Ciguatera Fish Poisoning
Caught this delicious guy down in the Florida Keys. I was 7 months pregnant at the time!
You’ve probably heard of ciguatera poisoning. You may even know someone who’s had it. Or worse yet, you yourself have gotten very sick from it. And when I say sick…I mean really sick. It’s on the list of things you do not want to experience. The true number of people who experience ciguatera poisoning is unknown but it’s estimated that 10,000 to 50,000 people who live in and travel to tropical areas will get sick each year. I know those numbers may sound high but it’s still considered a relatively rare disease. So what is ciguatera and how can we reduce our risk of getting ill while still enjoying the local signature dish of grouper bites?
What is ciguatera fish poisoning?
Ciguatera fish poisoning, or just ciguatera, is caused by toxins that accumulate in certain kinds of fish found in warm waters around reefs. These toxins are naturally occurring in an organism called a dinoflagellate, which is an algae-like plankton. The ciguatera toxin is passed up the food chain: small fish eat the algae, larger carnivorous fish eat the small fish, and eventually humans eat the larger fish. We can get ciguatera if we’ve eaten a fish that has accumulated enough of the toxins.
There are numerous kinds of ciguatera toxins but they are all clumped up together and just called ciguatera or ciguatera toxin. These variations of the toxin are found in different regions of the world and are thought to contribute to the various symptoms that may be experienced depending on where you are. The toxin cannot be detected in fish as it produces no change in smell, taste, or appearance and it cannot be destroyed by cooking, freezing, dehydrating, etc. So how can we avoid getting sick if we have no way of knowing if ciguatera is present?
Know which species of fish can carry ciguatera
It is estimated that over 400 different species of fish have been known to be contaminated with ciguatera. Some of the more popular ones that can be found on the dinner table are: grouper, barracuda, moray eel, snapper, Spanish mackerel, hogfish, amberjack, and coral trout. These are fish that are typically found in low-lying coastal areas in the tropics and subtropics. The two big fish that the CDC recommends avoiding completely are barracuda and moray eel which can carry the highest risk of ciguatera.
Any reef fish can have ciguatera toxins but keep in mind that not all fish of a species or from a particular area will be contaminated. Outbreaks of ciguatera can happen seasonally or sometimes after a major storm comes through and disrupts the reef system. If you can, talk to local fisherman to get a feel for what’s happening on the reef and if any localized outbreaks have occurred recently. Listening to cruisers nets and following regional Facebook groups or forums can also clue you in to if anyone has been sick lately.
Symptoms
In general, symptoms of ciguatera usually appear a few hours after eating a contaminated fish. There is no bio-marker (or way to test) to see if someone has ciguatera so a diagnosis is usually given based on symptoms and their recent history of fish consumption. Ciguatera is usually associated with gastrointestinal (GI), cardiovascular, and neurological and psychiatric symptoms which can last days to months. Some include the following:
GI
o Nausea/vomiting
o Diarrhea
o Stomach pain
Cardiovascular
o Arrhythmia (irregular heartbeat)
o High or low blood pressure
o Bradycardia (slower than normal heart rate)
Neurologic
o Extremity paresthesia (numbness and tingling in hands and feet)
o Myalgia (muscle pain)
o Arthralgia (joint pain)
o Puritis (itching)
o Headache
o Vertigo
o Fatigue
o Chills/sweating
o Dental pain or a feeling like your teeth are falling out
o Temperature dysesthesia (a reversal of hot/cold temperature perception)
Psychiatric
o Depression
o Memory loss
o Trouble concentrating
o Coma (very rare)
Usually the GI symptoms occur first and resolve within a few days. They can then be followed by some of the neurologic symptoms and these can stick around for weeks and, in some cases, months. Symptoms in some people can even be triggered months and years (yes, years!) after recovery by eating certain foods like coffee, nuts, and alcohol or by doing something strenuous like exercising. The neurologic symptoms can cause pain and discomfort and can really throw your nervous system for a loop. Temperature dysesthesia is a very distinctive symptom of ciguatera that affects most people but not all. It causes your body to reverse your hot and cold sensations. Imagine holding an ice cube and instead of feeling cold, it would feel like you were burning. Or taking a hot shower but all you feel is cold water. Kind of crazy that this toxin can pull an old switcheroo like that.
Ciguatera poisoning is rarely ever fatal but in severe cases it can cause dehydration and cardiac issues if the muscle of the heart is affected. Arrhythmias and changes in heart rate and blood pressure should be closely monitored, especially in people with pre-existing heart problems. The highest concentration of toxins can be found in fish organs like the liver and intestines, fish heads, and in fish eggs (called roe). Eating those organs has been associated with more severe cases so avoiding them all together is your best bet.
There may also be regional differences in how symptoms appear and which ones predominate. This is because of those variations of the toxin that exist depending on where you are in the world. For example, in the Caribbean, GI symptoms may predominate first followed by the neurologic symptoms while in the Pacific the neurologic symptoms may appear first and be more severe. This is not to say that you will or won’t experience certain symptoms depending on where you are because you could have any and all of them no matter your location.
Treatment
So what should you do if you suspect ciguatera poisoning? First and foremost, you should seek medical attention. Local clinics in areas where ciguatera is present will know whether you need more advanced medical care or if this is something that will take its course and you can monitor on your own. Dehydration is a big concern and IV fluids may be needed. Ciguatera poisoning is one of the few illnesses that have reporting requirements to local health departments which your medical provider should take care of. This is to help keep track of outbreaks and identify areas that may be carrying the toxin so fishing habits can be altered. Unfortunately, there are no well-established treatments for ciguatera poisoning itself and all treatment is geared towards alleviating symptoms and preventing more serious complications like dehydration. An intravenous drug called mannitol has been given in some cases to people admitted to the hospital quickly (within 48 hours of symptom onset) but the studies are not conclusive on whether it is all that beneficial or not.
How can you avoid ciguatera poisoning?
Fish are one of the healthiest foods on earth. They are a low-fat source of protein and provide many essential vitamins and minerals like vitamin D, calcium, zinc, iron, and magnesium. They are also rich in omega-3 fatty acids which are very important in maintaining a healthy heart and brain. You should absolutely include fish in your diet if you can or choose to do so, so don’t let the fear of ciguatera turn you away. As with anything, you can mitigate your risk by knowing what you are eating and where it was sourced from. Sustainable fishing practices prevent harvesting fish of questionable size and from known reefs that carry ciguatera. Avoid eating the two big no-no fish – barracuda and moray eels and stay away from those internal organs and fish heads. Get local knowledge before eating any fish and never eat a fish you can’t identify. Finally, make a plan on which fish, if any, you are going to eat. Will you stay away from all reef fish or just the large ones? When catching reef fish on your own try to avoid eating any fish over 6 lbs. (or 3lbs. if you want to be very conservative) or eating smaller portions of several different fish as opposed to eating a larger serving of just one. Stick to those middle-of-the-pack sized fish and boost your ego by telling “fish tales”. You know what I’m talking about - the story of the size of the fish caught is always more than the actual fish!
For more information you can check out the CDC or IAMAT (International Association for Medical Assistance to Travellers)
Anyone have any first-hand experience with ciguatera poisoning and want to share your story? Leave a short little blurb in the comments. Keep in mind the goal is to educate and raise awareness…knowledge is power.