ETIOLOGY 



303 



drinking the unboiled milk of animals suffering from the 

 disease. The mortality is not high. 



§ 227. History. Foot and mouth disease was quite 

 accurately described in the eighteenth century. Very destruc- 

 tive outbreaks are reported in 1S09 and in the early part of the 

 nineteenth century it was the source of much loss in southern 

 Europe. In 1883, Great Britain lost heavily from its ravages. 

 In 1S92, Prussia is reported to have had 8,000,000 cattle 

 affected. It was during the years 1890 and 1893 that the last 

 severe epizootic appeared in Germany. 



S 228. Geographical distribution. This disease seems 

 to be very largely restricted to Europe although it is alleged 

 to have been introduced into almost every cattle raising coun- 

 try. Its invasion into the United States has been prevented 

 by the enforcement of rigid quarantine measures. 



§ 229. Etiology. The specific cause of foot and mouth 

 disease has not been clearly demonstrated. It is generally 

 believed, however, that it is caused by a specific infection and 

 that every outbreak starts from some previous case or cases. 

 The virus is contained in the eruptions and given off from the 

 mouth and feet causing its wide distribution. Animals may 

 be infected directly by coming in contact with the disease, or 

 indirectly by being exposed to the virus in stables, cars or 

 other places recently occupied by infected animals. It is stated 

 that the virus is destroyed in a short time by drying, but some 

 writers maintain that it will persist for several months. 

 Animals that have passed through the disease ma}' carry the 

 virus for several months. The infected matter maj- be carried on 

 the clothing or hands of human beings and thus be transmitted 

 to animals or men. Milk is often the carrier of the virus. 



§ 230. Symptoms. The symptoms of foot and mouth 

 disease vary greatly in different epizootics, sometimes they are 

 quite mild and at others very severe. The first evidence of the 

 disease is a rise of temperature which in cattle rarely exceeds 

 104° F. This follows after a period of incubation of from 3 to 

 5 days although in rare cases it may be shorter or longer than 

 these limits. The mucous membrane of the mouth becomes 

 reddened, the appetite is diminished, and rumination ceases. 



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