A tick-borne illness caused by the bacterium Borrelia burgdorferi. Deer ticks can carry the bacteria that cause Lyme disease. 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. 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. Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by the Borrelia bacterium which is spread by ticks. The most common sign of infection is an expanding area of redness on the skin, known as erythema migrans, that appears at the site of the tick bite about a week after it occurred. If diagnosed in the early stages, Lyme disease can be cured with antibiotics. Without treatment, complications involving the joints, heart, and nervous system can occur. But these symptoms are still treatable and curable.