TUBERCULOSIS 155 



is opportunity for milk to serve as a transporting agent of 

 di>eise-prodiK-ing organisms from the farm to the city, not 

 at infrequent intervals, hut daily throughout the year. 

 The milk is subject to contamination with the organisms 

 causing disease in the milk-producing animal, and also with 

 those of man. Man is susceptible to a number of diseases 

 that primarily affect cattle. These facts place milk first 

 amon<r the inanimate objects in the distribution of disease. 

 The diseases most often spread by milk are tuberculosis, 

 typhoid fever, diphtheria, and scarlet fever. Some idea 

 of the importance of milk as an agent in the distribution of 

 disease is shown in the following summary of epidemics 

 that were traced to milk in Boston in the interval 1907 to 

 1911. 



1907 Diphtheria 72 cases 



1907 Scarlet Fever 717 cases 



1908 Typhoid Fever 400 cases 



1910 Scarlet Fever 842 cases 



1911 Tonsilitis 2,064 cases 



Water is probably to be classed as second in importance 

 to milk in the distribution of disease-producing organisms. 

 \Yhile some disease organisms can live in water for a vary- 

 ing period of time, this medium does not offer the oppor- 

 tunity for actual growth that milk does. Typhoid fever 

 is the principal disease that is water-borne. 



Bovine tuberculosis. A detailed discussion of this dis- 

 ease will be presented in a subsequent chapter. Only the 

 facts relevant to the relation of the disease in cattle to tu- 

 berculosis in man will be presented here. Tuberculosis is 

 a disease that affects many portions of the body. It is 

 characterized by the formation of nodules or tubercles, 

 which gradually increase in size, giving rise to abscesses, 

 the contents of which contain the tubercle bacilli. When 



