II. Epidemiology
- Most common in children ages 5 to 14 years
- Most common Helminth infection in the United States
-
Prevalence: 209 million children infected worldwide
- Worldwide, 30% of children are infected
III. Pathophysiology
- Intestinal roundworm (nematode) infection
- Humans are only known host
- Transmission
- Fecal-oral transmission of eggs
- Larvae hatch in duodenum
-
Worms live in ascending colon at cecum
- Female worms migrate to perineum at night
- May lay up to 15,000 eggs nightly
- Majority of eggs dry-out within 3 days
IV. Transmission
- Ingestion of Pinworm ova (20 day viability)
- Passed by fomites (hands, clothing, house dust)
- Female worms migrate to anus at night to deposit eggs
V. Symptoms
- Perianal or perineal Pruritus worse at night
- May also cause vaginal irritation
- Restlessness at night
VI. Signs
- Small (0.5 to 1 cm) white worms at perianal area
VII. Differential Diagnosis
- See Pruritus Ani
- See Pruritus Vulvae
VIII. Labs
IX. Course
- Self limited; resolves by 6 weeks (unless reingested)
X. Management
- Pyrantel pamoate (Pin-Rid, OTC)
- Dose: 11 mg/kg up to 1 gram PO for 1 dose
- Repeat dose in 2 weeks
- Avoid in pregnancy or age under 2 years old
- Available as over-the-counter medication, and only $20 per 2 dose course
- Mebendazole (Vermox, Emverm)
- Dose: 100 mg chewable for 1 dose
- Repeat dose in 2 weeks (per CDC and despite package insert)
- Avoid in first trimester of pregnancy or age under 1 year old
- Was not available as of 2012, and available as of 2016 at $740/course
- Albendazole (Valbazen, Albendazole)
- Dose: 400 mg PO for 1 dose
- Repeat dose in 2 weeks (age 2 or older)
- Avoid in first trimester of pregnancy or age under 1 year old
- As with Mebendazole, very expensive in U.S. (>$600/course)
XI. Management: Other measures
- Treat household contacts (esp. if 2 or more members affected)
- Encourage Hand Washing and morning shower or bath
- Clean all linen, clothing in hot water (eggs survive 2-3 weeks on objects)
XII. References
- Gilbert et al (2016) Sanford Guide to Antimicrobial Therapy, accessed IOS app 5/4/2016
- Kazura in Behrman (2000) Nelson Pediatrics, p. 1067-8
- (2016) Presc Lett 23(5): 28
- (2012) Presc Lett 19(3): 16
- Markell (1985) Pediatr Clin North Am 32(4):971-86 [PubMed]