MEASLES, SCARLET FEVER, MUMPS, DENGUE FEVER, ETC. 933 



The causative agent of foot-and-mouth disease is unknown. A 

 number of organisms have been cultivated from the vesicles and 

 mucous membranes of afflicted animals, but none of these could be 

 shown to have etiological significance. Loeffler and Frosch, 27 have 

 demonstrated that the virus contained in the vesicles may pass 

 through the pores of a filter. The virus is easily destroyed by 

 heating to 60 C. and by complete desiccation. 



One attack of foot-and-mouth disease protects against subsequent 

 attacks. This immunity in most cases lasts for years, though rare 

 cases of recurrence within a single year have been reported. Loeffler 

 has actively immunized horses and cattle with graded doses of virus 

 obtained from vesicles and with the sera of such animals has 

 produced passive immunity in normal subjects. 



27 Loeffler und Frosch, Cent, f . Bakt., 1, 1908. 



