CHAPTER III 



METHODS OF DISSEMINATION 



HOG cholera virus exists only in infected hogs 

 and in material contaminated by their excretions, 

 and this is the fundamental fact to which we must 

 repeatedly refer in accounting for new outbreaks. 

 There are numerous exceptions to the rule, but 

 the individual outbreak can usually be traced to 

 a definite source, and this fact is important in its 

 relation to measures for control. 



Shipping infected animals is probably the one 

 practice responsible for most new herd infections. 

 It is not uncommon for a breeder to become dis- 

 couraged when his hogs begin to die and to ship 

 all seemingly well animals to a distant market. 

 During the fall of the year especially one has but 

 to stand for a few hours at the unloading chutes 

 of some of our large stockyards in order to realize 

 how nearly universal this practice has become. 

 Thus most public stockyards harbor hog cholera 

 virus, and all hogs unloaded in them and later 

 taken to farms for feeding or breeding become 

 potential sources of danger. 



In the eastern states garbage feeding is re- 

 sponsible for more outbreaks of hog cholera than 



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