People get Lyme disease from bacterium called Borrelia burgdorferi, which is contracted from bites from infected ticks, according to the Centers for Disease Control and Prevention. An infected tick must be attached to the human host for 36 to 48 hours before the bacterium is transmitted, in most cases.
Blacklegged ticks, known as deer ticks, carry Lyme disease in the northeast, mid-Atlantic and north-central United States, notes the CDC. On the Pacific coast, the western blacklegged tick spreads the disease. Nymphs, or immature ticks, most often transmit Lyme disease. At less than 2 millimeters, these small ticks are more difficult to spot. Because adult ticks are easier to see, they are often removed before infection. The ticks feed during spring and summer.