Laboratory diagnosis of Lyme borreliosis in Scottish patients: a novel approach

Traditional two-tier (enzyme immunoassay [EIA] screening and Western blot confirmation) testing for the laboratory diagnosis of Lyme borreliosis (LB) is expensive, lacks sensitivity in the diagnosis of early LB, cannot distinguish between current and past infection and cannot be used as a marker for treatment response. The aims of the present study is to investigate the role of the C6 EIA as a screening assay, as part of two-tier EIA test strategy, and its use as a marker of treatment response or resolving infection in a routine diagnostic laboratory. The C6 EIA was significantly less sensitive than the Enzygnost Lyme link VlsE/IgG EIA (169/249 vs. 190/249 reactive sera, respectively; P = 0.0455, Fishers exact two-tailed test). The two-EIA strategy, utilising C6 EIA confirmation, was slightly more sensitive than traditional two-tier testing (82/151 vs. 67/151 positive sera). Twenty-seven patients were positive by the two-EIA strategy but negative by Western blot, raising questions of specificity, but 12 samples positive with the traditional two-tier testing were negative with the two-EIA strategy. There was no evidence to support the use of the C6 EIA for monitoring treatment response or resolving infection. The authors have devised a novel approach to detect LB in Scottish patients. For cases with a high clinical suspicion of disease, the C6 EIA could be incorporated into a two-EIA strategy, replacing the need for Western blot confirmation with a simpler, more cost-effective two-EIA strategy. Western blot confirmation would be reserved for those patients with discordant EIA results and whose clinical picture is more complex.