Lyme disease is a bacterial infection transmitted by deer ticks infected with the Borrelia burgdorferi bacteria. Named after the town in Connecticut where the disease was first discovered, Lyme disease causes a peculiar rash and arthritis symptoms. Lyme disease has been reported in nearly all U.S. states, although most cases are concentrated in the coastal northeast, Mid-Atlantic States, Wisconsin, Minnesota, and northern California. In addition to causing arthritis, Lyme disease can also cause heart, brain, and nerve problems. Follow the links below to find WebMD's comprehensive coverage about how Lyme disease is contracted, what it looks like, how to treat it, and much more.