PREVENTIVE MEDICINE 241 



tection afforded is certainly less than that produced by vaccination 

 with human tubercle bacilli. Finally, according to Vallee* a 

 vaccinated animal only offers a real resistance in proportion to 

 the extent to which it remains a carrier of the vaccinating 

 organisms. 



TUBERCULOSIS IN SWINE. 



The disease is of common occurrence among swine, and the 

 Chief Veterinary Officer of the Board of Agriculture in his recent 

 annual reports has drawn attention to its prevalence as found when 

 examining pigs suspected of having swine fever (see Annual 

 Reports for 19H, 1915, and 1916). Figures are quoted showing 

 that in Glasgow and Birmingham 3-5 per cent, of all pigs 

 slaughtered in these two cities were found to be affected with tuber- 

 culosis. It is certain that the disease is more extensive than these 

 figures indicate, for instance, in 1914 the disease was diagnosed on 

 633 different premises and affected 989 pigs among 8632 kept, or 

 11-4 per cent. No reliable figures are available to show the extent 

 of the disease within the United Kingdom. 



Infection, though usually of bovine, is occasionally of avian 

 origin, though the type of disease caused by the latter is not as a 

 rule so severe as that produced by the former. The Royal Com- 

 mission on tuberculosis also noted the presence of human tubercle 

 bacilli in certain lesions from swine. Though unweaned pigs are 

 at times found to become infected through the medium of the sow's 

 tubercular udder, the disease is far more frequent among older pigs, 

 and especially amongst those which are kept for breeding purposes. 



Infection is chiefly derived from feeding on skimmed milk con- 

 taining tubercle bacilli, slaughter-house offals, and from feeding 

 from troughs which have previously been used by tuberculous 

 cattle. Vallee and Villejeanf have pointed out facts showing the 

 frequency of infection in pigs fed with skimmed milk. In U.S.A., 

 where pigs were fed exclusively on grain in 1894 to 1895, only 

 0004 per cent, were tubercular, while in Denmark, where skimmed 

 milk was used, some 15 per cent, were tubercular. 



Tubercle bacilli are largely voided in faeces and the yards, pens, 

 food-troughs and food thus become contaminated, and in this way 

 infection may spread to other pigs. 



PREVENTIVE MEASURES. In the case of swine this should not 

 be so difficult as with cattle. Tuberculin should be freely used on 

 * Report to Tenth International Veterinary Congress. 

 t Journ. Comp. Path., 1904, Vol. XVII., p. 370, Trans. 

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