Pinworms are slender, white, threadlike worms about a third of an inch long that can infest the intestinal tract. Pinworm, the most common worm infection in the U.S., is a mild but annoying and disruptive childhood infection.

The human pinworm, Enterobius vermicularis, is a parasite that lives only in the human intestine, not outside the body. Pinworm in animals does not affect humans.

People blame pinworms for such childhood problems as teeth grinding, bed wetting, stomach aches, weight loss,...