FOOT-AND-MOUTH DISEASE. 883 



live animals, owing to its short period of incubation and to the 

 90-day quarantine for cattle (counting from date of shipment) and 

 15-day (counting from date of landing) quarantine for sheep and 

 other ruminants and swine which are at present enforced in the 

 United States at all ports of entry. 



FOOT-AND-MOUTH DISEASE. 



[PI. XXXIII.l 



Foot-and-mouth disease, also known as aphthous fever, epizootic 

 aphtha, and eczema contagiosa, is an acute, highly communicable 

 disease chiefly confined to cloven- footed animals and characterized 

 by an eruption of vesicles or blisters on the mucous membrane of the 

 mouth and on the skin between the toes and above the hoofs. The 

 vesicles rupture, forming erosions and ulcerations; there are also 

 salivation, tenderness of the affected parts, loss of appetite, lameness, 

 emaciation, and diminution in the quantity of milk secreted. 



The tremendous ravages of the disease are seen in the number and' 

 variety of the species attacked. While it may be regarded as essen- 

 tially a disease of cattle, hogs would seem to be as easy a prey. 

 Almost in the same grade of receptivity are sheep and goats. Next 

 in order of susceptibility come the buffalo, American bison, camel, 

 chamois, llama, giraffe, and antelope. Horses, dogs, cats, and even 

 poultry may occasionally become infected with the disease, the last 

 three being particularly dangerous as carriers of the contagion. 

 Man himself is not immune, and the frequency of his infection by 

 coming in contact with diseased animals is established by numerous 

 observations. 



As with other communicable 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 was not 

 until comparatively recent years that the erroneous conceptions of 

 its spontaneous origin as a result of climatic and meteorological 

 conditions, exhausting journeys, etc., were abandoned. It is now 

 conceded that foot-and-mouth disease is propagated by a specific 

 virus and that every outbreak starts from some preexisting outbreak. 



So far investigators have been unable to identify or isolate the 

 specific organism causing the disease, although 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 during the rise of temperature. 



