Chow Line: Tapeworms in Salmon a Potential Risk

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I heard a recent report that some salmon in the U. S. has been found to have tapeworms. That has me worried — is salmon still safe to eat?

In most circumstances, yes.

The report you are speaking of comes from a new study published this month in the Centers for Disease Control and Prevention’s journal Emerging Infectious Diseases. The study said that the parasitic Japanese broad tapeworm, also known as Diphyllobothrium nihonkaiense, was found in wild pink salmon from Alaska.

The study authors said that salmon from the American and Asian Pacific coasts and elsewhere pose potential dangers for persons who eat these fish raw. When the wild-caught salmon are transported on ice instead of frozen, the parasitic tapeworm may survive transport.

However, the risk of consumers becoming infected with a tapeworm is fairly low. The U.S. Food and Drug Administration requires that all fish except catfish, tuna and salmon in certain instances, if it is to be eaten raw, first must be frozen to kill parasites.

But, while the risks are low, consumers can take precautions to reduce the risk of foodborne illness when handling, preparing or eating seafood, according to the FDA. The federal agency says that while it is best to cook seafood thoroughly to minimize the risk of foodborne illness, those who prefer to eat raw fish should eat fish that has been previously frozen.

Commercially frozen seafood is frozen solid at a temperature of -35 degrees and stored at this temperature or below for a minimum of 15 hours to kill parasites.

However, for consumers who catch fish fresh, most home freezers have temperatures at 0 to 10 degrees, which may not be cold enough to kill parasites because it can take up to 7 days at -4 degrees or below to kill parasites, especially in large fish, according to the FDA.

Most seafood should be cooked to an internal temperature of 145 degrees, or until fish is opaque and flakes easily with a fork. In the case of shrimp, lobster and crab, the flesh should be pearly and opaque. For clams, oysters and mussels, cook until shells open. And for scallops, cook until flesh is milky white or opaque and firm.

The CDC and FDA offer these other tips to prevent foodborne illness from seafood:

  • Only buy fish that is refrigerated or displayed on a thick bed of fresh ice that is not melting (preferably in a case or under some type of cover).
  • Fish should smell fresh and mild, not fishy, sour or ammonia-like.
  • Whole fish and fillets should have firm, shiny flesh and bright red gills free from milky slime.
  • The flesh should spring back when pressed.
  • Fish fillets should display no discoloration, darkening or drying around the edges.
  • Don’t buy frozen seafood if its package is open, torn or crushed on the edges.
  • Avoid packages with signs of frost or ice crystals, which may mean the fish has been stored a long time or thawed and refrozen.
  • Wash your hands for at least 20 seconds with soap and warm water before and after handling any raw food.
  • Wash cutting boards, dishes, utensils and counter tops with soap and hot water between the preparation of raw foods, such as seafood, and the preparation of cooked or ready-to-eat foods.

If a parasite is present in a fish, FDA offers these tips:

  • Notify the store where you bought the fish so that the store can carefully inspect remaining fish.
  • Depending on the return policy of the particular store, you may wish to return or exchange the unused portion.

Remember, while freezing will kill the parasites that may be present in some fish, freezing doesn’t kill all harmful microorganisms. That’s why the safest route is to thoroughly cook your seafood.

Chow Line is a service of the College of Food, Agricultural, and Environmental Sciences and its outreach and research arms, OSU Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Tracy Turner, 364 W. Lane Ave., Suite B120, Columbus, OH 43201, or

Editor: This column was reviewed by Sanja Ilic, specialist in Food Safety for Ohio State University Extension.

Tracy Turner
For more information, contact: 

Sanja Ilic
OSU Extension, Food Safety