Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Diphyllobothrium latum

CZ: škulovec široký
EN: fish tapeworm

Occurrence:
Fish and Fish Products


Category:
Parasites


Foodborne Disease:
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diphyllobothriosis - abdominal distention, flatulence, intermittent abdominal cramping and diarrhoea


Description:
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Diphyllobothrium latum and other members of the genus are broad fish tapeworms reported from humans. They are parasitic flatworms. Diphyllobothriasis is the name of the disease caused by broad fish tapeworm infections and is characterized by abdominal distention, flatulence, intermittent abdominal cramping, and diarrhoea with onset about 10 days after consumption of raw or insufficiently cooked fish.

The larva that infects people, a "plerocercoid," is frequently encountered in the viscera of freshwater and marine fishes. D. latum is sometimes encountered in the flesh of freshwater fish or fish that are anadromous (migrating from salt water to fresh water for breeding). Bears and humans are the final or definitive hosts for this parasite. D. latum is a broad, long tapeworm, often growing to lengths between 1 and 2 m and potentially capable of attaining 10 m; the closely related D. pacificum normally matures in seals or other marine mammals and reaches only about half the length of D. latum.

Treatment consists of administration of the drug, niclosamide. The disease is diagnosed by finding operculate eggs (eggs with a lid) in the patient's faeces on microscopical examination. In persons that are genetically susceptible, usually persons of Scandinavian heritage, a severe anaemia may develop as the result of infection with broad fish tapeworms. The anaemia results from the tapeworm's great requirement for and absorption of Vitamin B12.

Consumers of raw and underprocessed fish are the target population for diphyllobothriasis. Foods are not routinely analyzed for larvae of D. latum, but microscopic inspection of thin slices of fish, or digestion, can be used to detect this parasite in fish flesh.


Pictures:

Diphyllobothrium latum
Source: Detail of mature proglotide of tapeworm
Diphyllobothrium latum
Source: Life cycle of Diphyllobothrium latum
Diphyllobothrium latum
Source: Tapeworm in small intestine of final host

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