Tapeworms can also infect humans as parasites and can cause serious symptoms. Thousands of different tapeworm species are known to science, although not all genres are considered for human infections. In the medical community, tapeworms are not only under discussion as pathogens, but due to the self-experiments of the Japanese doctor Koichiro Fujita also as a possible means of treating allergies. In addition, the parasites are occasionally used as an extremely controversial diet method.
Anatomy and occurrence of tapeworms
Tapeworms are at home in the intestine of vertebrates as endoparasites, with different genera specializing in different hosts. Often the name of the tapeworm already gives indications of the respective host animals, such as the fox tapeworm, dog tapeworm, beef tapeworm or fish tapeworm. However, this does not mean that these only attack the eponymous animals.
The anatomy of tapeworms is adapted to the living conditions in the intestine. To dock with the intestinal wall, they have special organs with suction cups and a hook ring (usually a so-called Scolex at the front end of the worm, rarely a rosette organ at the rear end). They are protected from the digestive enzymes in the intestine by their outer shell in the form of a so-called neodermis. At the same time, this serves for food intake by absorbing nutrients directly from the intestine of the host.
However, the worms do not have their own intestinal tract. The size of the tapeworms varies between a few millimeters and several meters depending on the species. For example, fox tapeworms only reach a maximum length of around 3.5 millimeters, the Gyrocotylidea become a maximum of 20 centimeters long. The fish tapeworm can reach up to 20 meters in length.
Origin and way of life: From the larva to the worm
Tapeworms are basically divided into the so-called monozoic tapeworm species and the real tapeworms. Their body shape resembles a flat band, the real tapeworms have a certain segmentation in the form of so-called proglottids. The proglottids usually contain both sex organs (almost all tapeworm species are hermaphrodites) and can be pinched off together with fertilized eggs.
The monozoic tapeworm species do not have this special feature of the proglottids, but also mostly have female and male reproductive organs. Fertilized eggs or proglottids are excreted with the host's faeces and the so-called oncospheres (first larval stage of the tapeworms) develop in them.
If these are taken up by suitable intermediate hosts, they grow into tapeworm larvae (also called Finns), most of which can settle in the tissue of various intermediate hosts as so-called metacestodes. There they remain in the Finnish stage until the intermediate host is again taken up by a suitable host. Due to their special anatomy, the larvae can also absorb nutrients in the intestine of the main host and the development of a fully developed tapeworm begins.
Depending on the type of tapeworm, infestations can vary greatly. While many types of worms hardly harm the human organism and cause no symptoms, others can have life-threatening consequences. The potentially life-threatening echinococcosis should be mentioned here, which is not caused by the adult worms, but by the larvae in the fin stage.
Signs of dog tapeworms
The dog tapeworm can be transmitted to humans through direct contact with the feces of infected dogs. This is possible if, for example, the oncospheres stick to the hands and are then taken in orally.
Sometimes the tapeworm eggs get into the organism through contaminated food. They penetrate the intestinal wall and migrate through the bloodstream until they settle in the tissues of various organs such as the liver, lungs, spleen, kidneys or brain.
The organism then tries to “encapsulate them” by forming a layer of connective tissue around the Finns. Hundreds of tapeworm larvae can grow in this blister-like cyst (also called hydatide), which are released when the hydatide ruptures in the organism.
The expansive growth of the cysts in so-called cystic echinococcosis also leads to the displacement of healthy tissue, which may lead to further complaints. According to the Robert Koch Institute (RKI), the cysts are most often found in the area "the liver (70 percent) and the lungs (20 percent)."
If larger cysts form in the liver as a result of cystic echinococcosis, this can lead to narrowing of the blood vessels and a backflow of blood flow in the area of the portal vein. This in turn is known, for example, as a possible trigger of so-called ascites (abdominal dropsy). The displacement of surrounding tissue structures often leads to abdominal pain.
The pronounced formation of cysts in the liver area can cause impairments in the bilirubin metabolism, which in turn is accompanied by the development of jaundice (jaundice). This is colloquially referred to as jaundice, since in the course of the increased bilirubin value in the blood there is typically a yellowing of the skin and yellow eyes.
In the case of dog tapeworm infestation, the hydatids often also form in the area of the lungs. This so-called lung echococcosis is accompanied by symptoms such as pain, shortness of breath and massive cough, especially when rupture with subsequent release of the larvae.
If the kidneys are affected, increased hydatid formation can lead to clearly perceptible symptoms such as kidney pain or flank pain or blood in the urine. If the tapeworm larvae have settled in the patient's brain or spinal cord, depending on their location, appropriate neurological deficiency symptoms can be observed as a possible consequence.
In general, with rupture of the cysts and subsequent release of fins, there is the possibility that the organism will react to this with an excessive reaction of the immune system in the form of an anaphylactic shock.
Symptoms of fox tapeworm infestation
The fox tapeworm in its adult form is rather harmless to humans, whereas the larvae can trigger life-threatening echinococcosis. The tapeworm eggs are excreted with the feces of the main innkeepers and can survive in the environment for a long time without damage.
If these are ingested orally by humans, for example using contaminated food, they reach the small intestine via the digestive tract. They penetrate the intestinal wall and are transported via the bloodstream to various organs such as the liver, lungs, spleen, bile or the brain.
There the tapeworm larvae settle in the tissue and initially a cyst forms, which is surrounded by further daughter cysts in the course of the so-called budding of the Finns. This is where the name of this form of tapeworm infection comes from, which experts call alveolar (blister-like) echinococcosis. In contrast to the dog tapeworm infestation, "however, a closed cyst does not form, but there is infiltrative growth of the larva, comparable to the growth of a malignant tumor," reports the RKI.
The newly formed Finns can spread through the blood and lymph channels in the organism and thus affect other organs. As the disease progresses, more and more foci of the disease form, which, if not treated, usually results in the death of the patient. However, the parasitic infections can go unnoticed for years before the first symptoms are caused by the expansive growth of the Finns.
These often remain inconspicuous at first. For example, abdominal pain, poor performance and chronic fatigue may be the first signs of alveolar echinococcosis. The already mentioned jaundice is another possible component of the symptoms. As a rule, however, the symptoms only become apparent when several organs are affected. Depending on the organ affected, numerous other, often life-threatening complaints can be observed.
Symptoms of fish tapeworms
The fish tapeworm is considered the largest parasite that can affect humans. It only grows in the body to its considerable length of up to 20 meters. The infection occurs through the ingestion of so-called pleroceroids (second larval stage of the fish tapeworm), which occur in raw fish.
In the intestine of cats, humans or dogs, the pleroceroids then grow into adult fish tapeworms. Their growth in the intestine is around nine to 15 centimeters per day. A fish tapeworm can survive in the intestine of humans for up to 25 years, although due to the enormous size of the parasites there is usually only one tapeworm per host.
The majority of the patients show no complaints in the course of the fish tapeworm infestation (diphyllobothriasis). In rare cases, however, vitamin B12 intake is impaired in such a way that anemia (anemia) and disorders of the nervous system (neuropathies) can occur. General symptoms such as fatigue, dizziness and diarrhea can also be observed in the course of diphyllobothriasis.
Seldom do those affected by fish tapeworm develop gallbladder and / or biliary tract inflammation, which in turn can be accompanied by symptoms such as upper abdominal pain on the right side, nausea and vomiting or the development of jaundice. If the bile ducts become blocked, this often results in light bowel movements and dark urine.
Beef tapeworms: typical symptoms
In the case of beef tapeworm, humans are the only known end hosts, but infections are rather rare in this country due to the regular veterinary meat examinations. In addition, the tapeworm larvae are killed when the meat is roasted and frozen (below -18 degrees Celsius).
Cattle and pigs act as intermediate hosts for the larvae of the beef tapeworm. However, the development into sexually mature adult tapeworms only takes place in the human digestive tract. These can reach a length of over ten meters.
The infection often goes completely unnoticed, but symptoms such as abdominal pain, diarrhea, constipation, nausea, loss of appetite, significant weight loss, headache and chronic fatigue may occur.
Many patients also experience an uncomfortable after-itch. The infection rarely takes a life-threatening course. This can be the case, for example, if the worms cause an intestinal obstruction, acute appendicitis or acute pancreatitis.
Symptoms of tapeworm infestation
If the pork tapeworm infects humans as the end host, this usually does not cause any noticeable symptoms, because the parasites are optimally adjusted to life in the human intestine. However, the intake of tapeworm eggs can lead to people acting as false intermediate hosts, with the fins settling in the tissue and various symptoms depending on the location.
Possible consequences are headaches, neurological deficits and potentially life-threatening meningitis. The adult pork tapeworms can reach a length of up to seven meters in the human body. Here too, worm movements, similar to beef tapeworms, can sometimes be felt as digging or grumbling in the digestive tract.
Signs of a dwarf tapeworm infection
In addition to rodents and primates, humans are the most important end host for the dwarf tapeworm. This special tapeworm genus can reproduce completely without an intermediate host and rarely causes complaints. If the infection remains undetected for a long time, however, symptoms such as diarrhea, bloating or abdominal pain can sometimes be observed in the course of the massive proliferation of dwarf tapeworms. Overall, the damaging effect of the dwarf tapeworm - especially in comparison with other tapeworm species - is extremely low.
Diagnosis of tapeworms
In many types of tapeworm, the proglottids are visible in the stool, which makes the diagnosis relatively easy. A microscopic examination can bring clarity here. In general, the examination of a stool sample in the case of infections with adult tapeworms provides very reliable indications of the present disease, even if further examinations may be necessary to determine the exact type of tapeworm.
The already mentioned echinococcoses, which are more difficult to detect, are far more threatening for humans. In the early stages of the disease, the diagnosis is usually extremely complicated. The most important diagnostic methods for echinococcosis are ultrasound examinations and, if in doubt, computer tomography (CT) or magnetic resonance imaging (MRI).
Blood samples often provide evidence of the disease, but negative results of the serological diagnostic methods do not in any way completely rule out infection. In case of doubt, only the removal and subsequent examination of a tissue sample brings definitive diagnostic certainty.
Therapy and treatment
An attack with adult tapeworms is usually carried out with the help of appropriate medication, which should cause the parasites to die. Niclosamide, mebendazole and praziquantel have proven particularly effective here. For example, a tapeworm infection is primarily treated with mebendazole or praziquantel. Praziquantel or niclosamide (rarely mebendazole) are mostly used for fish tapeworm. Niclosamide is primarily used against the tapeworm, alternatively praziquantel or mebendazole can be used.
Overall, drug therapy enables a relatively effective treatment of the different tapeworm types. According to the RKI, however, side effects such as abdominal pain, hypersensitivity reactions, nausea and vomiting can occur with the various drugs. Other possible side effects are anorexia, headache, dizziness, weakness, drowsiness, tiredness, urticaria (urticaria) or temperature increases.
The treatment of echinococcosis is significantly more difficult than the treatment of an infection with adult tapeworms. Accordingly, the Robert Koch Institute recommends that patients be treated in specially designated centers where interdisciplinary care is guaranteed. At the time of diagnosis, echinococcosis has often progressed so far that a complete recovery of the patient is hardly possible.
Basically, however, there is a good chance of recovery, especially if diagnosed early. For example, in the early stage of cystic echinococcosis, the affected tissue can sometimes be completely radically surgically removed. If the disease is already more advanced, however, there is often only the option of containing medication.
In this case, the growth of the cysts is slowed down or prevented by the administration of benzimidazoles such as mebendazole. A cure based solely on the medicines is not possible here. In inoperable cases, the medication must be taken lifelong, according to the RKI. In "curatively resectable findings, benzimidazole therapy is administered over at least two years."
According to the RKI, there are several therapeutic options for alveolar echinococcosis, depending on the clinical picture and stage of the cyst. For example, a watch-and-wait strategy is being followed for inactive cysts that do not cause functional problems. Single drug treatment with albendazole with accompanying check-ups or surgical removal of the affected tissue are also possible. Further medical treatment is usually also required after the operation.
The possibility of a so-called “puncture-aspiration-injection-reaspiration” (PAIR) is conceivable, in which a sterilizing substance (95 percent alcohol) is introduced into the cysts in order to prevent further growth. Since most patients can no longer achieve complete healing, lifelong medication is usually required.
Naturopathy can do little against echinococcosis. Against the infestation with adult tapeworms, however, it offers very promising starting points. In the first place, special diets are to be mentioned, with which the parasites are so difficult to absorb nutrients that they die. A corresponding diet can be set up for up to three weeks, in which the diet is geared towards low-carb and fermented foods (due to the lactic acid bacteria it contains).
Ginger, garlic, onions, juniper berries and the essential oil of oregano have a curative and preventive effect for tapeworm infections. How exactly the change in diet should look depends, among other things, on the constitution and the individual symptoms of the patient. It is also important to consider possible previous and concomitant diseases.
Tapeworm diet and other curiosities
At first glance, the idea of achieving weight loss through a parasite in the intestine seems understandable - albeit disgusting. In the corresponding forums you can find a lot of information about the purchase possibilities of tapeworm eggs and although there is an explicit warning about ingestion, people always try them out as a diet method.Danger: Taking the eggs cannot reduce weight and in the worst case scenario has life-threatening consequences. Because, as already shown:
- the life cycle of tapeworms in almost all species is aimed at at least one intermediate host, in which the larvae initially grow.
- Adult tapeworms could therefore only grow in the intestine by ingesting the larvae.
- However, these would only result in weight loss if the infestation was extremely pronounced.
- Such a pronounced infection would be associated with numerous other health complaints.
- Therefore, from a medical point of view, a willful tapeworm infection is strongly discouraged!
The self-experiments of the Japanese doctor and author Koichiro Fujita, in which he claimed to have successfully treated his hay fever with Japanese fish tapeworms, prompted increased media interest shortly after the turn of the millennium. The doctor infected himself by taking the tapeworm larvae. Since then, his immune system has been involved in the defense against the parasites and the response to the pollen has normalized, the doctor explained in an interview with “Zeit Online” in 2001.
At the time, Fujita had three Japanese fish tapeworms in its intestine. But although he claims to be extremely satisfied with the success of his measure, the doctor does not speak out for the broad use of tapeworms for therapeutic purposes. First of all, it would have to be scientifically clarified whether the tapeworms actually remedied the allergy.
However, further research in this direction seems to be appropriate, especially since the number of people with allergies has increased dramatically in recent years and possibly not tapeworms themselves, but substances secreted by them influence the immune response.
Precaution: How to protect yourself from tapeworm infestation
Different types of tapeworms can occur in the human gut. Depending on the species, transmission can take place, for example, from fin-containing raw beef (beef tapeworm) or contact with soil in which feces of infected foxes are found (fox tapeworm).
How to protect yourself from a worm infection:
- Avoid eating raw or underheated meat.
- Avoid insufficiently heated fish dishes (e.g. sushi).
- Always clean (fall) fruit, vegetables and lettuce thoroughly before eating.
- Do not eat unwashed berries or mushrooms.
- Wash your hands regularly - especially after using the toilet, before every meal, after gardening and after coming into contact with pets.
- Make sure that your children wash their hands thoroughly after playing with soil or in the sandpit.
- Have your pets dewormed regularly at the vet.
- Avoid "kissing" and licking the face of the dog and cat.
- Always remove dog feces from the shoes thoroughly and do not carry them into the apartment. (fp, nr)
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Dipl. Geogr. Fabian Peters, Barbara Schindewolf-Lensch
- Merck & Co., Inc .: Overview of tapeworm infections (accessed: August 13, 2019), msdmanuals.com
- Federal Center for Health Education (BZgA): Beef tapeworm (accessed: 13.08.2019), kindergesundheit-info.de
- Professional Association of Pediatricians e. V .: worm diseases (access: 13.08.2019), kinderaerzte-im-netz.de
- Mayo Clinic: Tapeworm infection (accessed: August 13, 2019), mayoclinic.org
- UpToDate, Inc .: Tapeworm infections (accessed: August 13, 2019), uptodate.com
- National Health Service UK: Tapeworms (accessed: 08/13/2019), nhs.uk
- U.S. National Library of Medicine: Tapeworm infection - beef or pork (accessed: August 13, 2019), medlineplus.gov
ICD codes for this disease: B68, B70, B71ICD codes are internationally valid encodings for medical diagnoses. You can find e.g. in doctor's letters or on disability certificates.