Pinworms
Pinworms: Excerpt from The 5-Minute Pediatric Consult
Terry Kind, MD
Pinworms - BASICS
Pinworms - description
- Infection by a small, white nematode (roundworm), typically Enterobius vermicularis
- Pinworms may also be caused by Enterobius gregorii in Europe, Africa, and Asia.
Pinworms - general prevention
- Decontaminate the environment by washing underclothes, bedclothes, bed sheets, and towels.
- Maintain good hand hygiene, including hand washing and proper toileting.
- Keep fingernails short and avoid nail biting.
- Treat family members and close contacts.
Pinworms - epidemiology
- Considered the most common helminthic infection of humans (the only known natural host) and the most common worm infection in US
- Occurs in school-aged children (5–10 years) and preschool children predominantly
- Does occur in adults, usually in those caring for infected children. Some individuals may be predisposed to having either heavy or light worm burdens.
- Not associated with poverty or personal hygiene
Pinworms - incidence
- US infection rates: 5–15%
- Occurs worldwide, but is more prevalent in temperate climates.
Pinworms - pathophysiology
- E. vermicularis eggs are ingested and hatch in the human’s stomach and duodenum. Then the larvae migrate to the ileum and cecum. Adult worms copulate in the cecum.
- The pregnant female pinworm migrates from the cecum to the anus ~5 weeks later and deposits eggs on the perianal skin (at which point the female pinworm usually dies). Thousands of eggs are laid, which may result in hundreds of worms.
- Pruritus is caused by the perianal deposition of eggs and a mucosal mastocytosis response. Other GI symptoms, such as anorexia or abdominal pain, may occur because of the mucosal inflammatory response.
- Granulomas may form if dead worms and eggs invoke an inflammatory response in ectopic locations such as the peritoneal cavity, vulva, cervix, uterus, and fallopian tubes.
Pinworms - etiology
Ingestion of organism via fecal–oral transmission:
- Can be spread directly, hand to mouth, or via fomites, such as toys, bedding, clothing, toilet seats, and baths
Pinworms - DIAGNOSIS
Pinworms - signs & symptoms
- Infection is characterized by perianal pruritus that occurs at night or just before waking.
- Difficulty sleeping, decreased appetite, and/or abdominal pain may occur.
Pinworms - history
- Prior pinworms or sibling with pinworms:
- Eggs can survive for several days in the environment, and the incubation period can be 1–2 months.
- Spread can occur between family members.
- Daytime itching:
- Pinworm infections usually cause perianal itching during the night or just before waking in the morning.
- Daytime perianal or perivulvar itching or irritation is likely owing to other causes.
- Fevers, diarrhea, or vomiting:
- Pinworms are highly unlikely to cause systemic symptoms (except in rare cases where they migrate aberrantly).
- Visible worms at night:
- Pinworms may be seen 2–3 hours after the child has gone to sleep. Female worms are 8–13 mm, and males are 2–5 mm.
- They may be visible as small, white worms in the perianal area at night.
Pinworms - physical exam
- Exam may be normal, and the child may be well-appearing.
- May have self-inflicted, perianal excoriation.
- Pinworms may be visible perianally.
Pinworms - tests
- Transparent tape, Scotch tape test:
- In the morning, prior to the child awakening and before defecation or washing, the adhesive side of transparent tape is applied to the perianal area.
- After removal, the tape is applied to a glass slide and examined under light microscopy for pinworm ova. Several samples may be necessary to see the pinworms.
Pinworms - lab
- Stool or urine samples for ova or parasites:
- Generally not helpful or recommended
- Very few ova present in stool (even more rare in urine)
- Blood count for eosinophilia:
- Generally not helpful or recommended
- Eosinophilia is not observed because usually there is no tissue invasion.
Pinworms - differencial diagnosis
- Infection:
- Other parasites (e.g., Strongyloides stercoralis)
- Nonparasitic vulvovaginitis (owing to bacterial or fungal causes)
- Dermatologic:
- Contact or irritative diaper dermatitis
- Irritative vulvovaginitis secondary to soaps, bubble baths, or lotions
- Anal fissures (usually cause pain rather than itching)
- Miscellaneous:
- Behavioral: Self-touching (normal)
- Sleep disorders not owing to nocturnal pruritus
- Hemorrhoids
Pinworms - TREATMENT
Pinworms - general measures
- Reinfection is common especially if not all close contacts are treated.
- Treat all symptomatic contacts, and consider treating close household contacts, especially if repeated infections have occurred.
- Infection may be asymptomatic and transmitted to others.
- Autoreinfection can occur if eggs remain under the nails.
Pinworms - medication
Single drug and dose therapy with one of the following agents:
- Mebendazole, 100 mg (available as a chewable tablet) PO once, may repeat in 2 weeks if symptoms still present
- Pyrantel pamoate, 11 mg/kg (maximum 1 g) PO once, may repeat in 2 weeks
- Albendazole, 400 mg PO once, may repeat in 2 weeks
- Experience is limited in children <2 years of age. Consider risks and benefits before use.
- Caution in treating pregnant individuals with antihelminthic medications because medendazole, pyrantel pamoate, and albendazole are all category C and are not recommended in pregnancy.
Pinworms - FOLLOW UP
Pinworms - prognosis
- Reinfection is common.
- With appropriate treatment, symptoms resolve within a few days.
- Any chronic symptoms are likely to be owing to recurrence rather than chronic infection, because the life cycle of the adult worm is short, with eggs being laid by the adult worm within 5 weeks.
Pinworms - complications
- Urethritis
- Vulvovaginitis
- Granuloma formation
- Pelvic inflammatory disease
- Bacterial superinfection of perianal excoriations
- Appendicitis (uncommon)
Pinworms - patient monitoring
Watch for signs of reinfection.
Pinworms - bibliography
American Academy of Pediatrics. Pinworm infection (Enterobius vermicularis). In: Pickering LK, ed. Red Book: 2006 Report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006, 520–522.- 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. 2004;20(5):372–375.
- Drugs for parasitic infections. Med Lett Drugs Ther. 2004:1–12. Available at http://www.medletter. com/freedocs/parasitic.pdf.
- Elston DM. What’s eating you? Enterobius vermicularis (pinworms, threadworms). Cutis. 2003;71:268–270.
- Grencis RK, Cooper ES. Enterobius, trichuris, capillaria and hookworm including Ancylostoma caninum. Gastroenterol Clin North Am. 1996;25:579–597.
Pinworms - CODES
Pinworms - icd9
127.4 Pinworm
Pinworms - FAQ
- Q: Could the child have acquired pinworms from a pet dog or cat?
- A: No, household pets are not involved in the life cycles of pinworms.
- Q: When can an infected child return to day care?
- A: After receiving the 1st treatment dose, the child can return to school or day care. It is prudent to bathe the child and to trim and scrub his or her nails prior to school re-entry.
- Q: Is it necessary to re-evaluate and retest a child once treated?
- A: No. However, reinfection is common.
- Q: Can pinworm eggs survive on bedding, toilet seats, or clothing?
- A: Yes, eggs can remain infectious in an indoor environment for up to 3 weeks.
- Q: Does pinworm infection cause nocturnal bruxism?
- A: There is no proof of any causal relationship.
- Q: How do the antihelminthic medications work?
- A: They inhibit microtubule function and cause glycogen deletion in the adult worms.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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