346' ACUTE EXANTHEMATOUS INFECTIOUS DISEASES 



organism and characterized by the formation of vesicles which 

 occur on the mucous membranes and skin. The mouth, the 

 interdigital space and the teats and udder are most often 

 affected. 



Occurrence. — The disease has been an occasional visitor to 

 the United States. In 1870 foot-and-mouth disease spread 

 from Canada into New England and New York; in 1884 ' 

 there was a limited outbreak in Portland, Maine; in 1902 

 again in New England, in the States of Connecticut, Rhode 

 Island, Massachusetts and Vermont; in 1908 it was intro- 

 duced through contaminated smallpox vaccine into New 

 York, Pennsylvania, Michigan and Maryland; in 1914 the 

 most wide-spread outbreak in the history of the country 

 occurred. Within three months the disease spread from the 

 Chicago stockyards to Michigan and Ohio and ultimately 

 infected twenty-one States and the District of Columbia. 

 The origin of this outbreak is in dispute, but it prob- 

 ably came from contaminated anti-hog cholera serum. In 

 Europe, Asia and Africa and in South America foot-and- 

 mouth disease is prevalent. While not an especially fatal 

 disease, it occasions enormous losses due to its rapid spread, 

 the damage it causes the milk industry, the losses entailed 

 through quarantine and the sequelae (loss of claws, mastitis, 

 etc.) which follow in the wake of an outbreak. The damage 

 done the cattle industry amounts to an average of $20 per 

 head for each animal affected. 



Etiology. — The cause is evidently an ultramicroscopic virus 

 which passes through coarse but not the finest bacterial filters. 

 The virus is present in the vesicles and is found in the blood 

 only in the early part of the fever stage. The saliva, tears, 

 milk and nasal discharge are infectious from contamination 

 with the contents of the vesicles. As the disease progresses 

 the virulency of the virus decreases. 



Natural Infection. — The virus of foot-and-mouth disease is 

 taken up by the digestive tract with food, water, bedding, 

 litter, etc. which have become contaminated principally by 

 the saliva of affected animals. Such intermediary agents as 

 stable utensils, mangers, watering troughs, clothing and the 

 hands of attendants, etc., may also harbor the virus. Railway 



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