Protection Against Disease 457 



Inoculation. Inoculation is successfully used to prevent such 

 diseases as typhoid fever. In the treatment to prevent typhoid 

 fever a virus composed of lifeless typhoid germs is injected 

 under the skin. Three treatments, about ten days apart, are 

 sufficient to secure immunity. There usually results a slight swell- 

 ing at the place of injection together with a little fever and depres- 

 sion, not sufficient, however, to interfere with one's daily routine 

 of work. Typhoid inoculation was effectively used in our Army 

 and Navy during the World War. No person is now allowed to 

 serve in our Army or Navy who has not received this treatment. 



Serum. Serum is a clear fluid that appears when the blood 

 of an animal clots. This fluid, except for the absence of certain 

 protein matter which is in the clot, differs but slightly in composi- 

 tion from the blood plasma. When serum, obtained from the 

 blood of an animal made immune by artificial means against some 

 special disease, is injected into the bodies of human beings, it acts 

 as a preventive of that disease by producing a substance that 

 will overcome the toxins or poisons formed by the disease germs. 

 This substance is called an antitoxin. 



The use of a serum has been remarkably successful in the 

 treatment and prevention of diphtheria. The diphtheria death 

 rate has decreased more than seventy-five per cent. Other dan- 

 gerous diseases now treated with serum are meningitis, an inflam- 

 mation of the membranes of the brain and spinal cord, and lock- 

 jaw, a form of tetanus. 



Action of an Antitoxin. An antitoxin does not destroy the 

 disease germs, as is sometimes supposed. What it does do is 

 to overcome the toxins or poisons made by the germs, thus pre- 

 venting their deadly effect on the nervous system. 



Quarantine. Quarantine is one of the most important 

 methods in combating infectious diseases. It consists in keeping 

 diseased and exposed persons separated from the well. Complete 

 isolation not only of individuals but sometimes of infected com- 

 munities becomes necessary in order to prevent the spread of dis- 

 ease. Quarantine is often used to stop travel on land or sea to 

 prevent the spread of a dangerous infectious disease. Evasion 

 of a quarantine ordinance is a punishable offense. 



