Lyme disease

Lyme disease is an infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. It is transmitted via the bite of an infected tick. Early symptoms may include fever, headache, and fatigue. A rash occurs in 70–80% of infected persons at the site of the bite after a delay of 3–30 days, and may or may not appear as the well-publicized bull's-eye. The rash is rarely painful or itchy, although it may be warm to the touch. About 20–30% of infected persons do not experience a rash. Left untreated, later symptoms may involve the joints, heart, and central nervous system. In most cases, the infection and its symptoms are eliminated by antibiotics, especially if the illness is treated early. Delayed or inadequate treatment can lead to more serious symptoms, which can be disabling and difficult to treat. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in North America, whereas Borrelia afzelii and Borrelia garinii cause most European cases. Borrelia is transmitted to humans by the bite of infected ticks belonging to a few species of the genus Ixodes. Lyme disease is the most common tick-borne disease in the Northern Hemisphere.