274 



HOW WE FIGHT BACTERIAL DISEASES 



through the use of a tetanus antitoxin. During the World War 

 soil-infected wounds were treated with this antitoxin and as a 

 result the death rate from tetanus was much lower than in previ- 

 ous wars. An antitoxin was also used successfully against gas 

 gangrene. Antitoxins are also used for certain types of dysentery 

 and against snake venoms. 



Active Immunity. Vaccination against Smallpox. — In 1796 

 Jenner first proved that inoculation with pus taken from a cow was 

 capable of preventing smallpox. Years later Louis Pasteur proved 

 that inoculation of chickens with an old weakened culture of chicken 

 cholera bacteria caused the chickens to be slightly ill for a short 

 time, but made them immune to chicken cholera. Their body ceUs 

 Were stimulated by the weakened germs to manufacture antibodies 

 which soon got the better of the germs and provided immunity. 



So it is with vaccination against smallpox. The virus or pus 

 used for inoculation contains germs of cowpox, which is probably 

 a weakened smallpox organism. Therefore when vaccination 

 " takes/' the body builds up a resistance to the germs thus in- 

 troduced, which ends in obtaining immunity against smallpox. 



Smallpox has been in the past a great scourge ; 90 out of every 

 100 persons in Europe used to have it. As late as 1898, in Russia 

 over 50,000 persons lost their lives from this disease in a year. 

 In some places smallpox has been brought under absolute control 

 by vaccination, though in other places, unfortunately, there are 

 outbreaks, due to the fact that some people do not beheve in 

 vaccination. The diagram tells its own story. 



1921 



1922 



78:7 Colored 



6S White 



132.7 Colored 



lU mite 



Deaths in 1921 and 1922 per 100,000 in a large western city. The annual num- 

 ber of deaths from smallpox per 100,000 in the entire registered area of the United 

 States was, in 1900, 1.9; in 1901, 3.5; in 1902. 6.6; in 1903, 4.2; since 1904 less 

 than 1. 



Rabies, or Hydrophobia. — Rabies (ra'bi-ez) , which is believed 

 to be caused by a protozoan parasite, is communicated in the 

 sahva from one dog to another by biting. In a similar manner 



