A METHOD TO DETERMINE THE COVERAGE OF IVERMECTIN DISTRIBUTION IN ONCHOCERCIASIS-CONTROL PROGRAMS

Onchocerciasis is a human filarial infection responsive for an estimat ed 750 000 blind and severely visually disabled people. In some Africa n countries, this disease represents the main cause of blindness, with , considerable socio; economic impact on the affected communities. Sin ce the introduction of ivermectin as a microfilaricidal agent, there i s hope that visual loss from onchocerciasis can be eliminated though c ommunity-based ivermectin-distribution programmes. The African Program me for Onchocerciasis Control (APOC) has now been initiated, by the Wo rld Health Organization and World Bank, to distribute ivermectin in 19 African countries where onchocerciasis is endemic. Estimates of iverm ectin coverage in distribution programmes for onchocerciasis control h ave so far been based on the number of treatments given, in any one ye ar, to a target population. There is a need for a standardized method to evaluate, measure and monitor coverage over time. In April 1996, a cluster random-sampling method was used to calculate coverage with ive rmectin in an urban population of 30 000 people in the Central African Republic. The method was adapted from that used used to determine cov erage by the WHO Expanded Programme on Immunization. It proved to be i nexpensive and easy to perform, requiring only local equipment and per sonnel. The method used and results obtained in Bossangoa and the pote ntial use of the technique in other distribution programmes are discus sed.