Scientists Discover Japanese Tapeworms in U.S. Salmon

While it has been long believed that the parasitic tapeworm that can invade the human digestive tract is only infecting fish found in Asia, a new study has discovered its existence in fish caught in Alaska.

The horrific tapeworm, which includes Diphyllobothrium nihonkaiense, also known as the Japanese broad tapeworm, is usually ingested by those who eat raw or undercooked fish.

According to the study published in the Centers for Disease Control and Prevention’s monthly journal “Emerging Infectious Diseases” on Wednesday, the parasite has also been discovered inside a wild salmon found in Alaska, CNN reported.

The discovery has led the researchers to hypothesize the possibility of infection among the salmon caught along the Pacific coast of North America.

First identified in 1986, the Japanese broad tapeworm has been considered one of the most common causes of tapeworm infection after infecting around 2,000 people then.

Continued research on the tapeworms by the Czech Science Foundation, however, has revealed that all cases of Tapeworm infections in Japan, South Korea and the Pacific coast of Russia, including the ones previously thought caused by the more common tapeworm Diphyllobothrium latum, were actually also caused by Japanese tapeworms.

A team of researchers then studied 64 wild Alaskan salmon back in 2013 to check if the same parasite would surface from the salmons’ internals. True enough, the scientists found larvae, around 8 and 15 millimeters long, which are, again, identified as Japanese tapeworms. The findings revealed that the species of Pacific salmon such as chum salmon, masu salmon, pink salmon and sockeye salmon are also carriers of Japanese tapeworms.

The report pointed out that since these salmon are exported on ice and then thawed before they are served in restaurants around the world, a Japanese tapeworm infection may surface virtually anywhere.

According to Vanderbilt University School of Medicine Preventive Medicine Professor Dr. William Schaffner, the Japanese version is not any different from other tapeworms since they are within the same family of tapeworms. Illness and symptoms are also expected to be the same, he said. Such tapeworms can reportedly grow up to 30 feet long in length, according to the CDC.

“Actually, most of the people who are infected don’t have symptoms,” Schaffner was quoted as saying.

For those unlucky few, they may suffer abdominal discomfort, nausea or loose stools, and some weight loss. In very rare cases, the infection may also cause massive medical problems.

Roman Kuchta, lead author at the Academy of Sciences of the Czech Republic stated that massive infections may result in intestinal obstruction and other complications.

“The infections can have a substantial emotional impact on patients and their families because segments are evacuated over a long period of time. More severe cases may require specialized consultations and complementary analyses, which are costly,” Kuchta said.

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