Pathogenic and potentially pathogenic mycobacteria are able to persist in t he body of mammals and birds in the nominal form and in the non-cultivating state - NKS and L-transformed variant. Such physiologically and morphologically altered forms of existence of mycobacterial infectious pathogens are not identified by routine laboratory methods, and the pathologies induced by them have atypical or latent clinical and epizootological signs. This is a very dangerous phenomenon, because livestock products from cows latently infected with mycobacteria will be biologically dangerous for consumers.
 M. bovis was isolated and identified in one of the samples of milk obtained at a non-sanctioned point of trade during a selective unsystematic examination of the milk of cows of the individual sector. The isolated epizootic culture of M. bovis possessed typical morpho-tinctorial properties, induced HST and was highly virulent for ants and rabbits, apathogenic for chickens. A cultural study gave a negative result. It was possible to isolate the culture only in a bioassay on houseflies with intratesticular contamination of a concentrated milk sample. And already from the positive biomaterial of ants that died from the tbc genoform, a pure culture of M. bovis was obtained on the Stonebrink medium of Polish production. There was no primary growth on other media.
 The milk had high-quality organoleptic properties, was very tasty and fermented well at room temperature, and was of good quality in appearance. But it was infected with an emerging pathogen of lethal anthropozoonosis. This case shows the urgent need for express indication of pathogenic and potentially pathogenic mycobacterial prokaryotes in each milk sample.