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No Fish Tale

By Joel Dovenbarger, BSN
Vice President, DAN Medical Services

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My dive buddy had quite a scare last year when we went diving in the Caribbean. After four days of diving, she developed numbness in her hands and her face. We thought she had decompression illness (DCI), but we had stayed well within our dive computer limits and we had completed safety stops on all our dives. She then experienced nausea, vomiting and diarrhea. The bottom line: she was treated for ciguatera fish poisoning. Is this a common problem in the Caribbean?

A: Each year DAN handles from a half-dozen to a dozen calls about ciguatera. Generally found between 35 degrees north latitude and 35 degrees south latitude around the globe, ciguatera is not a major complaint by divers, but it can be a very serious illness when someone eats sufficient amounts of toxin-laden fish. The toxin attacks the neurological, gastrointestinal and cardiovascular systems, and it causes a variety of generalized symptoms. When physicians diagnose decompression illness, ciguatera is one of the illnesses that must be ruled out. Many ciguatera symptoms are similar to decompression illness and can make diagnosis difficult.

Divers should remember some general information about ciguatera poisoning.

First, how do you contract ciguatera?

It is reportedly more common in reef fish and larger, older fish that are higher up on the fishes’ food chain. The most notable culprits are red snappers, amberjacks, groupers,  surgeonfish and barracudas. Cooking does not affect the toxin, which is undetectable by odor, color or taste. Although the toxin is not commonly found in the United States, it’s advisable to avoid eating the organ meats of any fish.

One can experience symptoms shortly after ingesting the fish, or they can begin in the hours following. Rarely do they occur after 24 hours. The most common gastrointestinal symptoms are abdominal cramps, nausea, vomiting and diarrhea, symptoms not generally associated with DCI.

Numbness in the face, hands and feet are common neurological signs, but they are not limited to these areas. When facial numbness occurs, we at DAN always ask if the diver has numbness around the mouth (perioral) or in the tongue. This particular sign occurs in ciguatera poisoning, but it is not usually reported in DCI. Another common sign of ciguatera poisoning is temperature reversal in the hands and mouth, where cold feels hot to touch and hot feels cool — also not a sign reported with DCI. Additionally, once ingested, ciguatoxin is reported to makes foods have a metallic taste.

Other generalized symptoms are muscle and joint pain, weakness, fatigue, rash and, less commonly, chills, itching, headache and dizziness.

If enough ciguatoxin is ingested, suffers can experience severe cardiovascular symptoms. The toxin can produce both hypertension and hypotension, with a very slow heart rate. And although it’s rare, ciguatera poisoning can be fatal.

For a full recovery, one must get immediate treatment. When used early to prevent some of the neurological symptoms, Mannitol, an intravenous solution, has been effective. Other medications are used largely to decrease the severity of symptoms such as the pain, itch, burning sensation and rash that can accompany ciguatera poisoning.

The duration of symptoms can vary, although the most severe signs and symptoms usually occur between six and eight days. In some cases, no treatment exists for continuing and intermittent symptoms. Little information exists about the duration of symptoms, but they can last for extended periods. With some people, the symptoms can recur when they eat fish or fish products.

As with DCI, it is best to call DAN if you have questions, and report symptoms as early as possible. Restaurants in the Caribbean carefully screen fish that can have the ciguatera toxin. Still, exercise caution in what you eat and take notice of any unusual symptoms after eating fish.

Ciguatera: Self-Limiting or Chronic?

By Cassandra Misunas

Note: Author and DAN Member Cassandra Misunas contracted ciguatera poisoning in October 1996. In February 1999, she created a website for people with the same malady. Ciguatera Support () offers a listening ear and a group "cyber-setting" for people who wish to connect with others who have experienced the disease. The following is anecdotal information gleaned from her web-based discussion groups.

If you’re a fisherman or a diver, chances are you’ve heard about ciguatera poisoning. And chances are, you believe it is a particularly nasty case of food poisoning that you don’t want to get; not necessarily a life-changing illness but definitely undesirable. Chances are, you could be wrong.

Of the fishermen and divers I have spoken to in Florida, not one of them truly knew the full effects of ciguatera. They knew you could get it from fish, but they had no idea of its impact. In addition, of the many doctor’s offices I polled in my area, not one of them had a full understanding of what ciguatoxin can do to the human body, and none of them realized how enduring the condition can be.

Statistically, only a tiny percentage of people who get ciguatera poisoning suffer from long-term effects, but for some, ciguatera poisoning has been life-changing. Some people have reported symptoms for one, two, three and even more years. Some have reported milder symptoms for much longer.

Sadly, physicians who don’t understand how long the effects of ciguatera poisoning can last brush some sufferers aside. This lack of understanding may come from the diversity of answers from researchers who are working specifically with molecular studies or from researchers who don’t have any real access to adequate follow-up data. Estimates from the CDC and other sources suggest that only 2-10 percent of United States ciguatera cases are reported.

Every researcher I have spoken to, from Florida to Hawaii to Australia, had a different answer to the longevity question: one year; two years; six months. This can send confusing signals to doctors, who then diagnose their patients with conversion reaction or depression. Such a diagnosis may devastate the patient who, in fact, may still feel the effects of a powerful neurotoxin.

Follow-up is critical in helping researchers and doctors understand the broader scope of ciguatera poisoning. But with so many cases of ciguatera poisoning going undiagnosed and with a lack of understanding in the medical community, follow-up is difficult. Ciguatera Support seeks to maintain a connection for follow-up and to provide an outlet for people who have had, or still feel the effects of, ciguatera poisoning.

So, how long can ciguatera last? "Two years to infinity," said one researcher. "We just don’t know enough about it to say for certain." Most people, however, experience symptoms from six to eight days, as noted in the accompanying article.

To understand ciguatera, education is key.