What Is a Tapeworm Infection?

Tapeworms are parasitic flatworms that can live in the intestines of animals and humans. You can get infected with a tapeworm by eating contaminated raw or undercooked pork, beef, or fish. Once inside your body, tapeworms can silently live in the intestines, absorbing nutrients from foods you eat.

Tapeworm infections don’t often cause symptoms, though some people may experience abdominal discomfort or digestive problems like diarrhea or nausea. Most tapeworm infections are easy to treat with antiparasitic medication. Some types of tapeworm can infect other areas in the body and may require additional treatments.

It's believed that fewer than 1,000 cases of tapeworm infection occur in the U.S. each year. The infection is more common in areas with poor sanitation and where people eat raw or undercooked meat.

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Types of Tapeworm Infections

Several types of tapeworms can infect humans. The four main tapeworm types that can lead to intestinal infection include:

• Beef tapeworm (Taenia saginata) spreads to humans by eating raw or undercooked beef. They are usually 13-39 feet long but can grow to be nearly 82 feet long.
• Pork tapeworm (Taenia solium) spreads to humans by eating raw or undercooked pork. They are usually 6.5-26 feet long. Swallowing eggs of this tapeworm can cause a type of infection called cysticercosis, when larval cysts develop in various body tissues, including the brain.
• Fish tapeworm (Diphyllobothrium latum) spreads to humans by eating raw or undercooked freshwater fish. They can grow to be anywhere from 6.5-49 feet long.
• Dwarf tapeworm (Hymenolepis nana) spreads to humans by ingesting tapeworm eggs in contaminated food or water. This type is more common in people with limited access to proper hygiene and sanitation. They get their name because they are much smaller than other tapeworms, growing to be about 2 inches long.
  

A tapeworm infection caused by a tapeworm of the Taenia species—like beef and pork tapeworms—may be referred to as taeniasis.

Tapeworm Infection Symptoms 

Because tapeworms adapt so well to your intestines, they often do not cause any symptoms. If you do have symptoms, they are often mild. Tapeworm infection symptoms may include:

• Abdominal pain or discomfort
• Diarrhea
• Nausea 
• Gas
• Change in appetite 
• Weakness
• Weight loss

You may be more likely to experience symptoms if you've been infected with tapeworm from beef or fish since those tapeworms are longer. Children are also likelier than adults to experience symptoms.

In many cases, people may not realize they have a tapeworm infection until they notice ribbon-like segments of the tapeworm in the stool (poop) or feel a piece of the worm moving out of the anus during or after a bowel movement.

What Causes Tapeworm Infections? 

Tapeworms enter the body when someone ingests the eggs or larvae of tapeworms. Eating raw or undercooked pork, beef, or fish containing tapeworm eggs or larvae is the most common cause of tapeworm infections. You may also get tapeworm from drinking contaminated water.

Once swallowed, the larvae or eggs hatch and latch onto the intestinal walls, where they develop into adults and continue to live, feed, and grow. Pieces of adult tapeworms containing eggs break off and exit the body in stool. The eggs can live in water, soil, or on plants for months. If a person or animal consumes the contaminated water or plants, they become infected with tapeworm.

You can also become infected with tapeworm by coming into contact with the feces of someone with a tapeworm infection. If an infected person does not wash their hands after using the bathroom and then handles food or touches shared surfaces like a doorknob, they can spread the infection.

Risk Factors

Eating or handling raw or undercooked pork, beef, or fish is the leading risk factor for tapeworm infections. Other risk factors include:

• Having poor hygiene, such as not washing your hands after using the bathroom 
• Lacking access to sewage sanitation 
• Living in or traveling to areas where eating undercooked pork or beef is common
• Working with farm animals or living on a farm 

How Is Tapeworm Infection Diagnosed?  

Healthcare providers diagnose a tapeworm infection based on your medical history, physical examination, and stool test results. 

To diagnose a tapeworm infection, your healthcare provider may begin by asking about your travel history, eating habits, and any symptoms you are experiencing. They will likely perform a physical examination to look for signs of tapeworm infection, such as abdominal tenderness or bloating.

A stool test can help rule out other possible causes of your symptoms and confirm a tapeworm infection. Your healthcare provider will ask for a stool sample and send it to the lab, where it is examined under a microscope to look for tapeworm eggs or segments of adult worms. Often, you will be asked to give three different stool samples on separate days.

Sometimes your healthcare provider may order additional diagnostic tests to confirm the diagnosis and check for complications. This may include a blood test to check for antibodies your body has produced to fight off the infection. The blood test can also assess for anemia—a condition when you don't produce enough healthy red blood cells—which can occur with fish tapeworm infections.

They may also order imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI) scans. These can help visualize the inside of your body to determine whether tapeworms have migrated outside the intestines to other internal organs.

Treatments for Tapeworm Infections  

Tapeworm is curable with treatment. Prescription medications known as antiparasitics are taken by mouth to kill the tapeworm and remove it from your body.

Biltricide (praziquantel) is the most common medication used for tapeworm infections and is given in a single dose. Albenza (albendazole) is an alternative and is taken over the course of three days.

Your healthcare provider may collect stool samples from you one and three months after treatment to ensure the infection is gone.

How To Prevent Tapeworm 

The best way to prevent tapeworm infection is to avoid eating raw or undercooked pork, beef, or fish. To prevent tapeworm infection, you should also:

• Wash your hands frequently with soap and water, including before and after you handle food and after using the bathroom or changing diapers 
• Wash and peel raw fruit and vegetables before eating 
• Drink bottled water or boil water for at least one minute when traveling in countries where tapeworm is more common 

Complications

Untreated tapeworm infections can lead to complications, such as: 

• Cysticercosis: This condition occurs when larvae of the pork tapeworm (Taenia solium) migrate to other parts of the body, such as the brain, skin, eyes, or liver. Cysticercosis can cause seizures, headaches, and vision problems.
• Anemia: Fish tapeworms absorb vitamin B12 from the foods you eat, which can lead to anemia since your body needs vitamin B12 to produce blood cells.
• Bowel obstruction: Although rare, tapeworms can block the intestines, which may require surgery to treat.
• Spreading to other organs: Some tapeworm species can migrate from the intestines to other organs, such as the appendix or liver. This can lead to problems like appendicitis or liver cysts.
• Allergic reactions: Some people are allergic to tapeworms, which can cause hives, itching, and difficulty breathing.

A Quick Review

Tapeworms are parasitic flatworms that can live in your intestines. Eating raw or uncooked beef, pork, or fish is the most common way people are infected by a tapeworm. Tapeworm infections don't usually cause symptoms. If they do, they are often mild and can include diarrhea, abdominal discomfort, weight loss, and nausea. 

Prescription antiparasitic drugs are the cornerstone treatment for tapeworm infections. Treatment can help prevent complications like cysticercosis, anemia, and bowel blockages. 

The best way to prevent tapeworm infection is to cook meat and fish thoroughly, wash fruits and vegetables before eating them, avoid contact with contaminated soil and water, and practice good personal hygiene.