6 Facts You Should Know About Tapeworms

Find out what you need to know about tapeworms and tapeworm infections.

Medically reviewed in March 2022

You’ve probably heard of them -- and been a little grossed out by the thought of them -- but tiny tapeworms made big news in 2015.

For starters, a California man was suffering from a terrible headache and went to the hospital. The headache’s cause: Tapeworm larvae formed a cyst blocking off circulation in his brain, nearly killing him. And a study was published revealing that an HIV-positive Colombian man died from cancer that a dwarf tapeworm spread to him.

Major complications like this are rare, though (in fact, tapeworm cancer had never been seen before). More often, the worms live quietly in the intestine, and people don’t even know they’re infected. Check out these facts you should know about tapeworms, the signs to watch for, tapeworm treatments and more.

What are tapeworms?
Tapeworms are flat worms with a sucker on one end and segments that can break off and release eggs. The parasites can enter the body and cause infections when people swallow the eggs or larvae. The worms can range in size from about an inch to -- are you ready for this? -- 10 yards or more, and they can live in the body for years, feeding off the nutrients in your gut. More than 9,000 different species of the worms are recorded, but only a few cause trouble for humans.

What symptoms can tapeworm infections cause?
Tapeworm infections usually cause no symptoms at all. Symptoms that do occur include abdominal pain, fatigue, loss of appetite, an upset stomach, diarrhea and weight loss. Some people develop nutritional deficiencies. Young children with bad infections may have headaches, an itchy bottom and trouble sleeping.

There’s one big exception: If people swallow the eggs of certain tapeworms, the worms can invade other parts of the body and form cysts in muscles, the brain or other organs. This serious disease, called cysticercosis, can lead to muscle or eye damage, headaches, seizures or even strokes.

Signs to look out for?
If you think you have a tapeworm infection, check your stool. You may be able to see tapeworm segments that you’ve passed.

How to prevent tapeworms?
Eating undercooked or raw beef, pork or fish can cause tapeworm infections. You can also get tapeworms by consuming food or water contaminated with feces from a person or animal that is infected. Make sure you and all the members of your family wash your hands properly, especially before making food and after using the bathroom or changing diapers. Also, ensure that all meat is cooked properly and double-check it with a food thermometer.

How are tapeworm infections treated?
See your doctor if you think you’re infected. You may need stool tests, an X-ray or other tests. If you are indeed infected, your doctor will probably prescribe a medication called praziquantel to treat it.

Can an infected dog or cat spread the infection?
Yes, but it’s unlikely. Pets normally become infected by swallowing a flea carrying a tapeworm. A person would also have to swallow an infected flea to get the worms, and this is incredibly rare.

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