Lyme disease

  • Definition

    Lyme disease is an inflammatory disease spread through a tick bite.

    This article offers a general overview on Lyme disease. For specific information, see:

    • Lyme disease - primary
    • Lyme disease - early disseminated
    • Lyme disease - chronic persistent

    Alternative Names


    Causes, incidence, and risk factors

    Lyme disease is caused by the bacterium Borrelia burgdorferi (B. burgdorferi). Certain ticks carry these bacteria. The ticks pick up the bacteria when they bite mice or deer that are infected with Lyme disease. You can get the disease if you are bitten by an infected tick.

    Lyme disease was first reported in the United States in the town of Old Lyme, Connecticut, in 1975. Cases have now been reported in most parts of the United States. Most of the cases occur in the Northeast, some parts of Minnesota and Wisconsin, the mid-Atlantic states, and along the Pacific coast. Lyme disease is usually seen during the late spring, summer, and early fall.

    There are 3 stages of Lyme disease.

    • Stage 1 is called primary Lyme disease.
    • Stage 2 is called secondary Lyme disease and early disseminated Lyme disease.
    • Stage 3 is called tertiary Lyme disease and chronic persistant Lyme disease.

    Risk factors for Lyme disease include:

    • Doing activities that increase tick exposure (for example, gardening, hunting, or hiking)
    • Having a pet that may carry ticks home
    • Walking in high grasses