VACCINATION AGAINST CHOLERA 71 



Vaccination Against Cholera. 



By the injection of the bodies of dead bacteria, or attenuated live 

 ones, especially those containing in their cells insoluble poisons, it 

 is possible to create in the animals experimented upon a powerful 

 active immunity against the action of living virulent bacteria of the 

 same species. 



By the attenuations of cholera spirilla, Haffkine has produced vac- 

 cines 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 vac- 

 cines, 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, 39 C., 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. The best method is to use a culture that 

 kills a guinea pig in twenty-four hours by peritoneal injection. After 

 the animal is dead, the peritoneal exudate is collected, and grown at 

 35 C., the most favorable temperature for the organism to multiply. 

 This exudate is injected into a second guinea pig, and its exudate is, 

 after incubation, injected into guinea pig number three, and the 

 process is done repeatedly until the virulent virus that is lethal in 

 eight hours is obtained. This is called vims fixe. After cultivating 

 this virus on agar, the surface growth is washed off with sterile water 

 (8 c.c.) and J part of this is used as a dose. As the virus rapidly 

 attenuates it must be reactivated by passing it through guinea pigs 

 from time to time. 



The first injection is given in the flank, and the second follows 

 in five days. Accordingly as the symptoms are severe, so will the 

 resulting protection be strong. Haffkine has given 70,000 injections 

 without an accident. . The following results were obtained by Haff- 

 kine who worked in India for the British Government: 



