Non-Traditional Vectors for Paralytic Shellfish Poisoning

Abstract

Paralytic shellfish poisoning (PSP), due to saxitoxin and related compounds, typically results from the consumption of filter-feeding molluscan shellfish that concentrate toxins from marine dinoflagellates. In addition to these microalgal sources, saxitoxin and related compounds, referred to in this review as STXs, are also produced in freshwater cyanobacteria and have been associated with calcareous red macroalgae. STXs are transferred and bioaccumulate throughout aquatic food webs, and can be vectored to terrestrial biota, including humans. Fisheries closures and human intoxications due to STXs have been documented in several non-traditional (i.e. non-filter-feeding) vectors. These include, but are not limited to, marine gastropods, both carnivorous and grazing, crustacea, and fish that acquire STXs through toxin transfer. Often due to spatial, temporal, or a species disconnection from the primary source of STXs (bloom forming dinoflagellates), monitoring and management of such non-traditional PSP vectors has been challenging. A brief literature review is provided for filter feeding (traditional) and nonfilter feeding (non-traditional) vectors of STXs with specific reference to human effects. We include several case studies pertaining to management actions to prevent PSP, as well as food poisoning incidents from STX(s) accumulation in non-traditional PSP vectors.

Cyanotoxins in inland lakes of the United States: Occurrence and potential recreational health risks in the EPA National Lakes Assessment 2007

“…Mouse toxicology studies have reported LD 50 's via i.p. injection with saxitoxins ranging from 1 to 10 mg saxitoxin/kg bw (summarized Chorus and Bartram, 1999;Deeds et al, 2008;Botana et al, 2010). Saxitoxin analogue toxicity has been reported to range from equivalent to less than 1% compared to the toxicity of saxitoxin (Wiese et al, 2010).…”

First report of the use of a saxitoxin–protein conjugate to develop a DNA aptamer to a small molecule toxin

“…One of the most harmful marine toxins, saxitoxin (STX) is primarily produced by several dinoflagellates as well as certain cyanobacteria (Deeds et al, 2008). Along with dozens of related congeners, STX makes up a suite of neurotoxins, which is referred to as paralytic shellfish toxins (PSTs) and are responsible for the human syndrome paralytic shellfish poisoning (PSP; Etheridge, 2010).…”

“…Along with dozens of related congeners, STX makes up a suite of neurotoxins, which is referred to as paralytic shellfish toxins (PSTs) and are responsible for the human syndrome paralytic shellfish poisoning (PSP; Etheridge, 2010). Molluscan bivalves represent the major vectors of PSTs to humans given their capacity to filter feed and accumulate high concentrations of the toxins; however, numerous non-traditional vectors such as crabs, lobster, and carnivorous snails have also been identified (Deeds et al, 2008). Despite seasonal toxic algal blooms in certain geographic regions, PSP cases are rare because of the effective biotoxin monitoring programs that have been implemented.…”

Evolutionary Acquisition and Loss of Saxitoxin Biosynthesis in Dinoflagellates: the Second “Core” Gene, sxtG

“…Dinoflagellates are known for the array of toxic compounds they produce, even though fewer than 100 species have been identified as synthesizing compounds toxic to humans (2). One group of toxins, saxitoxin (STX) and its documented 58 analogues, are potent environmental neurotoxins that can cause the severe human illness paralytic shellfish poisoning (PSP) upon consumption of vector species such as mussels, clams, and oysters (3,4). Within the dinoflagellates, STX is synthesized by species of the genera Alexandrium, Gymnodinium, and Pyrodinium (see Orr et al, 2011 [5], and references therein).…”