448 MILK 



this phenomenon, the first of which is the existence of acid-proof 

 bacilli which, when stained, simulate tubercle bacilli. This dif- 

 ficulty was eliminated when animal inoculation tests were recog- 

 nized as the only reliable method of determining the presence of 

 tubercle bacilli in milk. 



The second fact is the presence of large numbers of tubercle 

 bacilli in the dejecta of tuberculous animals. These dejecta 

 communicate bacilli to the milk through the air or by any other 

 means which permit the entrance of cow manure into milk. 

 Schroeder has made extensive investigations of this subject, and 

 has come to the conclusion that the dejecta are the chief source 

 of contamination, inasmuch as he found that 40 per cent, of 

 tuberculous cows emitted tubercle bacilli with the feces. All 

 investigators do not agree with this opinion, and considerable 

 uncertainty is involved in the results obtained, since some observ- 

 ers base their opinions on microscopic examinations, while others 

 test the virulence on guinea-pigs. Peterson's results, for example, 

 are by no means in agreement with those of Schroeder. Moore 

 has stated that milk is usually infected with tubercle bacilli when 

 it is taken from cows with tuberculous udders. It may, through 

 contamination with feces or uterine discharges, be infected when 

 drawn from cows with open lesions in the respiratory tract or 

 organs of reproduction. 



"Tubercle bacteria are not, as a rule, present in milk of cows 

 that react to tuberculin and which, on careful physical examina- 

 tion, exhibit no evidence of disease." 



Jordan and Arms found that 26.66 per cent, of feces from cows 

 which were shown to be tuberculous by the tuberculin test and 

 by autopsy contained tubercle bacilli. 



Unquestionably, a large percentage of tuberculous animals 

 discharge tubercle bacilli with their feces, and from this source 

 the bacteria easily gain access to milk. The consequence is that 

 milk from perfectly healthy animals may become contaminated 

 with tubercle bacilli. 



Diseased udders are surely the most prolific means of infecting 

 milk with tubercle bacilli. Moore states that "the number of 

 tubercle bacteria in market milk would be greatly reduced and 

 possibly entirely (?) eliminated by having frequent and thorough 

 physical examinations of the dairy cows, and the removal from the 

 herd of all individuals showing evidence of disease." 



Infection of cows with tuberculosis may occur by inhalation 

 or by ingestion. The latter mode is probably more common than 

 the former and, as a matter of fact, the disease frequently settles 

 on the peritoneum. But opinions on the subject are not entirely 

 in accord. Tubercle bacilli, like other bacteria, are destroyed by 



