232 HOG CHOLEKA 



made to check them the advantages of such efforts 

 become self-evident. 



It is not impossible to eradicate hog cholera. 

 The task presents no such difficulties as are en- 

 countered in the eradication of bovine tuberculo- 

 sis, for instance. Hog cholera does not exist long 

 unknown to the owner of the herd it infects; indi- 

 viduals apparently well do not regularly live year 

 after year disseminating the virus ; deaths due to 

 it are rapid and certain and the resulting losses 

 are obvious; it is a foe that strikes in the open. 

 The disease can be stamped out quickly in any 

 herd, and there is an immunizing agent so effec- 

 tive that prompt reporting is the breeder's surest 

 way to avoid loss. When we reflect on the sig- 

 nificance of these facts we may well be led to 

 wonder why the disease does not disappear. The 

 truth is that it does tend to do so, for undoubtedly 

 there are to-day many counties free from the dis- 

 ease that have suffered severely from it in past 

 years, and that will suffer again when the virus 

 once more is introduced from without. 



When once the virus finds its way into a locality 

 the methods by which it may spread from herd to 

 herd are innumerable but it is time that we direct 

 our attention to the sources of the original infec- 

 tions. We dissipate our energies in trying to con- 

 trol outbreaks of huge proportions instead of 

 concentrating them on the prevention of primary 



