In our latitudes, it is quite possible to become infected with fish tapeworm. Especially with self-caught, uncooked, that is, raw, fish, the danger is great.
What is fish tapeworm infection?
Tapeworms live as parasites in the intestines of humans or other vertebrates. There are many different types of tapeworms. Each species can cause different symptoms, although only a few species could become a danger to humans. In the picture, the head of a tapeworm. Click to enlarge. The fish tapeworm lives mainly in fresh water. Its intermediate hosts are small freshwater fish and crabs, which are consumed by the final hosts of the fish tapeworm (larger predatory fish, humans, dogs, cats, and other fish-eating mammals). The fish tapeworm, Diphyllobotrium latum, is found primarily in inland lakes of the Northern Hemisphere. Most commonly, brackish and freshwater fish such as trout, bass, and pike are infected with the fish tapeworm. The parasite nests in the internal organs, especially the liver, but also in the muscles and intestinal tract of intermediate hosts. Another subspecies – Diphyllobotrium pacificum – infects humans, seals and sea lions as the definitive host and is distributed mainly in the Pacific region.
Causes
Infection with fish tapeworm occurs in humans, dogs, and cats by eating raw or insufficiently fried or heated fish. The most common species of fish tapeworm is Diphyllobothrium latum, which is found primarily in the Baltic States, Russia, Scandinavia, Alaska, and North America. The parasite, which lives in the intestine of the final host, can grow up to 15 meters long and reach a lifespan of 10 years. The head of the fish tapeworm is equipped with suckers and a hooked crown, which it uses to attach itself to the small intestinal wall of its host. The parasite is a hermaphrodite that sheds individual tapeworm limbs once the fertilized eggs have matured in those limbs. Thus, the fertilized eggs of the fish tapeworm enter sewage with feces, where they are ingested by intermediate hosts and the development cycle begins anew, from fertilized eggs to larvae to fins and the sexually mature tapeworm in intermediate and definitive hosts.
Symptoms, complaints and signs
Infection with the fish tapeworm is usually asymptomatic. During the first three to six weeks after infection, the larva develops into the fish tapeworm, causing no symptoms. Only after this time does a fish tapeworm cause gastrointestinal symptoms such as nausea, vomiting and diarrhea in isolated cases. Occasionally, a loss of appetite sets in, which becomes noticeable relatively quickly through weight loss. Although otherwise no symptoms occur initially, a fish tapeworm must be treated medically. Otherwise, the parasite can remain in the body for weeks, months or even years and cause chronic symptoms. Often a vitamin deficiency occurs, which becomes noticeable through the signs of anemia – i.e. pallor, palpitations, breathing difficulties and sudden sweating. As the disease progresses, chronic gastrointestinal symptoms may also develop. Externally, fish tapeworm cannot be detected. However, the weight loss, in conjunction with the increasing feeling of illness, indicates a condition that needs to be examined and treated by a doctor. In addition, infection can often be traced to the consumption of a particular food or contact with a possibly infected human or animal. As a result, an infection can usually be diagnosed quickly and accurately.
Diagnosis and progression
Freshwater fish infected with fish tapeworm may contain viable larvae that pass to the final host through consumption. Fish tapeworm larvae can survive even in fish that have been frozen inadequately or only briefly. After ingestion of the larva, it takes about three to six weeks, depending on the developmental stage of the larva, for it to develop into the adult, sexually mature fish tapeworm in the intestine of the final host. Only after the completion of development into the fish tapeworm do the first symptoms appear, such as discomfort in the gastrointestinal tract, loss of appetite, feeling of fullness, nausea, vomiting, diarrhea and sudden weight loss. In many cases, infection with the parasite progresses without symptoms for many years, and in some cases the fish tapeworm is the cause of vitamin B12 deficiency, which can lead to anemia, heart and respiratory problems.Diagnosis of fish tapeworm infestation is relatively simple. Because the tapeworm sheds individual limbs containing sexually mature eggs in the intestine, these are easily detectable when the stool is examined.
Complications
Fish tapeworm infection can lead to some complications if left untreated. Initially, the parasite can cause mild gastrointestinal symptoms such as nausea and diarrhea. The associated loss of appetite sometimes leads to significant weight loss. If left untreated, the tapeworm may enlarge and spread to the internal organs. Possible late consequences are inflammation of the gall bladder and pancreas, and rarely appendicitis and intestinal obstruction. If larvae form, severe skin diseases, epilepsy and damage to the skeletal muscles can occur. However, infection with the fish tapeworm does not usually lead to the formation of larvae, provided there is no severe previous disease. Due to the high vitamin B12 consumption of the fish tapeworm, however, deficiency symptoms may occur. Rarely, a mild anemia develops as a consequence, which in turn is associated with complications. Typical symptoms of anemia are pallor, breathing difficulties and an elevated pulse. In general, however, severe complications of fish tapeworm infection are extremely rare. Once diagnosed, fish tapeworm can be removed without further symptoms in 90 to 100 percent of all cases. However, the prescribed medications (praziquantel, niclosamide) can cause side effects such as muscle pain, loss of appetite and fatigue. Patients with cardiac arrhythmias or impaired kidney or liver function may experience further complications.
When should you see a doctor?
In the case of fish tapeworm, a visit to the doctor is always necessary. The disease does not heal on its own and can lead to various complications and discomforts if not treated. As a rule, the doctor should be consulted whenever there is discomfort in the stomach or intestines after eating fish. Especially in the case of raw and uncooked fish, a doctor should be consulted immediately. In this case, severe weight loss or loss of appetite may indicate fish tapeworm. Nausea, diarrhea or severe stomach cramps are also typical symptoms of this disease. Therefore, if these complaints occur after eating or continue to occur without a specific reason, a doctor must be consulted. In acute emergencies or in case of very severe pain, an emergency doctor may also be called or the hospital may be visited. As a rule, a visit to a general practitioner or a pediatrician is sufficient for fish tapeworm. The treatment of the disease is carried out with the help of medication and in most cases leads to a quick success. Since the affected person can also get sick again with fish tapeworm, a doctor must always be consulted if the symptoms of the disease appear.
Treatment and therapy
Treatment for fish tapeworm is also relatively simple. Medications such as praziquantel or niclosamide can easily kill the fish tapeworm, which is then completely excreted in the stool. The prognosis for cure is good, as the tapeworm is usually completely gone after treatment with the worm-killing drug. In very rare cases, fins may form in the body of the final host, making treatment more protracted. Human-to-human infection is not possible because the fish tapeworm needs intermediate hosts for its development cycle. Worming medications require a prescription and may cause side effects such as abdominal pain and nausea in a few cases. Worming must be done consistently to ensure that all larvae are killed. In pregnant and breastfeeding women, the doctor must weigh whether these medications can be used.
Outlook and prognosis
The prognosis for fish tapeworm infestation is considered favorable. Complete recovery occurs in nearly 100% of those infected. If medical treatment is sought, there is already a marked improvement in health within a few days. The prescription drugs kill the worm. It is then eliminated from the organism on its own. The administration of the medication may cause side effects, which normally disappear completely after the medication is discontinued.Consequential damage is only to be expected in the case of a worm infestation by the fish tapeworm if there have already been severe health impairments up to the start of treatment. Without medical treatment, the health of the affected person may be impaired for a long time. The fish tapeworm has a life span of about 10 years and can reach a length of up to 15 meters in the human intestine. There is a decrease in well-being, weight loss, as well as a decrease in performance. An alternative to drug treatment for worm infestation does not yet exist to the extent needed. Despite the good healing prospects, worm infestation may recur in the course of life if raw fish is eaten. The prognosis and healing prospects are of a renewed disease is also favorable.
Prevention
For prevention, it is recommended to always adequately fry, cook or boil freshwater fish. If the fish is heated at about 60°C for five minutes, all larvae are killed. It is often recommended, especially for pregnant women, to avoid raw fish, such as most of it found in sushi. Cold also kills the larvae of the fish tapeworm. If the fish has been frozen for at least 24 hours at -18°C or 72 hours at -10°C, the tapeworm larvae cannot survive.
Aftercare
In the case of fish tapeworm, the options for aftercare are relatively limited. In this case, the disease must first be fully treated, and of course the source of the fish tapeworm must be removed and should no longer be consumed. This is a relatively simple disease that can be treated by simple means. Special complications usually do not occur. Since the fish tapeworm can cause nausea or diarrhea and vomiting, the stomach should be spared. The affected person is thereby dependent on gentle food, whereby greasy or salty dishes are to be avoided. Since the fish tapeworm also causes a high loss of water, the affected person should drink a lot, with water or juices being particularly suitable. Even after the symptoms have subsided, the stomach should still be spared, so that normal meals can only be taken again a few days after healing. If the fish tapeworm is treated with medication, it is important to take it regularly. Possible side effects or interactions should also be discussed with a doctor. As a rule, the life expectancy of the affected person is not reduced by this disease.
What you can do yourself
A fish tapeworm must be treated medically in any case. If an infestation is suspected, the patient should go directly to the doctor – preferably with a stool sample. The medical professional should be informed about possible causes, such as the consumption of fresh or brackish water fish, to facilitate the subsequent diagnosis of fish tapeworm. Medical treatment can be supported by some home remedies and measures. First, a balanced and mildly laxative diet is recommended. Fermented foods such as sauerkraut, cabbage and co. contribute to the rapid elimination of the fish tapeworm. As a general rule, foods with a high sugar content should be avoided in the event of a worm infestation. By avoiding sweet foods, the fish tapeworm is deprived of the vital fungal environment and dies quickly. This measure can be supported by homeopathic remedies. These include preparations such as Spigelia, Abrotanum and China, which are best taken in consultation with the doctor or a naturopath. Lastly, care should be taken to ensure adequate intimate hygiene. In addition, the exact cause of the fish tapeworm must be determined and in order to avoid a new infestation. A comprehensive medical history may be necessary for this purpose.
