CONTROL OF DISEASE 349 



Decline in prevalence and death rate of smallpox 



Where vaccination is generally employed 



Where vaccination is not employed 

 Dechne in prevalence and death rate of typhoid 

 Decline in prevalence and death rate of plague 

 6. Heredity and specific diseases 



Difference between inheriting a disease and inheriting suscepti- 



bihty to it 

 Danger of infection from members of family 

 Need for special precautions where immunity is absent 



Build up general systemic vigor 



Avoid possibly infectious contacts 



Avoid conditions that would break down resistance 



QUESTIONS 



1. During an epidemic, why are some people more likely to get sick 

 than others ? 



2. Why is anyone more likely to get sick at one time than at another ? 



3. Why are not doctors and nurses, who are brought more in contact 

 with sick people, more often sick than others ? 



4. How can we find out whether a person is susceptible to a given 

 disease ? 



5. What is the advantage of having physicians report certain dis- 

 eases to the state or city health officer ? What is the disadvantage ? 



6. How can we tell that a person carries the germs of a disease, if he 

 does not show the symptoms of that disease ? 



7. How can a person have the germs of a disease in his body and not 

 show the symptoms ? 



8. What is meant by vaccination ? 



9. For what diseases is vaccination possible ? 



10. Is it desirable that everybody should be vaccinated ? Should 

 everybody be vaccinated against all possible diseases ? What should de- 

 cide the question? 



11. What are the advantages of general use of vaccination ? What 

 are the disadvantages ? 



12. How does a knowledge of the family's history help in protecting 

 health ? 



