CONTROL OF HOG CHOLERA. 33 
ever, the case is different. There the disease is as widespread as it 
is in the United States. There, as in Canada, for many years the 
policy of quarantine, slaughter, and disinfection has been followed, 
but not with the same success. Hog cholera still exists and at certain 
times shows the same tendency to increase that is observed in the 
United States, where no country-wide systematic effort at control has 
ever been attempted. A number of factors have no doubt operated to 
prevent success in Great Britain by methods which have seemed to be 
effective in Canada. Among the most important of these may be men- 
tioned a large number of hogs in proportion to area, wide dissemi- 
- nation of the disease, and numerous avenues of communication and 
traffic through which the disease may be spread. 
SSRSSRRVE 
g 
70,000 
65,000 
FS5,000 
40,000 
SIOO0O 
FO OOO 
25,000 
£0,000 
ae a eh ie EN cages 
10,000 : 
poe (eaclnol shel [a0] Portas lodualoalidoah alah 
eA nme ena ae ee 
Fic. 2.—Course of hog cholera in Great Britain, 1894 to 1916. 
The course of the disease in Great Britain during the past 23 
years 1s indicated in figure 2. 
With the experience of Great Britain as an example, we in the 
United States with widespread disease, great numbers of hogs, and 
many channels of communication to serve as conveyors of infection 
could certainly not enter upon a campaign of eradication by quaran- 
tine and slaughter with any assurance of success, despite the fact 
that at first glance the problem appears to be simple. Then, too, 
