Tapeworm in Humans Symptoms, Signs, Treatment and Diagram

Tapeworm infection in humans is caused mainly by humans eating infected meat and fish that haven’t been cooked properly or drinking contaminated water. Even though there are few symptoms of tapeworms in humans, their existence sometimes can cause severe life-threatening problems. However, tapeworm infection in humans can easily be treated.

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It has been discovered that eating contaminated food and drinking contaminated water is the main cause of tapeworm in humans. This is because the tapeworm eggs normally enter humans from animals through food, most especially undercooked or raw meat. Also, tapeworm infection in humans can also be a result of human contact with contaminated water or infected animal feces.

However, it is called zoonosis when a tapeworm infection is passed from an animal to a human. Any human with tapeworm infection will require treatment to get rid of it. Moreso treatment has been proven to be very effective and can be completed in few days.

Table of Contents

What are Tapeworms?

Tapeworms or cestodes are flat long segmented worms that live in the intestine of humans and animals. They cannot live freely on their own, so they inhabit the gut of animals and humans. Hence, they are parasites that require at least two hosts. Adult tapeworms are usually parasites in the digestive tracts of vertebrates. This is why tapeworm is common in humans digestive tracts.

Most times their intermediate hosts are invertebrates. However, these worms are capable of infecting virtually all vertebrate species. Moreso, there are some common species of tapeworms in humans. Such common tapeworms in humans are beef tapeworm, pork tapeworm, fish tapeworm, dog tapeworm, dwarf tapeworm, unilocular hydatid, and multiocular hydatid.

What does a Tapeworm look like?

A tapeworm usually has a long flat body composed of a scolex. This scolex is used by the tapeworm for attachment to a host. The scolex of the tapeworm is followed by a linear series of reproductive units or proglottids. A scolex of the tapeworm has suckers or sucker-like organs often with hooks or spiny tentacles. They lack a digestive system but have well-developed muscles. Tapeworms actually lack special sense organs but have sensory endings in their tegument that are modified cilia.

The main body of tapeworms, which are the chain of proglottids is called a strobila. However, there is a germinative zone just behind the scolex where new proglottids are formed. As younger proglottids are differentiated in front of it, each individual proglottid moves outward in the strobila and its gonads mature.

The body of a tapeworm is unusual because it has no head. The scolex used for attachment is actually a remnant of the posterior part of the ancestral body. Segmentation of the tapeworm body is a replication of sex organs to increase reproductive capacity. However, this segmentation is not homologous to the metamerism found in Annelida, arthropods, and Chordata.

Diagram of tapeworm in humans - what a tapeworm looks like
Labeled diagram of tapeworm that affects humans

Conclusively, tapeworms have three distinct portions:

  • The scolex: The scolex functions as an anchoring organ. It attaches to the intestinal mucosa.
  • Neck: The neck is an unsegmented region. It has a high regenerative capacity that if treatment does not eliminate the scolex and neck, the entire worm may regenerate.
  • Body: The rest of the worm consists of several proglottids (segments). However, the proglottids closest to the neck are undifferentiated. Each proglottid develops hermaphroditic sex organs as they move caudally. The distal proglottids are gravid and contain eggs in the uterus.

How do Humans get tapeworms?

  • Ingesting contaminated food
  • Drinking contaminated water
  • Contact with contaminated soil
  • Human-to-human transmission
  • Insect-to-human transmission
  • Ignoring tapeworm infection risk factors
  • Reinfecting oneself

Humans get infected with tapeworms after ingesting the eggs or larvae of tapeworms. This can happen in several ways. However, common ways of infection include the following:

  • Ingesting contaminated food

Tapeworm infection in humans starts by ingesting the eggs of the tapeworm. This is mostly done when eating contaminated food. Food gets contaminated when infected with the tapeworm’s eggs or larvae. Once, an infected fish or meat that have the larvae cysts of the tapeworm is eaten raw or undercooked. These cysts reach the intestine and mature there into tapeworms. The adult tapeworm can live as long as 20 years and can even be up to 50 feet long. Eventually, the worm attaches itself to the intestine walls of its host. It can pass through the digestive system and end up in the toilet when the human passes stool.

A typical example of tapeworm in humans is common in countries where they practice raw fish consumption. Such countries like Scandinavia, Japan, and Eastern Europe. Raw or undercooked freshwater fish like salmon is their common source.

  • Drinking contaminated water

Tapeworm can get in humans by drinking water that is contaminated with tapeworm eggs or larvae. This is why one should avoid drinking water from sources that the water is not treated or purified.

  • Contact with contaminated soil

Tapeworm in humans can also be a result of contact with contaminated soil. For instance, if a host animal like a pig has a tapeworm in it, segments of the worm or its eggs may be passed in the pig’s feces. These eventually drop onto the soil and each segment may contain thousands of the worm’s eggs. Contact with such contaminated soil can lead to tapeworm infection in humans. For instance, the unhygienic habits of children playing with soil and then eating with their unwashed hands. Also, another instance is humans not washing their hands properly after gardening or catering for their infected livestock.

  • Human-to-human transmission

Tapeworm can be transmitted from a human to another human. For instance, is the dwarf tapeworm that can be passed from human to human. It is the only tapeworm in its human-to-human oral-anal cycle that can go through its entire life cycle in one single host.  The tapeworm eggs are passed from one human to another human or are recycle externally in a single host. However, the dwarf tapeworm infection is the most common tapeworm infection in the world.

  • Insect-to-human transmission

Humans can get infected by insects that pick up the tapeworm eggs. For instance, some types of beetles and fleas may pick up the tapeworm eggs by eating the droppings of infected mice or rats. Such insects can infect humans and are referred to as intermediate hosts of the tapeworm. This sort of infection occurs with dwarf tapeworm and is more common in places with poor hygiene practices.

  • Ignoring tapeworm infection risk factors

Humans can get easily infected with tapeworms when they ignore risk factors associated with tapeworm infection. Risk factors such as:

  • Poor hygiene: The risk of transferring infection into the mouth is higher if you don’t wash your hands frequently.
  • Exposure to animals: Infection can occur when frequently exposed to infected animals, especially in areas where their feces is not well disposed of.
  • Living in or traveling to certain places: One is at risk of infection when living in some certain area where sanitation practices are poor. In such places, the risk of tapeworm infection is higher.
  • Food habits: Some kinds of food habits can put one at risk of infection. Such as consuming undercooked or raw meat and fish. The eggs or larvae present in fish or meats may infect humans if eaten undercooked or raw. However, experts say that sushi for instance is safe if it has been frozen beforehand.
  • Reinfecting oneself

One could be under treatment and still reinfect oneself. This is possible if they do not follow good hygiene practices during treatment. This is because the tapeworm eggs will be present in human stool and if the person does not wash his/her hands after going to the toilet, the person puts himself at risk of reinfection.


(Taenia saginata) – Beef tapeworm in humans

Taenia saginata is called a beef tapeworm even though it lives in humans. It stays in the human intestine as an adult and its juvenile form occurs mostly in intermuscular tissues of cattle. A mature adult beef tapeworm may reach a length of 10m or more. Its scolex has 4 suckers for attachment to the intestinal wall. The scolex however has no hook and a short neck connects the scolex to the strobila. Gravid proglottids bear shelled infected larvae which become detached and pass in feces.

Lifecycle of beef tapeworm

The shelled larvae (oncospheres) of the beef tapeworm are swallowed by cattle. After being swallowed, they hatch and use their hooks to burrow into blood or lymph vessels through the intestinal wall, till they reach voluntary muscles. They encyst in the muscles and become bladder worms (cysticerci). In the muscles, the juveniles develop an invaginated scolex but remain quiescent.

However when raw or undercooked meat is eaten by a suitable host such as humans. The cyst wall dissolves and the scolex evaginates attaching to the intestinal mucosa. Then new proglottids begin to develop taking 2-3 weeks for a mature worm to form. Hence when a person is infected by one of these tapeworms, numerous gravid proglottids are expelled daily. Sometimes crawling out of the anus. Therefore humans get infected by eating undercooked beef, steaks, and barbecues. Hence infection is easily avoided when the meat is thoroughly cooked.

Read Taenia solium life cycle to get a more detailed explanation of the beef tapeworm life history.

Life cycle of Beef tapeworm in humans
The life cycle of Beef Tapeworm
Photo Credit: Textbook (Integrated Principles of Zoology, Fifteenth edition) by Hickman, Roberts, Keen, Eisenhour, Larson, I’Anson. Pg 306

Pork tapeworm (Taenia solium)

An adult Taenia solium (pork tapeworm) lives in the human small intestine while the juvenile of the worm occurs in the muscles of pigs. The scolex has both suckers and hooks arranged on its tip, the rostellum. The life cycle of this tapeworm is similar to that of the beef tapeworm. Though in this tapeworm case, humans get infected by eating insufficiently cooked pork.

However, pork tapeworm is much more dangerous than a beef tapeworm. This is because cysticerci and its adult can develop in humans. Hence if someone accidentally ingests eggs or proglottids, the liberated embryos will migrate to any organs and form cysticerci. This condition is called cysticercosis and common sites of infection are the eyes and brain. Therefore, infection in such places can cause severe neurological symptoms, blindness, or death.

Fish tapeworm (Diphyllobothrium latum)

An adult fish tapeworm lives in the intestines of humans, dogs, cats, and other mammals. However, the immature stages develop in fishes and crustaceans. It is the largest tapeworm that infects humans with its length up to 20m.

Fish tapeworm infection can occur anywhere in the world where people commonly eat raw fish. Infections are most common in the great lakes region, In the United States. In Finland, the worm can cause serious anemia not apparent in other areas.

Echinococcus granulosus (Unilocular Hydatid)

Echinococcus granulosus is a dog tapeworm that causes hydatidosis. This disease is a very serious infection in humans in many parts of the world. The adult worms develop in canines and the juvenile grows in more than 40 species of mammals. Mammals like monkeys, sheep, reindeer, cattle, and humans. Humans serve as a dead-end host for this tapeworm.

The juvenile stage of this tapeworm is a special kind of cysticercus called a hydatid cyst. It grows slowly but for a long time. Growing up to 20 years, it can reach the size of a basketball in an unrestricted site like the liver. If a hydatid grows in a critical location like the heart or central nervous system, serious symptoms may occur sooner. However, the main cysts maintain a single or unilocular chamber but daughter cysts bud off, each containing thousands of scolices. Each scolex eventually produces a worm when eaten by a canine. However, the only treatment is the surgical removal of the hydatid.

Are tapeworms contagious?

Once the tapeworm is inside the human body, the scolex attaches to the inner wall of the intestines. It feeds off the food being digested. However, pieces of the tapeworm eventually break off coming out of the body in feces, together with the eggs it contains. Thus if these infected feces gets into water or the soil it can infect other humans or animals.

Also, contact with this infected poop that contains tapeworm eggs can cause infection. Humans can pass tapeworm eggs to others when their hands are not washed after using the bathroom. Also, these tapeworm eggs in stool can spread into food or onto surfaces like tables top or doorknobs.

Symptoms of Tapeworm in humans

  • Nausea
  • General weakness
  • Diarrhea
  • Weight loss
  • Abdominal pain
  • Vomiting
  • Hunger or loss of appetite
  • Fatigue
  • Malnutrition
  • Vitamin and mineral deficiencies
  • Sleeping difficulties
  • Eggs, larvae, or segments of the tapeworm in stools
  • In severe cases, convulsion

Listed above are common signs and symptoms associated with tapeworms. Although most people that have a tapeworm are usually unaware and experience no symptoms. Sometimes the only sign of tapeworm infection they may have is the possible movement of segments of the worms in a bowel movement.

However, if symptoms occur they are usually abdominal pain, tiredness, weight loss, and diarrhea. Also, symptoms of tapeworm infection in humans will vary depending on the type of tapeworm. In addition, when a larvae infection finally produces symptoms, it’s possible the infection has been present for years. In some rare cases, such infection can be life-threatening.

Moreso, complications can occur as a result of tapeworm infection in humans. The type of tapeworm, several other factors, and whether or not the person receives treatment determine the risk of complications. Complicated conditions associated with tapeworms include:

  • Cysticercosis

Once a human ingests eggs of the pork tapeworm, there is a risk of infection. The larvae of the tapeworm can migrate from the intestine and infect other tissues and organs in the body. This eventually results in lesions or cysts. These larvae migrate to other parts of the body and cause damage to the eyes, brain, liver, and heart. Such infections can be life-threatening and seizures are the most common symptom of cysticercosis.

  • Hydatid disease

The hydatid disease is also known as Echinococcosis. This infection is caused by the echinococcus tapeworm. The larvae exit the gut and infect organs, most especially the liver. This infection can result in large cysts that place pressure on nearby blood vessels affecting circulation. However, surgery or liver transplantation is needed in severe cases.

  • Neurocysticercosis

Neurocysticercosis is a dangerous complication caused by pork tapeworm infection. As a result of this infection, the brain and nervous system are affected. Patients of this infection may have seizures, headaches, meningitis, vision problems, and confusion. The infection can lead to death in severe cases.

  • Blockage

Tapeworms in humans can cause serious complications like blocking the bile duct, pancreatic duct, or intestine. Though such cases are rare.

How to get rid of tapeworms in humans

  1. Go for stool analysis for diagnosis
  2. Get treatment if infected
  3. Prevent further infection

It is advisable to see your doctor if you suspect you have tapeworms. To be able to diagnose a tapeworm infection in humans, a stool sample may be required to identify the type of worm.

Diagnosing tapeworm in humans

For intestinal tapeworm infection, a stool sample analysis is required. The stool sample is viewed under the microscope for the presence of the worms, their eggs, or larva.

However, if tapeworms are not detected in the stool, the doctor may order a blood test. This blood test is to check for antibodies that have been produced to fight tapeworm infection.

Moreso, in severe cases, the doctor may use imaging tests like magnetic resonance imaging (MRI) or computed tomography (CT). This test is to check for damage outside the digestive tract.

Hence, anyone who has a tapeworm will need treatment to get rid of it as treatment is effective and can be completed in few days.

Treatment for tapeworm in humans

Treatment for tapeworm infection in humans may depend on the tapeworm type. However, treating an adult tapeworm infection is way easier than treating a tapeworm larvae infection. Tapeworm larvae infection can be more complicated. This is because as the adult tapeworm stays in the gut, its larvae may settle in other parts of the human body. Thus when a larvae infection finally produces symptoms, it is possible that the infection may have been in existence for years. This is why larvae infection can be life-threatening.

Oral medication

Normally tapeworms are treated with oral medication, so they may be prescribed. Thus the most common medicine for tapeworm infection is Praziquantel (Biltricide). Even some more severe complications of tapeworm infection are treated with medications too.

Medications paralyze the tapeworms. Hence it lets go of the intestine, dissolves, and passes from your body with bowel movements. Therefore if the worms are large, one may experience cramping when they pass.

The doctor may even advise the patient to take a laxative. This is to help the tapeworm come out in the stool. Also, if a patient has a pork tapeworm infection, the patient may be given an anti-emetic medication. This medication helps to prevent vomiting. During a tapeworm infection, vomiting can lead to reinfection by swallowing the tapeworm larvae.

From one to three months after treatments have been completed, there may be a need for the doctor to request another stool analysis. This is to recheck and confirm treatment. However, medications are very effective if followed properly.

Tapeworm medicine for humans
  • Albendazole (Albenza)
  • Praziquantel (Biltricide)
  • Nitazoxanide (Alinia)

Anti-inflammatory medication

A patient may have to take a course of anti-inflammatory steroids if the tapeworm infection affects tissues outside the intestine. This anti-inflammatory medication is to reduce swelling that must have been caused by the development of cysts.

Cyst surgery

Surgery may be needed if a patient has life-threatening cysts that have developed in vital organs. Surgery is required in a case where vital organs, such as the liver or lungs are affected. Before removing the cyst, the doctor may inject a cyst with medication to destroy the larvae.

Preventing Tapeworm infection in Humans

  • Avoid eating raw fish or meat.
  • Wash your hands before and after using the toilet.
  • Preserve your food well.
  • Wash your hands thoroughly with soap and warm water before eating or preparing any food.
  • Wash and Cook fruits or vegetables with well-treated water or boiled water.
  • Dispose of animal or human feces properly and minimize the exposure of animals to tapeworm eggs.
  • Cook your meat thoroughly to a temperature of at least 150°F.
  • If you have pets like dogs and cats, ensure they are treated for tapeworm.
  • Practice good kitchen hygiene.
  • You can freeze your meat and fish for some days before using them. Smoking or drying your meat or fish is not a reliable preservative method that can kill tapeworm eggs or larvae.