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:

Pork Tapeworms on the Brain
Avoiding Epilepsy Through Diet
Chronic Headaches and Pork Tapeworms
Not So Delusional Parasitosis

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.

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