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What are intestinal worms?

Intestinal worms, also called ‘soil-transmitted helminth infections’ or STH, are part of a group of parasitic and bacterial conditions known as neglected tropical diseases.

Helminths are worm-like intestinal parasites that live inside the digestive system and feed off nutrients from their host, causing the infected person to become malnourished and susceptible to disease and chronic illness.

Adult worms live in a person’s intestine, where they produce thousands of eggs each day. The infection is spread when eggs are passed in human faeces and contaminate the soil – a problem that is common in poor communities with inadequate sanitation. The eggs can be ingested when contaminated soil is found on unwashed vegetables, water sources or unwashed hands.

At first, symptoms of intestinal worms may be mild or non-existent, but infections can lead to diarrhoea, abdominal pain, weakness, anaemia and nutritional problems. The disease can affect cognitive and physical development, and in severe cases can be fatal.

As well as the physical symptoms, intestinal worms can decrease people’s quality of life, affecting their employment, education, fertility and happiness. Children may be forced to miss school, damaging their education and development.

Watch our video to learn more about intestinal worms.

1.5 billion people worldwide are infected with intestinal worms

Children aged about three to eight are most at risk

600 million school-age children live in at-risk areas

Source: WHO

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How are intestinal worms treated?

A health worker holds a pot of pills and pours some out into his hands.

Medication

Intestinal worms are treated with a single dose of medication donated by GlaxoSmithKline or Johnson and Johnson. Medication is distributed to schools and communities.

A community volunteer distributed treatment to protect against neglected tropical diseases to a woman.

Volunteers

Specially-trained school teachers play a key role in distributing and administering these vital treatments to school-age children in at-risk areas.

A close up photo of someone washing their hands.

Hygiene

Our deworming work also includes educating people about good hygiene. Access to clean water is vital to stop the disease spreading in communities.

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A school student smiles in the classroom. She's wearing a mask on her chin.
A school student smiles in the classroom. She's wearing a mask on her chin.

“I’ve had worms before. I didn’t feel well and I had a fever. My tummy was reeling.”

Norbertine, a student from Cameroon

What we’re doing

Sightsavers aims to control intestinal worms in the countries in which we’re running deworming programmes. These countries include Cameroon, Democratic Republic of Congo, Nigeria and Guinea.

Intestinal worms can cause symptoms such as anaemia, intestinal obstruction, inflammation of the colon, impaired development, and even death. Our NTD programmes aim to target entire communities of at-risk men, women and children to eliminate these diseases.

In 2023, Sightsavers treated more than five million people for intestinal worms, and trained more than 100,000 local volunteers to distribute medication through mass drug administration to treat a range of neglected tropical diseases, including intestinal worms. Medication is also distributed in schools, and the disease is frequently treated at the same time as schistosomiasis.

As part of our community and school programmes, we aim to educate local communities about the importance of hygiene to stop the spread of disease. Access to and use of clean water and sanitation, as well as good hygienic practices such as wearing shoes and washing hands, is vital for preventing and controlling the spread of intestinal worms.

A school student in a classroom is handed a tablet by a health worker, as other health workers and his classmates look on.

How we’re making a difference

Sightsavers works closely with GiveWell to deliver cost-effective treatments that protect children from schistosomiasis and intestinal worms.

Our work with Givewell

Page last reviewed: October 2024
Next review due: October 2027
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Find out about other diseases we treat

Neglected tropical diseases

More about intestinal worms

A school student in a classroom is handed a tablet by a health worker, as other health workers and his classmates look on.

Sightsavers’ deworming work gets $16.9 million funding boost

Sightsavers has been awarded $16.9 million to continue and expand its deworming work, after a funding recommendation from US charity evaluator GiveWell.

May 2023
A schoolboy receives medication from a female teacher.

Sightsavers’ deworming work receives extra funding to reach millions of children

Charity evaluator GiveWell has provided a further US$7.8 million to fight intestinal worms and schistosomiasis in Nigeria and Cameroon.

March 2022
A screengrab from a video chat, showing Alyssa Marriner and Cosmas Ejong.
Sightsavers blog

How can deworming change the world?

Ndellejong Cosmas Eljong, Sightsavers’ technical adviser for schistosomiasis and intestinal worms, tells us via video about his work to fight parasitic worm infections and how deworming can have a huge impact on communities around the world.

Sightsavers, November 2021