CHOLERA BACILLUS 2O$ 



teriolytic action, by which the cells are dissolved, and the toxin 

 liberated. Filtrates from young cultures are non-toxic. If 

 bouillon cultures are killed by chloroform, and then injected into 

 animals, toxic action follows. In cholera the pathogenic process 

 is mostly confined to the intestines. Toxic absorptions, due to the 

 liberation of toxic products by the bacteriolytic action of serum, 

 follow later. There is a desquamation of the epithelium of the 

 bowel, and epithelial flakes found in the watery discharges resem- 

 ble rice grains. Peyer's patches may become slightly swollen 

 and reddened, and later, there may be diphtheritic necrosis above 

 the iliocecal valve, and often a parenchymatous nephritis. The 

 vibrios do not enter the blood. 



Diagnosis. Bacteriological diagnosis of cholera is accomplished 

 by examining the alvine discharges. A mucous flake is mixed 

 with some peptone solution, this is incubated, and the spirilla, 

 if present, rapidly grow on the surface; after a few hours, plates 

 are poured from this surface growth, and from the plates liquefy- 

 ing colonies are picked out, and bouillon cultures made. These 

 are tested by serum, from horses artificially immunized by inject- 

 ing cholera spirilla into them. If the organism under examination 

 (after serum mixed with 2,000 to 3,000 parts of water is added) 

 agglutinates, it is considered to be the cholera spirillum. Both 

 in early and fatal cases, the agglutinating reaction is not available, 

 since it takes some time for the agglutinins to form in the blood. 

 Under the chapter on immunity an account of the PfeifTer reaction 

 is given, also one on vaccination against cholera infection, by 

 means of killed cultures, under the chapter on vaccines. 



Vibrios Allied to the Cholera Vibrio 



Several other vibrios have been discovered that resemble the 

 cholera vibrio. These are mostly found in potable water, and 

 though in many respects identical with the cholera vibrio, they 

 differ in essential points, i.e., pathogenicity, and in their agglutina- 

 bility with specific sera. The most important of these organisms 



