SEQUIM — A shellfish toxin that sickened three King County residents who ate mussels they harvested at Sequim Bay State Park baffles state health officials who call it a mystery that can only be solved through testing and analysis of water quality in all parts of Puget Sound.
The state Department of Health closed Sequim Bay to shellfish harvesting last week after it was confirmed that three people became ill in late June from a marine toxin, diarrheal shellfish poisoning — never seen before in unsafe levels in U.S. shellfish.
No other cases had been reported as of Monday, a state health official said.
Food contaminated with diarrheal shellfish poisoning biotoxin may not look or smell spoiled.
Diarrheal shellfish poisoning can cause diarrhea, nausea, vomiting, abdominal cramps and chills.
The ban on both recreational and commercial harvesting of all types of shellfish in Sequim Bay began Aug. 8, and a recall for all commercially sold shellfish from the area during the past two weeks also went into effect.
DSP comes from a toxin produced by a type of plankton long-known to live in high concentrations in Sequim Bay and around Puget Sound, said Frank Cox, marine biotoxin coordinator with the state Department of Health.
“It’s well documented that it’s here,” Cox said.
“The question now is why were we not having cases of the illness and nobody was reporting cases of it. Apparently, it’s been found in plankton for some time.”
Cox said he has known of the plankton in Sequim Bay that carry the toxin for at least 10 years.
Asked why it took from mid-July when the illnesses were first reported in King County to last week to confirm the toxin sickened three, Cox said:
“It takes time to get that information collected and reported and up the channels to people like us.”
The toxin is prevalent in parts of Europe and was recently found in British Columbia waters.
The Canadian Food Inspection Agency on Aug. 6 released a warning that told the public not to consume mussels because they may contain the diarrheal shellfish poisoning biotoxin.
The affected mussels were harvested by Island Sea Farms Inc. of Salt Spring Island, B.C.
Consumers who have purchased raw mussels from retailers from July 9 to Aug. 6 were advised to check with their retailer to determine whether they have the affected product.
The product mainly was distributed in British Columbia, Alberta, Saskatchewan, Manitoba and Ontario. However, it might have been distributed in other provinces and states.
Cox said all such products in Washington state have been recalled and experts do not believe the Sequim Bay toxin found is related to the Canadian case.
While Cox said he has only known of the plankton carrying the toxin since the late 1990s, others have been aware of its existence “for decades.”
“It’s here and apparently here in large numbers of cell counts,” Cox said. “So why is it not producing toxins and causing cases of illness?”
Cox said state Health is not set up to test water for DSP, so samples have to be sent to the U.S. Food and Drug Administration lab in Dauphin, Ala.
State Health and Jamestown S’Klallam tribal researchers have been studying the plankton and are working closely with the federal National Oceanic and Atmospheric Administration, he said.
“We’ve known it was here for a long time and not making people sick, so it didn’t get the attention, say, that PSP gets here,” Cox said.
Paralytic shellfish poisoning, also known as PSP or red tide, which has prompted closure of other beaches on the North Olympic Peninsula, is life-threatening.
DSP is not, Cox said.
Once plankton blooms die back, Cox said, then shellfish can be examined to see if DSP toxin is cleared from their systems.
Unlike bacterial contamination, the PSP and DSP is not killed by cooking or freezing.
High levels of PSP prompted the closure in late June of beaches directly on the Strait of Juan de Fuca from Discovery Bay west to Neah Bay to all recreational harvesting of all species of shellfish.
The closure applied only to sport harvesting, not to commercially harvested shellfish, which are sampled separately, health officials have said.
Dungeness Bay is the only beach between Discovery Bay and Neah Bay that remains open to recreational shellfish harvesting.
The June closure excluded Sequim Bay, which was closed at that time only to harvesting of butter clams, Dungeness Bay.
Butter clams hold on to the toxin for a longer period of time than other shellfish.
Discovery Bay and Kilisut Harbor, including Mystery Bay, are closed to butter clam harvesting only.
All ocean beaches are in a seasonal closure now.
All species means clams including geoduck, oysters, mussels and other invertebrates such as the moon snail.
Crab meat is not known to contain the PSP toxin, but crab guts can contain unsafe levels and must be discarded.
All areas are closed for the sport harvest of scallops.
The closures do not apply to shrimp.
For more information, phone the Marine Biotoxin Hotline at 800-562-5632 or visit the state website at http://tinyurl.com/4xmftw7.
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Sequim-Dungeness Valley Editor Jeff Chew can be reached at 360-681-2391 or at jeff.chew@peninsuladailynews.com.