Fish tapeworm

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Fish tapeworm
Fish tapeworm (Diphyllobothrium latum; formerly Dibothriocephalus latus), section from the proglottid chain

Fish tapeworm ( Diphyllobothrium latum ; formerly Dibothriocephalus latus ), section from the proglottid chain

Class : Tapeworms (Cestoda)
Subclass : True tapeworms (Eucestoda)
Order : Pseudophyllidea
Family : Diphyllobothriidae
Genre : Diphyllobothrium
Type : Fish tapeworm
Scientific name
Diphyllobothrium latum
( Linnaeus , 1758)
Fish tapeworm ( Diphyllobothrium latum ) in: V. Deschiens: Atlas de parasitologie . Paris, 1901

The fish tapeworm or pit head ( Diphyllobothrium latum ) belongs to the group of tapeworms . It parasitizes mainly in domestic dogs , very rarely in domestic cats and in humans . The condition is known as diphyllobothriasis .

Copepods , mainly of the genera Cyclops and Diaptomus, serve as the first intermediate host . The second intermediate host is mainly carp fish or other fish that feed on plankton . Pike are also often involved as paratenic hosts .


The distribution areas mainly extend over North and South America, Europe and parts of Asia. However, it also occurs sporadically in inland waters around the world. Particularly infested areas exist wherever fish is used raw as food. This is particularly true of Scandinavia , especially Finland , the Baltic States and the Curonian Spit . Today, however, a decrease in the infestation can be observed due to the changed eating habits in humans.

Diphyllobothriasis can be triggered in Europe and North America by one of the three species that occur , which are mostly undifferentiated and mainly referred to as Diphyllobothrium latum :

  • Diphyllobothrium latum (Linnaeus, 1758) in Europe, particularly Portugal and Spain
  • Diphyllobothrium dendriticum (Nitzsch, 1824)
  • Diphyllobothrium ditremum (Creplin, 1825)

In Scandinavia it is predominantly the latter two, in Poland predominantly Diphyllobothrium ditremum .

In other areas, other species may be incorrectly referred to as Diphyllobothrium latum as such, even in scientific publications.


The fish tapeworm is the largest representative of the tapeworm , the head ( Scolex ), unlike other Cestoda, has no hooks (Rostellum), but only two suction pits to attach to the intestinal wall of the host . Its body is divided into up to 4000 proglottids (segments). It becomes up to 20 meters long and up to 20 millimeters wide. In the last segment, the eggs are produced, there are male and female sex organs. The eggs are excreted through an opening in the last segment, the tocotrem .

Life cycle

Life cycle of the fish tapeworm ( Diphyllobothrium latum )

The eggs end up with the excrement of the final host (human, dog, cat) in suitable standing water, where they develop into a hexacanthene larva , known as coracidium in fish tapeworms . The coracidium is ingested by copepods of the genera Diaptomus and Cyclops . The procercoid matures in copepods . The crabs are ingested by carp fish as food, the parasites then penetrate the intestinal wall of the fish and develop into plerocercoid . It can happen that the fish is ingested by another predatory fish , which then serves as a paratonic host . The pike is an example . The final host ( human , dog , cat ) is then infected by ingesting the intermediate host (carp fish) or the paratenic host pike .

Harmful effect

When eating raw fish meat, the plerozerkoids are absorbed. The plerozerkoids develop into adult worms in the intestines of cats or humans, for example . The worm's daily growth in the intestine is 9 to 15 cm. After 3 to 5 weeks, the worms become sexually mature and begin to produce eggs. The parasite can persist in the intestine for up to 25 years. Since there is almost always only one worm in an ultimate host , the infestation is often not noticed. Diphyllobothriasis can rarely (in about 2% of those infected) cause macrocytic anemia due to a lack of vitamin B 12 , which is caused by the intake of large quantities by the fish tapeworm in the intestine. Serious effects have only been reported in isolated cases.

Prevention and therapy

The most effective measure is to avoid consuming raw freshwater fish. In the event of an infection caused by the fish tapeworm that requires treatment, praziquantel or niclosamide are used as antiparasitic agents .

Individual evidence

  1. a b c BBB - Diphyllobothrium spp. US Food and Drug Administration (English). Retrieved February 12, 2010
  2. Jorge E. Revenga: Diphyllobothrium dendriticum and Diphyllobothrium latum in fishes from southern Argentina: association, abundance, distribution, pathological effects, and risk of human infection. In: The Journal of Parasitology , 1993, pp. 379-383.
  3. Seung Yull Cho et al .: One case report of Diphyllobothrium latum infection in Korea. 1971.
  4. See Hans Adolf Kühn: intestinal parasites. In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition, ibid. 1961, pp. 834-841, here: p. 836.
  5. Karin I. Andersen, David I. Gibson: A key to three species of larval Diphyllobothrium Cobbold, 1858 (Cestoda: Pseudophyllidea) occurring in European and North American freshwater fishes. In: Systematic Parasitology , Volume 13, No. 1, 1989, pp. 3-9.
  6. a b c d catalogoflife: Diphyllobothrium
  7. catalog of life: Diphyllobothrium latum
  8. catalog of life: Diphyllobothrium dendriticum
  9. a b catalog of life : Diphyllobothrium ditremum
  10. Jan Henricson: The abundance and distribution of Diphyllobothrium dendriticum (Nitzsch) and D. ditremum (Creplin) in the char Salvelinus alpinus (L.) in Sweden. In: Journal of Fish Biology , Vol. 11, No. 3, 1977, pp. 231-248.
  11. Jan Henricson: The dynamics of infection of Diphyllobothrium dendriticum (Nitzsch) and D. ditremum (Creplin) in the char Salvelinus alpinus (L.) in Sweden. In: Journal of Fish Biology , Volume 13, No. 1, 1978, pp. 51-71.
  12. Patricio Torres et al .: Registro de nuevos casos de difilobotriasis humana en Chile (1981-1992), incluído un caso de infección múltiple por diphyllobothrium latum; Record of new cases of human diphyllobothriasis in Chile (1981-1992), including a case of multiple diphyllobotrium latum infection. In: Bol. Chil. Parasitol. Volume 48, No. 3/4, 1993, pp. 39-43.
  13. R. Grass Beck et al .: lognormal distribution of serum vitamin B12 levels and dependence of blood values on the B12 level in a large population heavily infected with Diphyllobothrium latum. In: The Journal of laboratory and clinical medicine. Vol. 59, March 1962, pp. 419-429, PMID 13901185 .
  14. Wolmar Nyberg: The uptake and distribution of 60 Co-labeled vitamin B 12 by the fish tapeworm, Diphyllobothrium latum. In: Experimental Parasitology , Volume 7, No. 2, 1958, pp. 178-190.
  15. G. Osorio, A. Daiber, R. Donckaster, M. Ubilla, I. Con, T. Anguita, R. Pinto: [Severe megaloblastic anemia due to Diphyllobotrium latum. First case identified in Chile (author's transl)]. In: Revista médica de Chile. Volume 102, Number 9, September 1974, pp. 700-703, PMID 4456522 .
  16. ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 290.

Web links

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