Borrelia afzelii is the only cause of Lyme disease.
Borrelia afzelii . Among 30 Borrelia known species , it is one of four which are likely to infect humans causing a variant of Lyme disease . Lyme disease . The most common sign of infection is an expanding area of redness on the skin , known as erythema migrans , that begins at the site of a tick bite about a week after it has occurred . In Europe and Asia , the bacteria Borrelia afzelii and Borrelia garinii are also causes of the disease .