THE CONQUEST OF DISEASE 



the guinea pig immune to infection and also of 

 curing the animal when infected. The treat- 

 ment was then tried in human typhoid, with 

 encouraging results. 



Following this Sir Almroth E. Wright pre- 

 pared a vaccine against typhoid which was first 

 employed in the British army, and is now 

 coming into general use. He employed rab- 

 bits and guinea pigs to determine its potency. 

 Two inoculations are necessary. The injec- 

 tions do not make the patient sick or require 

 him to give up work. Immunity lasts from 

 two to six years. It may last for a lifetime. 

 All regiments leaving for the tropics are 

 offered this inoculation, and each year a larger 

 percentage of the soldiers are accepting it. 

 Here are some of the statistics: In August 

 and September, 1905, 150 men of a single 

 regiment were inoculated, of these 23 re- 

 fused to accept a second inoculation. The 

 regiment reached India, September 28. A 

 month later typhoid fever broke out and dur- 

 ing the following few months 63 cases were 

 observed in the regiment. With but two ex- 

 ceptions the disease attacked only the men who 

 had not been inoculated, and both of these 

 exceptions were men who had refused the sec- 



62 



