Tectus niloticus (Tegulidae, Gastropod) as a Novel Vector of Ciguatera Poisoning: Detection of Pacific Ciguatoxins in Toxic Samples from Nuku Hiva Island (French Polynesia)

Abstract

Ciguatera fish poisoning (CFP) is a foodborne disease caused by the consumption of seafood (fish and marine invertebrates) contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genus <i>Gambierdiscus</i>. The report of a CFP-like mass-poisoning outbreak following the consumption of <i>Tectus niloticus</i> (Tegulidae, Gastropod) from Anaho Bay on Nuku Hiva Island (Marquesas archipelago, French Polynesia) prompted field investigations to assess the presence of CTXs in <i>T. niloticus</i>. Samples were collected from Anaho Bay, 1, 6 and 28 months after this poisoning outbreak, as well as in Taiohae and Taipivai bays. Toxicity analysis using the neuroblastoma cell-based assay (CBA-N2a) detected the presence of CTXs only in Anaho Bay <i>T. niloticus</i> samples. This is consistent with qPCR results on window screen samples indicating the presence of <i>Gambierdiscus</i> communities dominated by the species <i>G. polynesiensis</i> in Anaho Bay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses revealed that P-CTX-3B was the major congener, followed by P-CTX-3C, P-CTX-4A and P-CTX-4B in toxic samples. Between July 2014 and November 2016, toxin content in <i>T. niloticus</i> progressively decreased, but was consistently above the safety limit recommended for human consumption. This study confirms for the first time <i>T. niloticus</i> as a novel vector of CFP in French Polynesia.