Massachusetts has been forced to shut down 30 oyster beds along the coast south of Boston, including those in Duxbury, Katama Bay in Edgartown, on Martha's Vineyard due to an outbreak of Vibrio parahaemolyticus bacterium. This follows similar measures in Connecticut, which closed oyster beds and issued a voluntary oyster recall last month after 14 people became sick. In addition, health officials reported another outbreak of Vibrio in near Seattle.
Although the bacteria are commonly found in New England waters as well as Long Island Sound, this is the worst it has been since the 1960’s, with 50 cases confirmed by Massachusetts’s labs since May.
According to the CDC, approximately 4,500 cases of Vibrio infection occur throughout the US each year, causing watery diarrhea, abdominal cramping, nausea, vomiting, fever and chills within 24 hours, and lasting about three days before it passes. In fact, the agency states that severe illness is rare and occurs most often in individuals with weakened immune systems. V. parahaemolyticus can also cause an infection of the skin when an open wound is exposed to warm seawater.
While no one is sure why the outbreak us worse this year than in the past,Massachusetts Department of health associate commissioner Suzanne Condon thinks it may have to do with environmental changes caused by rising average water temperatures, although she noted that “average monthly daytime water temperatures in the region rarely approach the 81 degrees believed to be the threshold that triggers dangerous Vibrio growth.”
However, Michael Hickey, chief shellfish biologist for Massachusetts added that the “virulent Vibrio strains that aren't as temperature-sensitive may have been carried from overseas in ships' ballast water during the past ten years.”
Vibrio growth is not pollution-related.
For more information about V. parahaemolyticus, readers can either contact the Massachusetts Department of Health at 250 Washington St., Boston, MA 02108 617 624-6000 or the CDC at 1600 Clifton Rd., Atlanta, GA 30333 800 232-4636.