Tapeworm infection

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 21, 2016
StartDiseasesTapeworm infection

A tapeworm infection occurs when one or more parasitic flatworms invades the intestines or other organs of the human body. Among developed countries, the majority of these infections are easily treatable with oral medication and are rarely the cause of life-threatening symptoms. The head of a tapeworm looks like a sucker surrounded by sharp hooks and the parasite will use it to attach its long body to the intestine of their host.


Definition & Facts

Tapeworms or cestodes are white or cream-colored, flat, segmented parasites growing up to 20 feet long that live in the intestines of many common animals from huge whales to cattle, pigs and fish. These invertebrates have a long history and have been discovered in the fossilized dung of sharks from the Permian, a geologic period that took place over 250 million years ago. There are about ten species of tapeworm all belonging to the class Cestoda, though only six of them are known to regularly use humans as either primary or intermediate hosts.

Many of the known species are categorized by the animal they are most commonly found living in, such as T. saginata, the beef tapeworm or T. solium, the pork tapeworm. Another common species is H. nana found in rodents. D. canium infects cats and dogs, and D. latum is found in undercooked meat of fish from lakes and rivers around the world.  

Symptoms & Complaints

A tapeworm infection has many of the same symptoms as other types of food poisoning including nausea, diarrhea, stomach cramps, fever, and fatigue. Other issues such as unexplained weight loss and vitamin deficiency may occur depending on the length of time and the severity of the infection.

In rarer cases, tapeworms can cause large or small cystic masses or cysticercoids, allergic reactions to their presence in the body, and bacterial infections. Symptoms even more serious occur when the tapeworm's body segments break off and make their way into the meninges, spinal cord, brain, or appendix, leading to seizures and appendicitis


Tapeworm infections are caused by eating contaminated food or drinking contaminated water or accidentally ingesting tapeworm eggs usually as a result of poor hygiene. Sources of tapeworm infections include ingesting water that has been contaminated by feces of infected animals; ingesting undercooked or mishandled meat of an animal that has the infection; and lack of hygiene around household pets.

The infection is a three-stage cycle. First, tapeworm eggs are passed through the gastrointestinal tract of an infected animal or human. Secondly, another animal consumes the eggs by eating contaminated vegetation or drinking water that has been tainted. Inside the second animal, the tiny eggs hatch into the rice grain sized larvae. The freely moving larvae then attach themselves to whatever tissue is handy, often the walls of the large intestine. Thirdly, this animal is then eaten by another animal or a person and the cycle begins anew. 

Diagnosis & Tests

A stool sample is often all that is needed for a doctor to diagnose a tapeworm infection. Some species, however, do not regularly pass through the intestines so a blood test may be ordered to see if antibodies produced by the human body to fight the infection are present. For a more severe case, medical staff may utilize either a CT (computerized tomography) scan or an MRI (magnetic resource imaging) scan to rule out any further internal damage done by the worms. 

Treatment & Therapy

Fortunately, in the United States, tapeworm infections are rare and they are most often treated with oral medications. The most prevalent are niclosamide or praziquantel. These medications work by first paralyzing the worms in order to make them detach from any blood vessels they may be wrapped around or bodily tissues they are buried in.

Secondly, the parasites die and are then passed through the intestines and into the feces of the infected person, which is often painless though the larger worms may cause abdominal cramps. The success rate for treating tapeworm infections with oral medications in the United States falls between 85 percent and 95 percent, depending on the worm species. 

Prevention & Prophylaxis

Tapeworm infections are uncommon in the United States today due to rigorous regulations governing feeding commercially raised livestock such as chickens, cattle, pork and fish.

Precautions such as always washing one's hands with hot water and soap after using the toilet and before preparing food are the first steps in avoiding a cestode infection. There is no brand of hand sanitizer that kills tapeworm eggs or larvae, and it should never be used in place of hand washing.

Deep freezing meat such as fish and pork to negative four degrees Fahrenheit (negative twenty degrees Celsius) for at least twenty-four hours prior to cooking may also kill any cestode eggs or larvae that may be present. Proper thawing and always taking care to cook all meat to the recommended internal temperatures are other ways to break the tapeworm life cycle and prevent further infection. Keeping household pets up to date with checkups also helps mitigate the risk of having a tapeworm infection.

Less than one percent of known tapeworm infections in the United States, the United Kingdom or Western Europe have been life-threatening in nature. Sensibly, caution should always be taken while traveling in underdeveloped countries to wash and cook fruits and vegetables with boiled or chemically treated water before eating.

Any drinking water should be treated as suspect for the same reasons. All meat should be handled accordingly and should never be consumed raw. Countries in Africa, the Middle East, Eastern Europe, Southeast Asia, and Central and South America are often where people pick up beef and pork tapeworms. In Japan, Scandinavia, Alaska and other places where raw fish is commonly consumed, there may be a risk, even with a trusted source.