Community-based study to assess the efficacy of DEC plus ALB against DEC alone on bancroftian filarial infection in endemic areas in Tamil Nadu, south India.

As part of the Global Programme for Elimination of Lymphatic Filariasis (GPELF), India is implementing mass drug administration (MDA) with annual single dose of diethylcarbamazine (DEC) with and without albendazole (ALB). The impact of MDAs on filarial infections and soil-transmitted helminth (STH) infections was assessed during a 3-year period in two communities, one with DEC + ALB and the other with DEC alone. Prior to each MDA (during 2001, 2002 and 2003), filarial indices (microfilaraemia and antigenaemia) were assessed from blood samples of 450-650 persons aged 2-25 years and STH infections in stool samples (Kato-Katz method) from 325 to 500 children aged 9-10 years. Mosquitoes resting indoors were collected to determine the filarial infection status. The microfilaraemia prevalence decreased significantly (P < 0.05) in both arms, with the highest decline in the DEC + ALB arm (72%vs. 51%). Decline in micrefilaria intensity was also higher in the DEC + ALB arm (81.4%vs. 48.5%). In this arm alone, the antigenaemia prevalence was reduced significantly (62%; P < 0.001). The reduction in STH prevalence was lower in the DEC alone arm (6.5%; NS) than in the DEC + ALB arm (70.9%; P < 0.001). Also, the egg reduction in DEC alone arm was only half that of DEC + ALB arm (49%vs. 97%). Our community-based follow-up study showed higher and sustained benefits with regard to filarial and STH infections for the two-drug arm over the DEC alone arm. The trends suggest that at least 10 MDAs may be necessary to achieve the goal of elimination.