Diagnosis of bovine tuberculosis in free from tuberculosis farms of Ukraine

Abstract

The article presents the results of studies of cattle in five free from tuberculosis livestock farms during 2016–2020. Samples of biological material were collected and studied in the Laboratory for Tuberculosis Study of NSC “IECVM”. The causes of allergic reactions to mycobacterial allergens were established by a comprehensive method. The aim of the study was to conduct epizootological monitoring and to determine the causes of positive tuberculin skin test in cattle in five farms, which are free from tuberculosis. These farms are located in different regions of Ukraine. Epizootological, clinical, allergical, pathoanatomical, bacteriological and biological methods were used including a pathological examination of biological material samples (lymph nodes and internal organs), Ziehl-Nielsen staining of smears during bacterioscopy. Samples of biological material were preliminary treated with a 6.0% solution of sulfuric acid and inoculated on selective nutrient medium for mycobacteria cultivation. As a result of conducted study 15 cultures of nontuberculous mycobacteria were isolated from samples of biological material from cattle. It was found that these isolates were represented by five mycobacterial species from four husbandry farms. There were M. fortuitum, M. phlei, M. gordonae, M. smegmatis and M. scrofulaceum. In addition, two cultures of M. bovis were isolated from one herd. The causes of allergic reactions to mycobacterial allergens were established by a complex method using systematic simultaneous-allergic studies in cattle herds. In addition, appropriate measures were taken to prevent the spread of tuberculosis infection in one livestock farm. A control over the welfare of cattle herds where sensitization to tuberculin is caused by atypical mycobacteria should be carried out using a tuberculin (PPD) for mammals and an allergen from atypical mycobacteria. It is necessary to conduct preventive wet disinfection of places where animals are kept by using disinfectants that ensure the devitalization of mycobacteria in the environment