What is the pathogenesis of pinworm infection (enterobiasis)?

Updated: Jul 17, 2019
  • Author: Sun Huh, MD, PhD; Chief Editor: Michael Stuart Bronze, MD  more...
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The primary symptoms of pinworm infection include pruritus or a prickling sensation in the perianal area, which is produced when a gravid female pinworm migrates to the anal area and inserts her tail pin into the mucosa for ovideposition, usually at nighttime. E vermicularis lives in the small intestines, primarily the ileocecal region.

The movement of the female and the ova cause intense local itching. Ova may survive for up to 3 weeks before hatching. The hatched larvae can then migrate back into the anus and lower intestine, causing retroinfection. Embryonated eggs may be released into the air or onto fomites (eg, bedding, clothing, toys, paper money) or onto hands and then placed directly into the mouth and swallowed (autoinfection), after which they settle in the small intestines.

Pinworms that inhabit the cecum and adjacent areas typically cause no symptoms. Diarrhea due to inflammation of the bowel wall can occur during acute infection. Although pinworms have been found in the region of the appendix during histologic studies of acute appendicitis, the relationship is most likely incidental. [2]

Risk factors for pinworms include living with a person who is egg-positive, eating before washing hands, and poor personal or group hygiene.

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