INVESTIGATIONS CONCERNING THE SOURCES AND 

 CHANNELS OF INFECTION IN HOG CHOLERA 



By M. Dorset, C. N. McBryde, W. B. Niles, and J. H. Rietz 

 Biochemic Division, Bureau of Animal Industry, United States Department of Agri- 

 culture 



INTRODUCTION 



In hog cholera, as in other infectious diseases, the success of control 

 measures is largely dependent upon a knowledge of the channels through 

 which the infection is conveyed. Without such knowledge, or without 

 the ability to close the avenues of transmission, if they are known, con- 

 trol by sanitation can not succeed. It is commonly known that hogs 

 affected with cholera will transmit the disease to the nonimmunes which are 

 allowed to associate with them. It is further known that pens or lots 

 in which hogs sick of cholera have been kept are likely to harbor the 

 infection, and that healthy hogs placed in such lots are liable to con- 

 tract the disease. Many years ago, in a report issued by the Bureau of 

 Animal Industry,* the sources and channels of infection were enumerated 

 as follows: 



(a) Pigs purchased from infected herds, or coming in contact with those from in- 

 fected farms, or running over grounds occupied by diseased swine within two or 

 three months. 



(b) Infected streams may communicate the disease to herds below the soiu-ce of 

 infection. 



(c) Virus may be carried in feed, implements, and on the feet and clothing of 

 persons from infected herds and premises. 



(d) Winds, insects, birds (particularly buzzards), and various animals may trans- 

 port hog-cholera virus. 



This statement of the ways in which hog cholera is spread forms the 

 basis for our present-day sanitary regulations. It has seemed to the 

 writers that perhaps in actual practice one or more of these channels of 

 infection may be of preponderating importance, and that the determina- 

 tion of such a fact would greatly simplify the difficult problem of sani- 

 tary control. Although the experiments of the writers are not yet com- 

 plete, sufficient data have been secured to make it desirable to render 

 this report of progress, and it is hoped that others may undertake similar 

 investigations. Conditions in nature are so variable that a single series 

 of experiments can hardly yield results that would serve as a guide in 

 practice in different localities under diverse climatic conditions. 



' Hog cholera, its history, nature, and treatment. U. S. Dept. Agr. Dept. Rpt. 46, p. 123. 18S9. 



Journal of Agricultural Research, Vol. XIII, No. 2 



Washington, D. C. ( jqi ) Apr. 8, 1918 



mt Key No. A-36 



