1036 BACTERIA IN AIR, SOIL, WATER, AND MILK 



has long been a subject of controversy. That the bacilli may easily 

 enter the milk, when tuberculous disease o'f the udder is present, 

 stands to reason and is universally conceded. It is now believed 

 also, on the basis of much experimentation, that in systemically 

 infected cows tubercle bacilli may pass through the mammary glands 

 into the milk, without evidence of local disease in the secreting 

 gland. An experiment performed by the Royal British Tuberculosis 

 Commission 39 illustrates this point. A cow, injected subcutancously 

 with tubercle bacilli behind the shoulder, began to discharge tubercle 

 bacilli in the milk within seven days after inoculation and continued 

 to do so until death from generalized tuberculosis. 



Milk may become indirectly contaminated, furthermore, with 

 tubercle bacilli emanating from the feces of cows. It has been 

 shown that tubercle bacilli are present in the feces of cattle so early 

 in the disease that diagnosis can be made only by a tuberculin 

 test. 40 



Whether or not contaminated milk is common as an etiological 

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

 unsettled 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 

 during 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, 41 Kossel, Weber, and Huess, 42 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 comparatively susceptible 

 to bacilli of the bovine type. Whether or not such infection will 



30 Quoted from Mohlcr, P. TT., and Mar. Hosp. Serv. Bull. 41, 1908. 



40 KcJirocdcr and Cotton, Bull. Bureau Animal Industry, Wash., 1007. 



41 8 milk, Trans. Assn. Ainer. Physic., 18, ]JM):'.. 



4 - Kossel, Weber, and Huess, Tubcrkul. Arb. a. d. kais. Gesimdheitsamt, 1904, 

 1905, Hft. 1 and 3. 



