Tapeworms infect animals and humans. They live in your intestines and feed off the nutrients you eat. Symptoms can include nausea, weakness, diarrhea and fatigue, or you may not have symptoms. You may see eggs or worm pieces in your poop. Once you find a tapeworm, it’s easy to get rid of it.
A tapeworm is a flat, parasitic worm that lives in the intestines of an animal host. It commonly infects many different animals, including humans, livestock and domestic cats and dogs (usually meat-eating mammals.)
Like other parasites, the mature tapeworm can only survive inside the host animal, feeding off of the host’s own nutrients. The head attaches to the inside of your intestines and absorbs nutrients from the food digesting there.
Meanwhile, the body continues to grow and lay eggs. The eggs pass through the intestines of the host animal and out of their body in their poop. This is how the eggs will find their new host.
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The tapeworm gets its name from its flat shape, resembling a tape measuring ribbon. The body grows in segments. The tapeworm has three distinct parts: a head, which attaches to the host, an unsegmented neck, where new body segments generate from, and the segmented lower body.
Each body segment produces its own eggs. In some species, the segments break off with the eggs to pass through the intestines of the host in their poop. The segments look like little grains of white rice. Segments in poop are often the first visible sign of a tapeworm infection.
Tapeworm infection comes in two forms:
Intestinal tapeworms are adult tapeworms that have hatched and matured inside the intestines of a host animal. The mature tapeworms attach to your intestinal walls and absorb nutrients from the food digesting there. These tapeworms often cause no noticeable symptoms, and many people don’t realize they're infected. However, a severe infection can cause nutritional deficiencies, unexplained weight loss, nausea or diarrhea. Some tapeworms can live up to 30 years and grow up to 30 feet long.
You might hear your healthcare provider refer to your tapeworm infection as “taeniasis.” This term refers to an infection by tapeworms from the genus Taenia. Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm) and Taenia asiatica (Asian tapeworm — also from pork) are all species that target humans as their definitive host. However, other species also infect human intestines, including Diphyllobothrium latum (fish tapeworm) and Hymenolepis nana (dwarf tapeworm — a smaller variety).
An invasive larval infection can happen if tapeworm larvae in your intestines migrate outside of your intestines and enter your bloodstream and other organs. The larvae adhere to your insides and form cysts there — pockets of fluid that grow around the larvae as they grow. These cysts can cause a variety of complications, depending on where they are. Cysts in your lungs, liver or heart can grow big enough to disrupt those organs’ normal functioning. Cysts that adhere to your spinal cord or brain can cause neurological symptoms, such as seizures.
You can have a larval infection with or without an intestinal tapeworm. The pork tapeworm Taenia solium causes both intestinal infections and invasive larval infection. (The larval infection is known as cysticercosis.) Other tapeworm species only infect humans as larvae. These infections go by different names depending on the species — cystic hydatid disease (echinococcosis), alveolar disease, sparganosis and coenurosis — but they all manifest in the same way, as cysts. Some cysts don’t cause any trouble, but some do and you may need someone to remove them.
Tapeworm infection occurs around the world, particularly in countries where people commonly eat raw meat and fish and where sanitation is less rigorous. In the U.S., tapeworm infection is rare, but U.S. citizens can get an infection while traveling and bring it back with them. Worldwide, tapeworm infection rates are difficult to measure. Tapeworms often cause no noticeable symptoms, and many countries lack the resources to diagnose everyone who has symptoms. They may be more common than we can tell.
Tapeworms evolve in three stages: egg, larva and adult worm. The worm can’t survive outside of a living host, but the eggs and larvae can. Eggs pass from the original host through their poop into the local soil and water. There, they contaminate the food and drinking water of other animals. Animals who consume the eggs — including insects and fish — can incubate the tapeworm larvae. Humans become infected by accidentally ingesting the eggs or the larvae.
People in less-developed countries with inadequate sewage treatment are more likely than others to get an infection by contamination from poop. Human and animal waste that contaminates food and water supplies may include the microscopic tapeworm eggs. When humans ingest the eggs, they hatch into larvae in their intestines, and at this stage they become mobile. When the larvae migrate outside of your intestines, they cause an invasive larval infection.
In more developed countries, humans are more likely to get an infection from eating undercooked infected meat. Infected meat has tapeworm larvae embedded in the muscle tissue, which will survive if cooking or freezing doesn't kill them. Large freshwater fish, such as salmon, can get an infection. When humans eat the infected meat, the larvae transfer to their human intestines, where they mature into intestinal worms.
Intestinal tapeworms usually cause mild gastrointestinal symptoms, if any. They may include:
Cystic larval infections often cause no symptoms. They may be visible as lumps under your skin, or they may make themselves known by causing complications to your internal organs. This usually takes years.
Complications depend on which kind of tapeworm you have, whether it's intestinal or invasive, and where the invasive larvae are located.
If you suspect you might have an intestinal tapeworm, look for worm segments in your poop. If you have an invasive larval infection, you may find lumps on your body where the cysts have adhered. But if the cysts are more internal, you may not find them until they begin to cause complications.
Complications might happen if the cysts grow large enough to obstruct your blood flow or normal organ functioning. They can also happen when the larvae cysts have begun to rupture and die. This causes the larvae to enter your bloodstream again, which will alert your immune system that you have an infection. Your immune system will respond with typical symptoms of infection, such as fever.
Healthcare providers diagnose intestinal tapeworms by examining your poop in a lab. The lab can spot the tapeworm eggs and worm segments, if there are any, and they can identify which species of worm you have by certain features. The same medicine treats all of them, but the species will determine the correct dose. If you have the pork tapeworm, your healthcare provider will want to test for larva infection (cysticercosis) as well.
To check for an invasive larval infection, your healthcare provider may start with a blood test. The blood test will show if your body is producing antibodies to the larvae. If the blood test is positive, or if there is some other reason to suspect a larval infection, your healthcare provider will use an imaging test to locate the cysts. MRI and CT scans are good for looking inside your tissues.
You can easily kill tapeworms with anthelmintic drugs, including praziquantel (Biltricide®), albendazole (Albenza®) and nitazoxanide (Alinia®). Healthcare providers usually recommend praziquantel because it also paralyzes the worm, forcing it to dislodge from your intestinal wall. It's important to dislodge the neck of the tapeworm and pass it from your body, because the worm can regenerate itself from the neck. After treatment, your healthcare provider will want to continue checking your poop for any remaining signs of tapeworm infection for one to three months.
Healthcare providers take a tiered approach to treating tapeworm larval infections:
Risk is low in the developed world, but traveling in developing countries and experimenting with raw and undercooked meats can increase your risk. To prevent tapeworm infection, follow these guidelines:
It often takes a while to realize you have a tapeworm infection. Symptoms might not appear for months or years. Once you discover and treat a tapeworm, it'll die and pass from your body shortly. However, if you never discovered it, the tapeworm would eventually live out its life, die and pass from your body on its own after a period of years.
If you have an invasive larval infection and the cysts aren’t causing any symptoms or complications, your healthcare provider may recommend you leave them alone. In this case, the larvae would also live out their lifespans and eventually die after some years. Sometimes people don't discover them until they have already begun to die, causing an inflammatory response.
If you have an invasive larval infection that's causing complications, you have likely already had it for some time. Once your healthcare provider diagnoses it, they'll work to eliminate the problem cysts and manage your symptoms. Removing the cysts should relieve your symptoms, but in some cases, you may have irreversible damage to your organs or to your central nervous system.
If you’re living with an asymptomatic tapeworm larval infection that doesn’t require any treatment, just keep a look out for any emerging symptoms over time. Make sure you and your healthcare provider are aware of where the cysts are located in your body to help identify any strange symptoms in those areas. Notice any general inflammation or immune response, which might occur when the cysts begin to die. Your healthcare provider may want to prescribe medication at this time to manage symptoms.
Signs of tapeworm infection, when they do appear, can vary widely, especially tapeworm larval infections. You may not realize that your symptoms indicate a tapeworm, but you should always ask your healthcare provider about strange symptoms. If you have reason to suspect a tapeworm, such as foreign travel or a recent undercooked meal, make sure to mention it. If you think you’ve identified tapeworm segments in your poop, have it lab tested right away.
A note from Cleveland Clinic
Tapeworm infection has a “yuck” factor, but symptoms are usually mild and you can easily treat tapeworms once they're found. Complications only develop after many years. You aren’t likely to be infected by a tapeworm during ordinary life in a developed country. But if you do travel to developing parts of the world, or if you eat raw meat or fish, pay attention to any gastrointestinal symptoms. If you have symptoms, check your poop for signs of the worm. For peace of mind, contact your healthcare provider to discuss having your poop medically tested. Catching it early is the best way to avoid any complications from tapeworm infection.
Last reviewed by a Cleveland Clinic medical professional on 07/26/2022.
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