Onchocerciasis control

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Onchocerciasis, characterized by skin and eye lesions, is a parasitic disease caused by Onchocerca volvulus. It is transmitted by small black flies of the Genus Simulium, that breed in rapidly flowing rivers and streams. The adult parasites have a life span of 8-15 years, during which time they release thousands of microfilariae every year.

The microfilariae enter the skin and eyes and cause inflammation and disease. The WHO estimates that at least 17.7 million people are infected, 500,000 visually impaired and 270,000 blinded from onchocerciasis in 37 endemic countries; of which over 95% are found in Africa. The Onchocerciasis Control Programme in West Africa (OCP/WA) was the first major program developed to control the disease.

It was launched in 1974 initially covering seven countries in West Africa but was later extended to cover 11 countries. In 1987, Merck & Co. Inc. decided to donate ivermectin, for as long as necessary, to all people affected by onchocerciasis and the main strategy used to control onchocerciasis was and still is Community Directed Treatment with Ivermectin (CDTI) in meso-endemic and hyper-endemic communities.

Currently, onchocerciasis is no longer a public health problem in the 11 OCP/WA countries. A similar program, the African Programme for Onchocerciasis Control (APOC) was launched in 1995 and is on-going in 19 countries not previously covered by OCP/WA. This program aims at establishing sustainable community-directed ivermectin distribution within a period of 12 years. The treatment strategy is to get 100% geographic coverage of endemic areas in which at least 65% treatment coverage is attained in meso- and hyperendemic areas.

Ivermectin is a microfilaricidal drug and in the absence of macrofilaricides, it should be administered over many years (13-20 years) in order to eliminate onchocerciasis as a public health problem. Therefore, long-term compliance to ivermectin treatment by all eligible communities in both meso-endemic and hyper-endemic areas is crucial in achieving sustainable disease control.