UNITED STATES DEPARTMENT OF AGRICULTURE 
%; BULLETIN No. 584 ¢ 
Contribution from the Bureau of Animal Industry 
A. D. MELVIN, Chief 
Washington, D. C. Vv October 13, 1917 
THE CONTROL OF HOG CHOLERA, WITH A DISCUSSION 
OF THE RESULTS OF FIELD EXPERIMENTS. 
By A. D. MELVIN, Chief of the Bureau of Animal Industry, and M. Dorset, 
Chief of the Biochemic Division. 
CONTENTS. 
Page. Page 
Nature and prevalence of hog cholera......- 1 | Results of field experiments...........-.-.--- 7 
The serum method of control..........-....- 4 | The combating of hog cholera.._......-..--- 13 
Bieldtexperiments seesseccs sos ee seek e eee ee 5s PSMA Y oss wre epareta ciaice Hoeeraaewe seer eeienee 17 
NATURE AND PREVALENCE OF HOG CHOLERA. 
During the past three decades hog cholera has probably caused 
greater loss to the farming communities of the United States than 
any other animal plague. Originally appearing in the States of the 
Atlantic seaboard and of the Ohio Valley, it has gradually spread 
over the entire country, until at the present time the disease may be 
said to exist in endemic form in all parts of the United States. It 
is not always equally prevalent, but, on the contrary, at intervals 
assumes the character of a severe epizootic, sweeping over the entire 
country, only later to subside for a period of years, after which it 
again increases in prevalence. This characteristic of periodic preva- 
lence is well illustrated by the accompanying chart (fig. 1) prepared 
from statistics collected by the Bureau of Crop Estimates of the 
United States Department of Agriculture. 
For many years it has been known that hog cholera is an infectious 
disease, produced by a specific microorganism which develops in the 
bodies of affected hogs. Only swine are susceptible. The existence of 
the infectious agent in the bodies of infected hogs may be: readily 
demonstrated, but all efforts to isolate and grow the virus in labora- 
tories have resulted in failure. The microorganism in this respect 
resembles those which cause foot-and-mouth disease of animals and 
4571°—17—Bull. 584_—1 
