154 Agricultural Bacteriology. 



into a healthy herd, an outbreak develops, since many 

 of the animals of the herd will be very susceptible to the 

 disease. The bacteria are given off from the body of the 

 affected hog in the manure and are taken into the body 

 of the healthy animal with the food. 



No animal should be purchased from a herd in which 

 hog cholera has been present during the previous year. 

 Animals purchased should be kept in quarantine when 

 first brought onto the farm, and then placed with a small 

 part of the herd. If these exposed animals all remain 

 healthy after two to three weeks, it is safe to place the- 

 purchased animals with the herd. The method of keep- 

 ing hogs in separate houses instead of in a large hog^ 

 house has much to recommend it, for if cholera breaks out 

 in one part of the herd, it can often be kept from spread- 

 ing to the other sections of the herd. 



Hogs frequently acquire the disease from infected 

 cars, shipping crates, etc. The disease may be spread 

 from herd to herd by infected objects, such as farm tools 

 carried from one farm to another. The farmer himself 

 may inadvertantly serve to disseminate contagion, by 

 visiting his neighbor to inspect an infected herd and 

 bringing home the v virus of the disease in the slight 

 amount of manure that may cling to his shoes. Birds 

 and rats may also carry the disease. The exhibition of 

 hogs at fairs is often a means of bringing the animals in 

 contact with the disease. 



"When hog cholera is present in the neighborhood, the 

 greatest care must be taken to prevent its introduction 

 onto the farm. At the first signs of sickness in the herd, 

 all animals that appear healthy should be removed to an- 

 other field. All carcasses of hogs that have died of 

 cholera should be burned or buried very deeply, first cov- 



