If you are reading this article, chances are you love to eat fish just like I do. Unfortunately there are several things you should be aware of before consuming certain types of fish. I could eat fish on a daily basis, but some of the things that I will show you here should give you pause when deciding whether or not to eat certain types of fish or fish from certain locations. The state of Florida does a very good job of posting warnings on consumption of certain fish species or of fish from specific bodies of water. I think however, that informing the public about what could happen to them or their family members if they disregard these warnings is much more effective. Some of the things that you will learn in this article are down right scary.
The easiest way to describe symptoms from this type of poisoning is that in many ways it can act like nerve gas or insecticide poisoning. It is the most common food poisoning that is not associated with bacterial contamination in the United States. Almost all ciguatera poisonings come from consuming fish caught on semitropical coral reefs or in tropical regions. Most of us associate ciguatera toxin with barracuda. We should also associate it with snapper, grouper and the jack family. About 75% of ciguatera poisonings come from these four types of fish.
Ciguatera is naturally occurring and is due to organisms called photosynthetic dinoflagellate algae. The higher up the food chain a fish is, the more of the toxin from these organisms a it accumulates. Also, the size of the fish also has an impact on the amount of toxin. I have never personally seen a case here in north Florida, with the exception of two physicians that ate fish from south Florida prior to being stricken with this disease.
Unfortunately, freezing, freeze-drying, heating and gastric acid have no effect on the toxin's protein structure. It also does not affect the taste, odor or color of the fish. Fortunately, there are test kits that can be purchased to test fish before consuming. One such test is Cigua-Check(R) which is apparently a very easy test for anyone to perform. All that is needed is a small sample of the fish in question's meat.
Symptoms that can be expected from ciguatera poisoning include diarrhea, vomiting and abdominal pain usually within three to six hours after ingestion. Also, a characteristic symptom of ciguatera poisoning is the reversal of hot and cold perception. This means that you would feel cold when it is hot and visa versa. There are more than 100 other commonly reported symptoms to go along with the above, but ciguatera poisoning is rarely fatal and symptoms can last from weeks to months.
There is no cure for ciguatera poisoning, but the symptoms such as nausea, vomiting and diarrhea can be treated. The diagnosis is purely on clinical grounds and no test has yet been developed to detect ciguatera toxin in the human body. Also, there are specific remedies for many of the other symptoms associated with this poisoning.
Scombroid is not specific to, but most often associated with, tuna (albacore, blue fin and yellow fin), mackerel, wahoo, amberjack and marlin, among others too long to list, unless I want to run the risk of boring you to death. When these types of red-meat fish are improperly preserved their muscle is broken down by bacteria to produce several types of histamine. These histamines cause an allergic type of reaction which includes flushing, a sensation of being hot, asthma-type symptoms, headache, dizziness and low blood pressure. The symptoms usually subside within 12 hours without treatment. Sometimes however, medical attention is necessary (and should be sought) if asthmatic or other severe symptoms occur.
Scombroid can easily be prevented with the careful preservation of all red-meat fish. Refer to previous "From Sea to Seasoning" article (page 80 of GAFF Vol. 1, No. 1) on proper ways to keep fish cold.
A few saxitoxin poisonings have occurred in Florida. All seem to have occurred from the consumption of puffer fish. This is a very dangerous poisoning, leading rapidly to paralysis and death. I hope I don't really have to tell you this but, DON'T EAT PUFFER FISH! They don't look appetizing anyway.
Of all of the marine-born toxins and infections, this organism scares me the most and should scare the hell out of you as well. It has been getting more media attention as of late because it is being reported more. In my opinion, it is still under-diagnosed as a whole which leads to high morbidity and mortality rates.
Vibrio vulnificus is found world wide, but here in the United States, there are more cases reported from the Gulf of Mexico. It is naturally occurring and found predominantly in warm coastal waters. You can become infected with this by eating contaminated seafood (mostly raw oysters in my experience) or exposing a cut to the marine environment.
Typically, in a normal, healthy individual, nausea, vomiting and diarrhea are the predominant symptoms and usually self-limited. But, don't bet on it! Sometimes, in healthy people but more commonly in folks with liver disease or a dysfunctional immune system this bacteria crosses into the blood stream. The Center for Disease Control reports 50% mortality when this happens. In lay terms, half of the people with this blood infection die.
As stated in my previous article (page 77 of GAFF Vol. 1, No. 2) on Vibrio vulnificus, this infection is easily treated but unfortunately it is often not recognized early enough. Also, it is easily prevented by not consuming raw shellfish most especially in the warm months of the year when there are higher counts of Vibrio in our coastal waters and by not exposing open wounds to sea water. If they get cut in the water, I always put my patients on antibiotics even if the cut is minor and there is no sign of infection. For the patient, the penalty for being wrong is extremely stiff.
With all of the advisories that have been put out by the Center for Disease Control and our own Florida Game and Fish Commission concerning the consumption of many popular fish species along the Florida coast, I am amazed that they are so often ignored. I think that this is likely due to the fact that no one is explaining to the public what can happen if mercury exceeds an arbitrary "acceptable" level in the human body.
Mercury is a naturally occurring substance that has likely always been around in our marine environment due to erosion and volcanic eruption (although I'm no geologist). Unfortunately, the level of mercury has apparently increased due to industrial wastes such as coal burning plants, insecticides, computer manufacturing, household batteries and seed preservatives to name a few. In fact, probably several things within reach of you right now had mercury involved in it's production at some point.
One of the best-studied places on earth with respect to mercury contamination and poisoning is Minimata Bay, Japan. In the 1930s, mercury-laden industrial waste was being dumped into Minimata Bay. At the time, this was apparently an acceptable practice throughout the world. Over time, the mercury rose through the food chain until the fish in the Bay were contaminated. The villagers who consumed the fish suffered from multiple ailments and sometimes died. Babies born to poisoned mothers had multiple deformities including gnarled limbs, neurological defects and developmental retardation. In fact, methyl mercury, a particularly nasty form of mercury, is now thought to cause a form of cerebral palsy.
In our own local waters, contamination is no where near the level seen in Minimata Bay but we shouldn't look at it through rose-colored glasses either. With the help of a "mercury calculator" that can be found at http://www.gotmercury.org, I found that my consumption of 16 ounces of red snapper in a week's time gives me 390% more mercury in my diet than the acceptable Environmental Protection Agency limit. The level for grouper is not much different. I found this to be shocking, if not a bit depressing to say the least. I hope you will to.
We really don't hear much about mercury poisoning in the greater media. I think that this is likely due to the fact that most of us including the medical field are ignorant concerning what is an acceptable level of mercury in the human body. I suspect that even at levels considered acceptable we become prone to many neurological diseases not yet recognized to be caused by mercury.
Just when you thought fish was healthy, huh? Choose your poison: cholesterol-filled pork or mercury-laden fish. I'm not saying that I am not going to eat fish from here on out but, I am going to be cautious about the amount that I eat. I will also severely limit the amount of fish that my children consume as well. I will keep you posted on any new developments that I come across. In the meantime we should collectively put our feet at the throat of our law makers to clean up this mess. How about starting with the Everglades?