Detection of Tetrodotoxin Shellfish Poisoning (TSP) Toxins and Causative Factors in Bivalve Molluscs from the UK.

Andrew Turner,Steve Milligan,Alison O’Neill,Lewis Coates,Myriam Algoet,Lesley Bickerstaff,Dermot Faulkner,Hugh Mceneny,Craig Baker-Austin,Monika Dhanji-Rapkova,David N Lees

doi:10.3390/md15090277

Abstract

Tetrodotoxins (TTXs) are traditionally associated with the occurrence of tropical Pufferfish Poisoning. In recent years, however, TTXs have been identified in European bivalve mollusc shellfish, resulting in the need to assess prevalence and risk to shellfish consumers. Following the previous identification of TTXs in shellfish from southern England, this study was designed to assess the wider prevalence of TTXs in shellfish from around the coast of the UK. Samples were collected between 2014 and 2016 and subjected to analysis using HILIC-MS/MS. Results showed the continued presence of toxins in shellfish harvested along the coast of southern England, with the maximum concentration of total TTXs reaching 253 µg/kg. TTX accumulation was detected in Pacific oysters (Crassostrea gigas), native oysters (Ostrea edulis) common mussels (Mytilus edulis) and hard clams (Mercenaria mercenaria), but not found in cockles (Cerastoderma edule), razors (Ensis species) or scallops (Pecten maximus). Whilst the highest concentrations were quantified in samples harvested during the warmer summer months, TTXs were still evident during the winter. An assessment of the potential causative factors did not reveal any links with the phytoplankton species Prorocentrum cordatum, instead highlighting a greater level of risk in areas of shallow, estuarine waters with temperatures above 15 °C.

Highlights

Tetrodotoxin (TTX) is a highly potent neurotoxin [1] which is known to accumulate in a wide range of marine and amphibious species
Of the 477 samples collected from shellfish in classified production areas from England between 2014 and 2016 and tested in this study, TTXs were detected in 55 samples (12%) at summed TTX concentrations above the limit of reporting (LOR) of 2 μg/kg
The results obtained from this study provide evidence for the presence of Tetrodotoxins in bivalve molluscs sampled as part of the official control biotoxin monitoring programmes of the UK

Summary

Introduction

Tetrodotoxin (TTX) is a highly potent neurotoxin [1] which is known to accumulate in a wide range of marine and amphibious species. TTX is responsible for the highest fatality rate of all marine intoxications, being associated most commonly with accumulation in species of fish from the Tetraodontidae family, such as puffer fish [2]. TTX is a sodium channel blocker binding to receptor site 1 with activity similar to the saxitoxins responsible for Paralytic Shellfish Poisoning (PSP). TTX and a range of TTX analogues together termed Tetrodotoxins (TTXs) (Figure S1) are evidenced to be produced by wide range of bacterial species, including those from the genera of Vibrio, Bacillus, Aeromonas, Alteromonas, and Pseudomonas [5], the mechanisms of production are not yet elucidated.

Objectives

Methods

Results

Conclusion