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Pinworm is a parasite that lives in the intestine of humans. It appears as tiny white worms that look like thread. The female worms crawl out through the anus at night to lay eggs on the surrounding skin. They are about 1 centimeter long (size of a quarter) and may be seen near the anus 1-2 hours after the infected person goes to bed. The eggs hatch quickly, and the larvae (immature pinworm) return into the intestine.
Pinworm is common in children, and mothers of infected children. Childcare centres and other institutions often have cases of pinworm infections.
Many people who have pinworm do not have symptoms. Those with symptoms may have disturbed sleep, irritability and itching of the anus and vagina. Itching around the anus may cause scratches and skin infections.
Symptoms usually begin 2-6 weeks after an infective egg enters the body.
People can transfer infected eggs by hand from anus to mouth. Larvae from ingested eggs hatch in the small intestine. Infected eggs can also be found on surfaces such as clothing, bedding, food, or other items that may be contaminated with eggs of the parasite. The eggs can live for about 2-3 weeks outside of the body.
Pinworm can be diagnosed by looking for the pinworm eggs under a microscope. This can be done by patting the area near the anus with adhesive tape (scotch tape) before getting up in the morning. The tape is applied to a slide, sticky side down and then viewed under a microscope. It may be recommended to repeat this test 3 times to be sure that there are no eggs present and the person is not infected. Diagnosis can also be made by seeing the female worms in the anal area which can best be seen 2-3 hours after sleep.
Antiparasitic medication is effective in treating pinworm. It is recommended to treat all household members and people who share the same bed. Since the eggs can survive outside the body for 2-3 weeks, it is usually recommended to retreat in 2 weeks.
This information is intended to provide general health-related information about Pinworm. It is not intended to replace medical consultation by your physician and/or other health care professionals.
Sources: Red Book 2008, 26th edition, American Academy of Pediatrics Control of communicable Diseases Manual 2008, 19th Edition, David L. Heymann The Merck Manual of Diagnosis and Therapy, 18th Edition, Mark H. Beers, M.D. and Robert S. Porter, M.D Published 2006 Pinworms Fact Sheet, 2008, CDC Division of Parasitic Diseases.