SECTION VIII 



INFECTIOUS DISEASES 



HOG CHOLERA 



HOG cholera is a specific septicemic disease of 

 swine. It is contagious and infectious, and may 

 be either acute or chronic. The disease is 

 characterized by tissue hemorrhages and complications 

 of the intestinal mucosa and, less frequently, by hemor- 

 rhages of the lungs. 



Geographical distribution. The first identified 

 outbreak of hog cholera in the United States occurred in 

 Ohio in 1833. From this original center it has spread 

 widely and now prevails more or less continuously in 

 every state of the Union as well as in the surrounding 

 countries, including the island possessions of the United 

 States. The disease was positively recognized in England 

 in 1826, and it still prevails there. In 1896 approximately 

 one third of the swine population of England died of 

 cholera. The disease was introduced into Denmark in 

 1887, and spread into Sweden the same year. It also 

 appeared in France in 1887. Hog cholera, or a very 

 similar disease, appeared in Germany in 1866, Prussia, 

 Austria, and Hungary were invaded in 1895. From all 

 reports, it is apparent that hog cholera prevails in prac- 

 tically every country in which swine are maintained. 



Hog cholera was first investigated systematically in 

 America in 1885, under the directions of Salmon. The 

 disease was thought, and apparently proved at that time, 

 to be due to a short, rod-shaped bacteria. 



De Schweinitz and Dorset further investigated the 

 disease in 1903, and the Bureau of Animal Industry have 

 continued their investigations up to the present time. 



Extent. Information obtained from various sources 

 indicates that hog cholera has been prevalent in America 



169 



