Intestinal worms, also known as parasitic worms, are one of the main types of intestinal parasites in humans. They’re most commonly found in subtropical and tropical regions. Most intestinal worm infections only cause mild illness and can be treated with medication.

Worms enter by eating infected meat, especially pork, that’s raw or undercooked. When a person eats infected meat, stomach acid dissolves cysts in the meat to release worm larvae. The worms go to the intestine, grow up, mate, and lay eggs. After hatching, young worms go through the blood to the muscles.