Pinworms (Enterobius vermicularis) are small, threadlike roundworms that commonly infect the digestive system of humans, especially children between the ages of 5 and 10 years. Pinworms are parasites that live in the intestines and survive by eating nutrients from the person's food.

Pinworm infections are common and spread easily. They are usually caused by swallowing the eggs of the pinworm after coming in contact with an infected person or with an object that has eggs on its surface. Infection can also be spread when a person inhales airborne eggs, but this is rare. On rare occasions, pinworm infection persists because eggs hatch outside the anus and the young worms crawl back inside the body.

Symptoms of pinworms include:

• Itching around the anus. For most children this symptom is mild. Only rarely do children have very severe itching.
• Restless sleep (itching is worse at night).

Many people with pinworm infections do not have any symptoms. Some people get better without treatment. Pinworm infections are easily treated with medicine, and treatment can help prevent the spread of infection to others. Pinworms rarely cause serious health problems.