onchocerciasis

noun

on·​cho·​cer·​ci·​a·​sis ˌäŋ-kō-ˌsər-ˈkī-ə-səs 

ˌäŋ-kə-

plural onchocerciases

ˌäŋ-kō-ˌsər-ˈkī-ə-ˌsēz,

ˌäŋ-kə- 

: infestation with or disease caused by filarial worms (genus Onchocerca)

especially : a human disease marked by subcutaneous nodules, dermatitis, and visual impairment and caused by a worm (O. volvulus) found in Africa and tropical America which is transmitted by the bite of a female blackfly

called also river blindness

Examples of onchocerciasis in a Sentence

Recent Examples on the Web

Spearheaded by the World Bank, the program aimed to rid areas of the black flies that transmit river blindness, or onchocerciasis, an ancient scourge caused by parasitic worms that can rob people of their sight. —Patrick Adams, NPR, 5 June 2025

Ivermectin subsequently proved extremely effective in treating tropical diseases such as onchocerciasis and lymphatic filariasis, which devastate and disfigure poor people around the world; as with eflornithine, the World Health Organization listed it as an essential medicine. —Christopher B. Barrett, Foreign Affairs, 25 Sep. 2023

The century-old suramin, currently used to treat African sleeping sickness and river blindness (onchocerciasis), has also gotten some traction as a potential Covid-19 treatment. —Joshua Cohen, Forbes, 1 Jan. 2022

River blindness, also known as onchocerciasis, is the second leading cause of preventable blindness in the world. —Jeffrey R. Aeschlimann, The Conversation, 14 Oct. 2021

Both Ōmura and Campbell discovered avermectins, a class of compounds that can kill parasitic roundworms that cause crippling diseases, such as lymphatic filariasis, otherwise known as elephantiasis, and onchocerciasis or river blindness. —Rebecca Kreston, Discover Magazine, 5 Oct. 2015

Word History

Etymology

New Latin Onchocerca, genus of filarial worms (from oncho-, probably erroneously for onco-, from Greek ónkos "barb of an arrow" + -o- -o- + -kerka, feminine of -kerkos "having a tail [of the kind specified]," adjective derivative of kérkos "tail") + -iasis — more at angle entry 2, cercus

Note: The genus Onchocerca was introduced by the Austrian zoologist Karl Moriz Diesing (1800-67) in a brief Latin description of the worm Onchocerca reticulata appended to an article by J. Hermann, "Trichina, bei einem Pferde gefunden," Oesterreichische medicinische Wochenschrift, 1841, no. 9 (February 27), p. 199-200. Diesing's coinage is presumed to mean "hook-tailed," on the assumption that his oncho- is a mistake for onco-, but nothing in the description renders this self-evident. Perhaps the reference is to the spicule (copulatory organ) of the male.

First Known Use

1911, in the meaning defined above

Kids Definition

onchocerciasis

noun

on·​cho·​cer·​ci·​a·​sis ˌäŋ-kō-sər-ˈkī-ə-səs 

plural onchocerciases -ˌsēz 

: river blindness

Medical Definition

onchocerciasis

noun

on·​cho·​cer·​ci·​a·​sis ˌäŋ-kō-ˌsər-ˈkī-ə-səs 

plural onchocerciases -ˌsēz 

: infestation with or disease caused by filarial worms of the genus Onchocerca

especially : a human disease marked by subcutaneous nodules, dermatitis, and visual impairment that is caused by a worm (O. volvulus) found in Africa and tropical America and transmitted by the bite of a female blackfly

called also onchocercosis, river blindness

see craw-craw