Onchocerciasis (also known as river blindness) is a vector-borne disease that is transmitted from person to person via the bites of infected blackflies. The disease is caused by the parasitic filarial worm Onchocerca volvulus.

The blackflies introduce immature larval forms of the parasite into the human recipient; these larvae then mature into adult worms, mate and in turn release hundreds of microfilariae a day; these move through the body and cause a number of symptoms, including intense itching and skin rashes, swelling and ultimately severe dermatitis, impaired vision and ultimately blindness.

TDR has a long history of research to support the control of this disease, dating back to the partnership with the Onchocerciasis Control Programme that eliminated the mosquito that transmitted the disease in West Africa.

TDR research in collaboration with the African Programme for Onchocerciasis Control (APOC) has demonstrated how community-directed treatment with ivermectin (CDTI) is a sustainable and improved way of controlling the disease, and shows the possibility of eliminating transmission of the parasite.

More recently, research supported the identification of genetic markers of the parasite’s response to ivermectin and evaluating another compound, moxidectin, for its potential to accelerate elimination of onchocerciasis and expand the areas where elimination of transmission is feasible.

For more information, please contact Dr Annette Kuesel

TDR related research

Since its foundation, TDR has been at the forefront of a global fight to combat and eradicate onchocerciasis. It effectively became the research arm of the Onchocerciasis Control Programme (OCP) in West Africa, and then the African Progamme for Onchocerciasis Control (APOC).

Research on how to curb disease transmission in broad savanna regions of West Africa led to the breakthrough innovation of incorporating the Bti bacterium to control insect larvae, including that of the blackfly, in 1982.

TDR also contributed to the design of study protocols and dosage for the drug ivermectin, and connected the pharmaceutical owner, Merck, with the OCP networks. In 1986, with the drug about to be registered, CEO of Merck Dr Roy Vagelos made the momentous decision to donate the drug to whoever needed it, as long as it was needed. TDR and partners set up large-scale community trials under field conditions to move the drug from individual treatment in hospitals to mass drug administration, strengthening the value of ivermectin in the onchocerciasis control strategy.

To support this mass drug administration, a new model was proven that empowered communities to put in place their own system for ivermectin distribution and administration, with health services offering support and training.

Today, 98 million people in 31 sub-Saharan African countries receive annual treatments through this system.

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