Efficacy of five annual single doses of diethylcarbamazine for treatment of lymphatic filariasis in Fiji.

Annual single-dose treatments with diethylcarbamazine citrate (DEC) at a dose of 6 mg/kg have been reported effective in reducing microfilariae (mf) rate and density and applicable to large-scale filariasis control campaigns. However, the efficacy of such treatments has not been studied quantitatively in relation to different pretreatment levels of endemicity. This study of 32 villages in Fiji revealed that five treatments repeated annually steadily reduced village mf rate, and that the degree of reduction was not influenced by pretreatment levels of mf density or rate. This indicates that an annual dosage scheme is applicable to high-endemicity areas. The results also suggest that such treatment affected juvenile forms of Wuchereria bancrofti and may prevent them from reproducing.