Serological differentiation of Brucella-vaccinated and -infected domesticated animals by the agar gel immunodiffusion test using Brucella polysaccharide in mongolia.

To investigate Brucella infection in cattle, sheep, goat, reindeer and yak in Mongolia, serological reactions of Brucella-infected and -vaccinated domestic animals were compared by the agar gel immunodiffusion (AGID) test with a polysaccharide (poly-B) of the B. Abortus strain S-19. The sensitivity and specificity were compared with conventional serological tests that are commonly used in Mongolia, such as the rose Bengal test, the tube agglutination test and the compliment fixation test. A total of 73.3, 100, 100, 95.8 and 61.9% of the sera from suspected cattle, yak, goat, sheep and reindeer, respectively, that were positive in the compliment fixation test, were also positive in the AGID test. Sera from vaccinated cattle, sheep and goat were positive over 90% by conventional tests 3 months after vaccination, but were negative by the AGID. These results suggest that the AGID test may be useful to differentiate infected and vaccinated animals in the field.