Onchocerca volvulus (a nematode)
Onchocerciasis (river blindness) is transmitted through the bite of infected blackflies.
Nature of the disease
Onchocerciasis is a chronic parasitic disease, occurring mainly in sub-Saharan western Africa, in which adult worms are found in fibrous nodules under the skin. They discharge microfilaria, which migrate through the skin, causing dermatitis, and reach the eye, causing damage that results in blindness.
Onchocerciasis occurs mainly in western and central Africa, also in central and South America.
Risk for travellers
Generally low, unless travel involves extensive exposure to vectors in countries or areas at risk.
Avoid exposure to the bites of blackflies in countries or areas at risk.