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FOOT-AND-MOUTH DISEASE: 



INTRODUCTION FEOM ABROAD. 



The way by which foot-and-mouth disease is brought into 

 Great Britain and similarly situated countries from time to time, 

 notwithstanding the fact that into the former in particular the 

 importation of susceptible live stock is prohibited, is as mys- 

 terious as it is interesting. The subject has given rise to spas- 

 modic discussions, but the possibilities do not seem to have been 

 methodically debated in relation to the actual facts, so far as 

 they are known. The happenings from the beginning of 1919 

 have provided more material than in former years for a closer 

 analysis of the subject. It is not claimed that the results bring 

 finality to a question which for many years has baffled the best 

 scientists in Europe, but it may be that by elimination they 

 outline the direction to be followed in future inquiry. 



It may be accepted as established that Great Britain freed 

 from the disease in enzootic form is only invaded when the 

 disease is prevalent on the Continent, particularly when it pre- 

 vails in the north of France, Belgium and Holland. In the light 

 of recent experience, it would also appear that the greater the 

 prevalence, the more frequent are the invasions. 



Live stock being excluded as a factor, it is not unnatural that 

 suspicion should have fallen upon human beings coming from 

 the Continent where the disease is raging, and on imported 

 feeding stuffs and litter. It may be mentioned, however, to save 

 further discussion, that the importation of hay and straw, 

 except for exceptional purposes, has been prohibited since 1908, 

 and that the position as regards foot-and-mouth disease has not 

 apparently been modified in consequence. 



Initial Outbreaks and Secondary Outbreaks. — For the pur- 

 pose of analysis and discussion outbreaks of foot-and-mouth 

 disease fall into two classes, initial outbreaks of invasion, and 

 secondary outbreaks, which are local ramifications from the 

 initially established centre. As regards the latter, investigation 

 by the Ministry has seldom failed to establish satisfactorily the 

 way by which disease has spread. Much useful information 

 on this subject is available. It is with initial outbreaks of 

 invasion, however, that this article is mainly concerned, and 

 there have been 63 in the last 20 years. The term is applied 

 to those outbreaks which arise after the country has been 

 free from disease for more or less long periods, which are 

 far in excess of what we have reason to believe represents 



