The prevalence of infection in local communities has been used as the basis for the country-wide
repartition of onchocerciasis in Cameroon, following the principles for rapid epidemiological mapping of
onchocerciasis (REMO) developed by the World Health Organization. The levels of endemicity were
evaluated in 349 villages by rapid epidemiological assessment (REA), a method based on the examination
of nodules in males aged 2 20 years. An onchocerciasis map was then drawn from the epidemiological data
which had been collected previously, from clinico-parasitological surveys based on the examination of skin
snips, and the results of the REA surveys. The REMO surveys allowed the main onchocerciasis foci in
Cameroon to be accurately delineated, and several small endemic areas which had never been reported
before to be identified. The total 'at risk' population (i.e. those for which ivermectin treatment should be
considered as urgent or highly desirable) .was estimated by combining the epidemiological results and the
demographical data available from an administrative census. Those at risk were estimated to number 3.5
million, representing about 50% of the total rural population in Cameroon.