Health Encyclopedia

Pinworms

Definition

Pinworms are small worms that infect the intestines. They are common in children and easy to treat.

Alternative Names

Enterobiasis; Oxyuriasis; Threadworm; Seatworm; Enterobius vermicularis; E vermicularis; Helminthic infection

Causes, incidence, and risk factors

Pinworms are the most common worm infection in the United States, primarily affecting school-age children. Pinworm eggs are spread directly from person to person or by touching bedding, food, or other items contaminated with the eggs.

Typically, children are infected by unknowingly touching pinworm eggs and putting their fingers in their mouths. The eggs are swallowed, and eventually hatch in the small intestine. The worms mature in the colon. Female worms then move to the child's anal area, especially at night, and deposit more eggs. This may cause intense itching and the area may even become infected. When the child scratches the itching anal area, the eggs can get under the child's fingernails and be transferred to other children, family members, and items in the house.

Symptoms

Intense itching around the anus
Difficulty sleeping due to the itching that occurs during the night
Irritability due to itching and interrupted sleep
Vaginal irritation or discomfort in young girls (if an adult worm enters the vagina rather than the anus)
Irritated or infected skin around the anus, from constant scratching
Loss of appetite and weight (uncommon but can occur in severe infections)

Signs and tests

Pinworms can be spotted in the anal area, especially at night when the worms lay their eggs there. Your doctor may have you do a tape test. A piece of cellophane tape is pressed against the skin around the anus, and removed. This should be done in the morning before bathing or using the toilet, because bathing and wiping may inadvertently remove any eggs. The doctor will stick the tape to a slide and look for eggs using a microscope.

Treatment

The main treatment is a single dose of either mebendazole or albendazole (anti-parasitic medication), available over-the-counter and by prescription. More than one household member is likely to be infected, so the entire household is often treated. The single dose treatment is often repeated after 2 weeks, in order to treat eggs that hatched since the original treatment.

To control egg infestation, wash hands before meals and after using the toilet, keep fingernails short and clean, wash all bed linen twice weekly, and clean toilet seats daily.

Avoid scratching the infected area around the anus, because this contaminates the fingers and everything else that is touched afterwards. Keep hands and fingers away from the nose and mouth unless they are freshly washed. Carry out these measures while family members are treated with medication.

Expectations (prognosis)

Pinworm infection is fully treatable.

Complications

Pelvic inflammatory disease
Vaginitis
Re-infestation (repeated infection with the parasite)

Calling your health care provider

Call for an appointment if you or your child have symptoms of pinworm infection, or if you have seen pinworms on your child.

Prevention

Wash hands after using the bathroom and before preparing food. Wash bedding and underclothing frequently, especially those of any affected family members.

Review Date:9/5/2006
Reviewed By:D. Scott Smith, M.D., MSc, DTM&H, Chief of Infectious Disease & Geographic Medicine, Kaiser Redwood City, CA & Adjunct Assistant Professor, Stanford University. Review provided by VeriMed Healthcare Network.

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