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.

A girl at school holds a green cup and a deworming tablet, with her classmates in the background.

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.

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: World Health Organization

How are intestinal worms treated?

Medication

Intestinal worms are treated with a single dose of medication: either Albendazole® donated by GlaxoSmithKline, or Mebendazole® donated by Johnson and Johnson.

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

Volunteers

Medication is distributed to schools and communities. 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 of a child washing their hands under a water tap.

Hygiene

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

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 2022, Sightsavers treated more than 14 million people for intestinal worms, and trained more than 225,000 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.

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.

News / Fighting disease /

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.

News / Fighting disease /

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.

Blogs / Fighting disease /

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

Nine-year-old Khadijah at school with her friend after successful cataract surgery.

Nine-year-old Khadijah (right) is no longer at risk of going blind.

Will you help us ensure more children can enjoy a future free from blindness?

Want to hear more from Sightsavers? Join more than 170,000 supporters who receive inspiring emails about life-changing projects and ways to support our work.

Thank you for signing up

We’ll be in touch soon with stories about our life-changing work, plus ways for you to support Sightsavers and get involved.

You will receive regular updates about our work and can unsubscribe at any time by clicking the link in each newsletter, or by emailing [email protected]

For more information see our privacy policy

We protect sight, fight disease and make sure everyone can claim their rights.

Find out how your support can make a huge difference and change lives.

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.