An indirect enzyme-linked immunosorbent assay utilizing total antigen (ELISA-Gt) and sonicated (ELISA-Gs) of Mycoplasma agalactiae protein G was standardized for the detection of anti-M. agalactiae antibodies in goats. Eighty-six serum samples obtained from infected and uninfected flocks were used to evaluate the tests. The relative sensitivity of the ELISA-Gt and ELISA-Gs was 77.27% and 88.63%, respectively, while both had 95.24% of specificity. A survey of antibodies against contagious agalactia (CA) in 317 goats in Cariri microrregion, Semi-arid northeastern Brazil was undertaken by indirect ELISA-Gs, and 264 animals (83.28%) were positive. Considering the inexistence of vaccines against CA in Brazil, the high prevalence detected suggests the presence of intensive infection between caprine flocks in the microrregion.
