PREDICTIVE VALUE OF SEROLOGY IN DIAGNOSING LYME BORRELIOSIS

Aims-To compare the predictive value of immunoblotting and enzyme link ed immunosorbent assay (ELISA) in diagnosing Lyme borreliosis. Methods -An ELISA using a whole cell sonicate of the B31 strain of Borrelia bu rgdorferi was used to screen samples submitted for Lyme borreliosis se rology. A total of 1222 serum samples reactive in the ELISA were teste d by immunoblotting also using the B31 strain. Patients with other spi rochaetal diseases were tested by both methods to assess specificity, while those with erythema migrans were used to evaluate sensitivity. S ubjects with different clinical conditions, which may have been associ ated with Lyme borreliosis, were tested using both techniques. Results -Only 16.3% of serum samples from patients submitted for Lyme borrelio sis serology which were reactive by ELISA were confirmed as positive b y immunoblotting. This is unlikely to represent a sensitivity problem as 51% of samples from 53 patients with erythema migrans were detected by immunoblotting compared with only 28% by ELISA. Patients whose sam ples were negative by ELISA were also negative by immunoblotting. Seru m samples from patients with relapsing fever were reactive in both ELI SA and by immunoblotting, but for other test groups immunoblotting off ered increased specificity. Conclusions-Not all ELISA results could be confirmed by immunoblotting. Yet immunoblotting was both more sensiti ve and specific than ELISA techniques. As a result of these observatio ns ah ELISA results should be serologically confirmed by immunoblottin g. Though immunoblotting is not suited to large scale screening of sam ples, it can be used satisfactorily in conjunction with ELISA methods to improve the predictive value of serological tests for Lyme borrelio sis.