Towards improved differential diagnostics of bovine tuberculosis in the Republic of Dagestan

Introduction. Non-specific tuberculin reactions are among the most critical challenges in tuberculosis diagnosis, with their incidence increasing annually. Given the complex epidemiological challenges, improving bovine tuberculosis diagnostics is critically important. Objective. Development of effective comprehensive differential bovine tuberculosis diagnosis and introduction of improved techniques for the infection detection in farms with different animal health statuses in the Republic of Dagestan. Materials and methods. 1,670 cattle were subjected to tuberculin testing; 3,502 serum samples were used for serological testing, 112 samples for immunological testing, 57 samples of pathological material collected from animals and 76 environmental samples were used for bacteriological testing. Mycobacterium bovis, Mycobacterium bovis BCG, Mycobacterium avium, Mycobacterium scrofulaceum strains were used in the study. Results. Nonspecific reactions in the farms of all categories were found to be widespread in the Republic. Diagnostic value of intradermal and intravenous tuberculin tests in tuberculosis-infected herds was determined (9.4% of extra-detected diseased animals). Complement fixation test is poorly sensitive and highly specific. © Баратов М. О., 2025 Indirect haemagglutination assay results are not confirmed by conventional methods in most cases, which suggests their low specificity. 39 mycobacterial isolates were recovered from 57 biological samples and identified: 8 (20.5%) as M. bovis ; 31 (79.5%) as non-tuberculous mycobacteria (acid-fast species), among them 29 (93.5%) were identified as Runyon II organisms, 2 (6.5%) as Runyon III organisms. 43 isolates out of 76 environmental samples were recovered: among them 2 (4.6%) were identified as Mycobacterium bovis , 23 (53.5%) as Runyon II organisms and 18 (41.9%) as Runyon III organisms. Among culture media, Löwenstein- Jensen’s egg-based medium provides the best growth performance and most effective suppression of competing microflora. Conclusion. The obtained data provide a fundamental basis for developing an effective comprehensive method for differential diagnosis of bovine tuberculosis.