Nocturnal anal itching with discovery of filiform parasites

Specialty: Pediatrics.

• Pinworm infection
• Pediatric enterobiasis
• worms in the anus

Why it occurs

• Enterobius vermicularis infection or oxyuriasis (the helminth parasite colonizes the cecum and ascending colon; during the night, gravid females migrate through the anal sphincter and deposit thousands of sticky eggs in the perianal folds, causing an inflammatory reaction and intense local pruritus mediated by allergenic substances secreted by the parasite)
• Continuous self-infection due to anus-hand-mouth cycle (perianal scratching deposits eggs under the nails, facilitating their re-entry into the digestive system through finger sucking or nail biting)
• Contamination by domestic fomites (pinworm eggs are viable and highly infective for weeks in sheets, underwear, toys, carpets or household dust, facilitating massive intrafamilial transmission).

Initial workup

Direct visual diagnosis of adult female worms (small white, mobile, filiform parasites 8 to 13 millimeters in length) in the perianal region, gluteal region or sheets during the night or early morning using a flashlight. Graham tape test (test of choice if worms are not visible; gently press a clear adhesive tape on the perianal folds in the morning before defecating or washing, stick it on a glass slide, and examine microscopically for asymmetrical flat double-membrane eggs).

Standard management

• Antiparasitic treatment must be administered to all cohabiting family members simultaneously. Mebendazole — first choice oral antiparasitic; single dose of 100 mg orally for children over one year of age and adults; A second identical dose of 100 mg must be repeated after 2 weeks because the drug destroys the adult worms but does not affect the laid eggs, thus interrupting the reinfection cycle.
• Albendazole — effective alternative; single dose of 400 mg orally for children over 2 years of age, and 200 mg for children 1 to 2 years of age; repeat the same dose after 2 weeks
• Pyrantyl pamoate (dose of 11 mg/kg orally in a single dose, maximum 1 g, to be repeated after 2 weeks). Thorough domestic hygiene and washing of bed linen at 60°C.