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[ong-koh-ser-kahy-uh-sis] /ˌɒŋ koʊ sərˈkaɪ ə sɪs/
noun, Pathology
an infestation with filarial worms of the genus Onchocerca, common in tropical America and Africa, transmitted by black flies, and characterized by nodules under the skin, an itchy rash, eye lesions, and in severe cases, elephantiasis.
Also, onchocercosis
[ong-koh-ser-koh-sis] /ˌɒŋ koʊ sərˈkoʊ sɪs/ (Show IPA)
Also called river blindness.
1910-15; < New Latin Onchocerc(a) a genus of filarioid worms (oncho- (correctly onco- < Greek ónk(os) barb + -o- -o-) + -cerca feminine of -cercus -tailed < Greek, adj. derivative of kérkos tail) + -iasis Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for onchocerciasis
  • We treat about ten million people a year to prevent onchocerciasis, or river blindness.
  • The doctor says that those bugs carry onchocerciasis, or river blindness.
British Dictionary definitions for onchocerciasis


noun (pl) -ses (-siːz)
a disease found in parts of Africa and tropical America that is caused by a parasitic worm, Onchocerca volvulus, and transmitted to humans by various species of black fly. It results in inflammation of the skin and in some cases blindness Also called river blindness
Word Origin
C20: from Onchocerca, the genus of worms + -iasis
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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onchocerciasis in Medicine

onchocerciasis on·cho·cer·ci·a·sis (ŏng'kō-sər-kī'ə-sĭs) or on·cho·cer·co·sis (-sər-kō'sĭs)
A disease occurring in tropical Africa and Central America, transmitted by black flies and caused by infestation with filariform nematodes of the genus Onchocerca, especially O. volvulus, and characterized by nodular swellings on the skin and lesions of the eyes. Also called river blindness, volvulosis.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Article for onchocerciasis

river blindness

filarial disease caused by the helminth Onchocerca volvulus, which is transmitted to humans by the bite of the black fly Simulium. The disease is found chiefly in Mexico, Guatemala, and Venezuela in the Americas and in sub-Saharan Africa in a broad belt extending from Senegal on the west coast to Ethiopia on the east; in Africa its northern edge is about 15 N of the equator, and it extends as far south as Angola and Tanzania. It has also been reported in Colombia, northern Sudan, and Yemen.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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