Effect of single to triple dose DEC on microfilaremics up to 5 years

A 5-year study was conducted with 200 selected microfilaremic subjects bearing Mean microfilarial density (MMD) of 11.6 from 16 small foothill villages around Susunia Hill, Bankura, West Bengal during June 2001 to May 2002. All of them were treated with a single dose (6 mg/kg body weight) to triple dose diethylcarbamazine (DEC). On day 180, 365, 730, 1,095, 1,460, and 1,825, recurrence of microfilaremia were 0.0%, 6.0%, 15.5% (6 + 9.5), 27% (15.5 + 11.5), 42% (27 + 15), and 49% (42 + 7), respectively, and corresponding MMD were 0.0, 1.2, 1.4, 2.7, 6.2, and 7.8, respectively. Culex quinquefasciatus was incriminated as the vector and their infection and infectivity rates reduced to 4.2% and 0.81% from the initial values of 6.40% and 1.33%, respectively, after DEC treatment to selected mff carriers. Single-dose DEC treatment was found effective for reduction of microfilaremia and MMD but it was not always sufficient to eliminate all the microfilariae, especially when MMD was high (>40). For microfilaremics with high MMD, a single course (6 mg/kg body weight for 3 days) DEC treatment may be safe for the first instance.