Applied serology in the latter stages of the eradication of bovine brucellosis

Abstract

Late in the program to eradicate bovine brucellosis from Western Australia, Rose Bengal test (RBT) and complement fixation test (CFT) results on the serums from 2,307 cattle (from herds where infection was still present after a minimum of 3 complete herd tests) showed that 327 were positive in the CFT and 246 were positive in the RBT (p less than 0.001). Subsequent testing by the RBT, CFT and the indirect haemolysis test (IHLT) of 722 serums from cattle slaughtered as part of infected herds showed that of 177 cattle positive on culture, 138 were positive in all 3 tests, 9 were negative in all 3 tests and no animal positive on culture had a reaction only in the RBT. In the 177 cattle from which B. abortus was isolated, positive reactions in the CFT occurred in the serums of 159 of them. Application of the RBT as a screening test followed by a confirmatory CFT would have resulted in 149 of the 177 cattle being positive and application of the CFT/IHLT (double test) on the serums of all cattle in the herds would have resulted in 168 or the 177 being regarded as positive.