an infection caused by a bacteria (Borrelia burgdorferi) carried by deer ticks and transmitted to humans by the bite of an infected tick. Symptoms, caused by the body's immune response to the bacteria, vary and may include a rash at the site of the tick bite and flulike symptoms such as fever, headache, joint pain, and fatigue. Lyme disease was first reported in Lyme, Conn., in 1975. The primary treatment is antibiotics. Left untreated, Lyme disease can mimic several musculoskeletal diseases.