Pinworms are about the length of a staple and live in the rectum of humans.
While an infected person sleeps, female pinworms leave the intestines through the anus and deposit eggs on the surrounding skin. Itching around the anus, disturbed sleep, and irritability are common symptoms. If the infection is heavy, symptoms may also include loss of appetite, restlessness, and difficulty sleeping. Symptoms are caused by the female pinworm laying her eggs. Pinworm is the most common worm infection in the United States.