The Protection of Health 603 



of an individual with germs of a mild type or of a kindred disease. 

 It gives active immunity. 



Inoculation with antitoxin is curative or therapeutic and gives 

 passive immunity by neutralizing the toxin produced by the pathogenic 

 organisms. 



The three methods of preventing the spread of infectious diseases 

 are: 



1. Immunizing by vaccination or inoculation. 



2. Destruction of disease germs in the patient. 



3. Blocking all the ways of transmission and destruction or disin- 

 fection of all infective material that may serve as a carrier of the 

 germs. 



Immunity is due to chemical substances, which are produced by 

 the living cells of the body and are capable of neutralizing toxins, and 

 to the phagocytes, which, like scavengers, destroy invading germs. 



REVIEW QUESTIONS 



1. Upon what facts does the control of disease depend? 2. Name 

 the two general classes of disease. 3. By what are infectious diseases 

 always caused? 4. (a) What are the two kinds of pathogenic germs? 

 (6) What is a parasite? 5. (a) Mention several diseases caused by 

 protozoa. (6) Several caused by bacteria. 6. (a) Mention some 

 non-infectious diseases. (6) To what may such diseases be due? 



7. How are disease germs thrown off by a patient ? Give instances. 

 8. How may they be received by other persons? 9. (a) How may 

 tetanus bacteria be received? (&) How should suspected wounds be 

 treated? 10. Why should public utilities, such as the telephone, and 

 utensils, such as drinking cups, be considered dangerous to health? 

 11. Mention diseases transferred by insects, and how transfer may be 

 prevented. 12. Describe the possible r61e of the hands in disease 

 transmission. 13. How may food and drink be contaminated? 



14. What is immunity? 15. What is natural immunity? 16. In 

 what ways may immunity be acquired? 17. What is meant by 

 specific immunity? 18. What does susceptibility to disease mean? 



19. Mention important conditions determining susceptibility. 



20. What conditions favor natural resistance to disease? 21. What 

 does prophylactic mean? 22. Why may invading germs fail to cause 

 disease? 23. What conditions are necessary for the germ to cause 

 disease? 24. What would be the most effective measure to prevent 

 the spread of disease? 25. How is active artificial immunity pro- 

 duced? 26. Toward what diseases is such immunity effective? 



