For generations, people across sub-Saharan Africa, Yemen, and Latin America have battled against onchocerciasis or river blindness. In Nigeria alone — the world’s most endemic country — an estimated 50 million people are at risk. Despite this, a new chapter is unfolding.
Innovation is paving the way for more ethical blackfly-catching methods, supported in parallel by geospatial modelling to identify high probability sites to find flies. Together, these tools could help Nigeria eliminate the disease — building on the success of mass drug administration, or MDA, in controlling it.
In this episode of our docuseries with the Gates Foundation, Escape the Neglect: Stories from the front lines, Devex explores the country’s fight against the disease and the cutting-edge tools now driving progress toward elimination across West Africa.
One of 21 neglected tropical diseases, or NTDs, onchocerciasis is transmitted by bites from female infected black flies that breed near fast-flowing rivers. Its health and socioeconomic impacts can be devastating. River blindness was first reported in northern Nigeria in 1908. Today, blindness is said to strike entire villages in Nigeria, according to the experiences of Monsuru Adeleke, associate professor of public health entomology and parasitology at Osun State University.
After contracting the disease, symptoms can develop over the course of nearly 15 years, moving through different stages and symptoms, including severe itching and disfiguring skin conditions such as leopard skin. Eventually, the disease will take its toll on the person’s vision — “the end result will always be blindness,” said Adeleke. Besides these morbidities, the disease limits people’s ability to work, reducing productivity, and increasing reliance on other family members, which can also lead to social isolation and stigma.
To stop the disease in its tracks, the World Health Organization recommends that countries roll out MDA, community-wide campaigns of Mectizan, or ivermectin — donated by Merck — at least once a year for 10-15 years. To stop MDA safely, country programs are required to do a blackfly assessment to see if there is still ongoing transmission of onchocerciasis.
For decades, the only way for endemic countries, particularly in West Africa, to do this was to collect and test black flies through human fly catchers, who sit on the riverbank for several hours, exposing their skin, and using collecting tubes to capture any black flies that land on them. This practice has raised various ethical concerns because it puts fly catchers at risk of contracting the disease.
But thanks to the work of pioneering scientists and researchers in endemic countries such as Nigeria, a more ethical and targeted strategy is being developed to minimize people’s risk while fast-tracking elimination efforts.
The team at Osun State University is collaborating with local and international partners to develop innovative tools that strengthen blackfly surveillance and testing for infectivity. This work includes trap development, which began with the Esperanza window trap. Over years of continuous innovation, numerous other approaches have been tested, leading to today’s version: the Bellec trap, which is being further refined to improve safety and deployability, with support in part by the Gates Foundation. To help target their tools and resources, the team applies geospatial modeling to identify high-probability blackfly breeding sites, moving beyond outdated or assumed locations to ensure surveillance is focused on areas where transmission is most likely to persist.
Outside of the lab, engaging community leaders and training human fly catchers to install the traps have helped to create a sense of community ownership with knock-on benefits.
In 2015, at the beginning of its onchocerciasis elimination program, government figures showed that nine states in Nigeria had active ongoing transmission of the disease, and 11 states were inconclusive and required additional assessment to determine if there was ongoing transmission.
As of 2025, 11 states have successfully eliminated transmission of onchocerciasis, with 30.39 million people no longer requiring annual MDA. In addition, only three states still require additional assessment to determine if transmission is ongoing.
As they continue to experiment with and improve these modern tools and techniques, Nigeria’s innovative scientists are not only guiding their own country’s journey to elimination, but also inspiring other endemic countries across Africa and worldwide to accelerate their own elimination efforts.
Visit Escape the Neglect — a series exploring the extraordinary progress that countries are making in eliminating neglected tropical diseases, or NTDs, and showcasing promising opportunities to build on recent wins.
This content is sponsored by the Gates Foundation as part of our Escape the Neglect series. Click here to learn more.
