AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

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

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

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 μm X 50-60 μm) are usually not seen without a microscope.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Other Problems to be Considered

Roundworms
Yeast dermatitis

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Lab Studies

• Glass slide microscopic analysis may be performed to look for ova and female pinworms.
• • A specimen is best obtained by dabbing the stretched, unwashed perianal folds in the early morning with cellophane tape and affixing on to a slide.
  • A negative test for 5 consecutive mornings effectively rules out the diagnosis.
• Stool specimens are rarely diagnostic and are not indicated.
• In areas where pinworms are endemic, consider analyzing any removed appendiceal stump for infestation.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Emergency Department Care

• Antihelmintic treatment benefit must be weighed with the risk of adverse effects and the possibility of reinfection, which is seldom harmful.
• Strict handwashing is required after contact with patient, patient clothing, and stretcher.
• All bedding and gowns should be cleaned.
• Stretchers should be washed before further patient use.
• The entire household should be treated simultaneously.
• Treat itch, irritation, and excoriation symptomatically.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

It is important to empirically cover the entire household simultaneously for pinworms when a decision is made to treat.

Drug Category: Anthelmintics

Parasite biochemical pathways are sufficiently different from the human host to allow selective interference by chemotherapeutic agents in relatively small doses.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Further Outpatient Care

• Follow-up is recommended if the symptoms persist longer than 2 weeks or if signs of bacterial superinfection occur.

Complications

• Appendicitis
• Endometritis
• Impetigo or excoriations from perianal scratching
• Salpingitis
• Urethritis
• Urinary tract infection
• Vulvovaginitis

Prognosis

• Asymptomatic carriers are common.
• The cure rate with treatment is 90-95%.
• Re-infection is common, especially if not all contacts are treated simultaneously.

Patient Education

• Discharge instructions should include the following:
• • Strict handwashing should be completed after using the toilet or changing a diaper of an affected baby and before and after eating for 2 weeks.
  • All bedding and toys should be cleaned every 3-7 days for 3 weeks.
  • Underwear and pajamas should be washed daily for 2 weeks.
• For excellent patient education resources, visit eMedicine's Parasites and Worms Center and Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles, Pinworms and Anal Itching.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Media file 1:  Pinworms in a young patient.
	View Full Size Image
Media type:  Photo

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

1. 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].
2. 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].
3. 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].
4. Aydin O. Incidental parasitic infestations in surgically removed appendices: a retrospective analysis. Diagn Pathol. 2007;2:16. [Medline].
5. Erian M, McLaren G. Unexpected causes of gynecological pelvic pain. JSLS. Oct-Dec 2004;8(4):380-3. [Medline].
6. 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].
7. Hugot JP, Reinhard KJ, Gardner SL, Morand S. Human enterobiasis in evolution: origin, specificity and transmission. Parasite. Sep 1999;6(3):201-8. [Medline].
8. Jardine M, Kokai GK, Dalzell AM. Enterobius vermicularis and colitis in Children. J Pediatr Gastroenterol Nutr. Nov 2006;43(5):610-2. [Medline].
9. 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].
10. Gilbert DN, Moellering RC, Eliopoulos GM, et al. The Sanford Guide to Antimicrobial Therapy 2007. Sperryville, Va: Antimicrobial Therapy Inc; 2007:127,133.

Article Last Updated: Nov 1, 2007