DISTRIBUTION OF ONCHOCERCIASIS IN SELECTED RIVER BASINS OF 4 WEST-AFRICAN COUNTRIES

Detailed epidemiological mapping of eight river basins was conducted i n four West African countries as part of an effort to identify the com munities at risk of onchocercal blindness to guide a programme of larg e scale ivermectin distribution, attempting control of eye disease. Th e results show a surprising variability of pattern in the geographical distribution of intensity of onchocerciasis infections in the communi ties of the river basins investigated. These patterns were at time ver y different from what was expected on the basis of the available entom ological and demographic information. The technique of detailed mappin g proved very useful in achieving an excellent coverage of the communi ties at risk of onchocercal blindness where, so far, satisfactory trea tment coverage has been attained for four consecutive yearly treatment s.