Giant clams: New vectors of ciguatera?

Abstract

s / Toxicon 75 (2013) 205–223 206 immediate evaluation by a physician. In these cases, the risk of drowning is great because of pain and muscular malfunction. On our beaches envenomation by Physalia physalis is an emerging phenomenon whose magnitude remains to be evaluated in the coming years, and whose causes are unknown. http://dx.doi.org/10.1016/j.toxicon.2013.08.004 Giant clams: New vectors of ciguatera? M. Roue , P. Cruchet , A. Ung , T. Darius , M. Chinain , D. Laurent a,b Universite de Toulouse (UPS), UMR-152 (Pharma-Dev), Toulouse cedex 9, France b Institut de Recherche pour le Developpement (IRD), UMR-152 (PharmaDev), Papeete, Tahiti, French Polynesia c Institut Louis Malarde, Laboratoire des Microalgues Toxiques, Papeete, Tahiti, French Polynesia Ciguatera Fish Poisoning is a form of ichtyosarcotoxism caused by the consumption of tropical coral reef fishes that have accumulated ciguatoxins, neurotoxins produced by dinoflagellates of the genus Gambierdiscus. Ciguatera is prevalent worldwide in subtropical and tropical regions and is regarded as the most prevalent form of intoxication in French Polynesia. Giant clams, although frequently consumed in the South Pacific, are rarely incriminated in human intoxications. However, they are sometimes involved in strong and atypical Ciguatera incidents, as observed in French Polynesia, New Caledonia and Vanuatu. The symptoms of this particular poisoning include the characteristics of Ciguatera Fish Poisoning (itching, paresthesia and reversal of hot/cold sensations for example) associated with additional symptoms like the burning of the mouth and the throat that appear very quickly and may be sometimes followed by severe paralysis. Giant clams could thus constitute another link in the ciguatera food chain and the name “Ciguatera Shellfish Poisoning” was proposed to designate this newly ecotoxicological phenomenon. In order to decipher the origin of these uncommon human intoxications, giant clams were collected in Raivavae (French Polynesia) and in Lifou (New Caledonia) where Ciguatera Shellfish Poisoning incidents were reported. Here, we present the results relative to the bioguided (via the neuroblastoma cytotoxicity assay) fractionation by lowand high-pressure chromatography of extracts prepared from ciguatera-suspected samples. Concurrently, cyanobacterial mats have been frequently observed near giant clams in the toxic areas of Raivavae and Lifou. Although phylogenetically unrelated to dinoflagellates, cyanobacteria are also suspected to be a potential source of ciguatoxin-like compounds. Indeed, during cyanobacterial blooms, filter-feeding bivalve molluscs such as giant clams are likely to become contaminated, providing a new link for the transfer of cyanotoxins to upper trophic levels including humans. This possible relationship between the proliferation of toxic marine cyanobacteria, giant clams toxicity and CSP intoxications will be discussed. This study provides a better understanding of the eco-toxicological phenomenon of ciguatera and should contribute to the improvement of seafood poisoning risk assessment and management programs in ciguatera-prone coral reef regions worldwide. http://dx.doi.org/10.1016/j.toxicon.2013.08.005 Coupling a Torpedo microplate-receptor binding assay with mass spectrometry to detect freshwater and marine toxins acting on nicotinic acetylcholine receptor