Deep-Water Fish Are Potential Vectors of Ciguatera Poisoning in the Gambier Islands, French Polynesia

Abstract

Ciguatera poisoning (CP) cases linked to the consumption of deep-water fish occurred in 2003 in the Gambier Islands (French Polynesia). In 2004, on the request of two local fishermen, the presence of ciguatoxins (CTXs) was examined in part of their fish catches, i.e., 22 specimens representing five deep-water fish species. Using the radioactive receptor binding assay (rRBA) and mouse bioassay (MBA), significant CTX levels were detected in seven deep-water specimens in Lutjanidae, Serranidae, and Bramidae families. Following additional purification steps on the remaining liposoluble fractions for 13 of these samples (kept at −20 °C), these latter were reanalyzed in 2018 with improved protocols of the neuroblastoma cell-based assay (CBA-N2a) and liquid chromatography tandem mass spectrometry (LC–MS/MS). Using the CBA-N2a, the highest CTX-like content found in a specimen of Eumegistus illustris (Bramidae) was 2.94 ± 0.27 µg CTX1B eq. kg−1. Its toxin profile consisted of 52-epi-54-deoxyCTX1B, CTX1B, and 54-deoxyCTX1B, as assessed by LC–MS/MS. This is the first study demonstrating that deep-water fish are potential ciguatera vectors and highlighting the importance of a systematic monitoring of CTXs in all exploited fish species, especially in ciguatera hotspots, including deep-water fish, which constitute a significant portion of the commercial deep-sea fisheries in many Asian–Pacific countries.

Comparative Study on the Performance of Three Detection Methods for the Quantification of Pacific Ciguatoxins in French Polynesian Strains of Gambierdiscus polynesiensis

“…Conversely, LC-MS/MS proved to be more sensitive than CBA-N2a and rRBA for the detection of PbTxs in the dinoflagellate Karenia brevis [142]. Our results are also in agreement with previous studies showing that LC-MS/MS and/or CBA-N2a were more sensitive than rRBA or fRBA for the detection of CTXs in fish [87,89,127,136,143].…”

“…Similar observations were reported for the detection of P-CTXs in fish from Rapa Island [89]. However, a recent study showed contradictory results, with CBA-N2a giving higher P-CTX equivalents than rRBA in three deep-water fish specimens, while no significant difference was observed between rRBA and CBA-N2a estimates for one specimen [127]. The CBA-N2a also showed a significant correlation with two immunosensing tools for the detection of P-CTXs in fish [112].…”

“…The effective concentration at 50% (EC 50 , defined as the concentration of competitor at which the binding of the fluorescently labelled PbTx-2 is reduced by half) obtained under the two incubation conditions did not show any significant difference between the two tested temperatures and incubation durations. In most RBA-based studies, the binding reaction usually occurs at a temperature of 4 • C from 60 to 120 min for the detection of both VGSC activators, i.e., CTXs and PbTxs [17,81,[83][84][85]87,89,[117][118][119][120][121][122][123][124][125][126][127], and VGSC inhibitors, i.e., saxitoxins [128][129][130][131][132][133], but also gambierol and gambieric acid-A [54], and brevenal [134,135]. Our findings indicated that an incubation at 37 • C for 30 min showed the same efficacy in the detection and quantification of CTXs in G. polynesiensis, so this protocol was further applied in the following experiments.…”

The Occurrence, Distribution, and Toxicity of High-Risk Ciguatera Fish Species (Grouper and Snapper) in Kiritimati Island and Marakei Island of the Republic of Kiribati

“…Fish are an essential nutritional and gastronomic source for the people in the Republic of Kiribati and play a vital role in subsistence and commerce. Grouper and snapper are high in nutritional and commercial value but are prohibited or restricted for sale and consumption in some areas due to their CTX accumulation capacity [ 8 ]. This study investigated the occurrence, distribution, and toxicity of high-risk ciguatera fish species (17 species groupers and snappers) from Marakei Island and Kiritimati Island of the Republic of Kiribati.…”

“…Currently, more than 400 fish species are identified as ciguatoxic (e.g., moray eels, groupers, and snappers), and different accumulation capacities for CTXs were found among different species [ 6 , 7 ]. These toxic fish are usually bottom dwellers, and their toxicity depends mainly on their location [ 8 ].…”