Biology

Study suggests that sushi has gotten way wormier

Study suggests that sushi has ...
An Anisakis worm in a piece of raw salmon
An Anisakis worm in a piece of raw salmon
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An Anisakis worm in a piece of raw salmon
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An Anisakis worm in a piece of raw salmon

If you've ever thought that you got food poisoning from eating sushi, you might have actually gotten worms from the stuff. A new study indicates that such fish worms are now more common than ever – although chefs usually pick them out.

Conducted by scientists at the University of Washington, the meta-study actually involved combining data from previous studies conducted between 1978 and 2015. Those studies looked at the abundance of a parasitic worm known as Anisakis, in raw or undercooked fish flesh. It was found that over the 37-year period, there was a 283-fold increase in worm numbers.

Although Anisakis is commonly called the herring worm, it occurs in a wide variety of ocean fish. When ingested by humans, live worms typically only last for a few days. Within that time, however, they can make their way into the intestinal wall, causing symptoms such as nausea, vomiting and diarrhea. The condition is called anisakiasis or anisakidosis, and it usually goes away once the worm dies.

Fortunately, the researchers state that seafood processors and sushi chefs are pretty good at spotting and removing the worms from fish fillets. That said, concerned diners might wish to cut their sushi up to do a worm-check of their own, before eating it.

Unfortunately, though, things aren't so easy for marine mammals like whales, seals and dolphins. When ingested by such animals, the worms live on for some time in their intestinal tract, reproducing and being passed into the ocean within their feces.

Ironically, the increased Anisakis numbers may be due to the legislated protection of marine mammals, providing the worms with more opportunities to reproduce. That said, other contributing factors could include climate change, and increased waterborne nutrients from sources such as fertilizer in agricultural runoff.

A paper on the study, which was led by Asst. Prof. Chelsea Wood, was published this week in the journal Global Change Biology.

Source: University of Washington via EurekAlert

8 comments
Daishi
Eating uncooked food was always tempting fate. I have seem some data that Salmon has very high rates of parasites. Even if the chef removes the obvious large adult worms the smaller ones and larvae are probably still there and alive at the point of consumption. Maybe your body kills off the parasite, maybe same day one of the parasites evolves just enough to survive inside the human body. There is a reason people cook food.
Max.au
Sushi or sashimi? I would have thought sashimi would be the greatest risk rather than sushi.
xs400
Don't understand this fascination with raw meat. But we need all kinds. Someday raw meat eaters will provide some important value to science and humankind. I'm taking the less risk route for my nutritional needs, thanks.
Brian M
As Daishi says eating any sort of raw flesh is tempting fate. Not just sushi, but other meats such as beef etc.. As a species we learnt the advantage of cooking things for good reasons, unfortunately some people haven't got the message!
Tyler Jones
Haha, man, the sushi haters are out in force today! People take a risk every time they drive their car. Life is a constant series of risk and cost-benefit analysis choices. I'm sure everyone commenting here chooses to keep something in their life that is as or more dangerous than eating sushi, i.e. smoking, driving, etc.
Joneseyboy
Not to say there aren't risks to eating raw fish, but the reason cooking evolved for humans and our predecessors was the higher availability of protein in cooked meat. The fish should be expertly inspected or frozen for a period of time (not just overnight). You can easily look the time up.
Joneseyboy
I should have said " the higher availability of protein versus time in cooked meat" It was all about getting protein into the body as quickly as possible. Raw meat takes a long time to digest.
bwana4swahili
Yummy! Extra protein...