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Pinworms is a topic covered in the 5-Minute Clinical Consult.

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  • Intestinal infection with Enterobius vermicularis
    • Characterized by perineal and perianal itching
    • Usually worse at night
  • System(s) affected: gastrointestinal; skin/exocrine
  • Synonym(s): enterobiasis


Predominant age: 5 to 14 years

  • Most common helminthic infection in the United States
    • 20 to 42 million people harbor the parasite.
  • ~30% of children are infected worldwide.

Pediatric Considerations
More common in children, who are more likely to become reinfected.

Etiology and Pathophysiology

  • Small white worms (2 to 13 mm) inhabit the cecum, appendix, and adjacent portions of the ascending colon following ingestion.
  • Female worms migrate to the perineal areas at night to deposit eggs; this causes local irritation and itching.
  • Scratching leads to autoingestion of the eggs and continuation of pinworm’s life cycle within the host. Eggs incubate 1 to 2 months in the host small intestine. When mature, female pinworms migrate to the colon where they lay eggs around the anus at night, and the lifecycle continues.
  • Infestation by the intestinal nematode E. vermicularis

Risk Factors

  • Institutionalization
  • Crowded living conditions
  • Poor hygiene
  • Warm climate
  • Handling of infected children’s clothing or bedding

General Prevention

  • Hand hygiene, especially after bowel movements
  • Clip and maintain short fingernails.
  • Wash anus and genitals at least once a day, preferably during shower.
  • Avoid scratching anus and putting fingers near nose (pinworm eggs can also be inhaled) or mouth.

Commonly Associated Conditions

Pruritus ani

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Stephens, Mark B., et al., editors. "Pinworms." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms.
Pinworms. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms. Accessed April 24, 2019.
Pinworms. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms
Pinworms [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 24]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Pinworms ID - 116456 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -