DISEASES COMMUNICABLE IN MILK 



35 



three out of 10 cows that he examined were passing tubercle bacteria 

 in the milk and also the British Royal Commission found two out of four 

 cows with sound udders to be passing the germs in the milk. 



Market milk presents still a different aspect because the germs of 

 tuberculosis may be derived not only from cows with tuberculosis of 

 the udder but from any animal that has an open case, and even from hu- 

 man sources. Consequently such milk might be expected to be slightly 

 infected somewhat constantly. Table 16 presents the important Euro- 

 pean and American studies of the frequency of infection of market milk 

 with tubercle bacilli. 



TABLE 16. TUBERCLE BACTERIA IN MARKET MILK (a) 



(a) Compiled from table of BRISCOE and MACNEAL and from other sources. 



(6) Work done for East Prussian Herd Book Society with the object of detect- 

 ing and removing cattle with udder lesions. 



(c) Tests made at the time the city was starting a crusade against slop dairies and 

 the figures are probably too high to be applied to the average country herd supply- 

 ing the city. DR. B. C. FRAZIER states that in the tuberculin tests of between 600 

 and 1,000 cows in 1916 but three reactors were found. 



Of the Washington investigation it may be said that tuberculin tests 

 of herds supplying the city has shown 214 reacting animals out of 1,147 



