Lyme Disease (Lyme Borreliosis) is an infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borreliaburgdorferisensustricto is the main cause of Lyme disease in North America, whereas Borreliaafzelii and Borreliagarinii cause most European cases. The disease is named after the towns of Lyme and Old Lyme, Connecticut, US, where a number of cases were identified in 1975. Although it was known that Lyme disease was a tick-borne disease as far back as 1978, the cause of the disease remained a mystery until 1981, when B. burgdorferi was identified by Willy Burgdorfer.
Lyme disease is the most common tick-borne disease in the Northern Hemisphere. Borrelia is transmitted to humans by the bite of infected ticks belonging to a few species of the genus Ixodes (“hard ticks”). Early symptoms may include fever, headache, and fatigue. A rash occurs in 70–80% of infected persons at the site of the tick bite after a delay of 3–30 days (average is about 7 days), and may or may not appear as the well-publicized bull’s-eye (erythema migrans). The rash is only rarely painful or itchy, although it may be warm to the touch. Approximately 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. The term “chronic Lyme disease” is controversial and not recognized in the medical literature, and most medical authorities advise against long-term antibiotic treatment for “chronic Lyme disease”.