The Pinworm (Enterobius vermicularis) is a parasitic worm that causes a common intestinal parasite in humans. The entire life cycle, from egg to adult, of the Pinworm takes place in the human gastrointestinal tract of a single host. They are particularly prevalent in children, and finger sucking has been shown to increase incidence and relapse rates. It spreads from host to host through contamination, so Pinworms are common among people who live in close contact. Their distribution is worldwide, and it is most common in the United States, Western Europe, and Oceania.