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
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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
Cite this Entry
“Onchocerciasis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/onchocerciasis. Accessed 4 Nov. 2025.
Copy CitationKids Definition
onchocerciasis
noun
on·cho·cer·ci·a·sis
ˌäŋ-kō-sər-ˈkī-ə-səs
plural onchocerciases
-ˌsēz
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
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