Use of an indirect enzyme immunoassay for detection of antibody to Brucella abortus in fermented cow milk

The aim of the study was to establish whether the specificity of the ELISA-milk test is sensitive enough to detect Brucella antibodies reliably in fermented cow milk. The diagnostic method was established by means of reference standards and compared with conventional screening and confirmatory tests under field conditions (RBPT and ABR-test). Positive ELISA results are highly correlated with a positive result for the ABR-test. The sensitivity of the test on fermented milk compared with the test on the same milk when fresh decreased but not significantly: on fresh milk it was 89.7%, on day two 86.7% (pH=5.0) and day three 80.0% (pH=4.5). The specificity remained at 98.15%. The OD decreased significantly by 68% both at pH 4.5 and 4.0. The milk (fresh or fermented) dilution has a significant effect on the decrease of antibodies detection. Thus this brucellosis ELISA-milk test can also be used in fermented milk, however with a reduced sensitivity particularly at pH under 4,5.