The burden of onchocerciasis in Uganda.

Onchocerciasis is far more prevalent and far more of a public-health and socio-economic problem in Uganda than it was thought to be a decade ago. It appears that over a million Ugandans have the disease and nearly two million others live in endemic areas. A few years of annual treatment with Mectizan (ivermectin, MSD) have reduced the community microfilarial load (CMFL) in sentinel villages in Uganda by 52%-100%. The greatest reductions (100%) have been in those villages with the lower CMFL pre-treatment. Assessments at intervals of much less than 1 year should help to show how quickly skin cleared by Mectizan is re-invaded by microfilariae and give an idea of how frequently treatment should be given to produce the greatest benefits. It seems likely that it would be best to give Mectizan at intervals of < 1 year and that such frequent treatment only becomes feasible if Mectizan distribution is community-directed.