Clinical manifestations of Lyme borreliosis, serology and exposure to ticks among tick bite cases with evidence of Borrelia infection within three months after a tick bite.

EM = erythema migrans; n.a. = no tick available for testing.*C6 ELISA test results were scored as negative (ELISA index score, **Seroconversion of IgM and/or IgG in the immunoblot and/or in the C6 ELISA was considered as evidence of an early Borrelia infection. For seroconversion in the C6 ELISA, the ELISA index score was required to be ‡case #15 was excluded from risk analyses, as the development of Lyme borreliosis was almost certainly not attributable to the tick bite at baseline.