INFECTIOUS DISEASES I33 



dying, depends on the thoroughness with which 

 they are cleaned and disinfected. If the litter and 

 filth are not removed, the germs may live for 

 months. All litter about ithe yards must be 

 burned or removed to some place where the hogs 

 cannot come in contact with it, and whitewash 

 and disinfectants used freely. If the cleaning and 

 disinfecting is properly done, fresh hogs may be 

 brought onto the premises within a few weeks 

 after the disease has been checked without fur- 

 ther loss occurring^ but it is usually best to wait 

 two or three months before stocking up again, or 

 depend on the hogs that have survived the disease 

 for a fresh start, as there is some danger of a 

 second outbreak and the infection continuing for 

 a longer time. Where it is practical, the hogs 

 should be moved to another part of the farm and 

 new and better yards built. 



Serum-Therapy and Vaccination. — For a num- 

 ber of years, the Bureau of Animal Industry have 

 been experimenting with an anti-hog-cholera 

 serum and a vaccine, but satisfactory results from 

 this line of treatment have not been reported. In 

 the Twentieth Annual Report, Dr. Salmon states 

 that this line of experimental work will be continued, 

 and at some time in the near future a full report of 

 the work of investigation will be issued. 



There are several companies in this country 

 manufacturing so-called vaccines and antitoxins. 

 The commercial antitoxins are said to contain no 

 live hog cholera germs. Such preparations can be 



