A surge in cases of Lyme disease could be hiding in the forest. Scientists say the northeastern US might be staring at "the worst year yet" for the bacterial illness, reports Wired. The reason starts with acorns: In 2010, there was a huge crop of them, which led to a population boom of white-footed mice in 2011. The mice are essential hosts of the ticks that carry Lyme disease and infect humans. “We’re already working with health departments," says one researcher.