708 BACTERIA IN AIR, SOIL, WATER, AND MILK 



factor in human tuberculosis, must be considered at present as an un- 

 settled question. Behring, at the Congress of Veterinary Medicine, 

 at Cassel, in 1903, advanced the view that pulmonary- tuberculosis in 

 adults may be a late manifestation of a milk infection contracted dur- 

 ing infancy. He stated as his own opinion, moreover, that most cases 

 of tuberculosis in man are traceable to this origin. The problem is as 

 difficult of solution as it is important. In bottle-fed infants, infection 

 by means of milk unquestionably occurs with considerable frequency. 

 Smith,'^ Kossel, Weber, and Huess,^ and others, have isolated tubercle 

 bacilli of the bovine type from the mesenteric lymph nodes of many 

 infected children. Animal experimentation has, furthermore, revealed 

 that lesions in the mesenteric nodes, as well as later in the bronchial 

 lymph nodes, may occur as a consequence of feeding tubercle bacilli, 

 without any demonstrable lesions in the intestinal mucosa. It is thus 

 certain that infection by the ingestion of tuberculous milk may occur, 

 especially among young children who, as is well-known, are com- 

 paratively susceptible to bacilli of the bovine type. Whether or not such 

 infection will account for many cases of tuberculosis in adults is a ques- 

 tion which, for final solution, will require much more investigation. The 

 sole reliable method of approaching it lies in determining the tjrpe, 

 human or bovine, of the baciUi present in a large number of cases. Ex- 

 perience thus far seems to indicate that the bovine type is comparatively 

 rare in the pulmonary disease of adults. 



The value of the tuberculin reaction for diagnosis, and the elimination 

 of all cattle showing a positive reaction, for the prevention of tubercu- 

 losis, can not be overestimated. The failure of the test in diseased 

 animals is rare, and an accurate diagnosis can be established in over 

 90 per cent of diseased animals.^ The assertion that the cattle are 

 permanently injured by tuberculin injections is without scientific basis. 

 If this test were conscientiously carried out, and infected cattle elim- 

 inated, the dangers from bovine bacillus infection would be practically 

 eliminated, for there are but few instances in which science has been able 

 to furnish such definite information for absolute protection. It is need- 

 less to say, however, that the carrying out of such precautions is 

 subject to great expense and great diSiculties of organization. 



Dairy inspection is practiced in the vicinity of many of our larger 



> Smith, Trans. Assn. Amer. Physic, 18, 1903. 



'Kossel, Weber, and Huess, Tuberkul. Arb. a. d. kais. Gesundheitsamt, 1904, 

 1905, Hft. 1 and 3. 

 » MoMer, loc. cit. 



