Its hearty flavor and unique pink color make salmon one of the most highly sought-after fish. Farmed salmon tends to be less flavorful, so most fish connoisseurs prefer wild caught salmon from Alaska or the Pacific Northwest. Unfortunately, new information suggests that these United States salmon may be harboring some dangerous parasites. It turns out that a parasite from Japan seems to have traveled across the Pacific ocean and started affecting American fish.
Rare Japanese Tapeworm Parasite Found in Alaskan Salmon
It was commonly assumed that most wild caught salmon were not infected with any serious parasites because the Japanese broad tapeworm was only in Pacific salmon near Japan and Russia. However, microscopic examinations of wild Alaskan salmon reveal that this is not true. Researchers looked at thin slices of salmon from 64 different Alaskan salmon under a microscope.
The microscopic examination showed larvae ranging from 8 to 15 millimeters in length that were still expanding and contracting as tapeworms typically do. These live specimens were removed, and gene sequencing was used to identify the larvae. It turned out that they were plerocercoids which are the larvae of Japanese tapeworms.
The researchers looked at several different species of salmon in different locations. They found that Japanese tapeworms could be present in sockeye salmon, pink salmon, masu salmon, and chum salmon. Fish located anywhere along the Pacific region of North America may have these parasites, and anyone who eats fish infected with tapeworm eggs or larvae can end up being a host that passes the parasite on to other animals.
The study authors are not positive of how the Japanese tapeworm made its way all the way to America, but they have a few theories. It is possible that the parasites traveled from fish to fish all the way across the ocean. However, it is also possible that someone in America ate a tapeworm that was in salmon shipped from Japan, so the live tapeworm eggs could travel from a human host back to the water.
Japanese tapeworms are somewhat different from the Diphyllobothrium latum tapeworm that is more common in fish. Not only are they more rare, but the symptoms may be more mild. Some people do not even realize they have a Japanese tapeworm infection until the worm has reached 30 feet long.
Though milder symptoms seems like a good thing, it is actually problematic because it takes longer for a patient to be diagnosed. Patients might just feel bloated, have abnormal bowel movements, or lose a little bit of weight when they are infected.
Unfortunately, for the entire time the tapeworm is in their intestines, it is stealing nutrients and weakening them. In more severe cases, a patient can end up with a very painful intestinal obstruction. Though not a deadly encounter, it’s definitely a complication best avoided.
The results of the study show that Japanese tapeworms may be much more common than previously thought. People who regularly eat salmon may need to keep an eye out for the symptoms of a Japanese tapeworm. Fortunately, this parasite can easily be removed through noninvasive medical procedures as long as it is diagnosed early enough.
Safety Tips for Salmon Lovers
Since Japanese tapeworms have started infecting American salmon, you may want to think twice before snacking on a piece of raw salmon sushi in the future. Food safety experts from the CDC recommend that people eat salmon that has been cooked at 145 Fahrenheit for at least four minutes, or some methods of flash freezing salmon can also kill tapeworms. A little bit of extra caution can help to prevent the spread of these tapeworms.