302 INFECTIOUS DISEASES 



teenth century. It was introduced into England about 1839, and 

 in 1870 into Canada tliroui>li the importation of cattle from 

 England. From Canada the disease spread to the United 

 States. Very few animals were infected during the 1870 out- 

 break, and the disease was quickly stamped out in both countries. 



Europe has been unable to eradicate foot-and-mouth dis- 

 ease. The different outbreaks that occur from time to time cause 

 enormous financial loss. In the United States outbreaks of the 

 disease have occurred in the following years: 1870, 1884, 1902- 

 '03, 1908 and ]914-'15. In the first two outbreaks very few 

 cattle contracted the disease, and the infection was quickly 

 stamped out. The third and fourth outbreaks were more exten- 

 sive, and it was necessary to slaughter several thousand cattle 

 and hogs in order to eradicate the disease. The first four out- 

 breaks occurred in the eastern States, and the disease was pre- 

 vented from spreading to the principal live-stock centers of the 

 country, and the leading stock-raising States by slaughtering 

 the diseased and exposed animals and by county and State 

 quarantines. Early in the 1914-'15 outbreak, the disease spread 

 to the Chicago Stock Yards, and from there, through shipments 

 of cattle, to the princij)al live-stock sections of the country. The 

 financial loss resulting from this outbreak has amounted to several 

 million dollars. The Federal and State authorities have always 

 been successful in stamping out the disease in the United States. 



The specific cause of foot-and-mouth disease is a filterable 

 virus that is present in the serum from the vesicles, the saliva, 

 milk, and various body secretions and excretions from the sick 

 animal. In the early stage of the disease it is present in the 

 blood. None of the many investigators have been able to discover 

 the microorganism that produces the disease. 



Two of the outbreaks of foot-and-mouth disease in the United 

 States originated from an infected vaccine used for the inocula- 

 tion of vaccine heifers. The origin of the 1914-'15 outbreak has 

 not been discovered. "When introduced into a country, the dis- 



