Two pinworms next to a ruler: The markings are 1 mm apart.
  • Colloquially known as Pinworm (United States), Treadworm (UK and Australia) or Seatworm
    • Medical infectious name: Enterobiasis
  • Worldwide distribution
  • Risk factors (prevalence can reach up to 50% in these populations):
    • Age under 18
    • Institutionalized
    • Cohabitation with infected individual
  • Humans only known reservoir
  • Transmitted by fecal-oral route
  • Can survive outside of body for up to 3 weeks

Clinical Features

Differential Diagnosis

  • Idiopathic pruritus ani
  • Rectal tenesmus

Helminth infections

Cestodes (Tapeworms)

Trematodes (Flukes)

Nematodes (Roundworms)


  • Tape test
    • Most common
    • Touch transparent tape to the perianal region and examine for eggs under the microscope
  • Can also test by examining scrapings under patient's fingernails or examining perianal region 2-3 hours after patient falls asleep
  • Stool analysis does not work because of low egg burden in stool



Treatment targeted against Enterobius vermicularis

  • Mebendazole 100mg PO once THEN repeat in 2 weeks OR
  • Albendazole 400mg PO once (100mig if < 2yo) THEN repeat in 2 weeks OR
  • Pyrantel Pamoate (Pin-x) 11mg/kg (max 1g) THEN repeat in 2 weeks
    • Recommended for pregnant patients
  • All family members should be treated at the same time


  • Carefully hand washing after using the toilet, and before and after eating
  • Thoroughly launder all bedding, clothing, and toys to destroy any lingering eggs
  • Launder all bedding every 3-7 days for three weeks
  • Wash underwear and pajamas daily for two weeks

External Links

CDC: Enterobiasis

See Also