History of Discovery

Onchocerciasis is found mainly in Africa and in parts of South America and the Arabian Peninsula, where it was probably introduced from Africa through the slave trade. Official recognition and documentation of the disease only occurred when Western explorers entered these regions. The most important signs of the disease include blindness, and scaly, itchy, nodular skin, known as kru kru or craw craw in West Africa.

1875 The microfilariae of O. volvulus are first observed by the Irish naval surgeon John O'Neill when examining skin snips from patients suffering from craw craw in Ghana.

The adult worms are discovered and identified by Patrick Manson, Scottish medical scientist and a pioneer of Tropical Medicine.

Patrick Manson
Courtesy of Stanhope Bayne-Jones, MD









The morphology of the adult worms is described and reported at a meeting by German zoologist Rudolf Leuckart, using samples collected by missionaries from Ghana.

Rudolf Leuckart
Courtesy of Clendening, History of Medicine Library and Museum








The French physician and parasitologist Emile Brumpt recognizes that the infection occurs most commonly along river banks, and that the microfilariae in the skin come from the deeper cutaneous nodules where adult filariae reside. He also finds that there are no microfilariae in the blood.

Emile Brumpt
Courtesy of Institut Pasteur



Rodolfo Robles, a Guatemalan physician, sheds light on the life cycle and transmission of the parasite. Using case studies of coffee plantation workers in Guatemala, Robles hypothesizes that the vector of the disease is a day-biting insect, and more specifically two anthrophilic species of Simulium flies found in the endemic areas. Robles, however, did not conduct scientific research to verify his hypothesis.
1917 Robles publishes findings on a “new disease” from Guatemala associated with subcutaneous nodules, anterior ocular lesions, dermatitis, and microfilariae.
1920 The role of the microfilariae in causing the skin lesions is established by Jean Montpellier and A. Lacroix.



The role of blackflies in the transmission of onchocerciasis is proven by the Scottish parasitologist Breadalbane Blacklock in Sierra Leone. Blacklock collected wild S. damnosum flies and infected them by placing them close to infected individuals. He then traced the development of the parasite in the gut, thorax, head and proboscis of the flies.



The part played by microfilariae in blindness is elaborated by Jean Hissette in the Belgian Congo (now the Democratic Republic of the Congo). Note: The link between biting flies and skin lesions and blindness had already been made a long time ago by the Ghanaians living along the Red Volta river.


1972: Neafie of the Armed Forces Institute of Pathology (AFIP) gives a detailed description of the adult male and female worms.

This section was compiled using sources a, b and c, as indicated in References section