

VACCINATION AGAINST CHOLERA 79 



sterile curette. The pulpy substance thus obtained is mixed 

 with glycerine and stored for a month or more. The action of the 

 glycerine is to rid the virus of many of the bacteria, through, it is 

 supposed, a hydroly tic action. This virus is then rubbed into the 

 skin of the individual to be vaccinated under strict aseptic pre- 

 cautions. At the end of a week, a pearly white vesicle is formed, 

 and it is then considered that vaccination has "taken" and that 

 the individual is protected against variola. This action of 

 immunization is supposed to be complete on the fourth day after 

 the virus has been introduced. This is a matter that is difficult 

 to decide, but the immunization process is, no doubt, a very slow 

 one, like every other immunizing process where the immunity is 

 autogenous and active, and not passive, as in the case of diph- 

 theria anti-toxin. 



Persons who are entirely immune to variola will show twenty- 

 four hours after vaccination a distinct red areola without vesicles 

 or pustules; this is the reaction of immunity. Recent successful 

 vaccination leaves the patient in a condition of resistance and 

 four to six days after revaccination an areola surmounted by a 

 reddish papule is seen; this is vaccinoid. 



Vaccination Against Cholera 



By the attenuations of cholera spirilla, Haffkine has produced 

 vaccines which effectively protect individuals against infection 

 with cholera, or if they become infected with the disease, it is so 

 modified that they can, and do, more easily recover. He employs 

 two vaccines, a weak one and a stronger one. The weak one is 

 used to prepare for the stronger one, which is the effective vaccine. 



The weak, or first virus, is prepared by growing the cholera 

 vibrios at a high temperature, 39C., in a current of air. The 

 stronger is prepared by passing the vibrios through a series of 

 guinea pigs, so increasing the virulence that the virus is invariably 

 fatal to the guinea pigs in eight hours. After cultivating this 





