Effectiveness of spaced doses of diethylcarbamazine citrate for the control of bancroftian filariasis.

Forty-seven Wuchereria bancrofti microfilaria carriers were treated once weekly for 12 weeks with 6 mg/kg DEC-C. Microfilaria densities ranged from 1 to 101 mf/20 cmm (MfD-50 of 9.75 mf/20 cmm) before treatment. Of 42 persons who completed treatment, 26 (62%) were microfilaria negative in 1-ml venous blood samples. Microfilaria densities in the 16 patients that remained positive ranged from 1 to 50 mf/ml (MfD-50 of 2.59 mf/ml). Weekly spaced doses of DEC-C resulted in a significant reduction in the number of microfilaria carriers posttreatment, and in the level of residual microfilaremia when compared to daily administration of the drug. Administration of spaced doses of DEC-C also resulted in better patient compliance with less dropout from the program. The reason DEC-C is more effective in spaced doses still remains unclear, but the role platelets or other cells may play in mediating the action of the drug may be linked to the administration schedule.