Lyme disease is an infection caused primarily by the bacterium Borrelia burgdorefi (although other species of the genus can also cause the disease). Sometimes the infection is referred to as borreliosis. The disease is transmitted to humans via bites from infected ticks of the genus Ixodes. The disease is named after its first point of discovery in the towns of Lyme and Old Lyme, Connecticut, USA, in 1975. The bacteria responsible for the disease were not isolated and identified until 1981. Lyme disease is endemic in Northern Hemisphere temperate regions; it also occurs in other regions of the world.