Doctors Warn Parasitic Worms May Live in Your Sushi

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Ready to wiggle its way down to your stomach. Photo: Tomohiro Ohsumi/Getty Images

A new study gives sushi eaters a reason to take it easy, reporting there’s been an uptick in anisakiasis, a stomach infection caused by a worm that lives in fish, but can easily relocate to your stomach or intestines. It’s a common illness in Japan, where people eat lots of raw seafood, but doctors haven’t been aware of too many cases in the West until now, and researchers link the spike to the growing popularity of sushi. The larvae can infect a variety of fish — salmon, herring, cod, mackerel, sardines, anchovies, squid, halibut, red snapper — but die if the fish is frozen for several days, or cooked to at least 150 degrees.

In case you’re curious, they are indeed quite “worm-like”:

That thing’s big enough to be a roll ingredient. Photo: BMJ Case Reports

Freezing or cooking doesn’t make for palatable sushi, but to give an example of what damage the parasite can inflict, the study, published yesterday in the journal BMJ Case Reports, talks about a “previously healthy” 32-year-old who became violently ill after he ate raw fish. Doctors at a hospital found the worm “firmly attached” to his gut lining, which had become swollen and was causing him severe pain and nausea. The authors warn that “owing to changing food habits, anisakiasis is a growing disease in Western countries,” and caution anybody “with a history of ingestion of raw or uncooked fish” to maybe rethink that part of their diet. An expert also tells CNN the worms are supposedly “grossly visible” in fish.

For what it’s worth, the CDC adds that even if it evades detection, an anisakis parasite can still be removed in several different ways. No specific drug exists that can simply kill it dead, so endoscopic surgery is one popular option. Another involves more finesse — that is, physically grabbing it on its way down. This one’s just best left described by the CDC: “Some people experience a tingling sensation after or while eating raw or undercooked fish or squid. This is actually the worm moving in the mouth or throat. These people can often extract the worm manually from their mouth.” If it still sneaks by your fingers, that’s okay — you can always go vomit, as this will also “often expel the worm from the body.”

Doctors Warn Parasitic Worms May Live in Your Sushi