Lyme disease
Lyme disease is an infectious disease caused by at least three species of bacteria belonging to the genus
Borrelia.
Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in North America, whereas
Borrelia afzelii and
Borrelia garinii cause most European cases. The first known existence of the
Borrelia bacteria dates back to up to 20 million years ago. 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 entomologist Dr. 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. 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, and may or may not appear as the well-publicized bull's-eye.