TREATMENT OF MICROFILAREMIA IN ASYMPTOMATIC BRUGIAN FILARIASIS - THE EFFICACY AND SAFETY OF THE COMBINATION OF SINGLE DOSES OF IVERMECTIN AND DIETHYLCARBAMAZINE

Although combinations of ivermectin and diethylcarbamazine (DEC) have been shown to be superior to either drug alone in the suppression of b ancroftian microfilariae, their efficacy against infections with Brugi a malayi has never been investigated. The present, open trial is the f irst on the efficacy and safety of a combination of single doses of iv ermectin and DEC when used against microfilaraemias of brugian filaria sis. Twenty-one, asymptomatic but microfilaraemic (109-6934 microfilar iae/ml blood, with a median of 841/ml) men, aged 18-48 years, each rec eived oral doses of ivermectin (400 mu g/kg) and DEC (6 mg/kg) as a si ngle treatment. Twelve hours post-treatment, 96.5%-100% of the microfi lariae in each subject had been cleared and 12 of the subjects were am icrofilaraemic. A further reduction in microfilarial counts was eviden t 1 month post-treatment (mean clearance = 99.0%) and the counts conti nued to fall at least until the last follow-up, at 1 year post-treatme nt, when the mean clearance was 99.9% and 13 (68.4%) of the 19 subject s then investigated were amicrofilaraemic. All subjects experienced ad verse reactions of one form or another, lasting for up to 48 h post-tr eatment; these included fever, myalgia, headache, and lethargy. Postur al hypotension was recorded in two subjects and dilated, inflamed lymp hatic channels were seen in another two. The combination of ivermectin and DEC demonstrated a microfilaricidal effect superior to that of ei ther drug used alone, both in the initial rapid clearance of microfila riae and in sustaining the effect for 1 year. This finding has importa nt implications for the control of lymphatic filariasis.