Nearness to large
rivers eats the eye.
~ a Mossi saying
Onchocerciasis is an eye and skin disease caused by the filarial parasitic worm Onchocerca volvulus. It is transmitted to humans through the bite of the blackfly. These flies breed in fast-flowing streams and rivers, increasing the risk of infection to individuals living nearby, hence the common name of "river blindness".
Within the human body, the adult female worm (macrofilaria) produces thousands of baby or larval worms (microfilariae), which migrate in the skin and the eye and are the cause of morbidity. While mortality rates for onchocerciasis are null, the personal costs, and social and economic burdens are high.
Onchocerciasis is the second leading cause of preventable blindness in the world. More than 17.7 million people worldwide are infected, and 109 million people are at risk. Visual impairments occur in 500,000 of these people, including 270,00 cases of blindness. Over 90% of the disease occurs in Africa, with the rest occurring in six countries in Latin America, and in Yemen and the Arabian Peninsula.[j]
Public health initiatives, starting in 1974 with the Onchocerciasis Control Program, have incorporated a mix of vector-control and treatment efforts. While wide vector distribution, high numbers of vector, and varying strains of the parasite have provided obstacles, a number of non-governmental development organizations (NGDOs) and members of the private sector (e.g. Merck & Co.) have joined forces, so far with positive results, in an effort to eradicate the disease b 2007. The main control methods include treatment with the drug ivermectin, surgical removal of the worms by nodulectomy, and larvicide spraying in endemic foci. Experts conclude that the disease can be eliminated by controlling the vector and simultaneously killing the microfilaria in humans via ivermectin treatment for 14 years, the lifetime of the adult worm in the human body.
Current public health initiatives need to be strengthened, sustained, and expanded to continue being effective. They must also provide the support for a solid and lasting health infrastructure, with adequate human resources, in each of the endemic countries long after the programs officially end, to ensure that the 127 million people infected or at risk of being infected with onchocerciasis are able to avoid the burden of disease and lead productive, healthy lives.
This website was designed by the undergraduate students Katherine Vu, Jacqueline Papo and Jori Lambert, as part of Dr. Smith’s class on Parasites and Pestilence, at Stanford University. It contains information about the history, biology, clinical presentation, epidemiology, impact and control efforts of the disease. We hope that you find this collection of information useful, and feel free to contact us with feedback, questions…
Image source: World Bank, Africa Program for Onchocerciasis Control