Comparison of microscopic agglutination test and indirect elisa in the diagnosis of bovine leptospirosis = Comparação da soroaglutinação microscópica e elisa indireto para o diagnóstico da leptospirose bovina

The objective of this research was to compare the results obtained by the Microscopic Agglutination Test (MAT) and indirect ELISA using outer membrane proteins (OMP) of the serovar Hardjo as antigen (ELISA/OMP-Hardjo). Ninety-three samples of blood serum from 3 to 6-year-old cattle of both sexes with no history of vaccination for leptospirosis were used. To perform the MAT, live cultures of 14 Leptospira serovars representing 11 serogroups of L. interrogans were used as antigen. Outer membrane proteins (OMP) of the serovar Hardjo (ELISA-OMP/Hardjo) were used as the ELISA antigen. Of the 93 samples tested by MAT, 37 (40%) were positive.  None of the samples testing positive in the MAT were negative in the ELISA. Sensitivity was 100% and specificity 64%. A comparison of the MAT and ELISA-OMP/Hardjo tests showed 78% agreement and the Kappa index was 0.58 (p<0.0001).  The ELISA-OMP/Hardjo proved to be a sensitive test for the diagnosis of bovine leptospirosis, indicating its potential use as a screening test and for epidemiological studies. The titration results obtained by MAT and by optical density (OD) in the ELISA-OMP/Hardjo test showed a positive correlation, and as the antibody titers in the MAT increased, so did the OD in ELISA, demonstrating the correspondence between the tests evaluated here.