ONCHOCERCAL EYE DISEASE AND THE IMPACT OF MECTIZAN TREATMENT

Onchocerciasis continues to be a major cause of blindness, particularl y in those sub-Saharan African countries which are outside the area of West Africa monitored by the Onchocerciasis Control Programme (OCP). Onchocercal ocular disease and blindness develop as a result of long e xposure to onchocercal infection. Until 1987, suramin and diethylcarba mazine were the only drugs available for the treatment of onchocercias is and they could not be used for community therapy because of their t oxicity and the dosage schedules required. The registration of Mectiza n (ivermectin, MSD) for treatment of human onchocerciasis in 1987, and the donation of this drug by Merck & Co. for as long as it is needed, provided a new opportunity for the safe treatment and control of the disease. The data available on the impact of repeated doses of Mectiza n on ocular onchocercal disease indicate a significant reduction of oc ular microfilarial loads and regression of early lesions of the anteri or segment, including iridocyclitis and sclerosing keratitis. Such imp rovements are seen more rapidly when Mectizan is used than when onchoc erciasis is limited by vector control alone. Mectizan treatment also h as a beneficial effect on onchocercal optic-nerve disease and visual-f ield loss. Long-term maintenance of Mectizan therapy should lead to a reduction in the prevalence of blindness in endemic communities.