An ascarid is a worm that lives in the small intestine. Adult female worms can grow over 12 inches in length, adult males are smaller.
Ascariasis is the most common human worm infection.
Infection occurs worldwide and is most common in tropical and subtropical areas where sanitation and hygiene are poor. Children are infected more often than adults. In the United States, infection is rare, but most common in rural areas of the southeast. Most people have no symptoms. If you are heavily infected, you may have abdominal pain.