’ 
2 BULLETIN 584, U. S. DEPARTMENT OF AGRICULTURE. 
the very fatal yellow fever of human beings. The fact that the 
precise nature of the microorganism causing hog cholera has not 
been determined does not seem, however, to be an insuperable bar- 
rier to successful methods of control, for it is recognized that the 
virus is propagated exclusively in the bodies of infected hogs and 
from them conveyed to others. Knowing this, at first thought the 
problem of control would seem to be comparatively simple. Quaran- 
tine or slaughter of infected herds, supplemented by careful disin- 
fection, are clearly indicated as effective measures. But these are 
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Fic. 1.—Losses from hog cholera in the United States, years ending March 31, 1894-1917, 
inclusive. 
drastic measures, and before their adoption the cost of their enforce- 
ment must be weighed against the chances of success and the relative 
advantages of other modes of procedure. 
In Canada there are several million hogs, but cholera has never been 
widespread there. When it has occurred the veterinary authorities 
have promptly checked the disease by quarantining the farm, slaugh- 
. tering all hogs, disinfecting the premises, and prohibiting the re- 
stocking of the farm for a period of three months. In Canada, then, 
we apparently have an instance of the successful control of cholera 
by quarantine, disinfection, and slaughter. In Great Britain, how- 
