Common Tapeworms

Beef Tapeworm

• Beef tapeworms, or Taenia saginata, are spread through cows and can be found wherever beef is consumed. Humans become infected by beef tapeworms by eating undercooked beef infected with worm cysts. The beef tapeworm, most common in North and South America, Asia and Africa, most frequently affects cows and humans. Beef tapeworms can grow up to 25 feet in length in the human intestine.

Fish Tapeworm

• The fish tapeworm is found in North and South America, Europe, parts of Africa, and Japan. Known scientifically as Diphyllobothrium latum, the fish tapeworm is spread through consumption of infected freshwater fish that is raw or undercooked. Food sources include salmon and other fish used in sushi. The fish tapeworm is uncommon in animals and can grow up to 25 feet in length.

Pork Tapeworm

• The pork tapeworm is somewhat rare in North America but common in South America, Eastern Europe, India, China and Southeast Asia. Pork tapeworm is spread through pork meat that is contaminated with worm cysts and undercooked, though consuming contaminated food and water can also spread the parasite. The pork tapeworm, also known as Taenia solium, can grow up to 21 feet in length. Pork tapeworms sometimes penetrate the walls of the intestine, then travel through the bloodstream to infect organs such as the brain, spinal cord, muscles and even the eyes. This secondary infection is known as cysticercosis and can be very difficult to diagnose because symptoms appear only after months or years after the initial infection.

Dog Tapeworm

• Dog tapeworms are common in dogs and cats, though humans -- especially children -- can become infected. Infection in humans occurs after ingestion of an infected flea or louse from an infected pet. Pets are also infected when they ingest a flea or louse carrying a worm cyst, which is why deworming medication and medication to control fleas are both required to control the worm in pets. The dog tapeworm is also known as Dipylidium caninum and grow to about 24 inches in length. Humans can avoid this tapeworm by washing their hands after contact with pets.