Express methods for post-vaccinal diagnosis of brucellosis

The technology of express diagnostic methods against the background of specific prophylaxis of brucellosis in cattle has been developed. The Rose Bengal Test (RBT) as the most sensitive method and immunodiffusion reaction (IDR) with O-PS antigen as a differential test for the improvement of cattle herds were used for the study. Using the provocation method for detection the latent course of brucellosis we studied the blood serum of cows vaccinated with the B abortus 82 strain vaccine in a short time (in 21 days - up to 3 months) after immunization on farms with different brucellosis epizootic situation. According to the instruction of RBT, it is used in herds of non-immune livestock as a reconnaissance test when establishing a preliminary diagnosis for brucellosis. Therefore, the evaluation results of the Rose Bengal Test of the sample are taken into account only as “positiveˮ and “negativeˮ. It was found that the post-vaccination reactions of RBT, evaluated in crosses, completely coincide with the indicators of the agglutination reaction (AR). The experiments with artificial infection of intact and immunized with a strain 82 cows from brucellosis-prone areas confirmed that in healthy animals vaccinated with the vaccine from strain 82, the reaction rates are low, in contrast to animals with brucellosis. RBT indicators “+++ˮ and “++++ˮ correspond to AR in titers of 200 IU and above. Moreover, high levels of RBT absorb the indicators of the complement fixation reaction (CFR) at a dilution of 1 : 10 and above, as well as IDR. This fact made it possible to use RBT instead of the classical reactions - AR and CFR. The use of RBT proved to be the most effective when identifying latently ill animals, in combination with the immunodiffusion reaction with the O-polysaccharide antigen in a short time after immunization with the vaccine from strain B. abortus 82.