Abstract
BACKGROUND: The conventional 2-tiered serologic testing protocol for Lyme disease (LD), an enzyme immunoassay (EIA) followed by immunoglobulin M and immunoglobulin G Western blots, performs well in late-stage LD but is insensitive in patients with erythema migrans (EM), the most common manifestation of the illness. Western blots are also complex, difficult to interpret, and relatively expensive. In an effort to improve test performance and simplify testing in early LD, we evaluated several modified 2-tiered testing (MTTT) protocols, which use 2 assays designed as first-tier tests sequentially, without the need of Western blots. METHODS: The MTTT protocols included (1) a whole-cell sonicate (WCS) EIA followed by a C6 EIA; (2) a WCS EIA followed by a VlsE chemiluminescence immunoassay (CLIA); and (3) a variable major protein-like sequence, expressed (VlsE) CLIA followed by a C6 EIA. Sensitivity was determined using serum from 55 patients with erythema migrans; specificity was determined using serum from 50 patients with other illnesses and 1227 healthy subjects. RESULTS: Sensitivity of the various MTTT protocols in patients with acute erythema migrans ranged from 36% (95% confidence interval [CI], 25%-50%) to 54% (95% CI, 42%-67%), compared with 25% (95% CI, 16%-38%) using the conventional protocol (P = .003-0.3). Among control subjects, the 3 MTTT protocols were similarly specific (99.3%-99.5%) compared with conventional 2-tiered testing (99.5% specificity; P = .6-1.0). CONCLUSIONS: Although there were minor differences in sensitivity and specificity among MTTT protocols, each provides comparable or greater sensitivity in acute EM, and similar specificity compared with conventional 2-tiered testing, obviating the need for Western blots.