Diphyllobothrium infection may develop when a person consumes raw or undercooked fish infested with the parasite Diphyllobothrium latum (fish tapeworm). The larvae of the fish tapeworm then develop in the intestines. They reach full development after three to six weeks. An adult tapeworm may reach lengths of up to 30 feet. It is the most dangerous human parasite.

This form of tapeworm develops in hosts such as aquatic microorganisms and huge mammals that consume uncooked fish. Trout, perch, salmon, walleyed pike, and other freshwater fish species are examples of fish. Salmon, for example, can survive in both fresh and saline water and may host Diphyllobothrium larvae. Fish that has been lightly salted, smoked, or pickled may potentially harbor pathogenic germs. Animals transfer it through their excrement. 

Diphyllobothrium infection is most common in the Northern Hemisphere (Europe, newly independent nations of the Former Soviet Union, North America, and Asia), although it has also been reported in Uganda and Chile. Fish infected with Diphyllobothrium larvae are permitted to be moved to and eaten in any region of the globe.


Diphyllobothrium infection seldom causes symptoms. Tapeworms are most often identified when patients notice tapeworm eggs or segments in their feces.

Symptoms may include:

  • Weakness 
  • Diarrhea 
  • Weight loss
  • Abdominal discomfort
  • Vomiting 
  • Vitamin B12 deficiency
  • Pernicious anemia 


A stool sample is examined under a microscope to find tapeworm eggs or segments, which are used to make the diagnosis. Eggs are typically abundant, although finding them may require examining more than one sample of feces.


Diphyllobothrium infections may be cured with a single dosage of medicine without any lingering side effects. Praziquantel (Biltricide) and niclosamide are the two primary therapies for tapeworm infections (Niclocide).

  • Praziquantel. This medication is used to treat several types of worm infestations. It produces significant muscular spasms in the worm so that it may transit through the feces.
  • Niclosamide. This medication is indicated for tapeworm infections and eliminates the worms on touch. The worm is subsequently expelled via feces.

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