Regionally, the team saw a sevenfold increase in stings in northern Alaska between 1999 and 2006. In the interior, sting rates per 100,000 patients increased from 260 a year in 1999 to an average of 437 a year between 2000 and 2006.
Initial data from the study appear in the May 2008 issue of the State of Alaska Epidemiology Bulletin.
The report authors note that over the past 50 years, Alaska's average temperature has risen by 4 degrees Fahrenheit (2.2 degrees Celsius)—four times more than the global average.
Shifting seasons, new precipitation patterns, and rising temperatures already seem to be having an impact on insect populations in countries farther south that affect human health.
In Kenya and Latin America, for example, experts are beginning to document a connection between mosquito migrations tied to warming and new cases of vector-borne diseases such as malaria and dengue fever.
(Related: "Climate Change Spurring Dengue Rise, Experts Say" [September 21, 2007].)
While yellow jackets are not vectors for disease, their painful stings can in some people cause anaphylactic shock, an allergic reaction to their venom similar to an asthma attack.
According to the World Allergy Organization, roughly 4 percent of humans are allergic to bees, hornets, and/or yellow jackets. Severe cases can be fatal, with wasps and bees causing 30 to 120 deaths yearly in the United States.
Few scientists have specifically looked for a link between climate change and shifting yellow jacket populations, but there is anecdotal evidence that the insects have been moving north.
In 2004, for example, a Canadian entomologist confirmed the presence of yellow jackets in the village of Arctic Bay, Nunavut, where they had never been seen before.
Yellow jacket workers and male drones only live for a year. For the insects to persist in a region, a fertilized queen must survive the winter and emerge in spring with favorable conditions for building a new nest.
"In terms of recent climate changes in Alaska, the greatest warming has occurred during winter and spring—precisely the seasons to which insect survival is most sensitive," said John Walsh, professor of climate change and chief scientist at the University of Alaska, Fairbanks.
Report co-author Demain said there are many factors that play a role in yellow jackets' ability to thrive so far north, and no one is sure yet which ones are most impacting their boom.
He plans to develop a model to track regional precipitation and temperature variances that could then be correlated with insect-sting data.
A similar initiative called MoveBank, slated to launch in October, may help researchers such as Demain track and predict insect outbreaks.
MoveBank is a free visualization tool that uses data from researchers around the world to plot and view animal migration patterns.
The tool is the brainchild of Martin Wikelski, a zoologist and behavioral ecologist at Princeton University and a National Geographic Emerging Explorer. (National Geographic News is part of the National Geographic Society.)
"We know that things are moving northward," Wikelski said. "But we don't know what individuals are doing and how they decide [where to go]."
"With MoveBank, researchers who study yellow jackets in Alaska could input their data and then match it with global climate patterns and learn how things are changing."
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