First and most frequent localized early manifestation of the skin in the vicinity of the tick bite site with circular (disc-shaped) or oval, slowly centrifugally growing erythema, belonging to Lyme borreliosis. The infection is caused by Borrelia burgdorferi. Note: By definition, erythema migrans is called erythema chronicum migrans when it persists for more than 6 months. For further information see below. Erythema migrans.