422 



SMALLPOX AND ITS CONTROL 



(1749-1823) of England, who first made known the idea of vac- 

 cmation. The germ theory of disease had not yet been pre- 



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In 1874 vaccination was introduced into Prussia. Note the decrease in smallpox in the 

 following year. Vaccination is not compulsory in Austria. The above graphs indicate a direct 

 relation between the number of smallpox cases and compulsory vaccination. 



sented by Pasteur. Jenner, however, collected data from the 

 people who had had cow-pox, and afterward had resisted small- 

 pox infections. He began the scientific investigation of inocu- 

 lation. A dairy maid on a certain farm contracted cowpox. 

 Jenner took some pus from a sore on her hand and inoculated a 

 little boy with it. The boy became slighth^ ill, but soon recov- 

 ered. Later the boy was exposed to smallpox and even inocu- 

 lated with smallpox virus, but he did not contract the disease. 

 Evidently the cowpox infection had given him a protection 

 against smallpox. Jenner made many such experiments and pub- 

 lished his discoveries in his celebrated pamphlet An Inquiry into 

 the Causes and effects of the Variolae Vaccinae. 



The inoculation with cowpox was called vaccination (vacca — 



