Hazards of bovine tuberculosis as a matter of public health significance and potential human lung infections with bovine tubercle bacilli.

Following discovery of the tubercle bacilli by Professor Koch, three types of the organisms were soon recognized immunologically as separate and distinct entities, i.e., the human, bovine and avian. For several years thereafter, Koch, as well as many other reputable scientists in the field of bacteriology, contended that the host-species in each category would not contract tuberculosis when exposed to other types of the bacilli and, therefore, bovine tuberculosis was not transmissible to man. However, that conclusion was later exploded and Koch, after much reluctance, finally changed his former opinion in the premise. Consequently, the transmission of tuberculosis from animal to man soon became a generally accepted fact but not without reservations as to its clinical effects. A consensus prevalied that, although trtpmnissible to man, the condition produced by the bovine tubercle bacilli was confined mainly to certain circumscribed limitations such as glandular or lymph node infections and tuberculosis of the bone and joints, but it was not considered to be more than passively capable of producing pulmonary lesions of tuberculosis. With the development of better methods and more practical means of typing, greater stress in recent years has been attached to the importance and desirability of identifying the type of bacilli actually responsible for the disease when it occurs in man. Today bovine bacilli stand convicted not only as the causative agent of a variety of clinical forms, including progressive tuberculosis in man, but pulmonary tuberculosis of bovine origin has been established either clinically or on necropsy in an increasing number of human cases, particularly in European countries where bovine tuberculosis flourishes to a much greater extent among cattle a t the present time. Also an increasing number of generalized cases of tuberculosis in humans attributed to the bovine bacilli have been reported in several of these countries.