Tapeworms are flat, segmented worms that can invade the digestive tracts of people and animals. They're parasites, which means they need a host body in order to survive.
Tapeworms get into your body when you eat raw or undercooked meat. Beef tapeworms are rare in the U.S., but they can get into the food supply when people live close to cattle and conditions aren't clean. You're more likely to get tapeworms from undercooked pork in the U.S.
When tapeworm eggs get into your body, they can move to other places outside your intestines, like tissues and organs, and form larval cysts. This is called an invasive infection. If they enter your digestive tract as larvae, they turn into adult tapeworms in your intestines. This is called an intestinal infection.
Left untreated, adult tapeworms can live in a host body for up to 30 years. Their length varies, but they can grow to be anywhere from 6 to 22 feet.
Most people feel no different than usual when they have a tapeworm in their intestines. Symptoms that could show up include nausea, appetite loss, weight loss, diarrhea, belly pain, dizziness, or salt cravings.
The most serious symptoms happen when tapeworm larvae invade parts of your body outside the intestines. You may have serious problems with your nervous system, including seizures, or you could get headaches, masses or lumps, allergic reactions to the larvae, or problems with your vision.
A doctor can find out if you have a tapeworm by looking at a sample of your poop under a microscope. You may need a CT scan, MRI, or blood tests to check for invasive tapeworm larvae.
Your doctor may also ask if you've seen any parts of a tapeworm in your poop recently. Sometimes you can feel a piece of the worm move out when you go to the bathroom.
Prescription antiparasitic medications will kill adult intestinal tapeworms. The doctor will likely want you to take these even if you've only seen a segment of tapeworm come out in your stool. If the head and neck are still inside, the tapeworm can regrow itself.
If you have cysts from larval tapeworms, your doctor may give you a steroid medication in addition to an antifungal. Surgery might be an option if a tapeworm cyst is blocking the flow of fluid around your brain or spinal cord, or affecting your eyes.
To make sure you don't get tapeworms, only eat meat cooked to safe temperatures:
- 145 F for whole cuts of meat
- 160 F for ground meat
In general, washing your hands often -- especially if you have to touch human poop -- is a good idea, too.
If the thought of tapeworms makes you squirm, take heart. You probably won't ever get one. Less than 1,000 people in the U.S. get them a year. It's extremely rare to pick one up from your pet. And if you take the right steps to cook meat, you shouldn't get one from it, either.
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- Merck Manual: "Tapeworm Infection."
- CDC: "Cysticercosis," "Parasites -- Taeniasis," "Taeniasis FAQs."
- Mayo Clinic: "Tapeworm Infection."