Oyster illness muscles into Alaska
Warming waters blamed for food poisoning.
Alaska's dramatic warming trend seems to be affecting human health. A bacterium that plagues oysters has moved some 1,000 kilometres northwards into the warming waters of Prince William Sound, causing an outbreak of diarrhoea on a 2004 Alaskan cruise.
"We had no idea that we would ever get an outbreak in Alaska," says Joseph McLaughlin, a medical epidemiologist with the state's Department of Health and Social Services in Anchorage. McLaughlin's team investigated the cruise-ship outbreak and confirmed that Vibrio parahaemolyticus in oysters was the cause.
Alaska Department of Health and Social Services, Anchorage
The team says that rising water temperatures are probably the cause of the shift to the north. Average water temperatures at the farm that provided the oysters failed to drop below 15 °C in July and August for the first time in 2004. Temperatures that summer were on average 2 °C warmer than in previous years. And the farm records show that waters in the area have been warming by about 0.21 °C per year since 1997.
Being health workers rather than climate experts, the team says it cannot be sure that these rising temperatures are due to global warming.
But Prince William Sound, along with the rest of Alaska, is known to be heating up at a remarkable rate. Between the 1970s and early 2000s, winters in that state warmed by a startling 2-3 °C, compared with a global average of 1°C.
It wouldn't be the first time that a warming world has changed disease patterns. Paul Epstein, associate director of the Center for Health and the Global Environment at the Harvard Medical School in Boston, notes that disease-bearing ticks in Sweden are moving northwards as winters become warmer, for example.
McLaughlin and his colleagues have linked the consumption of Alaskan oysters to serious stomach trouble in 62 people last summer.
- McLaughlin A., et al. N. Eng. J. Med, 353. 1463 - 1470 (2005).