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This retrospective case study analysed the incidence and symptoms of ciguatera fish poisoning (ciguatera) in Guadeloupe (French West Indies) between 2013 and 2016. Cases attending the emergency departments of the two public hospitals and the reports received by the regional health authority in charge of monitoring (ARS) were compiled. Two hundred and thirty-four cases of poisoning were observed, with a mean annual incidence of 1.47/10,000 (95% CI): 1.29-1.66), i.e 5 times higher than the previously reported incidence (1996-2006). The main species described as being responsible for poisoning were fish from the Carangidae family (n = 47) (jack), followed by fish from the Lutjanidae family (n = 27) (snapper), Serranidae family (n = 15) (grouper), Sphyraenidae family (n = 12) (barracuda), and Mullidae family (n = 12) (goatfish). One case of lionfish ciguatera was observed. 93.9% of patients experienced gastrointestinal symptoms, 76.0% presented neurological signs (mainly paresthesia, dysesthesia and pruritus) and 40.3% presented cardiovascular symptoms (bradycardia and/or hypotension). A high frequency (61.4%) of hypothermia (body temperature <36.5 °C) was observed. This study reports for the first time the relatively high frequency of cardiac symptoms and low body temperature. The monitoring of ciguatera poisoning throughout the Caribbean region must be improved, notably after reef disturbance due to Irma and Maria major cyclones.

Ciguatera fish poisoning (ciguatera), a common poisoning caused by fish ingestion, is reviewed in the Western Atlantic and the Caribbean waters. It is endemic from Florida coasts (northern limit) to Martinique Island (southern limit), with outbreaks occurring from time to time. In the Caribbean, ciguatera causes a polymorphic syndrome with gastrointestinal, cardiovascular, and neurological signs and symptoms. Neurological and muscular dysfunctions can be treated by intravenous injection of D-mannitol. The lipid-soluble toxins involved are ciguatoxins that are likely produced by the dinoflagellate Gambierdiscus toxicus. G. toxicus strains are endemic in the Caribbean Sea and in theWestern Atlantic. Although it is likely that blooms of G. toxicus are ingested by herbivorous fishes, they are not implicated in ciguatera in the Caribbean. Rather, large carnivores (barracudas, jacks, snappers, groupers), consumers of smaller benthic fish, are often involved in ciguatera. Fish toxicity depends on fishing area and depth, fish size and tissues, and climatic disturbances. Ciguatoxins have been isolated and purified from Caribbean fish species. The structure of two epimers, C-CTX-1 and C-CTX-2 from horse-eye jack, comprise 14 trans-fused ether-linked rings and a hemiketal in terminal ring. Caribbean ciguatoxins are mainly detected in the laboratory by chicken, mouse, mosquito, or cell bioassays, and by analytical HPLC/tandem mass spectrometry down to parts per billion (ppb). A ciguatera management plan that integrates epidemiology, treatment, and a simple method of detection is required to ensure the protection of consumers.

Ciguatera poisoning was studied in the chicken where it gave rise to internal hypersalivation, acute motor ataxia, low rectal temperature and arrested growth. LD50 figures indicated that the chicken is two to five time at least more sensitive to ciguatoxin than the mouse. So the chick is very convenient for laboratory studies in ciguatera research.

A total of 259 specimens of 32 potentially ciguatoxic fish species from St-Barthelemy, Leeward Islands in the Caribbean sea were checked for ciguatoxin. It was found that flesh and viscera from 229 specimens belonging to 27 species (essentially bottom-dwelling species) were ciguatoxic. No correlation between toxicity and species size or diet was demonstrated since five of the six highly ciguatoxic species Seriola dumerili, Caranx latus, Caranx bartholomaei, Caranx ruber and Scomberomorus cavalla are large roving predators feeding mainly on fishes while the last species (Alphestes afer) is a benthic resident of very small size (less than 300 g) which feeds mainly on invertebrates. Small (less than 1 kg) benthic carnivorous fishes (invertebrate feeders), such as Bodianus rufus, Priacanthus arenatus, Mulloidichtys martinicus, Malacanthus plumieri and Halichoeres radiatus, are significantly ciguatoxic and play an important role in the transmission of ciguatoxin in the food chain. Other ciguatoxic species included large carnivorous fishes and the small surgeon Acanthurus bahianus. Furthermore, additional results suggest that most of edible benthic species from Saint-Barthelemy harbour ciguatoxin as well, though at an extremely low level. The ciguatera food chain in the Caribbean sea is therefore comparable with that described in the Pacific Ocean, except concerning small invertebrate feeders since their role in this chain is demonstrated for the first time.

1. Cigautoxins (CTX) were extracted from flesh and viscera of seven large roving predatory fishes: Caranx bartholomaei, Caranx latus, Seriola dumerili, Alectis crinitus, Scomberomorus cavalla, Sphyraena barracuda and Gymnothorax funebris. 2. Generally each extract consisted of close-related CTX which were separated according to their polarity by Florisil column chromatography into a fast-acting CTX containing group and a slow-acting CTX containing group. 3. The shortest survival time of mice (ts) was low for the former group (less than 10 min) and high for the latter (greater than or equal to 29 min). 4. The level of purity had no influence on the range of ts values. The presence of these two CTX groups in different extracts did not from experimental conditions. 5. Attempts to convert fast-acting CTX to slow-acting CTX and vice-versa were negative. G. funebris and S. barracuda had an especially high content of unstable fast-acting CTX. 6. Purification of the slow-acting CTX was achieved by fast elution chromatography and Sephadex LH20 gel filtration. 7. The ts values of these CTX were identical for five species (40-44 min) but not for S. barracuda (29-32 min). 8. Thus ciguatoxic extracts from Caribbean fish were composed of several close-related CTX.

Ciguatoxin-like substances were extracted from the viscera or the flesh of eight Caribbean fish species, including small invertebrate feeders and large carnivores. The had similar properties, i.e. pharmacological action, solubility, chromatographic behaviour on silicic acid or Sephadex LH 20 column, stability in a weak acid solution and instability in alkaline medium. However, Florisil column and thin-layer chromatography showed different ciguatoxins whose number depended on tissue or species but not on fish trophic level. Less polar ciguatoxins appeared in salted and dried flesh. Thus, fish ciguatoxins are believed to be closely related substances, possibly changing in structure according to particular experimental conditions.