INFECTIOUS DISEASES 171 



in fluids at room temperature for from two to three 

 months, but is destroyed by heating to seventy degrees 

 Centigrade for one hour. When dried it becomes more 

 resistant to the influence of high temperature. At the 

 temperature of an ice box the virulence of the virus is 

 retained for many months. It is very resistant to dilute 

 solutions of phenol, corrosive sublimate, and chinosol. 

 The length of time that virus may remain virulent on 

 infected premises has not yet been determined, but it 

 easily survives a single winter. 



In addition to the filterable virus, certain bacteria, 

 including one Spirillum, may be factors in the causation 

 of hog cholera. 



The Bacillus suipestifer is no doubt a factor in the 

 production of secondary lesions and of some of the compli- 

 cations of hog cholera, and from the original investigations 

 under the direction of Salmon and some recent experiments 

 it seems probable that an occasional outbreak of a disease 

 very similar symptomatically and anatomically to cholera 

 is caused by the Bacillus suipestifer. In fact, the intra- 

 venous injections of the Bacillus suipestifer that have been 

 recently isolated produce a septicemic disease that termi- 

 nates fatally in from one to three days. It has been 

 suggested that the disease produced by the Bacillus 

 suipestifer be designated para-cholera. 



The Bacillus suipestifer is a short, motile, rod-shaped 

 bacteria. It forms no spores, or at least none have been 

 demonstrated. This organism grows aerobically and 

 anaerobically on practically all artificial media. It will 

 withstand ordinary dessiccation for four months or even 

 longer, but sunlight destroys it when exposed only a few 

 minutes. This organism produces an acute or chronic 

 inflammation, and necrosis of the intestinal mucosa and 

 the mesenteric lymph glands. If the animals are previ- 

 ously starved and the acid reaction of the gastric juice 

 neutralized before feeding the cultures of Bacillus suipes- 

 tifer, they will contract an acute disease, with symptoms 

 similar to those of septicemia, and usually die on the 

 third day. Intravenous injections of the cultures pro- 



