Friday, February 1, 2013


Gambierdiscus toxicus
Ciguatera is an illness caused by a number of similar toxins such as ciguatoxin.  It is produced by dinoflagellates, mainly Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are eaten by herbivorous fish who in turn are eaten by larger carnivorous fish. Slowly the toxins move up the food chain and bioaccumulate. They accumulate in commonly consumed coral reef fish (e.g., barracuda, grouper, snapper, amberjack, and surgeonfish) but also in invertebrates. It is not difficult to picture that this can cause a problem. Furthermore, the toxin is odourless, tasteless and very heat-resistant to the point that it can't be destroyed by conventional cooking.

Symptoms of ciguatera poisoning mostly include gastrointestinal and neurological effects and they can last from weeks to years, and in extreme cases as long as 20 years, often leading to long-term disability. More and more ciguatera fish poisoning occurs outside “high-risk” areas which are usually tropical regions close to coral reefs where the consumption of coral reef fish is more common. However, consumer behavior has changed and ciguatera poisoning becomes more a concern for health agencies who need to extend their surveillance programs.  Fish related to the poisoning need to be traced back, we also need more information on harvest areas and in which species the toxins are prevalent. Only that can lead to prevention through education of the consumers. However, that might be limited by seafood mislabeling. 

In an editorial comment on a recent US CDC (Centers for Disease Control and Prevention) report it is explicitly stated that market substitution of seafood might hamper disease control and prevention programs. However, they also provide insight on how far DNA Barcoding already has made its way into the US regulatory environment:

Methods for fish species identification using DNA barcoding have been validated and are being implemented in several U.S. state and federal laboratories, as well as academic institutions. These methods have been applied to multiple ciguatera food poisoning cases. Ongoing collaborative efforts with federal, state, and local agencies tasked with consumer protection and food safety might be useful in controlling ciguatera food poisoning and mislabeling of fish.

It is rewarding to know that our research of the last years can make such a difference.

h/t Brad Zlotnick

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