How do ticks transmit the Lyme disease bacteria?

Immature (larval) deer ticks hatch from eggs and can become infected with Borrelia burgdorferi (the bacterium that causes Lyme disease) if they take a blood meal on a rodent which is already infected with Borrelia burgdorferi. The tick may then transmit the infection to new hosts when it takes its subsequent blood meals. These ticks have 3 developmental stages (larvae, nymph and adult) and must have a blood meal before they can molt (change) into the next stage. They live for 2 years, overwintering even in cold climates. The ticks must attach to the new animal host and feed for 12-24 hours before they can transmit the bacteria to infect the new host. Rodents, especially the white-footed mouse, serve as the natural wildlife hosts of the tiny larval Ixodes spp ticks. Middle stage ticks (nymphs) feed on a variety of wild and domestic species, including humans, rodents, horses, cats, birds, etc. Deer are the predominant wildlife host for adult ticks, but domestic animals, such as horses, ...  more