Two-year follow-up of the microfilaraemia of asymptomatic brugian filariasis, after treatment with two, annual, single doses of ivermectin, diethylcarbamazine and albendazole, in various combinations

Repeated, single, oral doses of combinations of ivermectin, diethylcarbamaz ine (DEC) or albendazole are recognized as important tools for parasite con trol in lymphatic filariasis. In order to assess the effects of re-treatmen t using these combinations in Brugia malayi infections, 40 asymptomatic mic rofilaraemics were re-treated at the end of the first year, with an additio nal, single, dose of the combination they had previously received. They wer e then followed-up for another year. The subjects, of both sexes and aged 1 4-70 years, each received a two-drug combination: ivermectin (200 mu g/kg) with DEC (6 mg/kg); ivermectin (200 mu g/kg) with albendazole (400 mg); or DEC (6 mg/kg) with albendazole (400 mg). The kinetics of microfilarial clea rance were similar to that seen during the first treatment, the members of the two groups given DEC having less intense microfilaraemias, 1 year after the re-treatment, than those given ivermectin with albendazole (P < 0.001 for each comparison). At this time, the two DEC groups also had a higher pr oportion of amicrofilaraemic individuals (22 of 26) than the ivermectin + a lbendazole group (three of nine). There were fewer adverse reactions in all the groups after re-treatment than seen after the first treatment. In coun tries such as India, where there is no co-endemicity of onchocerciasis or l oiasis, the options for control programmes in areas where brugian filariasi s is endemic are DEC alone or DEC in combination with ivermectin or albenda zole. Where there is no access to ivermectin, transmission control must be based on DEC alone or in combination with albendazole.