What is river blindness?

River blindness, or onchocerciasis, is a parasitic infection spread by flies that live near fast-flowing rivers. It causes severe skin irritation, itching and, eventually, irreversible blindness.

A close-up of a plastic vial containing the flies that transmit river blindness.

River blindness is spread by the bite of infected 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 and 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 leading to immense irritation, inflammation and itching. If the larvae travel to the eyes, it can cause irreversible sight loss.

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

Watch our video to find out more about river blindness.

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

How is river blindness treated?

A photo of two hands. In one hand there are three tablets.


Medication can help to prevent the disease spreading. It doesn’t cure blindness, but can help to stop any further sight loss.

Philomene, a volunteer community-directed distributor, stands smiling inside Massangam hospital


Tablets donated by Merck Sharpe & Dohme are distributed via local volunteers known as community-directed distributors.

A close-up showing black flies on a blade of grass


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 medication, Sightsavers treats both of the diseases together using mass drug administration.

In 2020, Sightsavers helped to distribute more than 8 million treatments for river blindness. Since our work began 70 years ago, we’ve provided more than 529 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
A young boy stands outside his home.

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 flies, causing severe itching and skin irritation, and can eventually lead to blindness.

Luckily, it can be treated with 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 the medication 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 the tablets 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

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