SPIRILLUM CHOLERA ASIATICS 123 



stroys it. In a moist state exposure to S5C. kills in ^ hour. In feces and in 

 water containing saprophytic bacteria they are destroyed in a few days. 



Cholera vibrio survives in bay water 7 to 49 days but will not multiply in it. 



Toxin. The cholera bacillus produces an intracellular toxin or toxins. 



The injection of living or dead cholera organisms into the subcutaneous 

 tissues, peritoneal cavity or into a vein produces immunity. The serum of 

 immunized animals contains agglutinins and amboceptors for the cholera 

 spirillum. 



Agglutinins also occur in the serum of many cholera patients. 



Pathogenesis. Different strains of the cholera spirillum show different 

 degrees of virulence. The cholera spirillum enters the body through the ali- 

 mentary canal and lodges in the intestine; other tissues are not invaded, but 

 the toxin is absorbed and passes into the general circulation. The infecting 

 organisms are discharged in the feces where they may be found in abundance. 

 The spirillum may also be found in the rectum and feces of carriers. 



While cholera is a disease of man exclusively, it can be simulated by artificial 

 means in animals. 



Virulent cultures of the cholera spirillum injected into the peritoneal cavity 

 of a guinea-pig usually cause peritonitis, toxemia and death. 



Diagnosis. There are so many vibriones found in water, and occasionally 

 in feces, which are indistinguishable from the cholera spirillum in morphology, 

 staining, growth on culture media and results from animal inoculation tests, that 

 identification of the cholera spirillum necessitates agglutination tests and is 

 often difficult. 



Isolation of the cholera spirillum from other organisms, occurring with it in 

 water and feces, is favored by the luxuriant and more r apid growth of the 

 cholera spirillum in certain liquid and solid media, notably Dunham's solution. 

 A valuable review of these selective media may be found in Hygienic Laboratory 

 Bulletin, No. 91, 1913, U. S. Public Health Service. 



The stools of cholera patients contain many cholera organisms and should be 

 examined immediately after passage as follows: 



Technique. Take a loopful of the dejecta 'and place in a tube containing 

 10 cc. of Dunham's solution. Incubate the tube at 37C. for 6 hours. Remove 

 a loopful of the culture from the top of the medium and draw the loop across 

 the surface of several plates without recharging it. Plain agar, plain gelatin 

 or Dieudonne's alkaline blood may be used for plating. Incubate agar plates 

 at 37C. and gelatin plates at 22C. to 25C. After 16 hours examine plates 

 and remove any colonies that appear to be cholera spirillum; transplant into 

 Dunham's solution, incubate at 37C. for 6 or 8 hours, remove a loopful and 

 make a hanging drop preparation. Examine with the microscope and if a 

 motile spirillum is found in pure culture, make transplants into milk on plain 

 agar and into Dunham's solution. Incubate for 24 hours at 37C. Test the 

 Dunham's solution for indol and the agar growth for Pfeiffer's reaction as fol- 

 lows: Scrape half the 24-hour-old growth off the agar and emulsify in 2 cc. 

 of sterile bouillon, make a hanging-drop and see that the emulsion is free from 



