Recently, I went to a Sushi restaurant and had myself a bowl of chirashi, a medley of sushi rice and raw fish. Like usual, I thought nothing of the meat and ate it without worry. Soon afterwards however, I began to feel a little…weird. My stomach felt very stiff and my voice tensed up; I felt like I had to puke.
Fortunately, the discomfort passed within an hour or two without any trips to the restroom, or the sink. I didn’t finish my meal and left feeling a little beat. It was no surprise that for a moment sometime in that episode, I had worried if I had seriously contracted something bad in the fish. Or the rice. Maybe something wasn’t fresh or was frozen at the improper temperature. I wouldn’t have had a clue.
In the United States, strict standards for consuming raw seafood has rendered almost all sushi safe. Of the over 20,000 cases of infection with seafood-associated parasites which occur worldwide, over ninety percent of them occur in Japan. Other cases have been reported in areas of coastal Europe. About 60 or so cases of Anisakiasis, infection through the ingestion of the parasite Anisakis simplex, occur in the United States, though this number is likely underreported due to undiagnosed cases.
Anisakid-infected marine life exists in all major oceans and are quite prevalent, especially in United States wild salmon. The source of human infection varies depending on the culinary culture of the country. For example, high risk dishes would be “smoked herring in the Netherlands, Scandinavian gravlax, Hawaiian lomi-lomi (raw salmon), Souther American ceviche, and pickled anchovies and raw sardines in Spain.” Different dishes are more likely to lead to infection depending on the country.
Infection symptoms are very similar to that of appendicitis. Often times however, gastric anisakidosis (infection) can be misdiagnosed as some form of peptic ulcer disease or “vanishing gastric tumor.” Since the worm is so small, it can be hard to spot and diagnose properly. Endoscopic extraction is the preferred treatment for such an infection. Delayed removal may end up giving enough time for the larvae to embed itself into the sub-mucosa, and surgical removal is occasionally required.
The best way to prevent against an anisakid infection is of course to throughly cook the fish to temperatures of above 140 degrees Fahrenheit. Smoking is not effective if adequate temperatures are not reached. Another common way of eating raw seafood especially in Asian countries is salting fish. Such a process does kill the anisakid larvae, but the salt concentrations must be high for a prolonged period of time. All fish intended to be consumed raw are required by the U.S. Food and Drug Administration to be flash frozen at -4 degrees fahrenheit for seven days. Fish are also gutted quickly upon catch to prevent or decrease the number of larvae from migrating to the flesh and edible parts from the intestinal tract.
While the dangers of infection are out there, the chances of becoming infected are still low, especially in the states. Whatever sickness I got that day ended up being nothing too major, despite the adrenaline rush through my head when I thought of the possibility of Anisakid infection.
Citation: Hochberg, Natasha S., and Davidson H. Hamer. “Anisakidosis: Perils of the Deep.” Clinical Infectious Diseases 51.7 (2010): 806-12. JSTOR [JSTOR]. Web. 10 Oct. 2016.