76 SWINE PLAGUE 



cultures tested by Smith. I have failed to obtain the reaction in a few 

 cultures, but usually it appears. 



Thermal death point.— "Din^ organism is destroyed in bouillon at 

 58° C. in ten minutes. A temperature of 56° C. for this time did not 

 destroy its vitality. 



Effect of drying. — These bacteria cannot stand drying. The bacte- 

 ria in a drop of bouillon dried on a cover-glass and kept at the room 

 temperature are destroyed in 24 to 36 hours. In similar preparations 

 made from agar cultures they resist drying from five to eight days. 

 The difference in the time between the two cultures is probably due to 

 the thicker layer in case of the agar preparations. 



Persistence of vitality in water a?id soil. — Experiments to deter- 

 mine the length of time this organism will live in water and in the soil 

 show that it is destroyed in water in test tubes in from nine to eleven 

 days. In the soil it was not found after eight days. Dr. Smith states 

 that it is destroyed in the soil after four days. 



Poiuer to resist disinfectants. — The bacterium of swine plague is 

 very sensitive to the action of disinfectants. A large number of these 

 agents have been tested. The followingare among the more important : 



Commercial sulphuric acid, % per cent, kills in 30 minutes. 



Commercial hydrochloric acid, % per cent, kills in 10 minutes. 



Lime, lime water kills in i minute. 



Lime, 0.015 per cent, kills in 30 minutes. 



Carbolic acid, % per cent, kills in 60 minutes. 



Carbolic acid, i per cent, kills in 5 minutes. 



Carbolic acid, 2 per cent, kills in i minute. 



Formalin, solution 1:2000 kills in 5 minutes. 



Trikresol, % per cent, kills in 5 minutes. 



Pathogenesis. — This organism is pathogenic for rabbits, guinea pigs 

 and mice amongthe smaller experimental animals and for swine. With 

 the virulent form rabbits inoculated either subcutaneously or in the 

 vein with very small, 0.001 c. c. doses, die of septicemia in from 16 to 24 

 hours. Guinea pigs are slightly less susceptible. When inoculated 

 subcutaneously withd. i to 0.2 c. c. of a bouillon culture, they die in 

 from 30 to 72 hours. Mice succumb in about 24 hours when inoculated 

 with a drop of the culture . Pigs inoculated intravenously usually die 

 from acute septicemia in from 18 to 36 hours. If they live longer there 

 may be decided lung lesions. (See report on swine plague. Smith ) 



§70. Symptoms. It is frequently difficult to recognize 

 symptoms distinctive of swine plague. The peculiarities of 

 swine render it exceedingly difficult to obtain evidence on 

 physical examination of lung disease. Sometimes this affec- 



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