"The rising temperatures of ocean water seem to have contributed to one of the largest known outbreaks of Vibrio parahaemolyticus in the United States," says Joseph McLaughlin of the Alaska Department of Health and Social Services, referring to the bacterium responsible for the outbreak.
He and his colleagues say 62 passengers fell ill on four separate, week-long cruises in July 2004. Vibrio parahaemolyticus is the most common cause of seafood-related illness in the U.S.
Temperatures in Alaskan waters were thought to be too cold to support bacteria levels known to cause the illness, but when the team tracked the outbreaks, the source turned out to be an oyster farm in Prince William Sound, 621 miles north of any previous source of tainted oysters.
Further tests show other oyster facilities in Alaska's Kachemak Bay and southeast Alaska had also begun to harbor the bacteria, which is only believed to grow in oysters where water temperatures are higher than 59 F.
McLaughlin says when water temperatures at oyster farms exceed 15 degrees Celsius, health officials should test for the virus, oyster nets should be moved to cooler waters, and the public should be warned to cook oysters before eating them.
Most of the cruise ship travelers who fell sick had eaten just one raw oyster. The bacteria took 12 to 36 hours to make them sick.
