Pinworms
Basics
Description
- Intestinal infection with Enterobius vermicularis
- Characterized by perineal and perianal itching
- Usually worse at night
- System(s) affected: gastrointestinal; skin/exocrine
- Synonym(s): enterobiasis
Epidemiology
Predominant age: 5 to 14 years
Prevalence
- 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; associated with multiple case reports of appendicitis
- 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 (1)
Risk Factors
- Institutionalization (prevalence >50%)
- 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
- Appendicitis
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Citation
Domino, Frank J., et al., editors. "Pinworms." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms.
Pinworms. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms. Accessed October 15, 2024.
Pinworms. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms
Pinworms [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 October 15]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116456/all/Pinworms.
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