FOOT-AND-MOUTH DISEASE. 415 



As witli Other comnmnieable diseases, the source and 

 origin of foot-and-mouth disease have given rise to 

 much speculation. The disease had been known in 

 Europe for centuries, but it vs^as not until comparatively 

 recent years that the erroneous conceptions of its spon- 

 taneous origin as a result of climatic and meteorological 

 conditions, exhausting journeys, etc., weve abandoned. 

 It is now conceded that foot-and-mouth disease is propa- 

 gated by a specific virus and that every outbreak starts 

 from some pre-existing outbreak. 



Investigators have so far been unable to identify or 

 isolate the specific organism causing the disease, al- 

 though numerous attempts have been made to cultivate 

 and stain it by laboratory methods. Experiments have 

 shown that the virus will pass through standard germ- 

 proof filters, thus indicating its minute size and the 

 reason it has not been detected by the staining methods. 

 The contagion may be found in the serum of the vesicles 

 on the mouth, feet, and udder; in the saliva, milk, and 

 various secretions and excretions ; also in the blood dur- 

 ing the rise of temperature. 



A wide distribution of the virus and a rapid infection 

 of a herd is the result. Animals may be infected directly, 

 as by licking, and in calves by sucking, or indirectly by 

 such things as infected manure, hay, utensils, drinking 

 troughs, railway cars, animal markets, barnyards, and 

 pastures. Human beings may carry the virus on their 

 shoes and clothing and transmit it on their hands when 

 milking, since the udder is occasionally the seat of the 

 eruption. It may also be carried by dogs, cats, rats, 

 chickens, pigeons, etc. Milk in a raw state may also 

 transmit the disease to animals fed with it. 



The observations made by some veterinarians would 

 lead us to suppose that the virus is quite readily de- 



