Serodiagnosis in early Lyme disease

Using a commercially available enzyme-linked immunosorbent assay (ELISA) and an immunoblot assay (IB), we tested sera from 100 patients with erythema migrans (EM) seen in 1991 a the Westchester County Medical Center Lyme Disease Diagnostic Center. Convalescent-phase sera were available from 59 patients. Fifty-five patients had EM of < 7 days' duration, 31 had EM of 7 to 14 days' duration, and 14 had EM of > 14 days' duration. During the acute phase of infection, 35 patients had a positive ELISA result and 43 had a positive IB result by the recently published criteria of Dressler et al. (F. Dressler, J. A. Whalen, B. N. Reinhardt, and A. C. Steere, J. Infect. Dis. 167:392-400, 1993) for interpretation of IB in patients with Lyme disease. A greater sensitivity of IB was observed in patients with EM of < 7 days' duration, as follows: 14 of 55 (25%) for IB versus 7 of 55 (13%) for ELISA (P = 0.144). Sera of all 14 patients with EM of > 14 days' duration were reactive by both tests, as follows: 13 positive and 1 equivocal by ELISA and 12 positive and 2 indeterminate by the IB. The band reactivity most frequently observed in the IB was to the 41- and 25-kDa antigens, the latter being the most frequent band observed in immunoglobulin M blots. Seroconversion was observed in 74 and 64% of evaluable patients by ELISA and IB, respectively, despite the use of antibiotic therapy.