CHAPTER VIII 



PATHOGENIC BACTERIA IN MILK. TUBERCULOSIS AS A TYPE 



Infective Diseases of the Cow communicable to Man by Milk. Pathogenic 

 Bacteria in Milk. Clinical Evidence ; Bacteriological Evidence. The 

 Tubercle Bacillus in Milk and Butter. Streptococcus in Milk. Tuber- 

 culosis as a Type. The Specificity of Tuberculosis ; The Biology of the 

 Bacillus Tuberculosis ; Tubercle Bacilli of Bovine and Human Origin 

 compared ; Polymorphism ; Pseudo-Tuberculosis ; Bovine Tuberculosis. 

 The Entrance of Tubercle Bacilli into Milk. Virulence of Milk contain- 

 ing Tubercle Bacilli. Powers of Resistance of Tubercle Bacillus. The 

 Acid-Fast Bacilli allied to the Tubercle Bacillus. 



We propose to deal with the disease-producing power of milk in 

 several chapters. In the present chapter general reference to the 

 subject will be made, and in particular the conveyance of tuber- 

 culosis by means of milk. The succeeding chapters will treat of 

 the chief epidemic infective diseases spread by infected milk. 



Infective Diseases of the Cow communicable to 

 Man by Milk 



Broadly speaking, the diseases of the cow which may give rise 

 to some form of disease in man are such as directly affect the 

 udder, or indirectly the milk. The chief of such diseases are 

 tuberculosis, mastitis, enteritis, and possibly foot-and-mouth 

 disease. Our views on the communicability of tuberculosis will 

 be stated subsequently, and the matter need not be discussed 

 here. It will be sufficient to say that we hold that the communi- 

 cability of this disease is possible, and may occur, between the 

 bovine species and man through the channel of milk. The disease 

 may not be chiefly, nor greatly, spread in this way, but that it 

 may be thus communicated, we do not doubt. Some facts will 

 be furnished to show the existence of the active agent of tuber- 

 culosis in cows and their milk. 



In regard to mastitis^ there is no doubt that the immense 

 majority of cases of what are called ordinary inflammation of the 



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