Rising Vibrio Levels Close Hood Canal Growing Areas

The Department of Health has announced it has halted commercial harvesting of shellfish in Hood Canal's growing areas 8 and 9 due to a rise in Vibrio parahaemolyticus (Vp) levels.  It has also warned commercial shellfish growers of rising levels in other areas of Puget Sound and for them to take extra precautions after harvesting to minimize the risk of illness being contracted by the public from shellfish consumption. The Department of Health has also warned the public about the increase in the risk of contracting Vibriosis from shellfish harvested recreationally.

Vibrio parahaemolyticus

 

Naturally Occurring
The naturally occurring bacteria increases during the warm summer months as water temperature increases. Exposure of oysters to the sun during low tides causes the internal temperature of oysters to rise further, which in turn results in the number of Vp bacterial cells within the oyster increasing. When consumed, these bacteria damage the inner wall of the intestine, resulting in Vibriosis. Its cousin, Vibrio vulnificus, passes through the intestinal wall into the blood stream, resulting in a far more deadly disease. Currently the waters outside of the Gulf states are too cold for Vv to grow, but some feel the increasing water temperatures from climate change may increase the risk of Vibrio vulnificus in more areas.

Months without R
The consumption of oysters in the months without R (May, June, July and August) has its grounding in two things. First, and most important, warmer temperatures increase the risk of contracting Vibriosis from Vp or its more deadly cousin Vibrio vulnificus (found in the Gulf state oysters harvested during the warm summer months). Second is that during the warmer months oysters spawn, causing them to become unsavory due to their oily and milky texture.

Genetic Manipulation of Oysters and Sterility
Taste issues brought on with spawning have been dealt with by the shellfish industry through genetically modifying oysters. This genetic manipulation results in an oyster which is sterile and does not "plump" from spawning during the months without R. The downside to the introduction of this oyster is the increase in consumption, raising the risk of contracting Vibriosis.

Food Safety
With any food there is risk of contracting illness. The risk of contracting Vibriosis from oysters is minimized by thoroughly cooking them. (Note - Cooking does not eliminate the risk of Paralytic Shellfish Poisoning, caused by toxins from the family of Alexandrium algae.) For additional information on shellfish safety the Department of Health has information on their web site as well as an interactive map showing areas which have been closed.