Summer is the season of Lyme disease, a bacterial infection transmitted to humans through the bites of blacklegged ticks.
Lyme is the most commonly reported vector-borne illness in the country. More than 20,000 cases are reported to the U.S. Centers for Disease Control and Prevention every year, but experts believe upwards of 300,000 individuals are infected annually. The CDC reports that 95 percent of cases in 2012 were concentrated to 13 states in the Northeast and Upper Midwest, where the tick is native.
But like many insect-carried diseases, Lyme is spreading thanks to climate change. Warmer weather across the continent has spread the home turf of Lyme-carrying ticks, numerous studies have found, including a recent one published in Environmental Health Perspectives (PDF).