An alarming new report from the Centers for Disease Control and Prevention has found that a Japanese parasitic tapeworm behind about 2,000 illnesses in Japan and parts of northeastern Asia but hadn’t been a problem over in North America. But now, authorities have found the tapeworm in North American waters off the coast of Alaska.

Tapeworm experts from the Czeck Republic and from Alaska found that salmon from the American and Asian Pacific coasts pose “potential dangers” to anyone who eat the fish raw. They used a molecular technique to confirm that this tapeworm was the same Japanese species that had been seen before on the other side of the Pacific.

The affected fish include chinook, coho, pink and sockeye salmon. It can also infect rainbow trout. The tapeworm is found burrowed near the spine of the Pacific pink salmon.

Raw foods always carry more risk than cooked foods, but this is an especially big risk for sushi lovers. Fortunately, however, almost all of the raw salmon on the market comes with no risk of this new parasite.

The CDC states: “Diphyllobothriosis is reemerging because of global importation and increased popularity of eating raw fish. We detected Diphyllobothrium nihonkaiense plerocercoids in the musculature of wild pink salmon (Oncorhynchus gorbuscha) from Alaska, USA. Therefore, salmon from the American and Asian Pacific coasts and elsewhere pose potential dangers for persons who eat these fish raw.

“The Japanese broad tapeworm, Diphyllobothrium nihonkaiense (Yamane, Kamo, Bylund et Wikgren, 1986) (Cestoda: Diphyllobothriidea) is the second most common causative agent of diphyllobothriosis in humans; ≈2,000 cases have been reported, mainly from northeastern Asia (1). However, recent studies that used molecular methods indicate that the number of human cases caused by this tapeworm may have been highly underestimated (1). In addition, increasing popularity of eating raw fish is probably responsible for the increased number of imported cases in regions where this infection is not endemic (1).”