Context: Diagnosis of infection with Borrelia burgdorferi, the cause of Lyme disease (LD), has been impeded by the lack of effective assays to detect active infection.
Objective: To determine whether B. burgdorferi-specific immune complexes are detectable during active infection in LD.
Design, setting, and patients: Cross-sectional analysis of serum samples from 168 patients fulfilling Centers for Disease Control and Prevention surveillance criteria for LD and 145 healthy and other disease controls conducted over 8 years. Tests were performed blinded.
Main outcome measure: Detection of B. burgdorferi immune complexes by enzyme-linked immunosorbent assay and Western blot.
Results: The B. burgdorferi immune complexes were found in 25 of 26 patients with early seronegative erythema migrans (EM) LD; 105 of 107 patients with seropositive EM LD; 6 of 10 samples that were seronegative [corrected] with culture-positive EM; 0 of 12 patients who were treated and recovered from LD; and 13 of 13 patients with neurologic LD without EM. Among 147 controls, B. burgdorferi immune complex was found in 0 of 50 healthy individuals; 0 of 40 patients with persistent fatigue; 0 of 7 individuals with frequent tick exposure; and 2 of 50 patients with other diseases.
Conclusion: These data suggest that B. burgdorferi immune complex formation is a common process in active LD. Analysis of the B. burgdorferi immune complexes by a simple technique has the potential to support or exclude a diagnosis of early as well as active LD infection.