Cause of Lyme Disease

The primary vector of Lyme disease in the U.S. is the black-legged deer tick (Ixodes scapularis) .  Other Ixodes ticks are also known to transmit the disease. Lyme disease is maintained in wild rodent populations, on which the larval and nymphal ticks develop. These immature ticks pick up the disease organism when they suck the blood of infected rodents. The nymphal and adult ticks then seek a larger host, such as deer or humans, to obtain their final blood meal and transmit the disease when they feed.