PATTERNS OF EPIDEMIOLOGY AND CONTROL OF ONCHOCERCIASIS IN WEST-AFRICA

This paper summarizes the work of the Onchocerciasis Control Programme (OCP) in West Africa, a programme which over a 22 year history has re duced the public health problems of blinding onchocerciasis in eleven countries of West-Africa through vector control and, more recently, iv ermectin distribution. The paper emphasizes the different approaches t o control the programme has developed in the different parts of the pr ogramme area which have been determined by the epidemiology of the dis ease (savanna/forest form), the migratory characteristics of the vecto rs, intensity of the disease before commencement of treatment, the com bined impact of vector control and ivermectin and the likelihood of in filtration of infective blackflies from outside the programme area. Th e programme has constantly monitored the impact of operations on the t rends in prevalence, incidence, annual transmission potential, ocular morbidity and species of fly populations, and as a result, has identif ied areas where special interventions are required until the programme comes to an end in 2002. The paper illustrates the changes in intensi ty of infection as measured by community microfilarial load and annual transmission potential over the duration of the programme control act ivities. The paper also defines and justifies the control strategies i n different areas and identifies areas for special interventions.