What is river blindness?

River blindness, or onchocerciasis, is a parasitic infection that can cause severe skin irritation, itching and, over time, irreversible blindness.

Emmanuel fishing in the Pru River: he stands in knee-deep water while holding a fishing net.

River blindness is spread by the bite of infected black flies that breed near fast-flowing rivers.

The disease’s connection to rivers gave rise to the term ‘river blindness’, which was coined by Lady Jean Wilson, wife of Sightsavers’ founder Sir John Wilson. It is one of a group of conditions known as neglected tropical diseases (NTDs).

When someone is bitten by the flies, worm larvae invade the body through the bite. These larvae develop into worms that can live for 15 years. Female worms produce thousands of microscopic larvae, known as ‘microfilariae’, each day, which spread through the body and can be passed on to others. When the microfilariae die, they cause a reaction in the body, leading to immense irritation, inflammation and itching. If the larvae travel to the eyes and cause a reaction, irreversible eyesight damage and sight loss can occur.

As well as pain, blindness and the associated stigma, one of the devastating outcomes of river blindness is that people are forced to move away from fertile river valleys where the disease is prevalent. As a result, people can struggle to find suitable areas to farm or grow crops, pushing families and communities into poverty.

120 million
people worldwide are at risk of contracting river blindness
37 million
people are infected. Most live in sub-Saharan Africa
people worldwide are blind because of the disease

How is river blindness treated?

A close-up of a hand holding Mectizan medication.


Mectizan® tablets can prevent the disease spreading. They don't cure blindness, but can help to stop any further sight loss.

A volunteer drug distributor.


Mectizan®, donated by Merck Sharpe & Dohme, is distributed via local volunteers known as community-directed distributors.

A man examines black fly larvae found near the the Agogo river in northern Uganda.


River blindness is also addressed by eradicating the flies that carry the disease, a process that is known as vector control.

What we’re doing

Sightsavers is working to eliminate river blindness in the countries in which we work by 2025.

Traditionally, river blindness and lymphatic filariasis have been treated through individual programmes. But because they are often detected in the same areas and can both be treated with Mectizan® tablets, Sightsavers treats both of the diseases together.

In 2017, Sightsavers helped to distribute more than 48 million treatments for river blindness. Since our work began 65 years ago, we’ve provided more than 389 million treatments worldwide to protect eyesight.

As part of our push to eliminate river blindness, in November 2017 we achieved a historic milestone: distributing the one billionth treatment to people affected by neglected tropical diseases. The billionth treatment, an antibiotic for river blindness and lymphatic filariasis, was administered to a seven-year-old girl named Dorcas, who was at risk of NTDs in a community in Kaduna State, Nigeria.


Emmanuel’s story

Meet 60-year-old Emmanuel, who lost his sight while earning a living as a fisherman after he contracted river blindness.

Read his story
Young boy Evans Anim smiles as he holds out his Mectizan medication, which he will take to protect him against river blindness.

Evans’s story

Evans Anim lives in the Ashanti region in southern Ghana, an area once plagued by river blindness. This parasitic disease is spread by black flies, causing severe itching and skin irritation, and can eventually lead to blindness.

Luckily, it can be treated with Mectizan® medication. When taken regularly, it stops the infection spreading and ensures children like Evans can grow up without suffering like his father, Kwaku, did.

Kwaku recalls what life was like before Mectizan® was available. “When I was younger, I lived with illness for a long time,” he explains. “The itching stopped me working: I kept stopping to scratch my skin. It kept me awake at night, and when I had to bathe the cold water hurt so badly sometimes I couldn’t wash. The scratching damages your skin, making it sore and hard.” Yet the itching wasn’t the only danger. “I know people who were completely blind because of the disease,” Kwaku explains.

Eventually, Kwaku heard about a Sightsavers programme to combat river blindness by training local volunteers to distribute Mectizan® in the community.“After I took the treatments for the first time, I felt good and my skin got better,” he says. “The flies are still here, but this is our home. If the treatment stopped, we would have to leave as it wouldn’t be safe for my family.

“Before the drug I was fearful and scared of going blind. Now I know I don’t have to be afraid. My children, they are young. Because of the treatments, they will grow up without blindness.”

Find out about other diseases we treat

Neglected tropical diseases

More about river blindness

Health experts during a monitoring visit to Aru in Ituri North.
Sightsavers blog

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Sightsavers surveillance manager Ndellejong Cosmas Ejong explains what has already been achieved in DRC, and how we’re pushing ahead to tackle these debilitating neglected tropical diseases.

Two medical staff clean eyes of men in traditional african dress.
Sightsavers from the field

November updates: highlights from around the world

News about a programme that has distributed more than 137,000 pairs of glasses across eight countries. Plus updates from Guinea, Cote d’Ivoire, Mozambique and more.

Okello Charles.
Sightsavers Reports

Okello’s story

After seeing many of his friends and family lose their sight to river blindness, Okello Charles volunteered to become a ‘fly catcher’, helping to eliminate the flies that spread the disease.

Learn how we’re fighting disease