Tapeworm infection is caused by eating the raw or undercooked meat of infected animals. Cattle usually carry Taenia saginata (T. saginata). Pigs carry Taenia solium (T. solium).
In the human intestine, the young form of the tapeworm from the infected meat (larva) develops into the adult tapeworm. A tapeworm can grow to longer than 12 feet and can live for years.
Tapeworms have many segments. Each segment is able to produce eggs. Eggs are spread alone or in groups, and can pass out with the stool or through the anus.
Adults and children with pork tapeworm can infect themselves if they have poor hygiene. They can ingest tapeworm eggs they pick up on their hands while wiping or scratching their anus or the skin around it.
Those who are infected can expose other people to T. solium eggs, usually through food handling.
Tapeworm infection usually does not cause any symptoms. However, some people may have abdominal discomfort.
People often realize they are infected when they pass segments of the worm in their stool, especially if the segments are moving.
Stool exam for eggs of T. solium or T. saginata, or bodies of the parasite
Tapeworms are treated with medications taken by mouth, usually in a single dose. The drug of choice for tapeworm infections is praziquantal. Niclosamide can also be used.
With treatment, the tapeworm infection goes away.
Rarely, worms can cause a blockage in the intestine.
If pork tapeworm larvae move out of the intestine, they can cause local growths and damage tissues such as the brain, eye, or heart. This condition is called cysticercosis. Infection of the brain can cause seizures and other nervous system problems.
Calling your health care provider
Call for an appointment with your health care provider if you pass something in your stool that looks like a white worm.
In the U.S., laws on feeding practices and the inspection of domestic food animals have largely eliminated tapeworms.
Avoiding raw meat and cooking meat well enough (to greater than 140 degrees F for 5 minutes) will prevent tapeworm infection. Freezing meats to -4 degrees F for 24 hours also kills tapeworm eggs. Good hygiene and hand washing after using the toilet will prevent self-infection in a person who is already infected with tapeworms.
King CH, Fairley JK. Cestodes (tapeworms). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 290.
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.