symptoms

Fish tapeworm symptoms, detection and therapy

Fish tapeworm symptoms, detection and therapy / symptoms
The fish tapeworm is a parasite. It is about 20 meters long with 3000 to 4000 Proglottiden, these are segments that each form a mature sexual reproductive system. The Skolex, the front end serves to attach itself in the gut of the host. For this purpose, the fish tapeworm has two elongated suction cups. Its eggs are yellowish in color and about 45 x 70 μm in size.

contents

  • distribution
  • The life cycle
  • Erstwirt: Rudder crab
  • The larvae mature in the fish
  • Mostly there are no symptoms
  • diagnosis
  • treatment
  • Danger in Germany?
  • How do you protect yourself??
  • Danger by sushi?

distribution

The fish tapeworm occurs mainly in subtropical, temperate and subarctic zones, and there in the area of ​​lakes. It is especially common in North America, Siberia, Scandinavia, the Baltics, Japan and Chile. Very often Inuit in Alaska and northern Canada fall ill with infestations with these tapeworms. For those affected, raw fish is the main food. In Japan, and now also in the US and Europe, eating sushi is the main reason to pick up such a tapeworm.

The consumption of sushi is one of the most common causes of infection with the fish tapeworm. (Image: yuliiaholovchenko / fotolia.com)

The infestation with fish tapeworms can be triggered in Europe and North America by one of the following species, the symptoms are largely identical:

  • Diphyllobothrium latum in Europe, especially in the Iberian Peninsula
  • Diphyllobothrium dendriticum
  • Diphyllobothrium ditremum

The life cycle

Humans become infected with the parasite by eating raw or inadequately heated fish. The fish tapeworm is not specialized in humans as a host: all mammals that eat fish, may be infected by him. Among the pets, these are mainly dogs and cats, especially affected are sled dogs in the Subarctic, which mainly feed on fish waste.

Erstwirt: Rudder crab

The proglottids contain eggs, and these worm eggs excrete the fish eaters with their fecal matter. If the excrements get into the water cycle, they contaminate the waters, and from the eggs grow the Koracidia, ciliate larvae.

These use small shrimps of the genera Cyclops and Diaptomus as the first intermediate hosts. Fish eat these crabs, then the fish serve as second intermediate hosts. Often these are carp-like and other plankton-eaters, sometimes also predatory fish such as pike.

The larvae mature in the fish

In the muscles of the fish, the coracidia grow into plericoidoids, into infectious larvae. If people now eat these fish, the infective larvae enter the human small intestine, where they can live for several years. 3 weeks after infection, the feces contain the first eggs. These eggs are excreted by the worm over the last segment.
The worm grows by 9 to 15 cm per day.

Those affected often do not realize that they have contracted a fish tapeworm. Only with heavy infestation do symptoms occur, such as Diarrhea up. (Image: Juan Gärtner / fotolia.com)

Mostly there are no symptoms

The affected people often do not notice the worm infestation, because usually no symptoms appear. Only a large amount of tapeworm segments in the body can lead to diarrhea, or the worm ball close the bile duct or intestinal lumen. If the worms get stuck in the upper small intestine, a vitamin B 12 deficiency can result.

Namely, the fish tapeworm absorbs vitamin B 12 more and more, and then the human body lacks in forming the red blood cells. The consequence is a special anemia, the pernicious anemia.

diagnosis

Usually the eggs occur in large numbers in the stool (up to one million per day) and can therefore easily be detected.

treatment

The worm infestation is easy to treat. 90% of the patients recover completely if they take the vermifuge Praziquantel once. Since usually only a tapeworm of these species affects a human, the proof of the Skolex in the feces is proof that the parasite has died.

Danger in Germany?

Domestic fish only rarely carry the fish tapeworm. There is a higher risk of becoming infected with imported fish from Northwestern Russia, the Baltic and Scandinavia. Tourists are at particular risk when eating raw fish in Scandinavia or the Baltics, Japan or South America.

In North America and Switzerland there were infestations with fish tapeworm by the sushi fashion.

How do you protect yourself??

Raw fish is only a problem when it comes from the fresh water. Saltwater fish never carry the parasite. Cooked, smoked, fried and frozen fish can be safely consumed because the heat and cold kill the pathogen.

Fried or boiled fish is not dangerous because the heat causes the pathogens to die. (Image: Oskar / fotolia.com)

Danger by sushi?

Veterinary examinations revealed that 70% of all sushi products had no borderline germ counts. Before preparation, this amount was as high as 83%, which meant that 13% of the germs got into the sushi during preparation. The attached washabi horseradish also has a disinfectant effect.

In Japan, however, the increased intake of sushi has caused several hundred registered cases of worm-triggered diseases.

Meanwhile, German legislation requires that raw fish beforehand be refrigerated for up to -20 degrees Celsius for at least 24 hours before being eaten. That's enough to eliminate the tapeworm. In addition, sushi is often made from deep-frozen fish, almost exclusively in most sushi bars in Germany.

A major problem is the sweet-fish carpaccio, which has been popular among gourmets for some years, and which cuts salmon, trout or pike into thin slices. As these are gourmet restaurants, the guests will of course not be served any deep-frozen fish. (Dr. Utz Anhalt)
Specialist supervision: Barbara Schindewolf-Lensch (doctor)