A well-traveled shellfish bug that has sickened thousands from Europe to Japan and South America over the past half century has finally found its way into Washington state’s prized mussel and clambeds.

The Washington Department of Health this week closed Sequim Bay, near the entrance to Puget Sound, to shellfish harvests after three people fell ill with Diarrhetic Shellfish Poisoning (DSP.) 

The same biotoxin had appeared earlier this month in mussels from two shellfish farms in British Columbia, sickening about 50 people. Canadian authorities warned consumers not to eat mussels sold by Island Sea Farms Inc. in late July.

DSP is an intestinal illness caused by a naturally occurring biotoxin that can be carried by certain marine dinoflagellates. Dinoflagellates are microscopic marine organisms that are an important part of the food supply for shellfish around the world.

Dinoflagellates also carry the far more dangerous Paralytic Shellfish Poisoning (PSP), which includes a highly toxic neurotoxin for which there is no cure. DSP, however, causes diarrhea and other symptoms that are not life-threatening and rarely require hospitalization.

DSP outbreaks had been reported in the Netherlands in the 1960s, followed by outbreaks in Japan, France, Scandanavia and South America.  Like other shellfish-related illnesses, DSP outbreaks occur in the summer months, when tidal shellfish beds are exposed to warming air temperatures.

But Northwest waters had been spared – until the last few weeks.

The Canadian Food Inspection Agency issued warnings for mussels sold across much of Canada with several brand names, including Saltspring Island, Albion Fisheries and Pacific Rim Shellfish and B&C Food. To date, the outbreak has been limited to shellfish from the two Island Sea Farms operations.

Washington’s outbreak affects a rural bay just outside Puget Sound. Health officials recalled all shellfish sold from the bay since August 1.  And officials believe that all of the recalled product has been removed from the market.

  • Janet Sklar, CDN, SNS

    Growing-up in Sheepshead Bay (Brooklyn, NY)we learned at a very early age not to eat raw seafood during the summer months. In other words, months that did not have an “r” in them: May, June, July and August. (I never eat any raw fish or shellfish throughout the entire year.)
    I believe that even with modern technology, inspection and detection, anyone who continues this irresponsible eating, is a fool.

  • Fool

    If the shoe fits… I can’t resist raw oysters, any time of the year, but this gives me pause. I always assumed oysters from the Northen BC Islands or off the Canadian East coasts would be safer than oysters from US Waters (esp. Gulf of Mexico – won’t touch them…). I’ve heard about not eating them in the summer, but when I ask reputable chef’s or seafood merchants, I’ve been told this doesn’t apply across the board and the beds they source from are always safe. They get them from different regions at different times of the year. Well, in July (and June) they were all coming from BC. Dang I don’t want to give them up.

  • Donna

    Cooking the shellfish will not prevent you from getting Diarrhetic Shellfish Poisoning (DSP). DSP toxins cannot be broken down by cooking. This warning applies to people who eat raw shellfish as well as people who eath them cooked.
    Hoping everyone stays in good health,