How common is tapeworm infestation in the US?

Updated: Apr 15, 2021
  • Author: Lisandro Irizarry, MD, MBA, MPH, FACEP; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Although many cestode infestations occur worldwide, only a few are common in the United States.

Diphyllobothriasis is an infection that occurs from eating raw or undercooked fish infected with Diphyllobothrium species. Diphyllobothrium organisms are present in lakes, rivers, and deltas of freshwaters. Eskimos in western Alaska and the West Coast of the United States are frequent hosts.

Echinococcus multilocularis causes alveolar echinococcosis, which occurs only in the northern hemisphere. In the United States, it occurs particularly in Alaska. Echinococcus granulosis causes hydatid disease, which occurs worldwide.

Although infection with T saginata (obtained from raw or undercooked beef) occurs worldwide, the prevalence in the United States is less than 1% because most cattle in the United States are free of the parasite. Infection with T solium is rare, but with the growing number of immigrants from endemic areas, the frequency is changing.

Infection with H nana is the most frequently diagnosed cestode infection in the United States.

Spirometra species cause sparganosis, which occurs accidentally in humans who ingest water containing infected cyclops, eating raw or inadequately cooked flesh of snakes, frogs, or birds. It has been reported mainly in the southeastern region of the United States.

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