484 MICROBIOLOGY 



cholera with the serum of hyper-immunized hogs. Like results 

 have been obtained with several other diseases more common 

 in the tropics. See References on immunity. 



VACCINES. 



Vaccines, vaccination and vaccine therapy. As origin- 

 ally used, vaccine meant an attenuated virus, that is, a virus 

 capable of producing a reaction of the body tissues that tended 

 to protect them against a later attack of the virulent virus. It 

 had for its purpose the production of immunity. The vaccine 

 of small pox is perhaps the best known example of this, al- 

 though those for anthrax and black leg have long been recog- 

 nized. The use of these vaccines is prophylactic in that they 

 were given before actual infection had taken place, and for 

 the purpose of protecting the individual. In 1885 Pasteur 

 brought forward a new idea with the introduction of his 

 antirabic vaccination. This vaccine is administered after in- 

 fection has taken place and immunity is induced so rapidly 

 that it prevents the more slowly developing attack of the 

 strong virus. Wright and Douglass 3 still further advanced 

 the methods of vaccination for therapeutic purposes by inject- 

 ing dead bacteria into the body of patients suffering with 

 various chronic affections due to these organisms. At first 

 Wright seems to have limited the application of his vaccine to 

 chronic conditions with well marked and usually external lo- 

 calization of the infectious processes. More recently the 

 practice of injecting dead bacteria (cultures of bacteria 

 heated sufficiently to kill the organisms) has been extended to 

 the more acute diseases such as typhoid in man and glanders in 

 horses and even to diseases of short duration such as pneu- 

 monia and to infections' in which there is a general systemic 

 intoxication and in bacteriaemia. 



The meaning of the term vaccine has been changed 

 through the development of vaccine therapy from an attenu- 

 ated virus to one in which the life of the organism has been 



3 Wright and Douglass. Proceedings of the Royal Society, Vol. 

 LXXII (1903) p. 357. 



