This week we are going to take an in-depth look at the facts and myths surrounding the dreaded ‘barracuda sickness’ – ciguatera poisoning.
The symptoms of ciguatera poisoning in humans are varied and sometimes bizarre. Ciguatoxin can affect the gastrointestinal, neurological and cardiovascular systems. |
Ciguatera (pronounced see-gwa-terra) comes from the Cuban word ‘cigua’, a term used by early Spanish settlers to describe a poisoning they experienced from ingesting a marine snail of the same name.
Ciguatera poisoning is caused by a tiny dinoflagellate or algae called Gambierdiscus toxicus.
This organism occurs naturally on coral reefs and is eaten by small grazing fish. These small fish are subsequently eaten by larger predator fish such as barracudas, groupers, snappers, jacks, moray eels and Spanish mackerel.
As the predator fish get older the concentration of ciguatoxin in their body increases and consumption by humans can be toxic. We have all heard at least one method of determining if a fish has ciguatoxin in its body.
One of the most common methods is to put a piece of the meat on an anthill and see if the ants will eat it. Another one suggests that a silver spoon will tarnish if placed in a cooking pot with ciguatoxic fish. Still another claims that putting grated coconut in boiling water with the fish will turn the coconut green.
Although many fishermen will disagree, these methods are not reliable and should not be counted on to accurately determine if a fish is safe to eat.
Recently a new product has become available called Cigua-Check. This quick, easy test can be found in sporting goods stores and pharmacies, and provides fishermen with a very accurate way to test their catch.
The symptoms of ciguatera poisoning in humans are varied and sometimes bizarre. Ciguatoxin can affect the gastrointestinal, neurological and cardiovascular systems. Gastrointestinal symptoms are often the first to appear and may include abdominal pain, nausea/vomiting and diarrhea.
Neurological symptoms may include paresthesias (numbness, tingling, and hypersensitivity) of the mouth and throat, painful paresthesias of the extremities, a perception of temperature reversal (cold feels hot and hot feels cold), vertigo, respiratory paralysis and weakness.
Cardiovascular symptoms are uncommon but can include bradycardia (slow heart rate), and hypotension (low blood pressure).
There is no actual cure for ciguatera poisoning, however the illness is self limiting and seldom fatal. Gastrointestinal symptoms will usually subside in two to five days but neurological problems can last for weeks or even months.
Doctors are currently experimenting with a drug called Mannitol to treat ciguatera poisoning. Testing of this drug has shown that it may render the ciguatoxin inert.
It is important to note here that another type of fish poisoning can produce some of the same symptoms as ciguatera. Scromboid poisoning occurs when we ingest fish that has not been properly refrigerated.
Certain types of fish such as mahi mahi (dolphin), tuna, mackerel, and sardines contain a high amount of histidine. As a result of inadequate refrigeration, bacteria convert the histidine to histamine. Ingesting high amounts of histamine will produce many of the same gastrointestinal symptoms as ciguatoxin and may also cause flushing, itching and a throbbing headache.
Scromboid poisoning is treatable with anti-histamines and symptoms usually subside in six to eight hours.
This weekly column is only an introduction to emergency care skills and is designed to increase interest in First-Aid/CPR training. For information on courses please contact the Red Cross, a medical professional, or a local dive shop
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