378 ACUTE EXANTHEMATOUS INFECTIOUS DISEASES 



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 probably 

 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 sequels (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 

 cars, stockyards, cattle pens, manure, hides, wool, milk, 

 veterinarians, butchers, cattle dealers, herders, etc., are also 

 carriers of the contagion. Hay, straw, feed and the like 

 imported from infected districts often spread the disease. In 

 1908, as noted, foot-and-mouth disease was introduced into 

 the United States by some calves used for the propagation of 

 vaccine virus, which had been inoculated with contaminated 

 lymph imported from Japan. It is very probable that 

 recovered animals ("germ carriers") may harbor the virus for 

 an indefinite period which accounts for sporadic outbreaks of 

 the disease in uninfected districts. 



While cattle are most predisposed, the disorder also attacks 

 sheep, swine, goats and buffalo. It is rare in horses, dogs and 

 cats. 



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