7 2 



IMMUNITY 



The immunity conferred by this mode of vaccination is not com- 

 plete until ten days after treatment. It is possible to vaccinate with 

 these relatively virulent bacteria because they are given under 

 the skin, a place where the 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 pos- 

 sible to create an immunity of a moderate kind against enteric fever. 

 The method has been perfected by Wright, and his mode of proce- 

 dure is to secure a virulent culture of typhoid, which is tested on 

 guinea pigs, and the minimum lethal dose for a 100 gram guinea pig 

 is used as the dose for man. This dose varies from .5 c.c. to 1.5 c.c 

 of an old culture sterilized by heat at 60 C., and preserved with 

 lysol. After the injection there is often redness and pain at the site 

 of inoculation, some fever and lymphangitis. The results obtained 

 in vaccinating the troops in South Africa are marked. Of the garri- 

 son of Ladysmith comprising nearly 12,000 troops, 1,705 were inoc- 

 ulated; 2 percent contracted typhoid afterward, and 4 percent of 

 these died of the disease. Among the non-inoculated, numbering 

 10,529, 14 percent contracted typhoid, and 3.12 percent of 10,529 

 died of the disease. It seems that this form of vaccination, in a 

 great measure, prevents the infection with typhoid, and modifies the 

 disease after infection occurs. 



