Diethylcarbamazine in the control of bancroftian filariasis in the highly endemic Ok Tedi area of Papua New Guinea: phase 1.

The effects of a well-spaced diethylcarbamazine (DEC) mass drug application in areas highly endemic for Wuchereria bancrofti in Papua New Guinea are not known. In 1986 a semi-annual single-dose 6 mg/kg body weight administration of DEC was initiated in the Ok Tedi area of Western Province, Papua New Guinea. The rate of bancroftian filariasis in the area was 39%. Within two years the rate of detectable microfilaraemia was reduced from 31% to 11% in the treated group. The mean blood density of the parasite was reduced from 79 to 19 microfilariae per 20 microliters. A survey of untreated villages in the immediate area (not surveyed before 1988) showed a filariasis rate of 39%. A 14-fold difference in the total microfilaraemia count was noted between the two groups when 1988 data were compared. A reduction in the annual rate of filariasis may be monitored through a well-established passive case detection program for malaria. The DEC treatment program was well accepted despite side-effects encountered in 20% of the treated population early on in the program. The success of the 2-year Phase 1 program has expanded into an annual single-dose administration of DEC over a larger area.