Enterobius vermicularis

Background

• Small, thin, white nematode
  • Adult females are 9 to 12 mm long, and adult males are 3 to 5 mm long
• Spread by fecal-oral route
• More common in preschool and school-aged children, institutionalized people, and household contacts of an index case

Clinical Manifestations

• Pruritus ani, or itching around the anus
• Excoriations can become secondarily infected

Diagnosis

• Stool microscopy may miss the eggs, since they are deposited outside the colon
• Diagnostic test of choice is the scotch tape test
  • in the morning, before washing or pooping
  • Press a piece of scotch tape about 2 x 10 cm against the anal and perianal regions several times
  • Stick the tape onto a slide
  • Microscopy can confirm the diagnosis
• Premade kits are available from labs and pharmacies

Management

• Antihelminthics:
  • Albendazole 200-400 mg p.o. once, repeated at 2 weeks
  • Pyrantel pamoate 10 mg/kg (max 1 g) p.o. once, repeated at 2 weeks
  • Mebendazole 100-200 mg p.o. once, repeated at 2 weeks
  • Others:
    • Pyrvinium embonate 5 mg/kg (max 400 mg) p.o. once, repeated at 2 to 4 weeks
    • For urogenital infections only: ivermectin 200 mcg/kg p.o. once, repeated at 2 to 4 weeks
• For chronic infections, the doses may need to be repeated every 2 weeks for up to 4 months
• Non-pharmacologic management should include handwashing and frequent changing and washing of underwear, pajamas, and bedsheets in order to prevent reinfection or transmission to other household members