320 Microbes and You 



finding with other diagnostic tests, including X-ray examination to 

 determine the nature and the extent of the focus of infection, 

 microscopic examination of sputum for the presence of acid-fast 

 organisms, and guinea pig inoculation with sputum or other test 

 material if clinical symptoms warrant such tests. 



The extensive application of tuberculin testing of cattle has 

 paid rich dividends, since a positive reaction in cattle is good 

 evidence that the animal has an active case of the disease and 

 should be slaughtered to prevent spread of the infection to healthy 

 cattle or to humans. 



VACCINES 

 Smallpox Vaccine 



When Edward Jenner demonstrated the effectiveness of small- 

 pox vaccine in 1796, a new attack on disease was available to 

 medicine. The word vaccine is derived from the Latin vacca, 

 which means cow, and the technic of vaccination had its origin in 



Fig. 54. Edward Jenner (1749-1823). {By permission from 

 Introduction to the Bacteria hij C. E. Clifton. Copyright, 1950. 

 McGraw-Hill Book Company, Inc.) 



