Tapeworms are intestinal parasites that are shaped similarly to a tape measure. A parasite is an animal or plant that lives inside another animal or plant.

A tapeworm cannot live freely on its own. It survives within the gut of animals, including humans.

Tapeworm eggs typically enter a human host from animals through food, particularly raw or undercooked meat.

Humans can also contract tapeworms if they have contact with animal feces or contaminated water. When an infection passes from an animal to a human, it is called zoonosis.

Anyone who has a tapeworm will need medical treatment to get rid of it. Treatment is about 95% effective and typically takes a few days.

Fast facts on tapeworms

  • Tapeworms are parasites that survive within another organism, known as the host.
  • They grow after the host ingests the eggs of the tapeworm.
  • Drinking contaminated water and eating contaminated food are the primary causes.
  • Oral medication is a common treatment.

The Taenia Solium tapewormShare on Pinterest
The Taenia solium (pork tapeworm).

Most people who develop tapeworms do so after ingesting tapeworm eggs or larvae. The common methods of transmission include:

Ingestion of eggs

Eggs can enter humans through:

  • food
  • water
  • contaminated soil

If a host animal, such as a pig, has a tapeworm, segments of the worm or its eggs may be present in the feces of the host. These drop onto soil, and each segment may contain thousands of eggs.

A human can contract tapeworms through:

  • drinking contaminated water
  • interacting with affected animals and contaminated soil
  • consuming contaminated food

The eggs hatch into larvae and make their way into the gut, or outside the gut and infect other parts of the body. This type of infection is most common with tapeworms that come from infected pigs, and is much less common if the original host was cattle or fish.

Eating affected meat or fish

If meat or fish have larvae cysts and are undercooked or raw, the cysts can travel to the human intestine, where they can mature into adult tapeworms.

An adult tapeworm can:

  • live as long as 25 years
  • be up to 50 feet long
  • attach themselves to the walls of the intestine
  • pass through the human digestive system and end up in the toilet when a person passes stool

Fish tapeworm infections are more common in countries where the consumption of raw fish is common practice. These include Europe, North America, and some countries in Asia. Undercooked or raw freshwater fish, such as salmon, are the most common sources.

Human-to-human transmission

The dwarf tapeworm can pass from human to human, according to 2015 research. It is the only tapeworm that can go through its entire life cycle in one single host. A dwarf tapeworm infection is the most common tapeworm infection globally in humans.

Insect-to-human transmission

Fleas and some types of beetles may pick up the eggs by eating the droppings of infected rats or mice. The insects are intermediate hosts, which can then be ingested by humans. After the egg is transmitted to a human host, the tapeworm transitions from an egg to the adult stage. This type of infection occurs with dwarf tapeworms and is much more common in areas where it is more difficult to maintain high levels of hygiene.

Reinfection

During treatment, humans can reinfect themselves if they have difficulty maintaining hygiene levels. The eggs will be present in human stool. If the individual does not wash their hands after going to the toilet, for example, there is a risk of reinfection.

Exposure to risk factors

Risk factors include:

  • Exposure to animals: This is particularly relevant in areas where feces is not disposed of appropriately.
  • Difficulty maintaining hygiene: If a person washes their hands infrequently, the risk of transferring infection into their mouth is greater.
  • Traveling to or living in certain parts of the world: In some countries and parts of countries where it is more difficult to maintain hygiene, the risk of tapeworm transmission is greater.
  • Consuming raw or undercooked meats and fish: Larvae and eggs present in meats and fish may transmit tapeworms to people if eaten raw or undercooked. Experts say that sushi is safe if a person has frozen it beforehand. The risk of contamination from fish mainly lies with freshwater fish.

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Eggs of the tapeworm Taenia.

Many people who have a tapeworm experience no symptoms and are unaware that they are hosting one.

If signs and symptoms are present, they often include tiredness, abdominal pain, weight loss, and diarrhea.

Symptoms vary depending on the type of tapeworm, and may include the following:

Complications

The risk of complications depends on several factors, including the type of tapeworm and whether the person receives treatment.

  • Cysticercosis: If a human ingests pork tapeworm eggs, there is a risk of larvae infection. The larvae can exit the intestine and travel to tissues and organs elsewhere in the body, resulting in lesions or cysts.
  • Neurocysticercosis: This is a dangerous complication of a pork tapeworm infection. It affects the brain and nervous system. The person may have headaches, vision problems, seizures, meningitis, and confusion. In very severe cases, the infection can be fatal.
  • Echinococcosis, or hydatid disease: The echinococcus tapeworm can cause this. The larvae leave the gut and travel to organs, most commonly the liver. The infection can result in large cysts, which place pressure on nearby blood vessels and affect circulation. In severe cases, a person may need surgery or liver transplantation.

Treating a tapeworm larvae infection is more complicated than treating an adult tapeworm infection.

While the adult tapeworm stays in the gut, the larvae may settle in other parts of the body. When a larvae infection finally produces symptoms, the infection may have been present for years. In some rare cases, larvae infection can be life threatening.

Oral medications

Doctors may prescribe oral medications. The digestive system does not absorb these drugs well. They either dissolve or kill the adult tapeworm.

A doctor may advise the person to take a laxative to help the tapeworm come out in their stool. If the person has a pork tapeworm infection, their doctor may prescribe them an antiemetic medication, which prevents vomiting. Vomiting during a tapeworm infection can lead to reinfection by swallowing the tapeworm larvae.

The person’s stools will be checked several times for a few months after the course of medication. These medications, if a person follows procedures correctly, are 95% effective.

Anti-inflammatory medication

If the infection affects tissues outside the intestine, the person may have to take a course of anti-inflammatory steroids to reduce swelling caused by the development of cysts.

Cyst surgery

If the person has life threatening cysts that have developed in vital organs such as the lungs or liver, they may need surgery. A doctor may inject a cyst with medication, such as formalin, to destroy the larvae before removing the cyst.

In human beings, tapeworm infections most commonly come from the following species:

  • pork tapeworm (Taenia solium)
  • beef tapeworm (Taenia saginata)
  • dwarf tapeworm (Hymenolepis nana)
  • fish tapeworm from raw freshwater fish (Diphyllobothrium latum)
  • dog tapeworm, which is more common in rural areas

The type of tapeworm will influence the infected area of the body and how severe the symptoms are.

Any individual who suspects tapeworm infection or has the symptoms described above should speak with their doctor. Some people may notice infection themselves after seeing parts of the adult tapeworm in their stool.

A doctor will check the stool by sending samples to a lab. Two to three stool samples may be necessary. The doctor may also examine the area around the person’s anus for signs of eggs or larvae.

The doctor may use the following diagnostic aids, depending on the type of tapeworm larvae infection:

Removing adult tapeworms from the body is simpler than managing a larvae infection.

Taking medication that kills the tapeworm is typically enough to ensure that the body will remove the tapeworm in stools. Medications are now advanced enough that surgery is often not necessary. However, the drugs prescribed are highly toxic.

If a tapeworm reaches the brain, a doctor may recommend surgery and medication together to remove the parasite, according to 2012 research.

There are several effective methods for helping prevent tapeworm infections, including:

  • Maintaining hygiene: Wash hands thoroughly with soap and water after using the bathroom, touching animals and insects, and before eating.
  • Food precautions: In an area where tapeworms are common, be sure to wash and cook all fruits and vegetables with clean water.
  • Livestock: Correctly dispose of animal and human feces. Minimize animal exposure to tapeworm eggs.
  • Meat: Cook meat to a temperature of at least 150°F (66°C). This will kill larvae or eggs.
  • Meat and fish: Freeze fish and meat for at least 7 days. This will kill tapeworm eggs and larvae. Experts say that smoking or drying meat or fish is not a reliable way to kill larvae or eggs.
  • Raw foods: Do not consume raw or undercooked pork, beef, or fish. Do not allow raw foods to touch other foods. A person should wash their hands after each time they touch raw meat or fish.
  • Dogs: If a person has a dog, they must make sure the dog receives treatment for tapeworms. They should also take special care with personal hygiene. They may wish to make sure the dog only eats cooked meat and fish, if given.
  • Surfaces: Make sure to clean and disinfect all frequently touched areas regularly.

Tapeworms are intestinal parasites that can live inside another animal or plant. They are more present in parts of the world where it is more difficult to maintain hygiene but can be ingested when consuming raw or undercooked meat and fish. Several types of tapeworms can infect humans.

A doctor may ask for stool samples or blood tests to diagnose tapeworms. Tapeworms can be treated through oral medications and laxatives. If a person follows treatment correctly, medications are highly effective.