Tapeworm Infection: Symptoms, Causes, Diagnosis, Treatment

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While uncommon in most of the United States, infection with tapeworms, a condition called taeniasis, is of more concern in the developing world. Tapeworms are a type of parasitic flatworm and some species can infect humans. Infections are more common in areas where sanitation facilities are lacking and people may be in close contact with animals. Tapeworm infections in humans occur most often as a result of eating undercooked or raw beef, pork, or fish from an animal that was infected.

A secondary cause of infection is improper handwashing after coming into contact with tapeworms or tapeworm eggs. In the case of the pork tapeworm, the eggs can be ingested, and when they hatch, they may go on to cause a serious infection called cysticercosis.

The different species of tapeworms include the beef tapeworm (Taenia saginata), pork tapeworm (Taenia solium), and the Asian tapeworm (Taenia asiatica), which is found in Asia and also infects pork. Freshwater fish can be infected with a broad tapeworm, Diphyllobothrium latum.

Symptoms

In most cases, infection with a tapeworm does not cause symptoms or causes few symptoms in the digestive tract. If there are signs and symptoms, they can include:

  • Abdominal pain
  • Diarrhea
  • Fatigue
  • Hunger
  • Lack of appetite
  • Nausea
  • Passing tapeworm segments in the stool
  • Weight loss

In the case of infection with pork tapeworm (T . solium) eggs, other body parts are infected when the tapeworm larvae migrate out of the digestive system and form cysts (which is called cysticercosis).

This may rarely result in masses or lumps under the skin or in body tissues or organs.

If cysts occur in the central nervous system or the brain there can be neurological symptoms (this is a condition called neurocysticercosis) and be quite serious. Some of the signs and symptoms of neurocysticercosis can include:

  • Headache
  • Seizures
  • Other neurological symptoms

Infection with the fish tapeworm (D​. latum) may lead to a lack of vitamin B12, which may cause anemia. Signs and symptoms of anemia can include:

  • Depression
  • Dizziness
  • Fatigue
  • Headaches
  • Low energy
  • Rapid heart beat
  • Ringing in the ears

Causes

A few factors put you at risk for developing a tapeworm infection.

Undercooked Meat, Pork, or Fish

The most common way that people are infected with a tapeworm is through eating undercooked or raw meat, pork, or fish. If the animal had tapeworms, the person eating the meat can also become infected.

The life cycle of a tapeworm begins with eggs. Tapeworm eggs can live outside of a host and in the environment (such as in water or on vegetation) for days or even months. Animals may become infected after eating vegetation or feed or drinking water that contains tapeworm eggs.

Now inside an animal host, the eggs hatch and mature into young tapeworms, which are mobile and can migrate out of the intestine and into muscle tissue. If not frozen or cooked properly to kill the infection, the meat contains living tapeworms, which can then be passed on to a human that consumes it.

Pork Tapeworm Eggs

A less common way of becoming infected with tapeworms is through contact with eggs from the pork tapeworm (T solium).

The eggs are shed in the stool from an animal or a human who is infected and can remain viable in the environment. This includes water, which is why it is important to take care to ensure drinking water is free of pathogens.

The eggs can also be ingested, for instance, if a person who is infected doesn’t wash their hands well after going to the bathroom and then handles food eaten by others. Pork tapeworm eggs can live on surfaces so it’s also possible to pass them on to other people through the use of objects that have eggs on them.

International Travel

While infection with tapeworms does occur in the United States, it is more common in the developing world.

Travel to areas where infections with tapeworms are more common is a risk factor. Preventing infection while traveling includes making sure meat and fish are cooked well and that fruits and vegetables are cooked in boiling water or water that has been treated properly to kill any potential pathogens. It’s best to avoid any food or drink that is suspect.

Diagnosis

Diagnosis of infection in the digestive system includes testing the stool for tapeworms and/or looking at the perianal area for eggs. In some cases, tapeworm segments may be visible in the stool. If this occurs, it is important to bring the stool sample to a physician or a lab in order to get it tested and receive a diagnosis. For others, there may be tapeworms on or around the anus that a physician can see during a physical exam.

For a stool test, which is necessary to find out which type of tapeworm is present, stool will need to be collected and given to a lab. This is usually done with stool being placed into a sterile container, either at home or using a bathroom at the lab, and given to lab technicians who will process it and send it for testing. It might be necessary to collect and test stool from several different bowel movements over a few days to make the diagnosis.

Blood tests for vitamin B12 levels and/or anemia may be done if there is an infection with the fish tapeworm. A serology blood test that detects cysticercosis-specific antibodies may be used to help diagnose cysticercosis, but this is not common. Imaging tests such as CT scan or MRI may also be done if there are complications from an infection with pork tapeworm eggs that have migrated to other parts of the body.

Treatment

In cases of intestinal tapeworm infection, treatment is with a medication that will immobilize the worms. Once the worms are unable to hang onto the lining of the intestine they will be passed out of the body with a bowel movement.

An antiparasitic drug commonly used to treat tapeworm infections is praziquantel (Biltricide). Praziquantel is given in a single dose. For infection with the Dwarf tapeworm (Hymenolepis nana), an antiprotozoal medication, Alinia (nitazoxanide), may be used.

For complications from infection with pork tapeworm eggs that have formed cysts, treatment will depend on the location of the cysts. The antiparasitic medication will be given but it may be necessary to use additional medications or treatments to manage infection and associated complications in other areas of the body.

A Word From Verywell

Infection with tapeworms is rare, even when traveling to areas where it occurs more commonly than it does in developed countries. Infections with most types of tapeworms are manageable with medication. What’s important is to get the infection treated and to follow up with a healthcare provider to ensure that treatment was effective.

Prevention is also key but is challenging in areas where there’s ​no access to clean water and sanitation facilities. In some areas of the developing world, infection with pork tapeworm eggs is a significant cause of permanent neurological problems. In the United States, infection is not common and is more of a concern in immigrant populations or for those who live in areas with farmed or free range livestock. 

View Article Sources
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  • Global Health – Division of Parasitic Diseases. "Taeniasis FAQs." Centers for Disease Control and Prevention. 10 Jan 2013.
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  • U.S. Department of Health and Human Services. "Safe Food Handling: What You Need to Know.” U.S. Food and Drug Administration. 30 Nov 2017.