Leighton and his team studied Lyme disease patterns in Canada to find out what variables they could use to anticipate outbreaks. He published his findings earlier this month in the Journal of Applied Ecology.
"Currently, the areas where we are seeing a larger tick population is in the eastern part of the country along the U.S. border," said Leighton, who observed that ranges for ticks are expanding by roughly 45 kilometers per year. He said the spread was linked to established Lyme disease hosts like white-tailed deer, suitable forest habitat and warmer temperatures.
"If you look historically, increases in temperature have been important [for Lyme disease]," he said. "The main thing that our study showed was that under warmer climate conditions, ticks move faster."
However, the disease itself doesn't move as quickly as its hosts. "Lyme disease risk lags behind the establishment of ticks by a number of years," Leighton said, noting that newly observed populations could serve as an early warning system for infections.
And you get proliferating infections
With this information, public health officials hope to prevent illnesses. Though Lyme disease has not been very prevalent in Canada in the past, with about 150 cases annually over the past several years, infections are on the rise. "That increase is consistent with what we've seen in the ecology of Lyme disease," said Nicholas Ogden, a senior research scientist at the Centre for Food-borne, Environmental & Zoonotic Infectious Diseases in Canada.
Ogden said eradicating ticks is expensive and difficult, so officials are concentrating on educating people about the disease, how to recognize it and how to prevent infections. "The ticks are living in woodland environments, so by and large, it's people involved in outdoor pursuits and outdoor activities [who are at risk]," he said. These individuals should wear long clothing, tuck pants into socks, wear pest repellents like DEET and check for ticks on their bodies and on their pets when operating in the wilderness.
Over time, disease-carrying ticks are likely to continue spreading, according to Andrea Smith, a biologist at York University in Toronto. "With warming temperatures and increased precipitation in the Arctic, disease vectors will have increased survivability and shorter generation times," said Smith. "On many different levels, climate change is making many different areas inviting to invasive species."
Human movement and development is also likely to accelerate spreading vectors by altering ecologies, according to Smith. Expanding cities and suburbs are pushing against forests, creating more opportunities for infections. By 2080, ticks may move northward by 1,000 kilometers, according to Smith.
However, she acknowledged that it's difficult to predict exactly how these changes will affect humans. Using bioclimatic modeling, Smith said it is possible to prioritize infection risks as Lyme disease slogs north. Still, she said the only real way to stop the illness is to stop animal movement. "We have to be ready to prevent the species from arriving, because once they arrive, it's too late to do anything," she said.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500