Scary Sushi Parasite on the Rise in Western Countries

A particularly nasty parasite known in Japan, which infects a few thousand people per year, is now being seen much more in the West, where sushi is now sold at supermarkets, run-down food courts, and gas stations.

Sushi, ceviche, crudo, poke…all of them seem crazy popular right now from what I see online, and I understand why. Raw or “acid cooked” fish tastes great, looks great, and if prepared correctly, has no ill-health effects. However, as I talked about in my post about sushi grade fish, if the products are not stored and handled properly you can have a big problem with parasites.

The Herring Worm Parasite


It is known as Anisakis simplex and there is no medication for an infection of this nematode. In rare cases, the parasite has to be removed from a patient’s stomach using endoscopy. The range of symptoms include pain, nausea, chronic ulcers and even life-threatening allergic reactions. Although most cases eventually go away on their own, if can be months of agony before that.

Parasitic worms from the genus anisakis are found in anchovies, cod, salmon, mackerel, halibut and even squid. It is also found in herring, where it was first discovered in the West after someone got infected from the infamous Dutch soused herring. The Dutch like their favorite snack nearly raw and so for decades these worms were only associated with herring in Europe. Anisakis simplex, the most common type is still known as the “herring worm” in medical literature. As if I needed another reason not to eat maatjes when I’m in Amsterdam.

As raw fish gains in popularity, so do the chances of finding the parasite. Experts estimate that anisakis infections are vastly underdiagnosed. Recent studies of fish in Spanish markets show large percentages of mackerel and blue whiting infected with Anisakis simplex. In Scandinavian countries, the infection is associated with eating raw or undercooked cod livers. South American infections are usually connected to ceviche consumption.

jack mackerel ceviche no parasite

Anisakis in the United States

Here in the US? The CDC has no idea how many infections there are annually, they don’t report on it. There is a very large possibility that anisakis infection – anisakiasis – goes unreported or misdiagnosed in the West, including the United States. Considering that our consumer culture has transformed the fine art of sushi into something that competes with Big Macs and the abominations from Taco Bell, I have not doubt anisakiasis is well represented here.

Do you have to give up sushi? No! If fish is properly handled (-20C for at least 72 hours but FDA/CDC recommends 7 days) with no cross-contamination, the parasite is killed off. Also, a trained sushi chef can find them in the fish, so let the pros handle it. And for the sake of humanity, stay away from the “half-price sumo roll with purchase of 10 gallons” offer next time you need gas.

Sources: CDC Website

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