Tapeworms are large, flat parasitic worms that live in the intestinal tracts of some animals. They are passed to humans who consume foods or water contaminated with tapeworm eggs or larvae.
Six types of tapeworms are known to infect humans, usually identified by their source of infestation: beef, pork, fish, dog, rodent, and dwarf, which is named because it is small.
Tapeworm infection in people usually results from eating undercooked foods from infected animals. Pigs or cattle, for example, become infected when grazing in pastures or drinking contaminated water. People can also become infected by eating contaminated fish that is raw or undercooked.
The parasites mature in the animal’s intestines to pea-shaped larvae. They spread to the animal's blood and muscles. They are then transmitted to people who eat the contaminated food. This method is more common with beef or fish.
Tapeworms can also be passed by hand-to-mouth contact if you touch a contaminated surface and then touch your mouth. This method is more common with pork.
The following factors may increase your chance of tapeworm infection:
- Eating raw or undercooked pork, beef, or fish
- Poor hygiene—not washing your hands can increase the risk of transferring tapeworm parasites by hand-to-mouth contact
- Exposure to cattle or pigs, particularly in areas where human and animal feces are not properly disposed
- Travel to underdeveloped countries with poor sanitary conditions.
Tapeworms may be seen in vomit or stool. In some cases, tapeworm infection may not cause any symptoms. If symptoms do occur, they may include:
You will be asked about your symptoms and medical history. A physical exam will be done. You may be able to self-diagnose tapeworm infection by checking your stool for signs of tapeworms.
Your bodily fluids and waste may be tested. This can be done with:
- Blood test
- Stool test
Images of your brain may be taken if there is concern that the larva of the pork tapeworm have migrated there. This can be done with:
Tapeworm infection is treated with oral medication. The medications work by dissolving or attacking the adult tapeworm. The medications may not target eggs. Proper hygiene is essential to avoid re-infection. Always wash your hands before eating or after going to the bathroom.
Your doctor will check stool samples at 1 and 3 months after you've finished taking your medication.
To help reduce your chance a tapeworm infection:
- Wash your hands with soap and hot water before eating or handling food
- Wash your hands after using the toilet.
- Freeze meat for 4 days or longer to kill the type of tapeworm that infects pork.
- Thoroughly cook meat at temperatures of at least 150°F (65°C). Avoid eating raw or undercooked food.
- When traveling in undeveloped countries, wash and cook all fruits and vegetables with safe water before eating.
- Get prompt treatment for pets infected with tapeworm.
Centers for Disease Control and Prevention
The World Health Organization
Public Health Agency of Canada
Beef tapeworm. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated January 19, 2011. Accessed June 19, 2014.
Centers for Disease Control and Prevention. Traveler's Health—Yellow Book: Taeniasis. Centers for Disease Control and Prevention website. Available at: http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/taeniasis. Updated August 1, 2013. Accessed June 19, 2014.
Fish tapeworm. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 17, 2010. Accessed June 19, 2014.
Pork tapeworm and cysticercosis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 5, 2014. Accessed June 19, 2014.
Silva CV, Costa-Cruz JM. A glance at Taenia Saginata infection, diagnosis, vaccine, biological control and treatment. Infect Disord Drug Targets. 2010;10(5):313-321.
5/6/2011 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Quet F, Guerchet M, et al. Meta-analysis of the association between cysticercosis and epilepsy in Africa. Epilepsia. 2010;51(5):830-837.
Last reviewed February 2015 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.