Helminth
Pinworm
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Pinworm
, Enterobius vermicularis, Enterobiasis
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
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
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
Symptoms
Perianal or perineal
Pruritus
worse at night
May also cause vaginal irritation
Restlessness at night
Signs
Small (0.5 to 1 cm) white worms at perianal area
Differential Diagnosis
See
Pruritus Ani
See
Pruritus Vulvae
Labs
Pinworm Test
Course
Self limited; resolves by 6 weeks (unless reingested)
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)
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)
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]
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