Tapeworm Infection

What is a tapeworm?

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.

What do tapeworms look like?

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.

What is a tapeworm infection?

Tapeworm infection comes in two forms:

Intestinal tapeworms

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).

Invasive tapeworm larval infection

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.

How common is tapeworm infection in humans?

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.

How do you get a tapeworm infection?

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.

What are the symptoms of tapeworm infection in humans?

Intestinal tapeworms usually cause mild gastrointestinal symptoms, if any. They may include:

• Hunger.
• Loss of appetite.
• Nausea.
• Fatigue.
• Stomach cramps.
• Diarrhea.

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.

What are the possible complications of tapeworm infection?

Complications depend on which kind of tapeworm you have, whether it's intestinal or invasive, and where the invasive larvae are located.

• Digestive system blockage. Rarely, some intestinal tapeworms may grow large enough to block passages in your digestive system, including your intestines, appendix, bile ducts and pancreatic duct.
• Vitamin deficiency anemia. The fish tapeworm especially likes to absorb vitamin B12, which can cause anemia.
• Allergies. You can have allergic reactions to the larvae, including itching, hives and breathing difficulties.
• Coughing and chest pain can occur when cysts attach to your lungs.
• Organ function disruption is a risk when larvae invade your liver, heart, eyes or lungs.
• Neurological symptoms can occur when larvae invade your central nervous system, including headaches, seizures, confusion, meningitis and brain swelling.

How do you know if you have a tapeworm?

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.

How is tapeworm infection diagnosed?

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.

How do you get rid of a tapeworm?

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.

What is the treatment for an invasive larval infection?

Healthcare providers take a tiered approach to treating tapeworm larval infections:

1. Watch and wait. If the cysts aren’t causing complications and aren’t in any dangerous locations, your healthcare provider may advise leaving them alone for now. They’ll keep an eye on them.
2. Manage secondary symptoms. If the cysts are causing complications, especially neurological ones, those symptoms may need treatment first. This might mean anti-seizure medication or therapy to reduce fluid buildup in or around the brain.
3. Corticosteroids. You can use anti-inflammatory medicine, such as corticosteroids, to treat cysts that are causing inflammation in your tissues.
4. Anthelmintics. Anthelmintic drugs (drugs that kill parasitic worms) can shrink cysts with living larvae in them. Your healthcare provider may give you anthelmintics along with corticosteroids to help reduce the inflammation that happens when the cysts begin to die.
5. Drainage. If you have cysts that are causing problems, drainage may be an option for some. Your doctor may be able to reach the cysts with a needle and puncture and drain the fluid through the needle. They finish by rinsing the larvae with antiparasitic medication.
6. Surgery. Cysts that threaten organ function may need surgical removal.

How can I reduce my risk of tapeworm infection?

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:

• Safe hygiene practices: Wash your hands with soap and water after using the toilet or interacting with animals and before handling food.
• Safe water practices: When water sources are untreated, boil for one minute before drinking. You can also filter your own water if the filter is rated absolute 1 micron or less and you dissolve iodine tablets in the filtered water.
• Safe meat preparation: Use a food thermometer when cooking meat. You should cook whole cuts to an internal temperature of at least 145 degrees Fahrenheit, then let them sit for three minutes before eating. You should cook ground meat to 160 degrees Fahrenheit. Smoking and drying meat won't prevent tapeworms.
• Safe fish preparation: Cook large freshwater fish, such as salmon, to an internal temperature of 145 degrees Fahrenheit. If you’re eating fish raw, it's safest to freeze it first. Many fine sushi restaurants acquire fresh fish that has been flash-frozen at –31 degrees Fahrenheit. Then they store the fish for up to 24 hours at –4 degrees Fahrenheit. Without deep freezing, you must freeze fish for seven days at –4 degrees Fahrenheit to kill parasites, according to the FDA.

How long will I have a tapeworm infection?

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.

How should I care for myself if I have an asymptomatic tapeworm larval infection?

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.

When should I see my healthcare provider?

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.