Eating raw or undercooked food is like playing Russian roulette with your stomach, but we've kind of seen sushi as the exception. We can no longer take raw sushi for granted, though, as there has been an uptick in sushi eaters getting sick from a disease called Anisakiasis.
Anisakiasis, according to the CDC, "... is a parasitic disease caused by nematodes (worms) that attach to the wall of the esophagus, stomach, or intestine."
Basically, there's a chain reaction where mammals like whales take dumps in the ocean, and larvae get infected. The larvae are eaten by crustaceans, then the crustaceans are eaten by fish and squid that are eventually used in sushi and are ultimately eaten by us.
When the fish in sushi is not cooked all the way, we ingest those parasites and they quickly take over our stomachs, irritating them, and leading to fevers and vomiting.
One example of this came from a report in the British Medical Journal about a 32-year-old man who had moderate abdominal pain, along with a fever and vomiting after eating sushi. An upper gastrointestinal endoscopy was performed on him, and they found a parasite attached to a swollen area in his stomach.
“Anisakis can infect salmon, herring, cod, mackerel, squids, halibut and red snapper,” Dr. Joana Carmo told CNN. “... Mainly in Japan because of the frequent ingestion of raw fish.”
While a bulk of the anisakiasis cases have come from Japan and Spain, there have been rising cases coming from the U.S. and South America, according to the CDC.
If left untreated, the gastric problems in your stomach can last for several months, leading to a surgery to remove the parasite.
Doing away with raw sushi sounds a little hard, but if you freeze the fish to -4 degrees Fahrenheit for 72 hours, it will kill the parasite. Also, if the sushi chef is properly trained, they can spot the anisakiasis.
So it all comes down either trusting your sushi chef or getting fully cooked sushi. May the odds be ever in your favor.