392 MAN'S IMPROVEMENT OF HIS ENVIRONMENT 



as 1898, over 50,000 persons lost their lives annually in Russia 

 from this disease. It is probably not caused by bacteria, but by 

 a tiny animal parasite. Smallpox has been brought under abso- 

 lute control by vaccination, tfee inoculation of man with the 

 substance (called virus) which causes cowpox in a cow. Cowpox is 

 like a mild form of smallpox, and the introduction of this virus 

 gives complete immunity to smallpox for several years after vac- 

 cination. This immunity is caused by the formation of a ger- 

 micidal substance in the blood, due" to the introduction of the 

 virus." Another function of the board of health is the prepara- 

 tion and distribution of vaccine (material containing the virus 

 of cowpox). 



Rabies (Hydrophobia). This disease, which is believed to be 

 caused by a protozoan parasite, is communicated from one dog to 

 another in the saliva by biting. In a similar manner it is trans- 

 ferred to man. The great French bacteriologist, Louis Pasteur, 

 discovered a method of treating this disease so that when taken 

 early at the time of the entry of the germ into the body of man, 

 the disease can be prevented. In some large cities (among them 

 New York) the board of health has established a laboratory where 

 free treatment is given to all persons bitten by dogs suspected of 

 having rabies. 



Vaccination against Typhoid. Typhoid fever has within the 

 past five years received a new check from vaccination which has 

 been introduced into our army and which is being used with good 

 effect by the health departments of several large cities. 



The following figures show the differences between number of 

 cases and mortality in the army in 1898 during the war with Spain 

 and in 1911 during the concentration of certain of our troops at 

 San Antonio, Texas. 



1898 2nd Division, 7th Army Corps, Jacksonville, Florida. 

 June-October, 1898 



Mean strength, 10,759. 



Cases of typhoid certain and probable, 2693. 



Death from typhoid, 258. 



Death from all diseases, 281. 



