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
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
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
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.