Pinworms are parasites. They are also called threadworms and are tiny white worms, about 1/2 inch long. The infection is most common in children younger than 10 years old.
Pinworm infection happens when a pinworm egg or adult pinworm is swallowed. Pinworms then travel down the digestive tract to the rectum, where they stay.
A child with a pinworm infection will have intense itching around the anus (rectal opening). The itching is worse at night when pinworms come out of the rectum and lay eggs around the anus.
An infected child may pass the infection onto others. Pinworms may travel from person to person on hands or things like clothing, towels, toilet seats, or bedding.
The infection is treated with 2 doses of medicine taken 2 weeks apart. The doctor may recommend that all family members should be treated at once, even those who don't have symptoms. This is to help make reinfection less likely.