Diphyllobothrium Latum, The Fish Tapeworm.

Diphyllobothrium latum is the Human tapeworm that comes from fish. Fish and copepod's (crustaceans found almost everywhere where water is available and they constitute the biggest source of protein in the oceans) are the intermediate hosts, while humans and bears are the definitive hosts. The fish, often pike or salmon, (second host) usually come from arctic and sub-arctic waters. Many encounters occur when the fish migrate from salt water to fresh water for breeding. Humans become infested with the Diphyllobothrium latum tapeworm by ingesting raw or undercooked fish.

The disease resulting from the infestation is called, Diphyllobothriasis. The symptoms are abdominal distention, flatulence, intermittent abdominal cramping, and diarrhea. An infestation of Diphyllobothrium latum may also cause an onset of anemia. The tapeworm competes for vitamin B12 and it is also thought to interfere with the absorption of the vitamin, leaving the host susceptible to both Pernicious anaemia and Megablastic anaemia.

The increased popularity of sushi increases the incidence of Diphyllobothrium latum infestations in the United States.