Threadworms, also known as pinworms, are tiny parasitic worms that hatch eggs in and infect the large intestine of humans.
Threadworms are the most common type of worm infection in the UK, and they are particularly common in young children, infecting up to half of all children under the age of 10.
Threadworms are white and look like a small piece of thread. You may notice them around your child's bottom or in your or your child's stools (poo).
They don't always cause symptoms. Some people notice itchiness around their anus (back passage) or vagina, which can be worse at night and can sometimes disturb sleep.
Read more about the symptoms of threadworms.
You can treat threadworms yourself with medication available at pharmacies. However, treatment does not kill the eggs hatched by threadworms. Good hygiene is the only way to prevent the eggs from spreading and causing further infection.
See your GP if you think that you have threadworms and:
- You're pregnant or breastfeeding.
- Your child has threadworms and they are under the age of two.
How are threadworms spread?
Threadworms are spread from person-to-person as a result of poor hygiene. If one member of a household is infected, there is a high risk that other members will also be infected.
It is therefore necessary to treat the entire household and to practise particularly thorough hygiene for six weeks (this is how long the worms live) to prevent re-infection.
Read more about treating threadworm infections.
Preventing threadworms
Threadworms can be prevented from occurring by always maintaining good hygiene.
Children should wash their hands regularly, particularly after going to the toilet and before mealtimes. Kitchen and bathroom surfaces should be kept clean.
Encouraging your children not to scratch the affected area around their anus or vagina (in girls) will help prevent re-infection and help to avoid a skin infection.
As itching is worse at night, wearing cotton gloves while sleeping may help.
Threadworm life cycle
Threadworms lay their eggs around an infected person's anus (back passage), usually at night. Along with the eggs, the worm also secretes a mucus that causes itching.
If the eggs get stuck on the person’s fingertips when they scratch, they can be transferred to their mouth or onto surfaces and clothes. Other people who touch an infected surface can then transfer the eggs to their mouth.
Threadworm eggs can survive for up to three weeks before hatching. If the eggs hatch around the anus, the newly born worms can re-enter the bowel. Eggs that have been swallowed will hatch inside the intestine. After two weeks, the worms reach adult size and begin to reproduce, starting the cycle again.
Humans are thought to be the only host for threadworms. Animals can't catch or pass on threadworms, unless the eggs are transported on the animal’s fur after contact from an infected person.
Read more about what causes threadworms.
