HOG-CHOLERA 271 



The excliange of help at thresliiiiii; and shreddiiiij;' time in noigli- 

 borhoods where there is an outbreak of hog-cholera is the most 

 common method of spreading the disease. Visiting farms where 

 hogs are dying of cholera ; walking or driving a team and wagon 

 throngh the cholera-infected yards; stock buyers, stock-food and 

 cholera-remedy venders that visit the different farms in a neigh- 

 borhood may distribute the hog-cholera virus through the infected 

 filth that may adhere to the shoes, horses' feet and wagon wheels. 

 Cholera hogs may carry the disease directly to a healthy herd 

 when allowed to run at large. Streams that are polluted with the 

 drainage from cholera-infected yards are common sources of 

 disease. 



Pigeons, dogs, coirs and buzzards that travel about the 

 neighborhood and feed in hog yards and on the carcasses of 

 cholera hogs may distribute the disease. Because of the active 

 part that dogs, birds and surface drainage take in the distri- 

 bution of hog-cholera, the practice of allowing the carcasses of 

 dead hogs to lie on the ground and decompose is responsible for 

 a large percentage of the hog-cholera outbreaks. 



Age is an important predisposing factor. Young hogs are 

 most susceptible to cholera, and this susceptibility can be greatly 

 increased by giving them crowded, filthy quarters. Infection 

 with lice, lung and intestinal worms, the feeding of an improper 

 ration and sudden changes in the ration lower the natural 

 resistance of a hog against disease. Pampered hogs usually 

 develop acute cholera when exposed to this disease. 



Hog-cholera is more virulent or acute during the summer and 

 fall months than it is during the winter and spring months. 

 After the disease sweeps over a section of country, it becomes 

 less virulent and takes on a subacute or chronic form. Out- 

 breaks of hog-cholera usually last two or three years in a neigh- 

 borhood. This depends largely on the number of susceptible 

 hogs that were not exposed to the infection the first season, and 

 the preventive precautions observed by the owners. 



