Ciguatera: the detection of neurotoxins in carnivorous reef fish from the coast of Cameroon, West Africa

Abstract

This work examined 64 large, carnivorous reef fish from the coastal waters of Cameroon for toxicity commonly associated with an incidence of ciguatera fish poisoning. The samples were also subjected to m-DNA analyses to confirm their taxonomic identification. The analyses showed that a subgroup of fish locally referred to as groupers are actually in the snapper family (Lutjanus spp.). Extracts from 22 barracuda Sphyraena barracuda and 42 snapper Lutjanus spp. samples were prepared and examined for the presence of ciguatera-like toxins. Sodium-channel activation was assessed by a sodiumchannel-specific bioassay using mouse neuroblastoma (N2a) cells. Extracts were also subjected to chemical analysis via liquid chromatography/mass spectrometry (LC/MS) to compare the mass of peaks of interest to the molecular weights of fish toxins previously described. Two barracuda and one snapper tested positive for a sodium-channel activator, i.e. presumptive ciguatoxin, in the N2a assay. LC/MS analyses showed that only these three samples contained high-intensity peaks, with masses of 1 222 amu and 1 279 amu. These results represent the first analytical report indicating the presence of sodium-channel-specific neurotoxins in fish from along the coast of West Africa. Given the importance of such marine carnivores to the nutrition and socio-economy of the coastal populace, education and disease management appear to be warranted.

Keywords: Cameroon; ciguatera; Gambierdiscus, Lutjanus spp.; marine toxin; N2a neuroblastoma; neurotoxin; Sphyraena barracuda

African Journal of Marine Science 2008, 30(3): 533–540