A pinworm infestation is caused by a type of roundworm known as Enterobius vermicularis.

What is going on in the body?

Pinworm infestation occurs all over the world. Humans are the only known hosts. A person gets pinworms by swallowing the eggs of the worm. Pinworm eggs remain alive for up to three weeks.

Pinworms generally find a home in the colon, or large intestine. At night, they come through the anus to lay their eggs on the surrounding skin outside of it. Sometimes the worms migrate to other areas of the body, including the following:

After leaving the colon to lay eggs or migrate to other parts of the body, the worms usually die. However, children and adults can sometimes reinfect themselves.

What are the causes and risks of the condition?

A pinworm infestation occurs when people swallow the eggs of the roundworm known as Enterobius vermicularis. Pinworm eggs can live for up to two weeks on clothing, bedding, toys, and other objects. A person can get a pinworm infestation by swallowing eggs from these surfaces. An individual can also be infested from fingers contaminated with the stool of an infected person.

School-age children and preschoolers are most prone to pinworm infestations. Mothers of infected children often become infested with pinworm. Other adults are less likely to have pinworms.