A pinworm infection happens when a person has pinworm parasites living in the intestine.
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The infection is caused by a specific type of small, thin, white roundworm. They look like a piece of thread and are about the size of a staple.
The infection spreads when a person eats the eggs of the worm. This can happen from contact with the stool of an infected person. It can also happen by touching clothing, bedding, food, or other items that contain them.
This problem is more common in children under 14 years of age. Other things that may raise the risk are:
Most people do not have symptoms. Those who do may have:
The doctor will ask about your symptoms and health history. A physical exam will be done. The doctor may see the pinworms in the area between the anus and genitals. This is enough to make the diagnosis.
Other people may need a tape test to look for pinworm eggs. A person may be asked to do the test at night when the pinworms are most active. A piece of clear tape is placed over the anus and removed. Any eggs will appear on the tape.
The doctor may also look for eggs by taking samples from under a person's fingernails.
A pinworm infection is treated with medicines.
To lower the risk of infection:
Healthy Children—American Academy of Pediatrics
National Institute of Allergy and Infectious Diseases
The College of Family Physicians of Canada
Enterobiasis. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/enterobiasis-pinworm-infection. Accessed November 25, 2020.
Parasites—enterobiasis (also known as pinworm infection). Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/parasites/pinworm. Accessed November 25, 2020.
Pinworm infestation. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/infectious-diseases/nematodes-roundworms/pinworm-infestation. Accessed November 25, 2020.
Truscott J, Abebe A, et al. Recognizing common parasitic infestations. JAAPA. 2017 May;30(5):1-6.
Last reviewed September 2020 by
EBSCO Medical Review Board
Marcin Chwistek, MD
Last Updated: 4/23/2021