vii TUBERCULOSIS OF THE COW 131 



In illustration of the close relationship between the 

 presence of tubercle bacilli in the milk and the presence of a 

 case of udder tuberculosis in the herd, the investigations of 

 Delepine, 1 dealing with the inoculation of milk samples from 

 Manchester and the surrounding districts, may be cited. Out 

 of 1385 farms 294 were found to be supplying tuberculous 

 milk. In consequence of this fact 276 of these farms were 

 inspected, and in 190 of them the veterinary surgeon, with 

 the help of the bacteriologist, was able to discover one or more 

 cows with tuberculous udders. After the removal of those 

 cows the milk generally ceased to produce tuberculosis in 

 guinea-pigs when examined on one or more occasions after- 

 wards. In the remaining cases (about 3 1 per cent) the source 

 of infection could not be found. From the inquiries made at 

 these 86 farms Delepine found that in at least 32 cases cows 

 had been sold between the time of collecting the sample and 

 examining the cows ; in others, the farmer had been buying 

 rnilk from other sources. From his inquiries he believes that in 

 most of these cases the source of the tubercle bacilli was from a 

 cow not on the farm, and gives as his estimate the following : 



Per cent. 



Tuberculous udders the cause of infection . . . 7 8 '6 

 ,, probably the cause of infection . 16*0 



Nothing definite to connect infection with the state of 



the cow ........ 5-2 



The fact, however, remains, that in 3 1 per cent of the cases 

 a cow with a tuberculous udder was not found, and its 

 presence could only be deduced with more or less probability 

 in a number of the cases. It is unfortunate that the mixed 

 milk from each of the herds which gave tuberculosis to 

 guinea-pigs, but which contained no cow with a tuberculous 

 udder, was not re-inoculated to see if it could then set up 

 tuberculosis. 



While these results emphasise the great significance of the 

 tuberculous udder, the writer reads them as also showing the 

 infectivity of milk without udder lesions, and to a greater 

 extent than Delepine admits, the more especially as the 

 diagnosis of udder tuberculosis was made with the assistance 

 of the bacteriologist. 



1 Report of Medical Officer, Local Government Board, 1908-9, p. 341. ' 



