A gruesome tapeworm that was once believed to infect only fish in Asia has been found in salmon netted in Alaska.

Eating Raw Or Undercooked Fish

A new study, which was published in the Centers for Disease Control and Prevention's journal Emerging Infectious Diseases, hint of the growing dangers of eating sashimi and sushi.

Americans who love to eat raw or undercooked fish may now have higher risk of getting an infection from parasites as researchers discovered Japanese broad tapeworm in wild pink salmon caught in Alaska.

Japanese Broad Tapeworm

The Japanese broad tapeworm, Diphyllobothrium nihonkaiense, was first recognized as a human parasite in 1986.

It has been reported in 2,000 illnesses in Japan and other parts of Asia and is known to affect humans who eat infected fish in eastern Russia and Japan. Now, the tapeworm was found in salmon caught in the North American waters off the coast of Alaska.

In 2013, Jayde Ferguson, from Department of Fish and Game, and colleagues, examined 64 wild Alaskan salmon.

By observing the musculature and the internal organs of the fish under a magnifying glass, the researchers discovered larvae measuring up to 15 millimeters long.

Carriers Of The Japanese Tapeworm

Gene sequencing later revealed that these were Japanese tapeworms. Based on the findings, four species of Pacific salmon are now known to be carriers of the Japanese tapeworm infection namely the chum salmon, pink salmon, masu salmon, and sockeye salmon.

"We report finding Japanese broad tapeworm plerocercoids in North America," Ferguson and colleagues reported. "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."

Infection May Go Unnoticed

The health effects of Japanese tapeworm infection are not generally serious. Most infections, in fact, go unnoticed because the parasites tend to cause few symptoms.

Some of those infected may only experience nausea or slight abdominal discomfort but there are instances when the infection can become a serious medical problem.

More Serious Health Effects Of Japanese Tapeworm Infection

In 2012, a Japanese man who enjoyed eating chilled salmon suffered from gastrointestinal distress. A meter-long "tape-shaped object" later emerged from his anus which turned out to be the parasitic Japanese broad tapeworm.

"The infections can have a substantial emotional impact on patients and their families," said study author Roman Kuchta, from the Academy of Sciences of the Czech Republic. "More severe cases may require specialized consultations and complementary analyses, which are costly."

Global Importation And Popularity Of Eating Raw Fish

Scientists also warned that the problem may spread if nothing is done about it. Global importation and the increasing popularity of eating raw fish help spread the parasite.

Salmon is often packed and transported in ice but not frozen. The tapeworm's larvae can possibly survive the trip and infect consumers in different countries worldwide which include New Zealand, China, and some parts of the United States.

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