Abstract
The aim of the study was to investigate the epizootic situation of brucellosis in Kazakhstan and to assess selected serological diagnostic methods and post-vaccination antibody responses used for brucellosis control in farm animals. Monitoring data and laboratory serological techniques were used to evaluate the epidemiological situation and post-vaccination antibody responses in experimental animals. Monitoring data for 2020-2023 showed that most cases of animal brucellosis were recorded in the northern regions (Kostanay and North Kazakhstan) and southern regions (Zhambyl and Almaty). Regardless of geographical location, small ruminants accounted for the highest proportion of infected animals, reaching 4.2% of all examined animals, whereas morbidity among cattle did not exceed 0.8-1.2%. In the analysed samples, the enzyme-linked immunosorbent assay and complement fixation test demonstrated sensitivity values of 95-100% and specificity of 95%. However, because of the limited sample size, these estimates should be interpreted cautiously. Vaccine preparations based on Brucella abortus and Brucella melitensis strains induced detectable humoral antibody responses that persisted for up to 12 months; however, protective efficacy was not assessed. These findings provide valuable information on the current epizootic situation and selected serological diagnostic methods and post-vaccination antibody responses in brucellosis control in Kazakhstan.