10 



In America the disease was introduced with early importations of cattle 

 and has been with us ever since. Modern methods of transportation by rail 

 and water have spread the disease from one end of the continent to the other. 

 N"o part of the country is entirely free from it, but it is more prevalent near 

 the great centres of population than in the remoter parts. 



IMPORTANCE. 



The importance of the disease must be estimated from two points of view, 

 first, the loss it entails upon the cattle owner, and second, the danger of com- 

 munication to human beings. 



Consider first its efi"ect upon the pocket of the owner of cattle, whether 

 farmer, breeder or dairyman. A serious percentage of the dairy cows of the 

 continent are affected and the disease is found in even a larger percentage of 

 dairy herds. 



The disesise is commoner in some regions than in others. 



It is no uncommon thing to find as many as 70 per cent or 80 per cent of 

 the cows in a herd diseased.* These animals will be in various stages of the 

 disease, some re2ently infected showing no sign of ill health, others badly 

 diseased, but outwardly appearing healthy, while a few are evidently breaking 

 down and wasting away. 



The loss to the owner is evident when a cow dies of the disease, or when 

 an apparently healthy cow is slaughtered for beef and found so badly affected 

 as to be unfi^t for food. 



The calves in such a herd do not long remain healthy. They catch the 

 disease before many months old and are a source of loss instead of gain. 



Although the disease is most frequently found in herds that are more or 

 less closely confined, such as dairy herds and pure bred cattle, other herds are 

 by no means free from it. Even range cattle are sometimes affected and the 

 infection spreads in spite of the open air life of the cattle. 



Tuberculosis is common among hogs. The public abattoirs report that 

 a serious percentage of all hogs inspected is found to be tuberculous. 



The aggregate of these losses among cattle and hogs is enormous, amount- 

 ing to millions of dollars every year, besides materially decreasing the food 

 supply of the country. 



Turning to the other aspect of the case, the danger of infection of human 

 beings with tuberculosis from cattle, we have only to consider a few facts to 

 realize its vital importance to every community. 



Milk is the staple food of infants and young children and is usually taken 

 in the raw state. If this milk is from a tuberculous cow, it may contain mil- 

 lions of living tubercle germs. Young children fed on such milk often contract 

 the disease, and it is a frequent cause of death among them. 



Meat from tuberculous cattle is not so likely to convey the infection for 

 several reasons. It does not so frequently contain the germs, cooking deslfroys 

 tjjose that may be present, and lastly, meat is not consumed by very young 

 children. 



