Pinworm Fact Sheet
Pinworms are the most common worm infection in the United States
Pinworms (Enterobius vermicularis) are small, white worms about the length of a staple that live in the rectum
of humans. About 20% of children will get pinworms. It is more common in school-age children than pre-
schoolers. Adults are rarely affected, except for parents of infected children. Infection often occurs in more
than one family member.
Anyone can get pinworms
While an infected person sleeps, female pinworms crawl out of the anus and lay their eggs on the
surrounding skin. People get pinworm infections from swallowing these eggs after touching an infected
person’s skin or personal belongings, such as clothing, bedding, and toys. Pinworms can spread as long as
the worm remains alive in the infected person. The eggs can survive up to 3 weeks on clothing and other
objects. Dogs and cats cannot transmit pinworms to people.
Signs and symptoms of pinworms may include:
Itching around the anus
Irritability and restlessness
Trouble sleeping
Loss of appetite
Some infected people have no symptoms at all.
Pinworm infections are diagnosed by the presence of eggs or adult worms
If an infection is suspected, scotch tape or a pinworm paddle (supplied by your doctor) is applied to the anal
region. The eggs stick to the tape or paddle and are later identified using a microscope. The test should be
done first thing in the morning since bathing or using the bathroom may remove the eggs. Often, the test
must be repeated 3 or more times to find the eggs and make the diagnosis. Adult worms may be seen in
stool.
Pinworm infections can be easily treated
Treatment is given in 2 doses, the second dose 2 weeks after the first. Underwear, pajamas, and bed sheets
should be changed after each treatment. Bed sheets and towels should be machine washed and dried on hot
settings. The eggs are sensitive to light, so curtains should be opened in bedrooms during the day. If the
infection comes back after treatment, the infected person and all close family members should get the same 2
dose treatment again. Exclusion from school or child care is generally not necessary, except in certain
situations.
Infestations can be prevented by reducing exposure to eggs
Wash hands before and after going to the bathroom.
Wash hands before eating.
Cut fingernails short and discourage nail biting.
Discourage scratching of bare anal areas.
Clean and vacuum living and sleeping areas.
Maryland Department of Health & Mental Hygiene Epidemiology & Disease Control Programs April 2008
