Lyme disease is caused by infection with the bacterium Borrelia burgdorferi carried by ticks. The disease is spread to people and pets by infected ticks, most commonly the deer tick (or the black-legged tick); it is not spread from person to person. Lyme disease is the most common tick-borne infectious disease in the United States.

Common symptoms may include a rash that looks like a bulls-eye, tiredness, fever, headache, stiff neck, muscle aches, and joint pain. If left untreated, those infected may develop arthritis, and nervous system and/or heart problems. If treated early, antibiotic therapy is generally effective.

To prevent Lyme disease, avoid tick bites. Examples of prevention measures include avoiding wooded areas with dense shrubbery and leaf litter, wearing protective clothing, using insect repellents, performing tick checks, mowing lawns, and keeping shrubs trimmed.