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May 05, 2011

The Perils of Ciguatera

Will your next fresh-caught fish dinner be a toxic time bomb?

amberjack

Unpredictable Outbreaks
The U.S. Food and Drug Administration warned fish ­processors to buy no fish caught within 50 miles of the productive Flower Garden Banks far off the Texas coast following ciguatera outbreaks in 2007. Not a single incidence of ciguatera had been attributed to the waters off Texas in recent memory but then, suddenly, there it was, with many cases of ciguatera from fish caught in the area.

I've fished some large Pacific atolls where the islanders commonly eat all fish from one end of the atoll while shunning them from the other side. For whatever reason, apparently the toxic phytoplankton had bloomed just in one area.

No one is certain why Gambiendiscus does bloom when and where it does, or why it endures in some areas or fades in others. Many factors might be involved, including water temperature and quality. But scientists believe the opportunistic plankton take advantage of increased algae growth on coral reefs that have been disrupted or degraded, whether by natural causes such as hurricanes or by humans from pollution, dredging and the like. Some have pointed out that reef communities growing on oil rigs and platforms might also provide new opportunities for Gambiendiscus.

Eight Days of Living Hell
I alluded previously to a disease that made its victim wish he or she were dead. It's important to understand that not all individuals eating ciguatoxic fish will suffer similarly. Indeed, some might remain completely asymptomatic; others might take a (relatively) mild hit, with symptoms limited mostly to gastrointestinal distress for a day or two. However, many victims are beset with a host of agonizing symptoms that can continue or recur over days, weeks or even years.

While ciguatera episodes generally do start out typical of most food poisonings, the effect of this neurotoxin on the nervous system is most likely to be both acute and chronic, miserable and frightening.

Among the affliction's many symptoms:

• hot and cold reversal
• intense pain in one's teeth and sometimes the feeling that  all of one's teeth are loose
• intense and burning itch
• numbness or tingling in extremities
• sharp, shooting pains in arms and legs, and/or heightened  sensitivity to pain
• pain when urinating
• blurred vision, dizziness
• various abnormal sensations
• malaise, physical weakness, extreme fatigue
• slowing of the heart
• hallucinations

Regarding the last, "Today I am experiencing a new symptom: hallucinations." So wrote a South African victim in a blog after he'd eaten some "great-tasting" barracuda (and also received an initial diagnosis of multiple sclerosis). He describes his visions as "dots that float around the room as if they have some sort of purpose."

Being unable to identify anything hot, since it feels cold to the touch, could even lead to scalding. One Australian marine biologist writes, "I had an enormous amount of difficulty telling if something was hot and had someone else run showers for me for two months."

The array of symptoms often masks the ailment. For example, a Kalamazoo, Michigan, ciguatera victim was ­diagnosed with MS. Five weeks later, after MRI scans, visits to neurosurgeons and four trips to the emergency room, she finally received the right diagnosis: ciguatera, contracted during a visit to the Dominican Republic 10 days before the onset of symptoms.

Just When You Thought It Was Safe
If there's any good news for those who contract the illness, nearly all sufferers live through it. Most recover in days or weeks, though granted, those generally mean some mighty miserable weeks.

But various symptoms often persist and, to make matters worse, certain triggers can induce symptoms with greater severity, even years later. Alcohol appears to be the most likely such trigger - as Pepperell found out over a beer in his favorite Aussie pub.

Another trigger: eating fish - apparently any fish! For example, Waldner cites the case of a University of Puerto Rico marine-science professor who contracted ciguatera from eating a piece of fresh almaco jack. "It took him months to recover," says Waldner, and the man steered clear of fish for a year. Then he had a meal of dolphin (mahi). Big mistake. "Although dolphin is considered to be a 'safe' species," says Waldner, "the meal resulted in full-blown ciguatera poisoning again."

Waldner explains that apparently some ciguatoxin remains in the blood of one who's contracted the disease; after several months, toxin levels in the Puerto Rico prof gradually dropped below a threshold, so he suffered few or no symptoms. But presumably, even a minute amount of the toxin from a source - such as the dolphin - can be enough to cross the threshold. "It's conceivable that older folks who come down with ciguatera may never be able to safely eat fish again," Waldner adds.

But wait - there's more. Ciguatera victims cite a number of other triggers all-too-well documented over many years, including eating nuts, chicken or eggs, drinking caffeine, and exposure to certain chemicals or fumes. Hard exercise, particularly in a hot environment, can bring on an attack. And, to pile on further insult, so can sexual activity.

Treatment on the Horizon
Nearly always, by the time a ciguatera victim gets the proper diagnosis, there's no treatment, and beyond (marginal) success in mitigating symptoms, there's going to be a whole lot of suffering going on.

That said, in recent years, it has seemed that mannitol - a sugar alcohol - given intravenously could help (though no one ever determined exactly why or how). But a check of literature on this shows mannitol to be variously helpful if administered with 48 hours of onset to absolutely worthless, depending upon the study.

The drug Brevenal appears to hold promise, perhaps as the first real treatment for the disease. Scientists recently discovered that this patented polyether compound could treat neurotoxic shellfish poisoning (typically a result of red tides) in humans. That toxin is related to ciguatoxin, so scientists in Australia and North Carolina acted (independently) on a hunch that Brevenal might treat ciguatera as effectively. Early results proved promising. The Brevenal apparently blocks the effect of ciguatoxin on sodium channels in cells, since that's what causes the nervous system to start going haywire. More trials are underway.

Ciguatera is a very scary disease. It's also one of the most common ailments from eating fish and considered a global health concern (that might be getting worse). All that said, your odds of getting it remain very low indeed. But the risk is there, and a little knowledge can go a long way to avoid it, especially for those of us who catch our seafood, and can pick and choose what we keep - keeping only smaller reef fish if we're after real peace of mind. And it's good to ­recognize the symptoms of the disease for what it is, should you or someone you know be suddenly laid low by a mysterious ailment after eating a meal of delicious fresh fish.

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Symptoms: It's All About Location
It seems that where one contracts ciguatera can make a difference in the nature of the ailment. That is, victims in the Caribbean region are more likely to suffer greater acute gastrointestinal distress with a more gradual onset of neurological effects than victims from the far Pacific, where neurological symptoms prevail and might be worse. The reason probably has to do with the composition of the toxin produced by the different species of Gambiendiscus. Of course exceptions abound, and the bottom line remains the same: Wherever you get ciguatera, it pretty much sucks.