Threadworm (pinworm)

Reviewed by Dr Stuart Crisp, paediatric specialist registrar and Dr John Pillinger, GP

What is threadworm?
Threadworm (Enterobius vermicularis) is the most common worm infection. Both children and adults can be infected, although it is mostly found in children.

How does infection spread?
Threadworm is passed from person to person and is usually spread via children.

The female worms lay eggs on a person's skin around the anus. This leads to itching and scratching of the area and then leads to eggs being transferred onto the fingers.

The eggs can then be passed by direct contact, or through sharing toys, pencils and food, etc.

Good hygiene is essential to stop the infection being spread, including washing hands and scrubbing under the nails before eating and after visiting the toilet.

Eggs can survive in dust for two weeks, which may lead to infection by inhaling dust. Children in childcare institutions are easily infected by each other.

Symptoms
Threadworm begins with an itchy feeling around your anus (back passage), usually at night under warm sheets. Without treatment threadworm may give rise to vaginitis (inflammation of the vagina) in girls and women. You can often see threadworms, a 1cm thread-like worm, in your child's stools or their bottom.

Treatment
Infected children or adults should be treated as soon as possible. The rest of the family should also be treated at the same time. Threadworm can be treated with one of two medicines, mebendazole or piperazine, both of which can be bought over the counter from pharmacies. Both medicines can be given as a single dose. Your pharmacist can give you appropriate advice.

Children under two years of age will need to be seen by a doctor. One treatment is usually enough.

Children can still go to school or childcare, in spite of having threadworms.

What can be done to control threadworms?

• If you have threadworms, it is important to shower in the morning in order to remove eggs and bacteria from the anal area.
• Wash your hands thoroughly after each visit to the bathroom and before each meal.
• Underwear should be changed daily.
• Bedsheets should be changed frequently, especially 7 to 10 days after the treatment.
• Infected children and adults should keep their nails short.
• Infected children should ideally wear cotton gloves when sleeping.
• Clean your home thoroughly, especially the bedrooms, and remove as much dust as possible.
• Do not eat food in your bedroom.
• If several family members are infected, you should all be treated on the same day.
• Avoid food and drinks containing a lot of sugar, and eat high-fibre food to prevent constipation.

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