Lyme disease is caused by tick bites.
Lyme disease , also known as Lyme borreliosis , is an infectious disease caused by bacteria of the Borrelia type . The most common sign of infection is an expanding area of redness on the skin , known as erythema migrans , that begins at the site of a tick bite about a week after it has occurred . Prevention includes efforts to prevent tick bites such as by wearing long pants and using DEET . Lyme disease is the most common disease spread by ticks in the Northern Hemisphere .