The black-legged (a.k.a. deer) tick transmits Lyme disease to humans. Removing a tick within 24 hours of being bitten can prevent transmission of the bacteria responsible for the disease. © Kent Wood/Science Source

Sharon Levy is a freelance science journalist and contributing editor to OnEarth, the magazine of the Natural Resources Defense Council.

Lyme disease, caused by the bacterium Borrelia burgdorferi, first emerged in the northeastern United States in the 1970s. Since then, the geographic range of the illness has expanded to the west, south, and north, and it has become by far the most commonly reported vector-borne disease in North America. Evidence is mounting that, on its northern front, the expanding range of Lyme disease is driven by climate change; warming temperatures allow new populations of the tick vector, Ixodes scapularis, to establish themselves in regions that were once too cold. Now a new study in EHP has quantified the relationship between warmer temperatures and the tick’s expansion into Canada.

Some historical and genetic evidence suggests Lyme disease was widespread in much of the contiguous United States prior to European settlement. The new work shows, however, that I. scapularis may now be spreading into regions it never occupied before, paving the way for disease to follow.

Read the full article here.