The common tapeworms that infect the human gut are the pork and, to a lesser degree, the beef tapeworm. They are very long (up to 5 metres) segmented worms that grow in the small bowel of humans after eating uncooked or partially cooked meat, which is contaminated with tapeworm cysts. Tapeworm segments filled with eggs are excreted in human stools and later may be swallowed by animals (pigs or cows). The eggs hatch in the animal’s gut and are carried in the bloodstream to the muscles of the animals where they become tapeworm cysts. Eating infected, uncooked meat of these animals completes the life cycle of the tapeworm when the eggs hatch, resulting in adult worms living in the human gut.
Most tapeworms result from eating poorly cooked pork which is infected with tapeworm cysts.
The pork tapeworm is Taenia solium and the beef tapeworm is Taenia saginata.