Doctors Warn of Painful Parasite Hiding in Your Sushi

Beware your next Seattle roll; doctors say it could contain something that should never be found in sushi (besides cream cheese): a "worm-like" parasite. A paper published Thursday in BMJ Case Reports says cases of anisakiasis are on the rise in the West due to the increasing popularity of sushi and other dishes involving raw or under-cooked fish. The report gives the example of a Portuguese man who was suffering vomiting, fever, and stomach pain. He told doctors he had recently eaten sushi, and they discovered an anisakis larva attached to his stomach lining, CTV News reports. According to CNN, the anisakis is a parasitic worm that lives in mackerel, squids, salmon, herring, cod, red snapper, and halibut.

There's no treatment for anisakiasis, which can also cause bowel obstruction and digestive bleeding, besides physical removal of the anisakis larva, which can require surgery, the Guardian reports. Anisakiasis is common in Japan due to the prevalence of raw fish in the diet, with between 2,000 and 3,000 cases diagnosed per year. But cases are starting to pop up in the US and elsewhere in the West. To avoid getting the parasite, patronize high-quality sushi restaurants. "Properly trained sushi chefs can detect anisakis larvae," one doctor says. "They are grossly visible in the fish." Or if you're making sushi at home, freeze the fish for at least four days beforehand to kill the larvae. (Tapeworm believed to be only in Asian salmon found in US.)