Recently I dropped by the new Fisher Mall in Quezon City. They claim to have a good selection of fresh fish at good prices (and they did). They had huge reef fish like the barracuda, dorado, canary rockfish (canaryo) etc. Curious about these fish I googled them up for cooking methods and found out about ciguatoxins.
Most probably you have not heard about ciguatera poisoning or ciguatoxins. Red tide is more often mentioned in the media .
Ciguatera has been known since the 1500s and is estimated to affect an estimated 50,000 people worldwide annually. ((FAO Ciguatera Fish Poisoning)) Ciguatera fish poisoning (CFP) is a type of food poisoning that is acquired mainly by eating large reef fish such as barracudas, snapper, moray eels, parrot fishes (loro), groupers, triggerfishes and amberjacks that is highly contaminated. These fish are most likely to cause ciguatera poisoning because they eat smaller fish that are also contaminated by ciguatoxins. The CDC also has a list of common fish that is known to carry ciguatoxins.
Ciguatoxins accumulate up the food chain and thus are mostly found in carnivorous, long living fish. Ciguatoxin is odourless, tasteless and very heat-resistant, so ciguatoxin-laden fish cannot be detoxified by conventional cooking. ((Ciguatera – Wikipedia))
Symptoms of ciguatera in humans include gastrointestinal and neurological effects. Gastrointestinal symptoms include nausea, vomiting, and diarrhea, usually followed by neurological symptoms such as headaches, muscle aches, paresthesia, numbness, ataxia, vertigo, and hallucinations. Severe cases of ciguatera can also result in cold allodynia, which is a burning sensation on contact with cold. Neurological symptoms can persist and ciguatera poisoning is occasionally misdiagnosed as multiple sclerosis.
In the Philippines, there were 7 reported cases of CFP from 2001 to 2010. This is quite small when compared to red tide which has recorded 540 outbreaks between 1983 and 2002. Nevertheless, it is good to be cautious. The cases included barracuda, tuna, baby mackerel (lupoy), skipjack tuna (tulingan), spanish mackerel (tanguinge), blue marlin (malasugi), red snapper (maya-maya). About 500 people in total were affected by fish coming from Navotas, Malabon, Maguindanao, Antique, Cebu, Samar, Iloilo. ((Detection of ciguatera fish poisoning in the Philippines))
Detection is hard as one would need laboratory test equipment. There is currently no effective treatment for ciguatera poisoning.