River Blindness, officially called onchocerciasis, is an infection that is transmitted through the bites of infected blackflies. This neglected tropical disease (NTD) causes intense itching, disfiguring dermatitis, and eye lesions that can lead to blindness. The infection is one of the leading causes of preventable blindness worldwide.

At Risk

People at Risk of Contracting River Blindness (Source: WHO)
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Onchocerciasis Endemic Countries Remain (Source: WHO)
Accordion Content

In the past 40 years, significant progress has been made to reduce the number of cases and the severity of river blindness globally. The transmission of the disease has been eliminated in four countries in Latin America where the disease was found in remote, rural areas often in coffee plantations. In Africa where the disease is widespread, the number of cases is declining. However, an estimated 200 million people are still at risk of infection in 30 countries. The disease is also prevalent in Yemen in the Wadis where the major manifestation is a cutaneous condition called “Sowda”.

The Task Force-based Mectizan® Donation Program (MDP) and the Neglected Tropical Diseases Support Center (NTD-SC) play key roles in the efforts to eliminate river blindness by 2025. MDP partners with other organizations to distribute large quantities of anti-parasitic medicines in endemic communities and NTD-SC conducts operational research to overcome barriers to the elimination of river blindness.

Managing Donations of Mectizan® for the Elimination of River Blindness

Mectizan® (ivermectin) is an anti-parasitic medicine that can eliminate river blindness when distributed annually to all eligible people living in communities where the disease is transmitted. In 1987, Merck committed to donate Mectizan® to endemic countries through MDP “for as long as needed and as much as needed” to treat river blindness. Since MDP was launched, Merck has donated an estimated 2.8 billion doses of Mectizan® for the treatment of river blindness. MDP is the secretariat of the Mectizan® Expert Committee (MEC), an independent body set up to provide medical, technical, and administrative oversight of the donated medicines. In 2017, MEC approved 258 million treatments for river blindness.

Overcoming Barriers to River Blindness Elimination Through Operational Research

NTD-SC drives a robust operational research portfolio to answer scientific questions about how to overcome barriers to the elimination of river blindness. NTD-SC collaborates with ministries of health, academic institutions, the World Health Organization, and other international organizations to help endemic countries reach elimination goals. More than 50 operational research studies are completed or underway in 18 African countries to map the distribution of river blindness, evaluate the effectiveness of diagnostic tests, and carry out other operational research to accelerate river blindness. A special focus of several studies is developing operational guidance for implementing river blindness elimination programs in areas where people are also infected with another parasite, Loa loa.


Countries Eliminated River Blindness (Source: WHO)
Individuals Treated in 2019 (Source: WHO)
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Yao Sodahlon, MD, MSc,

Director, Mectizan® Donation Program

Where We Work

To see where we work on river blindness, click here.


Did you know?

In 2007, Colombia became the first country to eliminate river blindness using treatments of ivermectin or Mectizan®


Header photo caption: A community health worker uses a dosing stick to measure the height of Ngo Yeba Anastasie in her home in Bafang, Cameroon to identify how much medicine for river blindness she should receive.

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