Development of an enzyme-linked immunosorbent assay for the detection of antibodies against Babesia bovis.

An enzyme-linked immunosorbent assay (ELISA) for antibodies to Babesia bovis was developed and evaluated in comparison with the indirect fluorescent antibody test (IFAT). The ELISA sensitivity and specificity, estimated with 100 positive sera from cattle experimentally infected with B. bovis and 108 negative sera collected from B. bovis-free herds, were 98.0% and 98.1%, respectively. Positive and negative predictive values were, respectively, 98.0% and 98.1%, and precision was 98.1%. No cross-reactions were detected with 80 sera from calves experimentally inoculated with Babesia bigemina. The ELISA was compared with IFAT using 110 cattle sera from an enzootically stable area and with 168 cattle sera from an enzootically unstable area. In both cases, there was a significant agreement between results of both tests (P=0.631 and 0.4725, respectively). In an epidemiological study performed with ELISA in the Pantanal region of the State of Mate Grosso do Sul with 1,365 cattle sera, 83.9% were positive for antibodies against B. bovis, characterizing this region as enzootically stable.