Effect of a single dose of diethylcarbamazine, albendazole or both on the clearance of Wuchereria bancrofti microfilariae and antigenaemia among microfilaria carriers: a randomized trial.

BACKGROUND

Lymphatic filariasis is a major vector-borne parasitic disease. The global programme to eliminate lymphatic filariasis was launched in 1997 and currently over 570 million people are covered under it in 48 countries. Mass annual single-dose drug administration of diethylcarbamazine (DEC), co-administrated with albendazole for 5-6 years and mass distribution of diethylcarbamazine-fortified salt are the two strategies for elimination of filariasis.

METHODS

Asymptomatic volunteers residing in Puducherry, India were screened for microfilaria (mf) by examining nocturnal thick blood smears. Those testing positive were randomly assigned to receive a single dose of DEC (6 mg/kg body weight) or albendazole 400 mg or both. Participants were hospitalized for 5 days. Membrane filtration count was used to assess microfilaraemia and ELISA (Og4C3) assay to measure circulating filarial antigens (CFA). Measurements were done before treatment and at 1, 2 and 3 years post-treatment. Viability of the adult worms was assessed by looking for the filarial dance sign (FDS) using ultrasound examination of the scrotum in men with hydrocele.

RESULTS

Fifty-four microfilaraemic Individuals were studied. The mf prevalence started decreasing only by day 180 posttreatment in the DEC group but much earlier in the other two groups (day 30 in the albendazole and day 90 in the DEC with albendazole group). The decrease in mfwas marginal (17.6%, 26.3% and 27.8%, respectively) by the end of year 1 posttreatment, but significant (96.7%, 78.6% and 93.3%, respectively) by the end of year 2 post-treatment (p < 0.05). By the end of year 3, the level decreased to 80% in the DEC, 90% in the albendazole and to 100% in the DEC and albendazole groups. However, the mf intensity decreased significantly (by 39%; p < 0.05) by day 7 post-treatment in both the DEC and DEC with albendazole groups, but only by day 30 in the albendazole group. In all the drug groups, the prevalence as well as intensity of CFA returned to pretreatment levels by the end of year 3 post-treatment.

CONCLUSION

Annual single-dose administration of all the 3 drug regimens significantly reduced antigenaemia levels. There were no significant differences in the efficacy and overall pattern of CFA clearance between the 3 drug regimens.