KEPORT OF THE BUEEAU OF ANIMAL INDUSTRY. 149 



in natural waters, we are forced to assume that they^ may live at least 

 a month in streams. This would be time enough to infect every herd 

 along its course. 



(c) Hog cholera germs are not immediately destroyed by drying. 

 Laboratory experiments show that they may retain their vitality 

 from two to four months. Hence it is not difficult to see how a per- 

 son walking on infected ground and among infected animals may 

 carry on his shoes and clothing dried germs of the disease to any 

 neighboring herd. For the same reason, hog cholera germs may be 

 carried from infected grounds to others by feed, and by farming im- 

 plements which have come in contact with infected ground. 



(d) There is no reason to suppose that currents of air have much 

 influence in spreading the disease. Observations at the Experiment 

 Station of the Bureau have left no doubt that healthy pigs may be 

 kept on the same farm with diseased ones in pens not more than 100 

 feet from the sick without becoming infected, provided the infec- 

 tion is not carried in feed and implements, or on the shoes and cloth- 

 ing of persons, from the sick to the healthy. Moreover, the disease 

 is an intestinal malady, and all evidence points to infection through 

 the food rather than through the air inspired. 



The agency of flies and other insects is, perhaps, equally limited 

 when infection is to be carried from one place to another. Our exper- 

 iments show very well that the sting or bite of an insect can not be 

 sufficient to produce the disease. It is possible, however, that they 

 may carry the virus from one place to another in the same yard. 

 This will be discussed more fully under another head. 



The agency of buzzards in distributing the disease in the Southern 

 States seems probable, although there is no positive proof. These 

 birds will readily consume carcasses of dead swine. If the hog chol- 

 era germs are not destroyed by digestion it is reasonable to assume 

 that the f eces contain the living germs, which may cause the disease 

 to break out at some distant place. Of course the remedy would be 

 to immediately destroy or bury dead animals. 



There is some reason to believe that rats, dogs, and perhaps other 

 small animals may carry the germs upon their feet or in their hair 

 and thus infect premises. It is probable that the contagion is only 

 rarely transported in this manner, but there are outbreaks the origin 

 of which it is difficult to explain otherwise. 



Granted, then, no communication between infected and uninf ected 

 farms, there still remains the danger of infected water-courses, upon 

 which it is impossible to lay too much emphasis. In fact, if the dis- 

 ease exists anywhere along a stream all farms below that point are 

 liable to infection unless use of the water in any form whatever is 

 given up during the season. 



By paying particular attention to these points there is no doubt 

 that the disease can be warded off even when in the immediate 

 neighborhood. Hog cholera is analogous to typhoid fever, dysentery, 

 and Asiatic cholera in man in many particulars, and there is a quite 

 unanimous opinion that these diseases are most commonly trans- 

 mitted through drinking water. The same may be predicated of 

 hog cholera, and the mysterious spread of this plague will no doubt 

 frequently be understood by examining the water-courses. 



When the disease -is in the neighborhood it has been customary 

 with some to feed swine on a so-called "preventive' 7 medicine. 

 These are frequently prepared or invented by individuals who have 

 little, if -any, knowledge of the action of medicines. The outcome 



