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.