Climate Change Linked to Cruise Ship Illness Outbreaks
- Climate Change Linked to Cruise Ship Illness Outbreaks
USA: October 6, 2005
BOSTON - Warming ocean waters may have tainted Alaskan oysters with a
bacteria that triggered four outbreaks of illness on a cruise ship among
people who ate the shellfish raw, researchers reported on Wednesday.
"The rising temperatures of ocean water seem to have contributed to one
of the largest known outbreaks of Vibrio parahaemolyticus in the United
States," said Joseph McLaughlin of the Alaska Department of Health and
Social Services, referring to the bacterium responsible for outbreak.
He and his colleagues said 62 people fell ill on four week-long cruises
in July 2004. Vibrio parahaemolyticus is the most common cause of
seafood-related illness in the United States.
"Alaskan waters were thought to be too cold to support" bacteria levels
known to cause the illness, said the McLaughlin team. But when they
tracked the outbreaks, the source turned out to be an oyster farm in
Prince William Sound, 621 miles (1,000 km) north of any previous source
of tainted oysters.
Further tests showed that 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 (15 degrees Celsius).
Temperature records from the area showed that the waters were more tepid
than at any time in recent history. The data also showed that
temperatures at the site have climbed gradually since 1976.
Based on the study in the New England Journal of Medicine, "we can't say
why ocean temperatures are rising," McLaughlin told Reuters.
But many climate experts have warned that warmer ocean waters are a
likely consequence of carbon dioxide pollution, which traps heat that
would normally radiate back into space.
Scientists predict that warmer temperatures will generate stronger storms
and shift local climate conditions, spreading various illnesses to new
"This is probably some of the best evidence to date that rising
temperatures in ocean waters might contribute to the incidence of
disease," said McLaughlin, "so we're definitely very concerned."
The researcher said 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.
As a result of the findings, nets have been moved to cooler waters. "That
seems to have worked," the researcher said.
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 ill.
Although it is seldom fatal, people with liver disease, diabetes or
immune system problems such as AIDS may die from the infection, which
killed 20 people in 2004, according to the Center for Science in the
Story by Gene Emery