SERODIAGNOSIS OF LYME-DISEASE - ACCURACY OF A 2-STEP APPROACH USING AFLAGELLA-BASED ELISA AND IMMUNOBLOTTING

An ELISA containing a purified flagellar antigen from Borrelia burgdor feri (FLA-ELISA) was evaluated. The FLA-ELISA, detecting IBM and IgG t ogether, did not have adequate specificity by itself. Good accuracy wa s obtained, however, when the FLA-ELISA was the first step in a two-st ep protocol that used immunoblotting as a conditional second test. Sam ples that scored positive or equivocal by the FLA-ELISA were evaluated with separate IgM and IgG immunoblots. The sensitivity of the two-ste p process for patients with erythema migrans or with later manifestati ons of Lyme disease was 64% and 100%, respectively. The specificity fo r healthy blood donors was 100% and was 90% for the aggregate of all p ersons with illnesses that may cause serologic cross-reactivity (98% i f the samples from relapsing fever patients were excluded). Test preci sion was 96% overall, 99% for Lyme disease case serum samples, 100% fo r specimens from blood donors, and 88% for samples from persons with o ther illnesses.