Researchers Find Japanese Tapeworm in Alaskan Salmon

If you have a penchant for consuming raw salmon, it might be time to take a break. A new study has found wild salmon caught in Alaska to be infected with a parasite.

The study, published by the Centers for Disease Control and Prevention (CDC) in the February edition of Emerging Infectious Diseases, has identified four species of Pacific salmon to be infected by the Japanese Broad Tapeworm — a parasite discovered in 1986 that can grow up to 30 feet long in your digestive tract. While an infection of this specific type of tapeworm is generally asymptomatic, it can cause a Vitamin B12 deficiency, abdominal discomfort, diarrhea, vomiting, weight loss, and intestinal obstruction.

The discovery was made after a team of researchers looked at a sample of 64 wild Alaskan salmon from five species in July 2013. By filleting the musculature of the fish and observing the internal organs under a microscope, they found Japanese tapeworm larvae (called plerocercoids) measuring from 8 to 15 millimeters in length.

Known infected species are: chum salmon, masu salmon, pink salmon, and sockeye salmon.

The findings of this study are significant, as it was previously believed that the Japanese tapeworm only infected fish in Asia. By identifying salmon from the American and Asian Pacific coasts to be carriers of the Japanese tapeworm, future cases can be prevented in the United States and in regions of the world where Alaskan salmon are exported like China, Europe, and New Zealand.

The authors of the study note that the purpose of the findings is not to freak out consumers, but to “alert parasitologists and medical doctors about the potential danger of human infection with this long tapeworm resulting from consumption of infected salmon imported (on ice) from the Pacific coast of North America and elsewhere.”

And the findings are not to say you need to eliminate salmon from your diet completely — consumers can eliminate any risk by properly cooking or freezing the fish. The U.S. Food and Drug Administration advises that cooking or freezing the fish can destroy the tapeworm. The CDC warns that “lightly salted, smoked, or pickled fish also may contain infectious organisms.”

Read more: Diphyllobothrium nihonkaiense Tapeworm Larvae in Salmon from North America from Centers for Disease Control and Prevention