Tapeworms are intestinal parasites that are shaped like 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 normally enter the human host from animals via food, especially raw or undercooked meat.
Humans can also become infected if there is contact with animal feces or contaminated water. When an infection is passed from an animal to a human, it is called zoonosis.
Anyone who has a tapeworm will need treatment to get rid of it. Treatment is 95 percent effective and can be completed in a few days.
Fast facts on tapeworms
Here are some key points about tapeworms. More detail and supporting information is in the main article.
- 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.
Most people who have a tapeworm experience no symptoms and are unaware of hosting one.
Symptoms may vary depending on the type of tapeworm, and they may include the following:
- eggs, larvae, or segments from the tapeworm in stools
- abdominal pain
- general weakness
- inflammation of the intestine
- weight loss
- altered appetite
- sleeping difficulties this may be as a result of other symptoms.
- convulsions in severe cases.
- vitamin B12 deficiency in very rare cases
The risk of complications depends on several factors, including the type of tapeworm and whether or not the patient receives treatment:
- Cysticercosis: If a human ingests pork tapeworm eggs there is a risk of larvae infection. The larvae can exit the intestine and infect tissues and organs elsewhere in the body, resulting in lesions or cysts.
- Neurocysticercosis: This is a dangerous complication of pork tapeworm infection. The brain and nervous system are affected. The patient 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 an infection called echinococcosis. The larvae leave the gut and infect 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, surgery or liver transplantation is required.
Treating 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 may be prescribed. The digestive system does not absorb these drugs well. They either dissolve or attack and kill the adult tapeworm.
A doctor may advise the patient to take a laxative to help the tapeworm come out in the stools. If the patient has a pork tapeworm infection, they may be given an anti-emetic medication, which prevents vomiting. Vomiting during a tapeworm infection can lead to reinfection by swallowing the tapeworm larvae,
The patient’s stools will be checked several times 1 to 3 months after the course of medication. These medications, if procedures are followed properly, are 95 percent effective.
If the infection affects tissues outside the intestine, the patient may have to take a course of anti-inflammatory steroids to reduce swelling caused by the development of cysts.
If the patient has life-threatening cysts that have developed in vital organs, such as the lungs or liver, surgery may be required. The doctor may inject a cyst with medication, such as formalin, to destroy the larvae before removing the cyst.
Most people become infected after ingesting tapeworm eggs or larvae. The common methods of infection include:
Ingestion of eggs
Eggs get into humans via:
- contaminated soil
If a host, such as a pig, has a tapeworm inside, segments of the worm or its eggs may be present in the feces of the host. These drop onto the soil. Each segment may contain thousands of eggs.
A human can become infected by:
- drinking contaminated water
- interacting with the animals and contaminated soil
- consuming contaminated food
The eggs hatch into larvae and make their way into the gut or outside, and infect other parts of the body. This type of infection is most common with tapeworms that come from infected pigs, and much less common if the original host was cattle or fish.
Eating infected meat or fish
If the meat or fish have larvae cysts and is undercooked or raw, the cysts can reach the intestine where they mature into adult tapeworms.
An adult tapeworm can:
- live as long as 20 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 stool is passed
Fish tapeworm infection is more common in countries where the consumption of raw fish is common practice, such as Eastern Europe, Scandinavia, and Japan. Undercooked or raw freshwater fish such as salmon, are the most common sources.
The dwarf tapeworm can be transmitted from human to human. It is the only tapeworm that can go through its entire life cycle in one single host. Dwarf tapeworm infection is the most common tapeworm infection globally.
Fleas and some types of beetles may pick up the eggs by eating the droppings of infected rats or mice. These insects can infect humans. The insects are referred to as intermediate hosts and the tapeworm transitions from egg to the adult stage. This type of infection occurs with dwarf tapeworms and is much more common in areas where hygiene practices are poor.
During treatment, humans can reinfect themselves if they do not follow good hygiene practices. The eggs will be present in human stool. If the individual does not wash their hands after going to the toilet, there is a risk of reinfection.
Ignoring risk factors for tapeworm infection
Risk factors include:
- Working with or exposure to animals: This is especially the case in areas where feces is not disposed of effectively.
- General lack of hygiene: If you wash your hands infrequently, the risk of transferring infection into your mouth is greater.
- Traveling to or living in certain parts of the world: In some countries, and parts of some countries where sanitation practices are poor, the risk of becoming infected with a tapeworm is much greater.
- Consuming raw or undercooked meats and fish: Larvae and eggs present in meats and fish may infect people if eaten raw or undercooked. Experts say that sushi is safe if it has been frozen beforehand. The risk of contamination from fish mainly lies with freshwater fish.
In human beings, tapeworm infection is most commonly caused by 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, more common in rural areas
The type of tapeworm will influence the area of the body that is infected and how severe the symptoms are.
Any individual who suspects tapeworm infection or has the symptoms described above should see their doctor. Some patients may notice infection themselves by checking their stool for parts of the adult tapeworm. However, a doctor is still needed to check the stool by sending samples to a lab. The doctor may also examine the area around the patient’s anus for signs of eggs or larvae.
The following diagnostic aids may be used, depending on the type of tapeworm larvae infection:
Removing adult tapeworms from the body is easier than managing a larvae infection.
Taking a medicine that kills the tapeworm is normally enough to ensure that the body will remove the tapeworm in stools. Medicine is now advanced enough that surgery is often not necessary.
However, the drugs are highly toxic. If a tapeworm reaches the brain, surgery and medicine may be used together to remove the parasite.
There are several effective methods of preventing tapeworm infection, including:
- Good hygiene: Wash hands thoroughly with soap and water after using the bathroom and before eating.
- Food precautions: In an area where tapeworms are common, make sure to wash and cook all fruits and vegetables with clean water.
- Livestock: Properly dispose of animal and human feces. Minimize animal exposure to tapeworm eggs.
- Meat: Cook meat to a temperature of at least 150 °Fahrenheit (66 °Celcius) thoroughly. 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.
- Raw foods: Do not consume raw or undercooked pork, beef, and fish.
- Dogs: If you have a dog, make sure they are treated for tapeworms. Take special care with your personal hygiene. Make sure your dog only eats cooked meat and fish.
- Kitchen hygiene: Make sure all work surfaces are regularly cleaned and disinfected.
Do not allow raw foods to touch other foods. Wash your hands after touching raw meat or fish. Experts say that smoking or drying meat or fish is not a reliable way to kill larvae or eggs.