EVALUATION OF THE ROSE BENGAL PLATE TEST, IN COMPARISON TO THE COMPLEMENT FIXATION AND MERCAPTOETHANOL TESTS, FOR THE SERODIAGNOSIS OF BRUCELLOSIS IN A Brucella abortus INFECTED BUFFALO (Bubalus bubalis) HERD.

Abstract

The purpose of this investigation was to evaluate the rose Bengal plate test (RBPT) for brucellosis serodiagnosis in a Brucella abortus infected buffalo (Bubalus bubalis) herd, comparing the results with those obtained by the mercaptoethanol (MET) and the complement fixation tests (CFT). Serum samples from 90 three-to-five-years-old cows were collected. Animals were unvaccinated against brucellosis. Every serum was tested by the three serological tests, and the results were compared by kappa (k) and the MacNemar chi-square, adopting as cutt-off the titre 25 for the MET and the titre 4 for the CFT. A good agreement was observed among the tests (RBPT versus CFT, k = 0.82; RBPT versus MET, k =0.92; MET versus CFT, k = 0.86), and the chi-square did not show significant difference. The relative sensitivity of the RBPT, when compared with the combination of the results of MET and CFT, was 93.03%, with a confidence interval (95%) ranging from 87.57% to 98.47%. Out of 43 animals considered infected by the combination of the results of the two other tests, three tested negative by the RBPT, suggesting the possibility of occurrence of false-negative results. KEY-WORDS: Brucellosis. Bubalus bubalis. Serodiagnosis. Rose Bengal plate test. Complement fixation test. Mercaptoethanol test.