The longest tapeworm ever found inside a human was one of the Diphyllobothrium latum species, and it was 82 feet (25 m) long. A tapeworm is a parasite that can live in the small intestines of some animals, and the Diphyllobothrium latum species has the ability to grow rapidly, at a pace of 0.4 inches (1 cm) every hour. The parasite makes its way into the human body when a person eats raw or undercooked meat of an animal that had ingested tapeworm eggs, which can even be in the muscles of the animal. Once inside the human body, the tapeworm lives within the small intestine. A tapeworm infection often does not cause any symptoms, but it can result in abdominal or digestive issues or an invasive bacterial infection.
More about tapeworms:
About 20 million people worldwide are infected with tapeworms at any given time.
A tapeworm can live inside its host for 25 years or more.
Researchers have discovered evidence of tapeworms being present in fossilized shark feces that are estimated to date to 270 million years ago.