51 



this way may be communicated by means of milk or meat 

 from diseased animals. 



(a) Milk. — Doubt no longer exists about milk from tuber- 

 cular cows being the means of conveying tuberculosis, par- 

 ticularly to infants and young children. Tubercular disease 

 of the intestines and glands is almost peculiar to children, 

 though we sometimes get it in adults as a secondary infection 

 from swallowing their own sputum. 



In such cases as these the gastric juice is weak and the 

 bacilli are then particularly active. Infection may begin at 

 the glands of the neck, or it may be a general infection or 

 extend only into the glands of the abdomen. 



Woodhead estimates that 79 per cent, of children dying of 

 tubercular disease contract it in the mesenteric glands. 

 Further, that it is most prevalent amongst children when 

 milk forms the principal article of their diet. 



Gerlach and Chauveau were the first 1o show that animals 

 fed on the milk from tuberculous cows contracted the disease, 

 Authorities are agreed that where there is a generalised 

 tuberculosis, or where the udder is affected, the milk is 

 highly infective, but they are not agreed as to whether the 

 milk may be infective in cases of local tubercular disease 

 where the udder is healthy. 



Bang, Bollinger, and Hirschberger believe that the disease 

 may be communicated by milk from tubercular cows even if 

 the udder is not affected. These observers have been able to 

 produce the disease by inoculation and by feeding experi- 

 ments with milk from a tubercular cow with a healthy udder, 

 and Woodhead and McFadjean were also able to produce 

 positive results in a very small percentage of cases ; but 

 while the negative results are the rule, nearly every observer 

 has been able to get some positive evidence. 



Klern * states " the feeding of calves with milk derived 

 from an udder containing tubercular deposits produced tuber- 

 culosis in these calves, but milk coming from a healthy udder 

 (though the cow had tubercles in the lungs) fails to produce 

 tubercles." 



The experimental researches for the recent Eoyal Commis- 

 sion seem to show that udder disease must be present before 

 the milk is infective. Milk given or inoculated into rabbits and 

 guinea pigs did not produce the disease when the udder was 

 not affected, though the cow had advanced tuberculosis. Still, 

 in view of the positive results obtained by different observers 

 by the feeding of animals with milk from tubercular cows in 

 which there was no udder disease, it would be much better 



* Pathology of Infectious Diseases. 



