RED TIDE, SHELLFISH - USA (03) (WA)
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International Society for Infectious Diseases <http://www.isid.org>
Date: 14 Sep 2012
Source: University Place Patch
More Pierce County Beaches Closed Due To Paralytic Shellfish Poison
Areas near Ruston Way, Solo Beach and Saltars Point are among the additional Pierce County beaches closed due to high levels of Paralytic Shellfish Poison.
Press release issued by Tacoma-Pierce County Health Department.
Unusually high levels of Paralytic Shellfish Poison (PSP) toxins were found in Tacoma's Commencement Bay shellfish. Toxin levels have been increasing since last reports in August , and more Pierce County beaches have been closed as a result. Recreational shellfish harvesting closures are in effect for all but a small portion of Pierce County beaches.
PSP toxins are not visible in the water or in shellfish. Eating shellfish contaminated with PSP toxins can be fatal. The toxins cannot be destroyed by cooking or freezing. PSP toxins can only be detected by laboratory testing. Conditions are changing rapidly and there will likely be more areas closed in the very near future. Recreational shellfish harvesters are advised to call the Washington State Department of Health Biotoxin Hotline at 1-800-562-5632 or access the Biotoxin website before harvesting shellfish anywhere in Puget Sound.
Tacoma-Pierce County Health Department has posted signs in impacted areas of the county, including Ruston Way, Dash Point County Park, Brown's Point Park, Owens Beach, Point Defiance boathouse, Narrows Park, Day Island marina, Wollochet Bay boat launch, Fox Island Bridge, Solo Beach, Saltars Point, and Sunrise Beach County Park warning people to not eat shellfish from these areas.
The closure includes clams, oysters, mussels, scallops and other species of mollusks. Crabs and shrimp are not included in the closure.
Commercial beaches are sampled separately and commercial products should be safe to eat.
ProMED-mail from Health map alerts
[Red tide is caused by several toxic algae. Depending upon the toxin, it is also known as paralytic shellfish poisoning (PSP), because it causes shellfish to be toxic for consumption.
_Alexandrium_ spp. is one of many members of this genus. Some members may not be toxic. However, generally, the genus is found in coastal waters high in nitrogen content. These organisms produce a neurotoxin, like many of the organisms capable of causing paralytic shellfish poisoning (PSP). The neurotoxin is considered fatal for humans consuming contaminated shellfish and may be dangerous to humans and animals who swim in waters that are 'blooming' with the organisms.
Ocean spray containing the organisms may also cause illnesses, including rashes and eye irritation in people. Some species of this genus are capable of causing 'red tide' that may be visible for long distances along a coast line.
PSP is a significant problem in several geographic areas, especially on both the east and west coasts of the USA. Produced by several closely related species in the genus _Alexandrium_, PSP toxins are responsible for persistent problems due to their accumulation in filter-feeding shellfish, but they also move through the food chain, affecting zooplankton, fish larvae, adult fish, and even birds and marine mammals.
_Alexandrium_ blooms generally do not involve large-cell accumulations that discolor the water and may instead be invisible below the water surface. Low-density populations can cause severe problems due to the high potency of the toxins produced. Furthermore, _Alexandrium_ spp.
can grow in relatively pristine waters, and it is difficult to argue that anthropogenic nutrient inputs are stimulating the blooms. These characteristics are important when considering mitigation and control strategies.
Often PSP is associated with red tides or algal blooms. Red tide is caused by an organism called _Karenia brevis_, which in high concentration can make the water look red. The organism releases a toxin that paralyzes the respiratory system of fish and other marine life.
Airborne toxins, water spray, and splashes in an outbreak have kept people from beaches while leaving others with irritated eyes and throats. Red tide irritates the skin of people exposed to it and can cause itchy eyes, scratchy throats, and coughs. Harvesting from affected areas for personal consumption is discouraged. Red tide poisoning symptoms include nausea and dizziness and may last for several days.
Previously the organism causing red tide was known as _Gymnodinium breve_, but it has been reclassified in the taxonomy of dinoflagellates. Its new name is _Karenia brevis_, or _K. brevis_.
Karenia was chosen in honor of Dr Karen Steidinger, a prominent red tide scientist from the Florida Marine Research Institute in St Petersburg, Florida (http://www.mote.org/index.php?src=gendocs&ref=%28renamed%29%20Red%20Tide%20Update_608&category=Ecotoxicology).
Pierce County, Washington may be found on the interactive healthmap
at: <http://healthmap.org/r/3q3G> - Mod.TG]
[Photo of red tide:
<http://www.whoi.edu/cms/images/5_47876.jpg> - JW]
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