8o 



IMMUNITY 



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

 (8 c.c.) and % 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 injec- 

 tions without an accident. The following results were obtained 

 by Haffkine who worked in India for the British Government: 



The immunity conferred by this mode of vaccination is not 

 complete until ten days after treatment. It is possible to vac- 

 cinate with these relatively virulent bacteria because they are 

 given under the skin, a place where life of the vibrios soon ceases. 



During an attack of cholera the vibrios do not enter the blood 

 but remain in the deep layers of the intestinal mucosa. 



Vaccination Against Typhoid 



By the injection of sterilized cultures of typhoid bacilli, it is 

 possible to create an immunity of a moderate kind against enteric 

 fever. The method was perfected by Wright, and his mode 

 of procedure is to secure a culture of typhoid both virulent and 

 able to call forth a large amount of anti-body in the injected 

 person, which is tested on guinea pigs, and the minimum lethal 

 dose for a loo-gram guinea pig is used as the dose for man. This 

 dose varies from .5 c.c. to 1.5 c.c. of a culture sterilized by heat 



