Diarrhetic Shellfish Poison (DSP)
Microscopic and SEM images of Dinophysis
Dinophysis sp.
In Europe, the consumption of shellfish that have filtered cells of the dinoflagellate genus Dinophysis have led to cases of intestinal upset. Two varieties appear responsible for DSP: Dinophysis acuta and D. acuminata. Because of these symptoms, this syndrome has been designated as Diarrhetic Shellfish Poisoning or DSP. DSP is a significant problem in northern Spain, Ireland, and the Mediterranean/Adriatic Sea. The toxin has been detected in shellfish in Eastern Canada. While no cases of DSP have ever been reported along the West coast of the U.S., the organisms that cause this poisoning are commonly found in British Columbia and Puget Sound in Washington State. Very recently (in 2003), the toxins have been detected in shellfish from British Columbia and are more than likely to be found wherever the organisms are present.
The toxin in DSP appears to be okadaic acid and some related compounds, the dinophysistoxins. The toxins are fat soluble, have high molecular weights, and belong to a class of compounds called polycyclic ethers. Interestingly, these compounds (see chemical structures below) are somewhat similar in chemical structure to the rather exotic marine toxins that are associated with Ciguatera Fish Poisoning or Tropical Fish Poisoning in that the repeating polyether moieties are present in these molecules.
While at first glance, diarrhea would appear to be a relatively minor ailment compared to symptoms of PSP and domoic acid; the DSP toxins have been reported to be tumor promoting agents. Due to the relatively minor and generic symptoms associated with DSP, it is difficult to diagnose whether outbreaks of this particular poisoning have occurred in the U.S....
