Enterobius

Background

Enterobious vermicularis life cycle.

• Enterobius vermicularis
• Colloquially known as Pinworm (United States), Treadworm (UK and Australia) or Seatworm
• 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

Two pinworms next to a ruler: The markings are 1 mm apart.

• Pruritus ani (intense itching of the perianal region)
  • Worse at night
• Rarer symptoms include abdominal pain, appendicitis and vulvovaginitis or dysuria in females

Differential Diagnosis

• Idiopathic pruritus ani
• Rectal tenesmus

Helminth infections

Cestodes (Tapeworms)

• Taenia saginata
• Taenia solium (Cysticercosis)
• Diphyllobothrium latum
• Hymenolepis nana
• Echinococcus granulosus

Trematodes (Flukes)

• Fasciola hepatica
• Fasciolopsis buski
• Opistorchis viverrini
• Schistosoma spp
  • Schistosomiasis
• Chlonorchis sinensis
• Paragonimus spp.

Nematodes (Roundworms)

• Ascaris lumbricoides
• Enterobius vermicularis (Pinworm)
• Filarial worms
  • Loa Loa
  • Onchocerciasis
  • Lymphatic filariasis (Elephantiasis)
    • Wuchereria bancrofti
    • Brugia malayi
    • Brugia timori
• Hookworm
  • Necator americanus
  • Ancylostoma duodenale
  • Cutaneous larva migrans (Ancylostoma braziliense)
• Dracunculiasis
• Strongyloides stercoralis
• Trichuris trichiura (Whipworm)
• Anisakis
• Toxocara spp.
• Trichinosis

Evaluation

• 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

Management

Treatment targeted against Enterobius vermicularis; All family members should be treated at the same time

Adult

• Mebendazole 100mg PO once, THEN repeat in 2 weeks OR
  • Okay during breastfeeding
• Albendazole 400mg PO once, THEN repeat in 2 weeks OR
• Pyrantel Pamoate (Pin-x) 11mg/kg (max 1g), THEN repeat in 2 weeks
  • First choice for pregnant patients
    • Treat in pregnancy only if the infection is compromising the pregnancy (i.e. weight loss, sleeplessness); withhold until the 3rd trimester if possible.

Pediatric

• 2 years or older:
  • Mebendazole 100mg PO once, THEN repeat in 2 weeks OR
  • Albendazole 400mg PO once, THEN repeat in 2 weeks OR
• <2 years
  • Albendazole 200 mg PO once, THEN repeat in 2 weeks

Prevention

• 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

Disposition

• Outpatient treatment

External Links

• CDC: Enterobiasis

See Also

• Parasites
• Pruritus ani