Pinworm eggs
Pinworm eggs
Pinworm, close-up of the head
Pinworm, close-up of the head
Pinworms
Pinworms

Pinworm

Definition:
A common intestinal parasitic infection which primarily affects children.

Alternative Names:
Enterobiasis; Oxyuriasis; Pinworm infection

Causes, incidence, and risk factors:
Pinworm infection is due to the small worm called Enterobius vermicularis. It is the most common worm infection in the United States and it most commonly affects school-age children. Its only reservoir are humans, and it is transmitted from person-to-person by ingesting eggs (oral-fecal route), or by contact with contaminated bedding, food, or other items. Upon ingestion of eggs, larvae eventually hatch in the small intestine and worms then mature in the colon. Female worms then migrate to the anal area especially at night and deposit their eggs -- which may lead to itching and sometimes infection of the involved area.
Symptoms:
  • intense itching around the anus
  • irritability (usually caused by itching and interruption of sleep at night)
  • sleep disturbance (usually due to itching that occurs during the night when the adult worms migrate out through the anus to lay their eggs)
  • decreased appetite and weight loss (this is uncommon but can occur in severe infections)
  • vaginal irritation or discomfort in young girls (if an adult worm enters the vagina rather than the anus)
  • excoriation and irritation of the skin or infection around anus from constant scratching
Signs and tests:
Pinworms may be spotted on inspection of the anal area as the worms will often lay their eggs in the adjacent anal area in particular at night.

TAPE TEST:
A sample is collected by pressing a piece of cellophane tape against the skin around the anus, then sticking the tape to a microscope slide for later observation. This should be done in the morning before bathing or using the toilet as the eggs may be inadvertently removed. The slide is then placed under the microscope and observed for pinworm eggs. The presence of eggs is diagnostic.
Treatment:

The mainstay of treatment is antiparasitic medication such as pyrantel pamoate, mebendazole or albendazole. As more than one household member is likely to be infected, treatment of the entire household is often recommended. In addition, treatment is often repeated after 2 weeks.

General measures to control infestation are washing hands before meals and after use of the toilet, keeping fingernails short and clean, laundering all bed linen twice weekly, and cleaning toilet seats daily. Avoid scratching the infected area (area around the anus) as this contaminates the fingers and everything else that they subsequently touch. 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 and carries an excellent prognosis.
Complications:
Calling your health care provider:
Call for an appointment with your health care provider if symptoms of pinworm infection develop or if you have seen pinworms on your child.
Prevention:
Good personal hygiene with emphasis on washing hands after using the bathroom and before preparing food is essential. Minimizing overcrowding, frequent washing of bedding and underclothing in particular of affected individual is also important.

Review Date: 11/24/2001
Reviewed By: Rocio Hurtado, M.D., Infectious Diseases Division, Massachusetts General Hospital and Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.
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