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Helminth Infections
Onchocerciasis
Onchocerciasis is disease caused by infection with filarial worms (Onchocerca volvulus). In humans the worms live in the subcutaneous tissue where they shed young known as microfilaria that enter the blood stream. The worms are transmitted from person to person through the bite of black flies (Simulium spp.). Over time the body's immune response to the worms can lead to blindness; a condition known as river blindness, because this disease occurs primarily along rivers where the black flies live. Merck pharmaceutical company in conjunction with the World Health Organization and the Clark Foundation have undertaken a major attempt in Africa to eradicate this parasite. In many parts of Africa the prevalence of onchocerciasis has been reduced by 90%. Nevertheless it is estimated that 150,000 people in sub-Saharan Africa are still afflicted by onchocerciasis and it remains the fourth leading cause of blindness in the world.
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