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Key Features

Essentials of Diagnosis

  • Nocturnal perianal pruritus

  • Identification of eggs or adult worms on perianal skin or in stool

General Considerations

  • Enterobiasis is transmitted person-to-person via

    • Ingestion of eggs after contact with the hands or perianal region of an infected individual

    • Food or fomites that have been contaminated by an infected individual

    • Infected bedding or clothing

  • Autoinfection also occurs

  • Eggs hatch in the duodenum and larvae migrate to the cecum

  • Females mature in about a month and remain viable for about another month

  • During this time they migrate through the anus to deposit large numbers of eggs on the perianal skin

  • Due to the relatively short lifespan of these helminths, continuous reinfection is required for long-standing infection

Demographics

  • Enterobius vermicularis is common cause of intestinal infections worldwide, with maximal prevalence in school-age children

Clinical Findings

Symptoms and Signs

  • Most persons are asymptomatic

  • Perianal pruritus is common, particularly at night due to the presence of the female worms or deposited eggs

  • Insomnia, restlessness, and enuresis are common in children

  • Perianal scratching may result in excoriation and impetigo

  • Mild gastrointestinal symptoms have also been attributed to enterobiasis, but associations are not proven

  • Serious sequelae are uncommon

  • Rarely, worm migration results in inflammation or granulomatous reactions of the gastrointestinal or genitourinary tracts

  • Colonic ulceration and eosinophilic colitis have been reported

Differential Diagnosis

  • Tinea or candidiasis of the anogenital region

  • Hemorrhoids

  • Proctitis

  • Contact dermatitis

  • Strongyloidiasis

  • Anal fissure

  • Idiopathic anogenital pruritus

Diagnosis

Laboratory Tests

  • Pinworm eggs are usually not found in stool

  • Diagnosis is made by finding adult worms or eggs on the perianal skin

  • A common test is to apply clear cellophane tape to the perianal skin, ideally in the early morning, followed by microscopic examination for eggs

  • The sensitivity of the tape test is reported to be about 50% for a single test and 90% for three tests

  • Nocturnal examination of the perianal area or gross examination of stools may reveal adult worms, which are about 1 cm in length

  • Eosinophilia is rare

Treatment

Medications

  • Single oral doses of albendazole (400 mg), mebendazole (100 mg), or pyrantel pamoate (11 mg/kg, to a maximum of 1 g)

  • The dose is repeated in 2 weeks due to frequent reinfection

Therapeutic Procedures

  • Other infected family members or contacts should be treated concurrently

  • Treatment of all close contacts may be appropriate when rates of reinfection are high in family, school, or institutional settings

  • Standard handwashing and hygiene practices are helpful in limiting spread

  • Perianal scratching should be discouraged

  • Washing of clothes and bedding should kill pinworm eggs

Outcome

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