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February 7th, 2013
Ciguatera Is Hot (But It Could Be Cold)
The news about the cases of ciguatera fish poisoning in New York (NY Times here, MMWR here) reminded me of several unusual things about this form of “harmful algal bloom,” as it is so artfully called by the experts.
Specifically, here are six:
- Symptoms are bizarre. It starts out like a standard case of gastroenteritis — nausea and vomiting — but since ciguatera is a neurotoxin, here’s some of the weird stuff that follows: tingling, numbness, bradycardia, hypotension, muscle cramps, tooth pain, and most famously, “paradoxical dysesthesias”, where cold feels hot and hot feels cold. You ask 100 ID doctors about that last symptom, and 99 will shout, CIGUATERA! Just don’t do it in a crowded room.
- We can’t detect it. Vegetarian fish ingest the ciguatera toxin by eating algae off of seaweed and coral reefs; it’s then further concentrated inside larger fish (barracuda, grouper, snapper, amberjack, and surgeonfish) when these little fishies are eaten. (Don’t blame the big fish — this is what fish do — see image.) The problem is that the neurotoxin is odorless and colorless; fish with ciguatera toxin look and smell totally fine. Various folk remedies in Australia and the Caribbean (where ciguatera is common) have been proposed, including allowing cats to be our taste testers: if a cat eats some of the fish and is fine afterwards, then we will be too. Of course, this means adding a significant amount of time to your meal preparation — bad for work nights — and what if you don’t have a cat? Still, it sure beats the other method, which involves putting the fish in an ant pile, and seeing whether the ants avoid the fish — they apparently can tell. But would you want to eat the fish after it’s been in an ant pile? If you’re really worried, better get one of these gizmos, a Cigua-Check.
- We can’t prevent it. The toxin is heat- and cold-stable; our stomach acidity doesn’t touch it either. This means that fish that are perfectly handled, look and smell fresh, and are then cooked appropriately still can have high levels of ciguatera toxin. Freezing, pickling, and marinating also do nothing. What other kind of food poisoning is so occult and so impervious to best practices? Scary!
- Treatment is “supportive.” Beware any condition for which treatment is “supportive.” What this really means is that modern medicine is a lot like what it was several decades (OK, centuries) ago. We “support” the patient while he/she has nausea, vomiting, tingling, numbness, bradycardia, hypotension, muscle cramps, and tooth pain — and thinks that cold things are hot and hot things cold. No anti-toxin, no antibiotic, sorry. After a certain amount of time with this “support”, the patient slowly gets better, and we can take credit for it.
- The words are unfamiliar. We deal with bugs that have complicated names all the time, so barely bat an eye at Acinetobacter calcoaceticus–baumannii or parvovirus B19 or Diphyllobothrium latum. But the ciguatera toxin arises from marine dinoflagellates of the genus Gambierdiscus, specifically Gambierdiscus toxicus. What the heck is that?
- The ID boards are obsessed with marine toxins. Based on the number of practice board questions that deal with ciguatera, scombroid, and paralytic shellfish poisoning, you’d think that these conditions occur almost as frequently as the common cold. One way you can tell someone who is preparing for their ID boards is that they are suddenly experts on these weird diseases, casually mentioning scombroid as the possible cause of any sort of flushing, or red tide as the cause of diarrhea. Fortunately, this sort of diagnostic bias fades very quickly after taking the exam.
If the above six items are not enough, here’s a fun fact: Nobel Prize-winning novelist Saul Bellow had a severe case of ciguatera poisoning, using it as a key plot line in his final novel Ravelstein. One critic actually credited the ciguatera illness as making Ravelstein his favorite Bellow novel and concluded by making a bold proposal:
It certainly seems to me that a number of American novelists could benefit from a cruise to the Western Caribbean of the sort Bellow took, and as many sumptuous seafood meals (red snapper and barracuda especially recommended) as necessary to raise the level of their art through a slightly less-than-lethal dose of cigua.
I suggest that they bring their cats.