The risk factors for Lyme disease are all related to black-legged tick exposure. If you live, work, or spend significant time in a densely wooded or grassy area, you are at increased risk of Lyme disease because these environments have large numbers of the animals that harbor ticks (rodents, deer, and small birds). Black-legged ticks are most common in the Northeast, Midwest, and Northwest regions of the U.S.

If you do spend time in wooded or grassy areas, having areas of your skin exposed increases the chances of ticks attaching to you. Also, failure to detect and remove ticks from the skin greatly increases the chances that an infected tick will transmit the disease. Ticks must complete a blood meal before they are able to pass on the Borrelia burgdorferi bacterium.