The genus of spirochaetes which (compared with the treponema and leptospira) are larger (up to 30μm), more refractile, stain by conventional methods, and possess open coils of large wave-length. Both commensal and pathogenic species occur, and some are cultivable on special media.
Borrelia, a group of bacteria characterized by their spiral shape, are transmitted through tick bites. These bacteria are responsible for causing two distinct conditions: relapsing fever, an infectious disease marked by recurring episodes of fever, and Lyme disease.