Problems of paraallegic reactions to tuberculin in cattle

The article presents the results of the analysis of epizootic, clinical, simultaneous allergic study of cattle for tuberculosis and bacteriological examination of samples of biomaterial, feed, scrapings from feeders, and feces. It was found that over four years, 87 cows reacting to tuberculin were detected on the farm, among which no clinically sick cows were found. In four simultaneous allergy tests of cattle, 45 cattle were found to be reactive to tuberculin and an atypical mycobacterial allergen (AAM). In 41 animals, reactions to AAM were more intense compared to reactions to mammalian tuberculin. Mycobacterial cultures were isolated from biomaterial from 4 cows, as well as samples of feed, feces from walking areas, and scrapings from feeders, which were positively stained by the Ziehl-Nielsen method. According to the cultural, morphological, and biochemical characteristics, the isolated mycobacterial isolates belonged to the species M. phlei and M. fortuitum, which did not cause the development of tuberculosis in guinea pigs, but caused sensitization to tuberculin and AAM. These results suggest that atypical mycobacteria persisting in the body of cattle cause short-term sensitization to mycobacterial allergens. To control the epizootic situation with tuberculosis and to determine the nature of allergic reactions, as well as to differentiate specific from paraallergic and pseudoallergic reactions in safe farms, it is necessary to use a comprehensive method of testing livestock for tuberculosis. Application of this research method allowed us to determine the nature of allergic reactions to tuberculin in a short time (within 1-3 months), to keep 41 healthy animals in the herd, and to reduce economic losses caused by unjustified slaughter of productive animals