Lyme Disease Transmission
The Lyme disease bacterium (Borrelia burgdorferi) is spread through the bites of black-legged ticks. Other tick species found in the United States have not been shown to contribute to the transmission of Lyme disease. Most cases of Lyme disease in humans occur in the late spring and summer.
In the northeastern and north central United States, the black-legged tick (or deer tick, Ixodes scapularis) transmits Lyme disease. In the Pacific coastal United States, the disease is spread by the western black-legged tick (Ixodes pacificus).
Black-legged ticks usually live for two years and have three feeding stages: larvae, nymph, and adult. When a young tick feeds on an infected animal, the tick takes the bacterium into its body along with the blood it consumes. The bacterium then lives in the tick's gut. If the tick feeds again, it can transmit the bacterium to the host it is feeding off of. Usually the new host is another small rodent, but sometimes the new host is a human.
Most cases of Lyme disease in humans occur in the late spring and summer, when the tiny black-legged nymphs are most active and human outdoor activity is greatest.
Although adult ticks often feed on deer, these animals do not become infected. However, deer still play a big role in transporting ticks and maintaining tick populations.
Other tick species found in the United States have not been shown to contribute to Lyme disease transmission.
Many people have questions about other modes of Lyme disease transmission, including:
- Person-to-person contact
- Transmission during pregnancy and while breastfeeding
- Transmission from blood
- Transmission from pets.
There is no evidence that Lyme disease transmission occurs from one person to another. For example, a person cannot get infected from touching, kissing, or having sex with a person who has Lyme disease.