Pinworm Infection
Pinworm infection (enterobiasis) is a disease caused by intestinal roundworms.
Pinworms are the most common parasite in children in the United States.
Infection follows ingestion of pinworm eggs (ova). Eggs can be transferred from the area around the anus of an infected child to clothing, bedding, or toys. Eggs can survive outside the body for as long as 3 weeks at normal room temperature. These eggs can be transferred, often by the fingers, to the mouth of another child, who swallows them. Eggs sometimes are ingested in contaminated food. Children may reinfect themselves by transferring eggs from the area around the anus to their mouth. Children who suck their thumbs are at increased risk of infection.
After ingestion, the eggs hatch in the intestinal tract, and young worms migrate to the rectum and lower intestine. Pinworms mature in the lower intestine within 2 to 6 weeks. The female worm then moves to the area around the anus, usually at night, to deposit her eggs. The eggs are deposited in a sticky, gelatinous substance that adheres to the skin. The eggs and gelatinous material cause itching.
Symptoms and Diagnosis
Most children who carry pinworms have no symptoms. Some, however, feel an itching sensation around the anus and scratch the area. The skin can become raw and superficially infected with bacteria. In girls, pinworms may cause vaginal itching and irritation.
The diagnosis of pinworm infection is made by finding the worms or eggs. The search for adult pinworms is best conducted by examining the child's anus about 1 to 2 hours after the child has been put to bed for the night. The worms are white and hair-thin, but they wiggle and are visible to the naked eye. Eggs can be obtained by patting the skin folds around the anus with the sticky side of a strip of transparent tape in the early morning before the child wakes up. The tape can be taken to the doctor for microscopic examination.
Treatment
A single dose of mebendazole, albendazole, or pyrantel pamoate, repeated after 2 weeks, effectively cures pinworm infection. Many doctors recommend treating the entire family. Despite drug therapy, reintroduction of the disease is common after treatment. Clothing, bedding, and toys should be washed and the environment vacuumed to try to eliminate any eggs. Anti-itching creams or ointments applied directly to the area around the anus may provide relief from itching.
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