Ciguatera poisonings: A global review of occurrences and trends

Ciguatera is an important form of human poisoning caused by the consumption of seafood. The disease is characterised by gastrointestinal, neurological and cardiovascular disturbances. In cases of severe toxicity, paralysis, coma and death may occur. There is no immunity, and the toxins are cumulative. Symptoms may persist for months or years, or recur periodically. The epidemiology of ciguatera is complex and of central importance to the management and future use of marine resources. Ciguatera is an important medical entity in tropical and subtropical Pacific and Indian Ocean regions, and in the tropical Caribbean. As reef fish are increasingly exported to other areas, it has become a world health problem. The disease is under-reported and often misdiagnosed. Lipid-soluble, polyether toxins known as ciguatoxins accumulated in the muscles of certain subtropical and tropical marine finfish cause ciguatera. Ciguatoxins arise from biotransformation in the fish of less polar ciguatoxins (gambiertoxins) produced by Gambierdiscus toxicus, a marine dinoflagellate that lives on macroalgae, usually attached to dead coral. The toxins and their metabolites are concentrated in the food chain when carnivorous fish prey on smaller herbivorous fish. Humans are exposed at the end of the food chain. More than 400 species of fish can be vectors of ciguatoxins, but generally only a relatively small number of species are regularly incriminated in ciguatera. Ciguateric fish look, taste and smell normal, and detection of toxins in fish remains a problem. More than 20 precursor gambiertoxins and ciguatoxins have been identified in G. toxicus and in herbivorous and carnivorous fish. The toxins become more polar as they undergo oxidative metabolism and pass up the food chain. The main Pacific ciguatoxin (P-CTX-1) causes ciguatera at levels=0.1 microg/kg in the flesh of carnivorous fish. The main Caribbean ciguatoxin (C-CTX-1) is less polar and 10-fold less toxic than P-CTX-1. Ciguatoxins activate sodium ion (Na ) channels, causing cell membrane excitability and instability. Worldwide coral bleaching is now well documented, and there is a strong association between global warming and the bleaching and death of coral. This, together with natural environmental factors such as earthquakes and hurricanes, and man-made factors such as tourism, dock construction, sewage and eutrophication, may create more favourable environments for G. toxicus. While low levels of G. toxicus are found throughout tropical and subtropical waters, the presence of bloom numbers is unpredictable and patchy. Only certain genetic strains produce ciguatoxins, and environmental triggers for increasing toxin production are unknown.

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world. It causes substantial human health, social, and economic impacts. The illness produces a complex array of gastrointestinal, neurological and neuropsychological, and cardiovascular symptoms, which may last days, weeks, or months. This paper is a general review of CFP including the human health effects of exposure to ciguatoxins (CTXs), diagnosis, human pathophysiology of CFP, treatment, detection of CTXs in fish, epidemiology of the illness, global dimensions, prevention, future directions, and recommendations for clinicians and patients. It updates and expands upon the previous review of CFP published by Friedman et al. (2008) and addresses new insights and relevant emerging global themes such as climate and environmental change, international market issues, and socioeconomic impacts of CFP. It also provides a proposed universal case definition for CFP designed to account for the variability in symptom presentation across different geographic regions. Information that is important but unchanged since the previous review has been reiterated. This article is intended for a broad audience, including resource and fishery managers, commercial and recreational fishers, public health officials, medical professionals, and other interested parties.