Advantages of an annual single dose of ivermectin 400 μg/kg plus diethylcarbamazine for community treatment of bancroftian filariasis

Abstract In 1994 and 1995, 2 supervised single dose treatments for bancroftian filariasis were given to all inhabitants (>3500) aged ⩾3 years on a Polynesian island. This island is divided into 4 political zones. Each zone was treated with a different dosage of the combination ivermectin (IVR) and diethylcarbamazine (DEC) as follows: (1) IVR 400 μg/kg plus DEC 6mg/kg, (2) IVR 400μg/kg alone, (3) DEC 6mg/kg alone, (4) IVR 400 μg/kg plus DEC 3mg/kg. 1717 inhabitants (aged ⩾20 years) had venous blood sampled when treated. The reductions in microfilaraemia prevalence rates one year after treatment were, respectively, 32%, 11%, 14% and 32%. The reductions in microfilaraemia levels one year after treatment were, respectively, 96%, 80%, 82% and 95%. Stool specimens from 82 children aged 6 years were examined for intestinal nematodes just before and just after treatment. IVR 400 μg/kg significantly reduced the prevalence and intensity of trichiuriasis. The combination IVR+DEC is a powerful tool for the control of lymphatic filariasis. Further studies are required to determine the appropriate presentation of DEC (salt and/or tablets), the frequency of treatment, and the duration of the control programme necessary to eradicate this disease.