Serologic diagnosis of Lyme disease.

Indirect fluorescent antibody tests and enzyme-linked immunosorbent assays are being used as laboratory aids for the diagnosis of Lyme disease and related disorders. Depending on the needs, polyvalent or class-specific reagents can be used to detect total immunoglobulins (Ig) or IgM and IgG antibodies. The sensitivities of these assays are relatively low when serum samples are obtained from patients within 3 weeks after onset of erythema migrans and are tested by either the IFA method or ELISA. During neuritis or arthritis, IgG antibody levels are usually elevated, and serologic verification is more easily achieved. Cross-reactivity occurs when sera from patients with Lyme disease, relapsing fever, or treponemal infections are screened against heterologous antigens, but these diseases can usually be separated clinically or by further seroanalyses. Although IFA tests and ELISA are both suitable for confirming Lyme disease, the objective results and the ability to perform many more analyses make ELISA the preferred method.