Evaluation of the Fluorescence Polarization Assay (FPA) for diagnosis of brucella melitensis infection of goats in Argentina.

AIM

Determine the optimal cut-off and the use of Fluorescence Polarization Assay (FPA) to improve the detection of brucellosis in individual goats in Argentina.

METHODS

Sera from 96 goats from a flock with abortion due to B. melitensis biovar 1 were used to assess the efficacy of the FPA to detect brucellosis in goats. FPA results were compared with those of the Buffered Antigen Plate Agglutination test (BPAT) confirmed by Seroagglutination in tube (SAT), the competitive enzyme-linked immunosorbent assay (c-ELISA) and the indirect enzyme-linked immunosorbent assay (i-ELISA). Sera from 554 goats free from brucellosis were tested with the BPAT, SAT, c-ELISA and i-ELISA to determine its Specificity. Vaccination had not been performed in the flocks evaluated.

RESULTS

The most appropriate cut-off was selected for the FPA by using MedCalc software. It was fixed at 87 mP giving a sensitivity and specificity of 98.1% (CI 89.9-99.7) and 92.8% (CI 90.4-94.7). The relative sensitivity compared with i-ELISA and c-ELISA was 97% and 92.9% respectively. The relative specificity compared with i-ELISA and c-ELISA was 97.5% and 98% respectively. The kappa measures of agreement between tests was higher than 0.75 CONCLUSION: The high correlation between FPA results and other serological methods with sera goats is indicative of the excellent performance of FPA technique in diagnosis of caprine brucellosis and we endorse it as a recommended method.