Epidemiology & Risk Factors
- Most common helminthic infection in the US.
- Most frequent in school-aged children (5–10 y/o), institutionalized individuals, daycare settings.
- Transmission: Fecal-oral route (ingestion of eggs via contaminated hands, clothing, bedding; autoinfection via perianal scratching).
Clinical Features
- Perianal pruritus: Predominantly nocturnal (female worm migrates to perianal skin to deposit eggs at night).
- Restless sleep, insomnia, irritability.
- Vulvovaginitis / pelvic inflammation in young females (due to retrograde worm migration into genital tract).
- Perianal excoriations secondary to scratching.
Diagnosis
- Initial & Confirmatory Test: Clear adhesive tape test (Scotch tape test) or perianal swab.
- Performed early in the morning before bathing or defecation.
- Microscopic identification of oval eggs with one flattened side.
- Key Labs: Normal peripheral eosinophil count (non-invasive tissue parasite; remains confined to GI lumen).
Differential Diagnostics
- Perianal Streptococcal Dermatitis: Diff by bright red, sharply demarcated perianal erythema, severe painful defecation, (-) tape test.
- Ascaris lumbricoides: Diff by pulmonary phase (Löffler syndrome with cough/eosinophilia), intestinal obstruction, non-nocturnal symptoms.
- Trichuris trichiura (Whipworm): Diff by rectal prolapse, bloody diarrhea, anemia, barrel-shaped eggs with bipolar plugs on stool O&P.
- Atopic/Contact Dermatitis: Diff by skin lesions elsewhere, absence of eggs on microscopic exam.
Management
- First-Line Anthelmintic Therapy:
- Pyrantel pamoate (OTC option) OR Albendazole / Mebendazole (single oral dose). c
- Repeat Treatment:
- Repeat initial dose in 2 weeks to eradicate newly hatched larvae (drugs kill adult worms, not eggs).
- Household Contacts:
- Treat all household members simultaneously regardless of symptoms to prevent reinfection.
- Hygiene Measures:
- Wash all bed linen, towels, and clothing in hot water.
- Keep fingernails short and clean.
Complications
- Secondary bacterial skin infections (e.g., Impetigo, Cellulitis) from scratching.
- Vulvovaginitis, salpingitis, pelvic peritonitis (rare migration).
- Appendicitis (rare luminal obstruction by adult worms).