This is an enzyme immunoassay for the detection og IgG antibody to Brucella in human serum or plasma. Brucellosis is transmitted through contaminated and untreated milk and milk products and by direct contact with infected animals, animal carcasses. In the acute stage of the disease, there is an initial production of IgM antibodies followed closely by production of IgG antibodies. IgG-class antibodies may decline after treatment; however, high levels of circulating IgG-class antibodies may be found without any active disease. Rising levels of specific antibody in paired sera can be regarded as serological evidence of recent infection. The presence of specific IgM in a single specimen may also indicate a recent infection, although IgM-class antibodies may persist for months following acute disease.