Onchocerciasis epidemiology and demographics
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Kalsang Dolma, M.B.B.S.[2]
Overview
Onchocercal infections are found in tropical climates. About 99% of onchocerciasis cases occur in Africa. Also, the parasite is found in limited areas in the Americas and in Yemen in the Middle East.
Epidemiology and Demographics
World
Onchocercal infections are found in tropical climates. The main burden is in sub-Saharan Africa. The World Health Organization (WHO) estimates that 37 million people are infected with O. volvulus worldwide; of these people 270,000 are blind and 500,000 have some sort of visual impairment. Some 90 million people are at risk for becoming infected with the parasite. About 99% of onchocerciasis cases occur in Africa. As of 2008, about 18 million people were infected with this parasite; about 300,000 of those had been permanently blinded.[1] Onchocerciasis is currently endemic in 30 African countries, Yemen, and isolated regions of South America.[2] Over 85 million people live in endemic areas, and half of these reside in Nigeria. Another 120 million people are at risk for contracting the disease. Due to the vector’s breeding habitat, the disease is more severe along the major rivers in the northern and central areas of the continent, and severity declines in villages farther from rivers. Travelers who do not stay long in those areas have little risk of developing the disease, as it requires prolonged exposure to the fly bites and parasite introduction. According to a 2002 WHO report, onchocerciasis has not caused a single death, but its global burden is 987,000 disability adjusted life years (DALYs). The severe pruritus alone accounts for 60% of the DALYs. Infection reduces the host’s immunity and resistance to other diseases, which results in an estimated reduction in life expectancy of 13 years.[2]
America
The parasite is found in limited areas in the Americas and in Yemen in the Middle East.
References
- ↑ "What is river blindness?". Sightsavers International. Archived from the original on 2007-12-15. Retrieved 2008-01-28.
- ↑ 2.0 2.1 "Epidemiology". Stanford University. 2006.