River blindness: How Congo-Brazzaville is tackling the neglected tropical disease along Congo River

The mighty Congo river, known as the world’s deepest river in the world, reaching a depth of 220 meters and roughly 4,700 kilometers long, has the second-largest water volume after the Amazon.

An imposing water way dividing two countries; the Democratic Republic of Congo (DRC) to the north, and the Republic of Congo to the south. The glittering metropolis of Brazzaville and the vibrant city of Kinshasa, DRC’s capital face each other across the Congo River.

But as furious waters, cascade down the Congo River's length, emptying into the Atlantic Ocean, the busy water way provides a perfect breeding ground for a parasite that can cause blindness, a neglected tropical disease (NTD), scientifically known as Onchocerciasis.

“It is called river blindness because it is caused by parasites transmitted by blackflies that breed in fast-flowing rivers and streams,” Dr Elizabeth Juma, head of World Health Organization’s Expanded Special Project for Elimination of NTDs (ESPEN), tells TRT Afrika.

People living and working near these rivers are repeatedly bitten by infected flies, and the parasites over time can lead to severe eye damage and blindness, hence the name “river blindness.”

Millions of people from both Congos live by the banks of the river, depending on it for food, water and transportation.  “Transmission occurs along river systems on both sides of the Congo River, reflecting the shared ecology of blackfly breeding sites.”

This WHO estimates that in Congo Brazaville alone, about 2 million people live in areas considered endemic for Onchocerciasis. Veronique Loukombo is one of them. Prominent white pigmentation stretch the front length of her leg’s tibia bones, testament to years of itching and scratching.

 “Since I started taking medication given by the teams who came by, I am no longer ill,” she says.

“The disease is debilitating with symptoms including intense itching, skin rashes and thickening, particularly among adults in productive age-groups leading to inability to work,” Dr Juma explains, adding: “The disease causes long-term poverty and social stigma in affected communities. “                     

Loukombo knows she is lucky. The disease ultimately causes permanent blindness, a situation she escaped as treatment became available in her community. Since 2001, the Ministry of Health in Congo Brazzaville, with the support of WHO, conducted annual mass drug administration campaigns in endemic areas.

“Mass treatment stops transmission of larvae to flies and protects entire communities,” Juma notes, explaining that ivermectin medicine kills the parasite larvae and prevents disease progression.  

After more than 20 years of the campaign, the proportion of people infected with the disease has significantly dropped from 35% in 2001, to 3% in 2024.

Jean Blaise Mabouka a resident of Bilaungou village recalls how the rainy seasons brought along flies, whose bites not only left them itching but also with sight issues. “A lot of people couldn’t see properly and they were scratching their bodies all over the place.”

Their exposure to bites from the blackly however reduced following years of surveillance and vector control, where blackflies were targeted by clearing vegetation around fast flowing streams where they bred.

“When communities understand and lead treatment delivery, protection is stronger and more sustainable,” Juma reckons, noting effective surveillance and reporting of cases contributed to the successes recorded in Congo Brazzaville. To eliminate the disease however, strong cross-border coordination with neighbouring DRC is required due to the shared river basin.

River blindness is endemic in 29 countries in the WHO African Region. After nearly 50 years of control efforts, in 2025, Niger became the first country in Africa to eliminate transmission of onchocerciasis through sustained mass treatment and vector control.  Niger joined 4 other countries from South America (Columbia, Ecuador, Guatemala and Mexico) that have eliminated this disease.

On World NTD Day, marked every year on January 30, “we are reminded that NTDs are diseases that sustain persistent poverty and inequity but are also diseases we know how to defeat” Juma notes. Health experts say river blindness is one of over 20 Neglected Tropical Diseases that disproportionately affect the poorest and most marginalized populations.

“With sustained investment, strong government leadership, and community engagement, elimination is within reach, particularly in Africa where progress over the past decade has been remarkable,” Juma, the head of Expanded Special Project for Elimination of NTDs (ESPEN) – WHO Africa region, concludes.