Pinworm Infection

What is pinworm infection?

This infection is caused by a small, white intestinal worm called Enterobius vermicularis (EN-ter-O-be-us ver-MIK-u-lar-is). Pinworms are about the length of a staple and live in the rectum of humans. While an infected person sleeps, female pinworms leave the intestines through the anus and deposit eggs on the surrounding skin.

What are the symptoms of a pinworm infection?

Itching around the anus, disturbed sleep, and irritability are common symptoms. If the infection is heavy, symptoms may also include loss of appetite, restlessness, and difficulty sleeping. Symptoms are caused by the female pinworm laying her eggs. Most symptoms of pinworm infection are mild; many infected people have no symptoms.

Who is at risk for pinworm infection?

Pinworm is the most common worm infection in the United States. School-age children, followed by preschoolers, have the highest rates of infection. In some groups nearly 50% of children are infected. Infection often occurs in more than one family member. Adults are less likely to have pinworm infection, except mothers of infected children. Child care centers, and other institutional settings often have cases of pinworm infection.

How is pinworm infection spread?

Pinworm eggs are infective within a few hours after being deposited on the skin. They can survive up to 2 weeks on clothing, bedding, or other objects. You or your children can become infected after accidentally ingesting (swallowing) infective pinworm eggs from contaminated surfaces or fingers.

How is pinworm infection diagnosed?

If pinworms are suspected, transparent adhesive tape (often called the "scotch tape test") or a pinworm paddle (supplied by your health care provider) are applied to the anal region. The eggs become glued to the sticky tape or paddle and are identified by examination under a microscope. Because bathing or having a bowel movement may remove eggs, the test should be done as soon as you wake up in the morning. You may have to provide several samples to your health care provider for examination. Since scratching of the anal area is common, samples taken from under the fingernails may also contain eggs. Eggs are rarely found during lab examinations of stool or urine. At night, the adult worms can sometimes be seen directly in bedclothes or around the anal area.

Pinworm Infection Symptoms

What are the symptoms of pinworms?

Intense itching around the anus and/or vagina are the classic symptoms of pinworms. Less common pinworm infection symptoms range from

  • upset stomach to loss of appetite,
  • irritability, restlessness, and
  • insomnia.

Most infected individuals have few or no symptoms but, if the infection is heavy, the symptoms can be correspondingly more severe.

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