326 



Constant 



this one woman, and all these 61^ people, 

 it was discovered later, had never been 

 vaccinated or had not been vaccinated 

 for a long time. The immunity obtained 

 through successful vaccination may last 

 only twelve months or it may last for 

 many years. 



The few unvaccinated people in a 

 community such as you and I live in are 

 relatively safe because all the rest of us 

 have been vaccinated. Vaccination is not 

 the haphazard process it was in Jenner's 

 day. The vaccine is most carefully pre- 

 pared. Calves are carefully cared for and 

 tested to make sure they are free from tu- 

 berculosis and other diseases; then they 

 are inoculated with cowpox virus. As the 

 disease develops, a large amount of mate- 

 rial is taken from the pustules of the calf; 

 this contains a virus closely related to 

 the smallpox virus. It is later purified in 

 the laboratory and tried out on experi- 

 mental animals to test it for purity and 

 strength. Throughout, it is handled with 

 the greatest care so that when a doctor 

 scratches vaccine into your body, he is 

 certain that he is not introducing germs 

 of other diseases with the vaccine. Why 

 are some people opposed to vaccination? 

 See Exercise 5. 



Nebraska 

 "Wisconsin 

 Minnesota 

 Illinois 



Care Is Needed for Health unit vi 



The work of Jenner and Pasteur. Jen- 

 ner vaccinated against smallpox long be- 

 fore the germ theory of disease had been 

 established. He did not know about the 

 existence of bacteria or filterable viruses; 

 he could know nothing about the weak- 

 ening of bacteria and virus. He did not 

 understand why or how vaccination pre- 

 vented smallpox. Therefore the same 

 method could not be applied to other 

 diseases. On the other hand, Pasteur's 

 work served as the foundation for many 

 further discoveries because it was based 

 on accurate information. Actually Pas- 

 teur saved very few lives through his 

 immunization against rabies, since rabies 

 was never a widespread disease in man; 

 but since his discovery of immunization 

 pointed the way to the prevention of 

 many other diseases, it has been said 

 about Pasteur that "he saved more lives 

 than Napoleon took in all his wars." Do 

 Exercise 6. 



Typhoid fever and immunization. Ty- 

 phoid fever is an infectious disease caused 

 by a germ that enters the body with 

 food or drink. After the germ is swal- 

 lowed, it settles in the digestive tract 

 causing a severe general illness and often 

 damaging the intestine. During the course 



New Hampshire 



Fig. 295 A graph based on the nnvibe)r of cases of typhoid (and the related disease, 

 paratyphoid) in five states with an excellent record and in the one state which had the 

 worst record. (Based on reports in 1(^44-1^4$.) What health practices reduce the num- 

 ber of typhoid cases? (See pages ^26 and 34^-348.) 



