Sushi Worm Parasite

Image Credit: Sally Plank

Sushi Worm Parasite

There was a report recently of a woman in San Francisco suffering from gnathostomiasis. I had learned about the disease while I was in medical school, but never actually saw a case. Evidently, it’s now on the rise. Clinically, the disease commonly presents as “migratory cutaneous swelling” (bumps on the skin that move around). Why? Because there’s a worm under there that migrates through the tissues under the skin and causes recurring episodes of migratory swelling or creeping eruptions. The worm’s head has rings of little hooks that allow it to burrow through tissue. There is no effective treatment, other than removal of the worm. Since humans are basically dead-end hosts for the larva, they can’t develop into mature worms. The symptoms patients experience are due to the organism wandering throughout the body (see Migratory Skin Worms from Sushi).

In addition to burrowing under our skin, it can also crawl into our eyeballs. The 42-year-old woman is described as having a four-year history of migratory swellings on her face, then a little bleeding from the eyelid… and we know where this is going. No problem, though! We can make a little cut, stick in some forceps, locate the worm, and then just pull the sucker right out of the eyeball. If you have any pimples on your face that move around, better to have your doctor grab them before they start swimming around in your eyes.

By far the most serious manifestation is when they get into your brain. As the worm migrates along the nerves, the patient can experience excruciating pain. The condition can lead to paralysis, bleeding in the brain, and finally death. However, in non-cerebral disease, it’s the worms that die, though it may take about 12 years.

How do the worms get into our brain, causing so-called neurognathostomiasis? Gnathostoma worms are highly invasive parasites. After you leave the sushi bar, the larvae can penetrate the wall of your intestine. They can then enter the brain through the base of the skull, crawling along the spinal nerves and vessels. They start out in the nerve roots, enter the spinal cord, and then can climb up into the brain. The worm isn’t poisonous or anything; it’s just the migration of the worm through the body that causes direct mechanical injury because of tearing of nerve tissues.

The bottom line: This diagnosis should be considered in patients who present with nonspecific little lumps and bumps, especially when there is a history of frequent consumption of raw fish.

Thankfully, most raw foodists stick to plants and thereby avoid scenarios like this: A 21-year-old woman experienced acute, severe pain in her mouth immediately after swallowing a raw squid. It seems consuming a squid with “sperm bags and an active ejaculatory apparatus” can result in the “unintended ejection of the sperm bag” and injury to the oral cavity. The researchers conclude that eating raw food, especially living organisms, can be risky. Though some living organisms (plants!) may be substantially less risky than others.

This is like my Tongue Worm in Human Eye or Cheese Mites and Maggots videos. Extremely rare, but extremely fascinating (to me at least!).

There is one parasitic infection that is much more common and a major cause of disability worldwide, though, neurocysticercosis:

I think the only other sushi videos I have are Fecal Contamination of Sushi and Allergenic Fish Worms, though the nori seaweed is good for you (Which Seaweed Is Most Protective Against Breast Cancer? and Avoiding Iodine Deficiency).

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Discuss

Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.


64 responses to “Sushi Worm Parasite

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  1. Welp, there was my daily dose of reality. Sushi was the last bit of “meat” we were consuming. This report didn’t’t make me fearful; rather, it made me aware of the increased risk associated with eating raw fish. Got me thinking… if we can’t really trust cooked fish, why in the world have we been eating raw fish???!!! Thank you again Dr. Greger.




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    1. While I no longer eat fish or any meat for that matter, I gave some frozen and thawed sockeye salmon to my cat recently, because a person who was “helping me”, fed a hot dog to my cat. “Mow” lost her appetite for Organix (organic) food for cats and I wanted to get her habit to change, quickly. But, Mow has not felt well since. Should I take her to the Vet. (I know Dr. Greger is not a Vet, but he is a consultant for the Humane Society.




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      1. Wild Salmon including Copper River Salmon, Sockeye Salmon etc are especially exposed to parasites and need to be treated as I mentioned above. Freezing to minus 20 F is helpful but in the wild salmon prep process a combination of salt, vinegar and freezing is employed. Please consult with your vet if the cats’ symptoms persist.




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      2. I have a pet cat question, too. I wish there was “a Dr. Greger” for pets!!! My cat is diabetic. I told my vet about the video Dr. Greger has that says that fat in the diet can get in muscle cells in people and block sugar from getting in. Our vet said, “But cats are DIFFERENT from people.” I have no way of knowing what cat food is best for my diabetic cat–e.g., reduced fat products? (The vet says to provide less food with rice and any other carbs in them whereas with people, that is not quite true.)




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        1. Thank you for your question. Unfortunately, we can only speak on the topics of human nutrition. Cats do have different needs than we do and can get sick if they’re not receiving the right nutrients. A veterinary physician is going to be your best resource on this.




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      3. Hi Susan: Unfortunately, we can only speak on the topics of human nutrition. A veterinary physician is going to be your best resource on this. If you’re concerned, we would recommend calling your local vet to make an appointment. We hope your furry friend is feeling better soon!




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  2. Gnathostomiasis is ONLY from fresh water fish and NOT from salt water fish. So just from that, highly unlikely to contract it in a sushi restaurant. Also, since most “sushi grade” fish are flash frozen as soon as caught to maintain freshness, that super cold quick freeze kills the parasites.

    It is possible to contract other parasites from sushi in restaurants but more likely in cheap, store front type places than quality ones




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    1. Your comments are completely erroneous Salmon is a salt water fish as salmon crosses the fresh salt/ water barriers as it enters its adult stage, feeds in the ocean as it grows and later returns to its birthplace to spawn.
      Flash freezing salmon is not enough to kill the parasites mentioned. In my sushi restaurant I treat all salmon with a salt and vinegar process the Japanese call ‘Shimeru’ and then expose the treated salmon to at least 48 hours of intense freezing below minus 10 degrees F.
      This is enough to kill the parasite.

      Farm raised salmon may not pose as much as a risk as wild salmon but especially wild Alaskan salmon and others must be treated in the method detailed above to avoid these dangerous parasites.

      When you eat salmon sushi/sashimi in a Japanese restaurant, you must ask the chef if he has followed the procedure. That is the bottom line.

      Salmon should never be eaten raw without being processed




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      1. Many years ago I was employed briefly on a fish processing ship in Alaska.
        The first job they gave me was standing in a refrigerated room cutting worms out of ocean-caught fish as the fillets passed by on a conveyor over a light table, which showed the worms clearly. This was, of course, a different worm, but it does show that seafood has its’ own parasites, and they could certainly be missed if they are smaller, or are missed for any number of reasons.




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  3. I wonder if there is any possibility of cross-contamination when consuming plant-based sushi at a sushi restaurant? Would it be enough to transmit these parasites?




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  4. I really enjoy this website and Dr. Greger’s work. After reading the blog, my first question was, “what kind of fish?” So, I googled it. https://en.wikipedia.org/wiki/Gnathostomiasis

    It appears, the possibility of ingesting this worm at the appropriate stage on the North American continent at a regular sushi restaurant is very, very, very, very rare. Please read the Wikipedia article – link above.

    All information is valid, but scare tactics don’t help me make intelligent decisions.

    Thanks for your great work! :) I do appreciate it!




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  5. As noted by another poster this is a food handling issue as sushi grade fish should have been harvested from salt water, and kept frozen for a week. There are plant based food handling issues as well, how many times do we hear of salmonella cases in lettuce/spinach from improperly handled greens? If you want to read about a horrible parasite, google rat lungworm disease.

    Although the information here has convinced me to move to a more plant based diet I still eat fish. (wild caught personally from a clean source) As great as a vegan diet sounds I just can’t get past the vitamin B12 problem. Fish are also rich in Vitamin D & DHA which Dr. Greger also recommends taking as supplements. It seems to me that excluding all but plants is the same nutritional reductionism that the supplement industry is guilty of…




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      1. We are omnivores, B12 deficiency from a plant only diet proves it. What else are you missing by not getting all your nutritional needs from whole foods other than B12? DHA? Your body is a very complex mechanism, I find it hard to believe science has identified the one and only nutrient required not provided in a vegan diet.




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        1. Ron, I hope you will take a look at the following and consider altering your position for your own sake, at the very least. B12 is not missing from people who eat vegetables without washing them like the animals you eat who don’t wash theirs; that’s how you’re getting your B12. I prefer a simple tablet.

          https://www.drmcdougall.com/misc/2007nl/nov/b12.htm

          BTW, I am no longer an omnivore and am healthier for it for sure.




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          1. Liisa,
            Thank you. This was a balanced, well written article and I look forward to investigating the website further. I see how microorganisms on unwashed vegetables could provide B12 as well as any other compounds not yet identified in a plant only diet, but presents the risk of other parasites.

            I think it most important to have a whole foods diet, and yes mostly plants. Maybe one day I cut out the fish all together, well written articles like the one you have provided help move me that direction. But scare tactics like this particular blog post or emotional tirades like Scott’s below definitely do not help!




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        2. In research I heard about recently (sorry, I can’t provide the reference, but it was a Youtube discussion with Dr Fuhrman, Brenda Davis, and two others) they gave the figures on B12 and it turns out that more omnivores are short of it than those of us who avoid animal protein. As we get older it’s harder to absorb.

          The animals we expect to get it from get it from the dirt on plants they eat. They don’t make it any more than we do.




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          1. That would have been the panel discussion during “The Real Truth About Health” conference Rebecca… Brenda and Joel were amazing that year :)

            TRTAH conference has a YouTube page with all the vids… I’d explore the work of Brian Clement as well, he wrote a book called Killer Fish, very interesting read on this subject. I personally wouldn’t touch fish with a ten foot pole and I ate a lot growing up (I’m Italian and we even eat the eyes of the fish, so gross looking back lol)… The ocean is toxic, and this worm is this is the least of our worries when it comes to why we should stop consuming fish. Everything we might want from them we get from plants and they are extremely fatty to boot. Let’s also consider that the industry is eating itself out of existence and we will have no fish in the coming years, the loss of species in our oceans is devastating, an environmental disaster.

            http://www.therealtruthabouthealth.com
            https://www.youtube.com/watch?v=3GoOeI-982I




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            1. Marcello Di Santo, Thank you. I think that is the Youtube video I was listening to. I’ve bookmarked it to watch again when I’m not sleepy, as I was the first time.




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        3. Ron, . . .in addition to the other comments posted about getting B12 from bacteria on plants, let me also contribute that B12 can be a problem for an omnivore, in terms of not assimilating enough of it. It can be a very common vitamin shortage in the elderly for which they are often tested. A severe B12 deficiency can cause symptoms that mimic dementia and is often tested for in nursing homes. When my own father was elderly I had to give him, a heavy meat eater, B12 shots for 6 weeks. So the issues regarding B12 are not necessarily for only the vegan.




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    1. Ron, I recommend reading “The World Peace Diet.” It was recommended to me and I reluctantly read it because I wasn’t sure it was very scientific. However, it stopped my consumption of fish, for sure. I recommend it to you now.




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    2. As great as a vegan diet is, I just can’t get past those that continue to be complicit in the exploitation, enslavement, abuse and murder of innocent sentient beings.

      Let alone those that hunt fish, hooking them through their jaws and lips, and pulling them out of the water where they suffocate to their excruciating death.

      Veganism is compassion to the fellow animals we share this planet with.




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    3. B12 “problem”? Since B12 is synthesized by bacteria and is found in dirt and soil, If sanitation is the problem for you, just get your B12 from the source like all animals do…drink straight from any natural body of unpurified water, dig up some root veggies and eat them without washing well, go make some mudpies, etc, problem solved. Personally, even though I generally avoid supplements, this is one exception I am good with since the other sources that store it seem riddled with multiple bigger problems.




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      1. I do not think it is about not killing animals which have no other purpose in life but to survive and feed humans. However, fish are not safe to eat so why talk about your value judgement when it is obvious that the oceans are contaminated with toxins and microplastics. Much of the contamination of plants is a result of animal manure, pesticides or the soil if handles properly during transportation.
        Agriculture animals also are a large user of resources like water and land besides a significant addition to the problem of climate change.




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  6. When I was young and foolish (I’m older now), I ate sushi and, at times, steak tartare. While it’s no fun to lose one’s looks, health and memory, there are some benefits to maturity.




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  7. Though this is gross, what is scarier to me are the multitude of invisible viruses, bacteria and other contaminants in all animals that are eaten as food.




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  8. I know this is mainly talking about sushi but it meanions raw fruits and veggies having less risk. Therefore that means there are some risks. How do you wash raw fruits and veggies thoroughly enough to insure safe consumption? I eat a lot of raw fruits and veggies.




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    1. I know this is mainly talking about sushi but it mentions raw fruits and veggies having less risk. Therefore that means there are some risks. How do you wash raw fruits and veggies thoroughly enough to insure safe consumption? I eat a lot of raw fruits and veggies.

      Sorry typo in first post so retyping




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  9. My husband and I are plant-based nutritarians (thanks to Dr. Joel Fuhrman) and sometimes we eat vegan sushi made in a restaurant. Someone asked about possible parasitic cross contamination but I have not seen that question answered. Anyone have good information on that issue?

    Thanks




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  10. Like toxins and microplastics are not enough to keep sane people away from consuming wild fish, there is antibiotics in farm fish and worms in raw fish!!!!




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  11. Hello Dr. Greger,

    I cannot find the case you describe in the literature. The closest I came was this case I’ve posted below. I’m assuming these are not the same case as the patient you describe presented differently. Would you possibly be able to provide a reference to the case you wrote about? I’d love to read it. It might even get me off raw fish altogether. Thanks!

    Am J Dermatopathol. 2011 Dec;33(8):e91-3. doi: 10.1097/DAD.0b013e31821cf4a6.
    Gnathostomiasis in a patient who frequently consumes sushi.
    Jarell AD1, Dans MJ, Elston DM, Mathison BA, Ruben BS.

    Abstract

    A 45-year-old woman presented for evaluation of a solitary pruritic nodule on the abdomen that suddenly appeared 3 weeks before. She was healthy without a significant medical history, travel history, exposures, medications, or pets. She reported that she consumed sushi at least weekly in the city of San Francisco. A punch biopsy revealed a superficial and deep perivascular and interstitial infiltrates consisting of lymphocytes, plasma cells, and many eosinophils. Most notably, there was a parasite centered in the reticular dermis with prominent lateral chords, a well-developed muscular esophagus, and an intestine that contained a brush border and multinucleate cells. Evaluation of these histological sections by the Centers for Disease Control and Prevention determined the parasite to be a nematode of the genus Gnathostoma. The patient underwent a systemic work-up for gnathostomiasis, including imaging, and no other abnormalities were found. She completed a 3-week course of albendazole and has remained asymptomatic since the biopsy of her abdominal lesion. Although gnathostomiasis is often a systemic illness, this patient did well with apparently only localized cutaneous disease. Gnathostomiasis should be considered in patients who present with nonspecific papules and nodules, especially when there is a history of frequent consumption of raw fish.




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  12. Thank you Sharon, you just confirmed my suspicion. Dr. Greger appears to have confused the case of the 45 year old woman in San Francisco who only had a solitary pruritic nodule in her abdomen, had it removed, and responded well to meds, with a 41 year old man in Bangladesh who had the migratory worm in the eye.

    From Dr. Greger’s Article: “The 42-year-old woman is described as having a four-year history of migratory swellings on her face, then a little bleeding from the eyelid… and we know where this is going.”

    I’m going to tried to give him the benefit of the doubt that this was just an error in research, not an attempt to mislead his audience. As far as I can tell there has only been one reported case in the literature occurring in the United States, particularly among people who have not recently returned from travel from another country where this problem is endemic. That case was the lady in San Francisco with the single module on her abdomen. No bleeding eyeballs, etc.

    I’m certainly willing to admit that I am misunderstanding or misreading the literature. I would really like to either be corrected, receive clarification, or otherwise I would like Dr. Gregor to correct the record.

    It’s extremely important that we be able to trust Dr. Gregor’s case reporting that he bases his research and presentations on.

    Thank You.




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    1. I think you’re right – in the video narration / blog text it should be 41 year old Indian male, not 42 year old American female with the intraocular gnathostomiasis. Or the 32 year old Indian woman contracted it (Table 1).
      I would never eat raw fish anyway…




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      1. I love raw sushi, but I am extremely selective as to where I get it from. Despite the fact that there are a plethora of sushi restaurants where I live, my wife and I only go to the best ones where they appear to have the best trained sushi chefs. Of course that’s no guarantee, but it does add some peace of mind to the experience.




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        1. Right on JaySal

          Know your Japanese restaurant and their preparation protocols.

          Salmon is a salt water fish as salmon crosses the fresh salt/ water barriers as it enters its adult stage, feeds in the ocean as it grows and later returns to its birthplace to spawn.
          Flash freezing salmon is not enough to kill the parasites mentioned.

          I own a Japanese restaurant that specializes in sushi and salmon in particular(Copper River, Tasmanian and Scottish). We treat all salmon with a salt and vinegar process the Japanese call ‘Shimeru’ and then expose the treated salmon to at least 48 hours of intense freezing below minus 10 degrees F.
          This is enough to kill the parasite.

          Farm raised salmon may not pose as much as a risk as wild salmon but especially wild Alaskan salmon and others must be treated in the method detailed above to avoid these dangerous parasites.

          When you eat salmon sushi/sashimi in a Japanese restaurant, you must ask the chef if he has followed the procedure. That is the bottom line.

          Salmon should never be eaten raw without being processed




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          1. Both farm and wild fish is not safe to eat. Do some research on microplastics and toxins in fish, not to mention the possibility of over-indulgence in animal protein…




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    1. From what I read in the literature, The best first course treatment for this particular parasite is surgical removal followed by a course of a medication like albendazole. However if the parasite(s) is in a location that’s difficult to isolate or the patient is not a good surgical candidate they may try the by medications by themselves first.




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  13. I’m vegan. I eat vegan sushi. But sometimes I order vegan sushi from a restaurant that also serves raw fish sushi. Should I be concerned?




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  14. Not all sushi uses raw fish or seafood. The actual raw fish dish is called sashimi, unless it’s rolled into rice and seaweed (sushi) so that distinction needs to be clarified. I’m assuming we won’t get parasites from cooked seafood or fish in the sushi. Of course, we could avoid this completely and eat vegan sushi.




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      1. Raw fish can be consumed as sashimi(fish without rice usually 3 slices per serving), sushi nigiri( raw fish on a flavored ball of sushi rice) or maki cut rolls(raw fish rolled into rice and nori laver)

        -Each of these iterations has the potential of exposing the ingester to the parasite because the fish is raw

        Remember clearly that raw, unprocessed salmon has this dangerous parasite.

        However if a reputable sushi bar processes the raw salmon properly (see my note above), it kills the parasite and is safe to eat.

        This conversation is not about cooked sea food or vegetarian options which obviously have their own degree of potential risks from unsanitary dynamics inside a kitchen.

        This conversation only involves certain species of fish that carry a parasite and must be carefully processed to avoid human contamination http://www.sybaerites.com




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  15. I teach intro science classes at a community college. My students need a lecture in order to understand the content –and they need a lecture where the professor is watching them, looking for that visual feedback that tells us if they’re getting it, or need a few more minutes and an alternate explanation. I include lots of in-class work as well, but flipping is not a good option for me. These students have been spoon-fed (teaching to the test) in high school, many of them not even allowed to take precious textbooks home with them. Independent learning isn’t something they have any experience with. I’d love to see flipping work (I’d LOVE not to lecture!) but the intro students need a transition to college to teach them how to do some independent reading and note-taking before they’re required to do it all on their own.
    anneau van cleef et arpels trefle copie http://www.lemeilleurbijoux.cn/fr/pure-alhambra-ring-c3_85_90/




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  16. I read recently that Nori, used in sushi rolls may contain bits of ground shrimp or shells. Does that mean they may not be a totally plant based source of seaweed? Also is this true?




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