS ON MANSONELLA-OZZARDI

A microfilaria survey was conducted in Trinidad in 1992, 12 years afte r mass treatment with spaced doses of diethylcarbamazine citrate (DEC- C) for the control of Bancroftian filariasis; 348 persons were examine d using thick blood smears and a membrane filtration technique. They i ncluded 104 who had participated in the mass chemotherapy campaign in 1980. No Wuchereria bancrofti microfilariae were detected among 66% of the population examined. In 1980, 86 of 592 persons examined were fou nd to be infected with W. bancrofti, 140 with Mansonella ozzardi and 4 4 with mixed infections, while in 1992, only M. ozzardi infections per sisted despite treatment with DEC-C. Of the 104 persons reexamined 12 years later, 46 had M. ozzardi, of which five were new cases, but none had W. bancrofti. During both the 1980 and 1992 surveys, low microfil ariae rates for M. ozzardi were observed among those 19 years of age o r younger. Of the 302 persons newly examined in 1992, 29 were infected with significantly (P < 0.001) more males (79.3%) than females (20.9% ) being microfilaremic. The combined results showed similar prevalence rates for M. ozzardi from 23.3% to 21.6% in 1980 and 1992. Nuclepore membrane filtration and thick blood films were very efficient in demon strating the presence of microfilariae. The usefulness of these method s and spaced treatment using DEC-C are also discussed.