Infections Sen-etions and Proflufts. 5-] 3 



virulent in feeding as lyell as in inoculation experiments; in 3 cows, by inoculation 

 on'l' ion°"® ^'°^^' ^'•^' ^^^'^'^^S only (guinea pigs used in this experiment receive<l 

 8U to 1-0 ec. ot whole milk daily for 2 to 3 months). Similar results were obtained 

 by Moussu. The milk of tuberculous cows with clinically and anatomically healthy 

 udders gave positive results in 7 out of 57 guinea pigs that were treated. Calves 

 were also infected by feeding. Martel & Guerin examined 20 udders of slaughtered 

 animals; m all cases the parenchyma as well as the mammary glands were free 

 from observable lesions. The secretions of 4 of these udders proved infectious 

 lor guinea pigs. Finally De Jong found virulent tubercle bacilli in the milk 

 of 3 out of 10 cows with slight closed tuberculosis. 



One reason which led Ostertag to conclude that a transmission of tubercle 

 bacilli into the circulation did not take place under normal conditions was that 

 the inoculation of a guinea pig with milk of a cow which had received a large dose 

 of bacillary material into the circulation 11 days previously, produced negative 

 results. The experiments of Prettner who made reiieatcd injections of pure cultures 

 of tubercle bacilli into the circulation of 2 buffalo coavs, and those of Coquot & 

 Cesari who injected an emulsion of bacilli into the mammary artery gave similar 

 negative results. But Griffith demonstrated the infectiousness of milk in the course 

 of the first week after the subcutaneous injection of bovine tubercle bacilli; Titze 

 produced the same result with human tubercle bacilli. In one case they appeared 

 24 hours after the injection of the culture, in another they could be demonstrated 

 daily after the third week for 144 days and in some cases as late as 16 months 

 after the injection. As a rule they are excreted from one quarter of the udder 

 only, probably as the result of a focal infection without local symptoms. Smith 

 found that bovine as well as human bacilli injected intravenously into a cow, 

 appeared in the milk after a few days. The human bacilli appeared also in the 

 feces and the urine. The udder was not visibly affected in either case. 



When Ave take into consideration that even animals with 

 a mild infection may at any time suffer an attack of the ndder 

 throng-h metastasis, and that neither the beginning of the attack, 

 nor the stage of the disease can be recognized bv a clinical 

 examination, the claim that milk from merely reacting cows 

 may be dangerons is by no means groundless. 



In milk of normal appearance tubercle bacilli when present are 

 evenly distributed. If the milk is coagulated, watery or flaky, the bacilli 

 are usually found mostly in the solid parts. If milk is allowed to stand 

 the bacilli have a tendency to collect in the cream. Similarly the cream 

 of separator milk and the walls of the centrifuge contain the bacilli in 

 the greatest numbers. 



The milk of a single cow with an infected udder may infect a large 

 quantity of milk from healthy cows if added to it. For this reason the 

 milk from creameries or milk stations is so generally infected. Thus 

 Petri in Berlin found 14% of 64 samples infected ; Beck of the same city, 

 30% of 56 samples; Delepine & Niveau, of Manchester, 11.7% of 401 

 samples and 18.5% of 108 samples; Preisz, of Budapest, 13.8% of 58 

 samples; Eber, in Leipsic, 10.5% of 21 samples. Rabinowitsch found 

 that the mdk from creameries which demanded the tuberculin test for 

 all dairies was free from tubercle bacilli, while on the other hand where 

 only clinically infected animals had been removed the milk was found 

 infected. 



Of course, milk from healthy animals may become infected with bacilli in 

 the process of milking. There is always abundant opportunity for this in infected 

 stables, especially where the floors and the bedding have been soiled with the 

 excretions and secretions of animals with open tuberculosis. Where stables are kept 

 in a generally unsanitary condition and where careful cleansing of the udder before 

 milking IS disregarded, where the first few streams of milk are not discarded, 

 additional opportunities for infection are offered. Dirty milk utensils and soiled 

 hands of the milkers naturally play an important role in bringing about an infection 

 of the milk of otherwise healthy animals. 

 Vol. 1-33 



