Enterobiasis, also known as pinworm or threadworm, causes perianal itching that is often worse at night and can disrupt sleep. Examination of the anus and application of cellophane tape to the area can reveal the presence of pinworms under a microscope. Treatment involves a single oral dose of an anthelmintic drug for all family members to eliminate the infection from the entire household and prevent reinfection through contaminated surfaces.

1. Enterobiasis (Pinworm or Threadworm)
Presentation
The patient complains of perianal itching which is worse at night, and may contribute
to insomnia or superinfection of the excoriated perianal skin. Often, an entire family is
affected.
What to do:
• Examine the anus to rule out other causes of itching, such as rectal prolapse,
fecal leakage, hemorrhoids, lice (pediculosis), fungal infections (tinea or
candidiasis), or bacterial infections (erythrasma).
• Look for pinworms directly (especially if the patient comes in at night), and by
pressing the sticky side of cellophane tape wrapped around a tongue blade to
the perianal skin. Examine the tape under the low power of the microscope for
female worms, approximately 1 cm long, 0 5mm in diameter, with pointed tails.
(Use shiny rather than "invisible" tape, because the latter's rough surface makes
microscopy difficult .)
• If you see pinworms or still suspect them, administer a single oral dose of
pyrantel pamoate 11mg/kg (maximum l gram) to all family members (Antiminth
oral suspension, lml per l0lb). Alternate drugs include mebendazole (Vermox)
100mg in a single po dose (not for infants and pregnant women) and pyrvinium
pamoate.
• Explain to all concerned that this is not a dangerous infection, and that it should
be eradicated from the whole family after one treatment (which may be
repeated in two or more weeks if there are recurrences).
Discussion
Pinworms mostly live in the colon, and females migrate down to the perianal skin to lay
eggs at night. Eggs on contaminated fingers re-enter via the mouth, but remain viable
for several days on surfaces around the house. Perhaps 10% of the U.S. population
harbors pinworms, especially children.