Tapeworm dangers from sushi grow

Researchers are warning that a spike in human parasite infection from the Japanese broad tapeworm is likely due to the increase in popularity of eating raw fish as well as the presence of the tapeworm in salmon from Alaska.

The researchers found the tapeworm Diphyllobothrium nihonkaiense in wild pink salmon from Alaska, according to a study published in the CDC's Emerging Infectious Diseases journal. That means salmon from the Pacific Ocean coasts in both Asia and America could be risky to people who eat it raw, such as in sushi and sashimi.

"For decades, the possible occurrence of the Japanese broad tapeworm on the Pacific coast of North America was ignored, but since 2008, human infection with adult tapeworms and natural infection of carnivores (wolves and bears) with adult tapeworms have been confirmed by use of molecular markers," the researchers wrote in the published study. "Our main intent is 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."

The researchers are concerned that Pacific salmon could be a source of human infection because the fish is often exported on ice, but not frozen, allowing the parasite to survive transport. That could pose a risk to consumers in China, Europe, New Zealand, and the rest of the United States.