Introduction
Background
Enterobius vermicularis (pinworm) is the most common intestinal parasite in the United States. Despite primarily living in the gut, the most common chief complaint is anal itching (pruritus). Most patients, however, are asymptomatic.
Pathophysiology
E vermicularis lives in the small intestines, primarily the ileocecal region. The gravid female migrates to the anus and deposits eggs in the perianal skin folds, usually at nighttime. 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.
Frequency
United States
E vermicularis is the most common helminth in the United States. General prevalence in children is reported to be 0.2-20%. Prevalence in institutionalized persons is reported to be 50-100%.
International
Similar prevalence has been reported in European countries.
Mortality/Morbidity
Pinworm infestation is very rarely fatal; death and morbidity are from secondary infection. A 28-68% increased risk for appendicitis is associated with pinworm infestation.1
Sex
Overall, males are affected twice as often as females are except in people aged 5-14 years, when females predominate.
Age
School-aged children have the highest prevalence.
Clinical
History
- Most patients are asymptomatic.
- The most common complaint is anal itching (pruritus), usually nocturnal or in the early morning.
- Other possible complaints include the following:
- Abdominal pain (even mimicking an acute surgical process)
- Irritability
- Restlessness
- Vaginal itching
- Pelvic pain
Physical
- Perianal excoriations secondary to scratching may be found.
- The pale-colored female pinworm (10 mm; male 3 mm) may be visibly seen in the perianal region.
- Eggs (30 μ m X 50-60 μ m) are usually not seen without a microscope.
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| Treatment & Medication: Pinworms |
| Follow-up: Pinworms |
| Multimedia: Pinworms |
| References |
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References
Ramezani MA, Dehghani MR. Relationship between Enterobius vermicularis and the incidence of acute appendicitis. Southeast Asian J Trop Med Public Health. Jan 2007;38(1):20-3. [Medline].
Ajao OG, Jastaniah S, Malatani TS, et al. Enterobius vermicularis (pin worm) causing symptoms of appendicitis. Trop Doct. Jul 1997;27(3):182-3. [Medline].
Arca MJ, Gates RL, Groner JI, et al. Clinical manifestations of appendiceal pinworms in children: an institutional experience and a review of the literature. Pediatr Surg Int. May 2004;20(5):372-5. [Medline].
Aydin O. Incidental parasitic infestations in surgically removed appendices: a retrospective analysis. Diagn Pathol. 2007;2:16. [Medline].
Erian M, McLaren G. Unexpected causes of gynecological pelvic pain. JSLS. Oct-Dec 2004;8(4):380-3. [Medline].
Hong ST, Choi MH, Chai JY, Kim YT, Kim MK, Kim KR. A case of ovarian enterobiasis. Korean J Parasitol. Sep 2002;40(3):149-51. [Medline].
Hugot JP, Reinhard KJ, Gardner SL, Morand S. Human enterobiasis in evolution: origin, specificity and transmission. Parasite. Sep 1999;6(3):201-8. [Medline].
Jardine M, Kokai GK, Dalzell AM. Enterobius vermicularis and colitis in Children. J Pediatr Gastroenterol Nutr. Nov 2006;43(5):610-2. [Medline].
Jeske J, Kamerys J, Ochecka-Szymanska A. Efficacy of mebendazole in treatment of selected parasitoses--a retrospective study. Wiad Parazytol. 2000;46(1):127-39. [Medline].
Gilbert DN, Moellering RC, Eliopoulos GM, et al. The Sanford Guide to Antimicrobial Therapy 2007. Sperryville, Va: Antimicrobial Therapy Inc; 2007:127,133.
Further Reading
Keywords
Enterobiasis vermicularis, pinworm, intestinal parasite, anal itching, pinworm infestation
