. 2017 Oct 5;43(10):194–199. doi: 10.14745/ccdr.v43i10a01

Table 1. 2009 national Lyme disease case definition.

Confirmed case	Probable case
Clinical evidence of illness with laboratory confirmation: isolation of Borrelia burgdorferi from an appropriate clinical specimen OR detection of B. burgdorferi DNA by PCR OR clinical evidence of illness with a history of residence in, or visit to, an endemic area and with laboratory evidence of infection, i.e., positive serologic test using the two-tier ELISA and Western Blot criteria	Clinical evidence of illness without a history of residence in or visit to an endemic area but with laboratory evidence of infection: positive serologic test using the two-tier ELISA and Western Blot criteria OR clinician-observed erythema migrans without laboratory evidence but with history of residence in or visit to an endemic area

Confirmed case

Probable case

Clinical evidence of illness with laboratory confirmation:

clinical evidence of illness with a history of residence in, or visit to, an endemic area and with laboratory evidence of infection, i.e., positive serologic test using the two-tier ELISA and Western Blot criteria

Clinical evidence of illness without a history of residence in or visit to an endemic area but with laboratory evidence of infection:

clinician-observed erythema migrans without laboratory evidence but with history of residence in or visit to an endemic area

Abbreviations: DNA, deoxyribonucleic acid; ELISA, enzyme-linked immunosorbent assay; PCR, polymerase chain reaction