The Guardian: Raw deal: sushi-loving California man discovers 5ft 6in tapeworm


Last January, the federal Centers for Disease Control and Prevention (CDC) put out a warning of an elevated risk of parasitic larvae that can grow into tapeworms being found in Pacific Ocean salmon, including Alaskan wild salmon that is popular in the US and elsewhere.

Cooking kills the tiny larva; sushi is supposed to be flash-frozen to kill such parasites too. Larva may survive in poorly prepared raw salmon, then take up residence in a human digestive tract.

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The Japanese avoid eating raw salmon because of the worm problem. Don’t know why outside Japan, salmon is so popular in sushi and sashimi.

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In New York all fish to be consumed raw is flash-frozen for 48 hours. Our local supermarket in Zurich does the same thing. Since I have learned this, I have a hard time eating raw fish anywhere else.


My parasitology prof assured me that most sashimi has been flash frozen right on the boat. He indicated that the biggest problems were people living right on the coast accessing fish that wasn’t flash frozen.

Flash freezing is definitely one way to go. But it is generally only mandated for sashimi grade fish not lower quality fish. I know much fish is frozen on deep sea boats but not necessarily on day boats. And sushi bars who are cutting corners on the cost of produce could well use cheaper non-sashimi grade fish.

Another good control point is to only eat sushi/sashimi in a restaurant with a very well trained chef. One of the key parts of the training is to spot parasites as they are slicing up the fish.

And of course if you are a sushi/sashimi fanatic it can’t hurt to pop a worming tab when you dose the dog…

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The story didn’t reveal where the man sourced his salmon. The flash-frozen hence safe is helpful from commercially sourced sashimi. However, many people think “the fresher the better” and don’t realize that their sushi fish has been frozen. So when their sportfishing friends gift them a freshly caught fish, they slice it up and eat it thinking that’s the best way. If only they’ve seen pictures of the tuna auctions in Japan. Those fish are rock hard frozen!

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True! I have taken pictures of that in Tsukiji market in Tokyo.

But I would still like to try super fresh sashimi and deworm tablets if necessary.

Light reading about salmon consumption is Japan. Thanks to Norway. I saw whole frozen Russian salmon at the market in Hokkaido. Probably cheaper than Norwegian.

Salmon sushi is popular these days at Kaitenzushi (sushi on conveyor belt). Just had a quick look at my Japan trip photos and saw salmon sashimi in a few meals. I much prefer tuna, sea urchin, mollusk and shellfish sashimi.

Tuna is a deep sea fish so the boats flash freeze it on board as they can be at sea for quite a long time.

The danger is probably more in fish sourced from day boats or farms where it doesn’t need to be frozen in order to get it to market fresh.

Hence salmon being an issue as its so often farmed.

Farmed salmon is an issue even when consumed cooked.

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Honghe Hani Rice Terraces, Yuanyang County, Yunnan
Credit: inkelv1122, Flickr