102 ' ' ' tuberculosis. 



infected straw, etc., were avoided as much as possible, they failed in spite of numerous 

 experiments in producing tuberculosis with milk from a tuberculin reacting animal, and 

 frequently not even with the milk from an animal clinically affected, but free from 

 tuberculosis of the udder. 



From the standpoint of milk hygiene the fact is important that 

 in the work of tuberculosis eradication by the agricultural societies 

 the examinations for tubercle bacilli in the mixed milk of individ- 

 ual herds were mostly negative after the clinically affected tuber- 

 cular animals had been eliminated. According to the works of 

 Muller and Hessler until July 1907, 2,949 samples of mixed milk 

 of individual herds were examined; all of these herds were sub- 

 jected to the Siedamgrotzky-Ostertag method of eradication. From 

 30 to 200 cows participated in each test and 156 herds gave milk 

 free of tubercle bacilli. As eliminators of tubercle bacilli were 

 found : 



Two cows with udder tuberculosis, 8 times each. 



One or more COW T S with tuberculosis of the uterus, 16 times. 



One or more cows with tuberculosis of the uterus, 6 times. 



Once kidney and uterine tuberculosis. 



Once pulmonary and intestinal tuberculosis. 



Once a cow whose saliva contained tubercle bacilli and 



19 times open pulmonary tuberculosis. 



In five positive tests there was no clinically demonstrable form 

 of tuberculosis, and the subsequent tests of immediately drawn con- 

 trol samples remained negative. These five cases w r ere observed in 

 the beginning of the eradication work. 



The remaining 2,793 milk samples were free of tuberculosis in 

 spite of the fact that among the animals of these herds there were 

 surely a great number which would have positively reacted to 

 tuberculin tests. 



The five cafes observed at the beginning of the eradication work, in which the 

 milk contained tubercle bacilli, although clinically open cases of tuberculosis could not 

 be found on stable examination, are explained by Hessler in that the milk became contami- 

 nated with particles of the feces from pulmonary cases of tuberculosis, which had not yet 

 developed clinically. This is also suggested by the smaller number of bacilli found in the 

 milk. 



Tubercle bacilli therefore occur in the milk in great numbers 

 when animals with open tuberculosis, and tuberculosis of the udder 

 stand in the stable. Milk from animals which manifest their tuber- 

 culosis by a positive tuberculin reaction, will usually be free from 

 tubercle bacilli. Such cows belong to the least dangerous class. 

 Nevertheless the investigations of Rabinowitsch, Kempner, Rav- 

 enel and others, who obtained positive inoculation results with milk 

 from reacting animals, prove that such milk may at times contain 

 tubercle bacilli in small numbers. Ordinarily however this will 

 not be the case, and the milk of such animals may, as a whole, 

 be considered free from tubercle bacilli. 



Therefore it appears evident that under present conditions of 

 milk production the ingestion of tubercle bacilli with milk is possi- 

 ble at almost all times. 



