STATE HYGIENE 539 



no use in compensating a man for destroying his pigs, if 

 the feeding of others on ' swill and wash ' can produce the 

 disease spontaneously, as has actually been stated by a 

 Minister responsible to the country for all matters con- 

 nected with the contagious diseases of animals ! 



The organism producing the disease is perfectly well 

 known, and to make light of or ignore its existence, and its 

 extreme infectivity, will not help to get rid of swine fever. 



Infection is probably always brought about through the 

 digestive canal, by food or earth soiled by the excreta of 

 affected animals ; after a variable incubative period, of 

 from ten to twenty days, the disease develops. If very 

 acute 80 per cent, or 90 per cent, may die, if less acute 

 50 per cent, or 60 per cent., while probably in all outbreaks 

 there are some animals that though affected never develop 

 any decided symptoms of the disease. 



Years of experience have taught the important lesson 

 that pigs may suffer from the disease in a chronic form, 

 that is to say, may actually be affected with the disease, 

 and give no pronounced evidence of it. Nor is this con- 

 fined to swine fever, it is just as evident in glanders, 

 tuberculosis, and pleuro-pneumonia. Prom a point of view 

 of repression of swine fever by legislation, this is of the 

 utmost importance. The Swine Fever Lifected Areas Order 

 of 1896 allowed the movements of swine which appeared to 

 be healthy, but it is clearly shown by clinical observation 

 that apparently healthy pigs may be the subject of the 

 disease, and to permit their movement is only adding fresh 

 centres for infection. 



This regulation was framed in the same year that a 

 Departmental Committee of the Board of Agriculture pub- 

 lished a report of its investigations, in which it spoke of 

 swine fever being infectious and contagious, sometimes so 

 acute as to kill in two days. But it further brought to 

 light the fact that there was a slowly progressing obscure 

 form of the disease, not attended by the ordinary symptoms, 

 but equally infectious and contagious. 



Ignorance of the condition which is probably now the 



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