Pinworm infection is the most common type of intestinal worm infection in the United States. Pinworms are thin and white, measuring about 1/4 to 1/2 inch (about 5 to 13 millimeters) in length.
While the infected person sleeps, female pinworms lay thousands of eggs in the folds of skin surrounding the anus. Most people infected with pinworms have no symptoms, but some people experience anal itching and restless sleep.
Pinworm infection occurs most often in school-age children, and the microscopic eggs are easily spread from child to child. Treatment involves oral drugs that kill the pinworms and thorough washing of bedclothes, bed linens and underwear. For best results, the entire family should be treated.