The Freaky Fish-Borne Illness You've Never Heard Of

If you’re a seafood lover, you should be aware of ciguatera. (Photo: Corbis/Mascarucci)

You know you run the risk of contracting foodborne illness if you eat raw seafood, but there’s a little-known toxin that can show up in some cooked fish — and new research has found it’s more prevalent than scientists previously thought. 

A new study published in the American Society of Tropical Medicine and Hygiene found that poisoning from ciguatera, a toxin that can make you sick when you eat certain types of fish, is 28 times more common than previous data suggests. The most recent estimate from the state of Florida found that one out of every 500,000 residents becomes sick from ciguatera poisoning each year, but the Centers for Disease Control and Prevention estimates that only 2 to 10 percent of ciguatera cases are actually reported in the U.S. 

Ciguatera is found in algae that grows in warm water and it’s eaten by some plant-eating fish, as well as the carnivorous fish that eat them. Barracuda is the most likely to carry ciguatera, says Felicia Wu, PhD, a professor in the Department of Food Science and Human Nutrition at Michigan State University,but it also can show up in more common fish we eat like grouper, snapper, mackerel, and mahimahi. 

For the study, scientists analyzed nearly 300 reports in Florida from 2000 to 2011 and conducted an email survey of 5,352 fishermen to estimate how often ciguatera poisoning occurs and where it’s located. While they discovered that ciguatera poisoning happens the most in people who fish near Miami, the Florida Keys, and the Bahamas, if you eat food from those regions, you run the risk of contracting it.

Ciguatera poisoning has even occurred in major metropolitan areas: The CDC issued a report in 2013 about a series of outbreaks that affected 28 people in New York City.

Related: 5 Hidden Facts the Food Industry Doesn’t Want You to Know

With many restaurants and seafood markets importing fish from around the world, the odds of coming across ciguatera-infected fish may be going up. “The global market of fish sales and consumption makes it possible that exposure to the toxin has increased over the past decade,” Benjamin Chapman, PhD, an assistant professor and food safety extension specialist at North Carolina State University, tells Yahoo Health.

“Ciguatera is the most common marine food poisoning,” study author Elizabeth Radke, PhD, who conducted the study while at the University of Florida’s Emerging Pathogens Institute, tells Yahoo Health. She says it’s a “significant health concern” in the Caribbean and South Pacific, but adds that you’re more likely to contract salmonella or E. coli from fish in the U.S. than you are to contract ciguatera. 

But here’s the scary part: Unlike salmonella or E. coli, ciguatera isn’t killed off by cooking the fish. Freezing won’t kill it either, says Radke, and there’s no way to detect ciguatera in fish by looking at it.

Symptoms include nausea, vomiting, and neurologic symptoms like tingling fingers or toes. According to the CDC, people who experience ciguatera poisoning also may find that cold things feel hot, and hot things feel cold, and the symptoms can last for years. And, while people can be treated for their symptoms, ciguatera has no cure.

Related: 5 Types Of Fish You Should Avoid Eating

While experts say it’s a good idea to take a pass on eating barracuda (which you probably do anyway), they also say you’re probably fine to eat the other types of fish that can carry ciguatera since the risk that they contain the toxin is low. However, if you experience symptoms of ciguatera poisoning, call your doctor immediately. 

Radke says there is some evidence that ciguatera is becoming more prevalent, and experts are monitoring the situation. “If we start to see cases moving further north, it will be a warning for the rest of the world,” she says.

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