Tainted fish: some varieties more likely to have toxin

By Deborah Kotz, Globe Staff

On August 6, 2010, a 16-year-old teenage girl and her 47-year-old mother went to a hospital emergency department with diarrhea, light-headedness, and pins and needles sensations around their body after eating barracuda that was purchased at a New York fish market; hours later, four more family members who had eaten the fish arrived at the hospital with the same symptoms.

About a year later, four people got the same illness after eating grouper at a Manhattan restaurant. One was a man who swam two miles a day before his illness and wound up with severe walking difficulties for several months afterward.

The federal Centers for Disease Control has received 28 reports of ciguatera fish poisoning in New Yorkers that occurred from August 2010 to July 2011, according to a report released by the agency on Thursday. Before that, the CDC received only 21 reports of this fish poisoning in New York City over the previous decade.

Ciguatera fish poisoning or CFP results from eating fish that have accumulated certain toxins found in algae. Large, predatory, fish that live in warm waters by coral reefs -- such as grouper and barracuda -- are most likely to have these toxins called ciguatoxins.

What’s most concerning about CFP is that there’s no treatment beyond symptom management. While nausea and vomiting usually resolves after a few days, some people experience neurologic symptoms like loss of sensation in their feet and hands for weeks or even years.

“It’s very unusual for us to see these kinds of outbreaks,” said Nancy Clark, assistant commissioner for environmental disease prevention at the New York City Department of Health. “It’s something we’re keeping our eye on.”

Unfortunately, there’s no way to cheaply test fish for ciguatoxins before they’re sold on the market. Lab tests to confirm the presence of the toxin are expensive and not practical for widespread use, according to the CDC. They’re only used when an outbreak is suspected.

Most fish eaters in Massachusetts don’t need to worry to much about the fish they eat in local restaurants, but one Pittsfield couple developed the illness some years back after eating red snapper in Florida. Those who travel to the Caribbean and Mexico may want to also take certain precautions when ordering fish there.

“Our tip is if you want to avoid any risk at all,” Clark said, “don’t consume fish known to carry the toxin. If you really love to have barracuda, we’d advise you eat only a smaller size fish.” That’s because the smaller fish tend accumulate less of the poison.

The complete list of fish that have been known to carry ciguatoxins include: barracuda, black grouper, blackfin snapper, cubera snapper, dog snapper, greater amberjack, hogfish, horse-eye jack, king mackerel, and yellowfin grouper. The CDC keeps an updated list with photos on its website.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.