Onchocerciasis, pronounced ɒŋkəˌsəːʃəsɪs, is a parasitic infection caused by the nematode Onchocerca volvulus. It is commonly known as river blindness as the blackflies that transmit the parasites breed near fast-flowing rivers. The word has a complex spelling due to its Greek and Latin roots. The oncho- prefix comes from the Greek word onkho meaning 'bulge', while the cerc- suffix comes from the Latin word for 'tail'. The -iasis suffix is used in medical terminology to indicate a disease caused by a particular organism.
Onchocerciasis, also known as river blindness, is a parasitic disease caused by the filarial worm Onchocerca volvulus. The disease is transmitted to humans through the bite of infected black flies of the genus Simulium. These flies breed in rapidly flowing rivers and streams in rural areas of tropical Africa, Latin America, and Yemen.
Upon transmission, the female worms release thousands of microscopic larvae, called microfilariae, into the skin and eyes of the infected individual. The microfilariae migrate throughout the body, causing a variety of symptoms. The most distinctive manifestation is severe itching and skin lesions, particularly around the eyes, face, and extremities. Over time, repeated exposure to the parasite can lead to irreversible blindness, hence the name river blindness.
In addition to skin and eye problems, onchocerciasis can affect the lymphatic system and internal organs, causing enlarged lymph nodes, skin atrophy, and nodules under the skin. The disease can have a profound impact on affected communities, leading to reduced productivity, economic hardship, and social stigma.
Prevention and control strategies for onchocerciasis revolve around mass drug administration with the antiparasitic medication ivermectin. This drug kills the microfilariae, preventing further transmission of the disease. Vector control measures, such as insecticide-treated bed nets and insecticide spraying, also play a role in reducing black fly populations.
Efforts to eliminate onchocerciasis as a public health problem are ongoing, with the goal being to interrupt transmission in affected regions and ultimately eradicate the disease worldwide.
The word "onchocerciasis" comes from the combination of two terms: "oncho" and "cerciasis".
1. "Oncho" derives from the Greek word "onkos" (ὄγκος), meaning "swelling" or "mass". It is used here to refer to the characteristic nodules that form under the skin in people infected with the disease.
2. "Cerciasis" is derived from the Greek word "kerkiazein" (κερκιάζειν), which means "to make blind". The term encompasses the severe ocular complications that can occur in advanced cases, leading to blindness.