In a recent report published in February by the Centers for Disease Control and Prevention, scientists in conjunction with state officials have found Diphyllobothrium latum (popularly known as Japanese broad tapeworm) worms and larvae in Alaskan salmon.
The Japanese tapeworm had a 99 percent positive match with tapeworms found in the 64 samples of Alaskan salmon collected in July 2013. One larva also tested positive for Diphyllobothrium nihonkaiense. Scientists further stated that salmon from the Pacific coast of North America may represent a source of human infection. Since most fish transported overseas usually go unfrozen (on ice), the risk of infection becomes quite high and poses serious threats to people in other countries as well. “Increasing popularity of eating raw fish is the likely factor accounting for an increased number of imported cases in areas where this infection is less endemic,” the scientists wrote.
In another press release by Kim Stryker, Manager at the State Department of Environmental Conservation’s Food Safety, stated that the Japanese broad tapeworm had no immediate concerns on food safety apart from eating uncooked fish. So, popular fish dishes like ceviche and sushi might be the main concern. Kim Stryker stated, “It would be a really big risk factor if the product was eaten raw, and that includes ceviche.”
Although tapeworm outbreaks are rare in the US, scientists have stated that their recent discovery means that risk is re-emerging in all parts of the country, particularly among the consumers of raw fish. Possible symptoms of tapeworm infection may include nausea, abdominal discomfort, diarrhea, and weight loss.
Freezing fish is not only done for long distance transportation but also to control parasite hazards, as most parasites don’t survive freezing. The Alaskan Food Code requires all fish to be frozen before serving, the law which applies to all households and businesses in Alaska. The measure is considered to be effective in prevention of an outbreak. The Alaskan Seafood Marketing Institute has reported that Alaska accounts for around 90 percent of Pacific salmon consumed in the US, and most factories has started to freeze fish before exporting.
The Japanese broad tapeworm is not a new parasite. In fact, in the late 80’s it accounted for about 2000 cases of human worm infections in North Asia. As noted, these recent studies touch on consumer’s eating habit and encourage more lab work on the life cycle and interaction of the parasite.