Lyme disease is the most common vector-borne disease in the United States. Lyme disease is caused by the bacterium Borrelia burgdorferi and rarely, Borrelia mayonii. It is transmitted to humans through the bite of infected blacklegged ticks.Lyme disease causes a rash, often in a bull's-eye pattern, and flu-like symptoms. Joint pain and weakness in the limbs can also occur. Most people with Lyme disease recover completely with appropriate antibiotic treatment. For those who develop syndromes after their infection is treated, pain medication may provide symptomatic relief.