Oncocerciasis is a disease caused by a parasitic worm that is transmitted through the bites of blackflies. The word oncocerciasis is spelled /ɒn.kəʊ.sɜːˈkaɪ.əsɪs/ in phonetic transcription. The initial "o" is pronounced as a short "o" sound, followed by the stress on the second syllable "ko". The "c" sounds like a "k" sound, followed by an "er" sound, pronounced as "ər". The "iasis" ending is pronounced with a long "i" sound and an "s" at the end.
Onchocerciasis, commonly known as river blindness, is a parasitic disease caused by a microscopic worm called Onchocerca volvulus. It is primarily transmitted through the bite of infected blackflies (Simulium genus) found in riverside areas of Africa, Latin America, and Yemen. The disease affects millions of people, particularly in rural communities located near fast-flowing rivers.
The infection begins when an infected blackfly bites a person, subsequently introducing the larvae of the worm into the skin. Over the course of several months, the larvae develop into adult worms, which can live for up to 14 years in the human body. The worms primarily reside in subcutaneous nodules, but female worms release thousands of microfilariae (the offspring) into the skin and eyes, causing various symptoms.
Onchocerciasis mainly affects the skin and eyes. Early symptoms include intense itching and skin rash, while long-term infection can lead to severe visual impairment and even blindness. Other ocular complications include inflammation in the cornea and lesions on the retina. Additionally, subcutaneous nodules may form, containing adult worms.
The control and prevention of onchocerciasis primarily rely on widespread efforts to control the blackfly population by using insecticides. Mass drug administration of ivermectin, an anti-parasitic drug, is also an effective strategy to treat the disease. Community involvement is vital for successful elimination programs.
Efforts to combat onchocerciasis have been successful in several regions, leading to its elimination in certain countries. However, continuous surveillance and preventive measures remain critical to ensure the complete eradication of this devastating disease.
Infestation with a species of Oncocerca; it is marked by the presence of nodular subcutaneous swellings, formed of a fibrous cyst wall encircling the coiled parasite.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "oncocerciasis" is derived from two Greek roots: "onko" meaning "a swelling" and "kirkos" meaning "a circle". The term was coined by Sir Patrick Manson, a Scottish physician, in 1893 to describe a disease caused by the parasitic worm Onchocerca volvulus. The name reflects the characteristic swelling and circular appearance of the nodules that form beneath the skin due to the worm infection.