PROPHYLACTIC VACCINATION 273 



against smallpox immunization may last for a considerable number of 

 years, while with other organisms, such as the staphylococcus or pneu- 

 mococcus the immunity is of relatively short duration. 



The aims of vaccination are either to cause prophylactic resistance 

 against disease or to increase an already established resistance. Proph- 

 ylactic vaccination against typhoid is an example of the former, while 

 the vaccine treatment of furunculosis or gonorrhea are examples 

 of the latter. 



The term vaccine is derived from vaccinia or cowpox, and the method 

 of protective immunization against smallpox with vaccinia virus was 

 called by Jenner " vaccination." This great empirical work was placed 

 on a sound scientific basis by Pasteur after he had discovered the 

 method of protective inoculation against chicken cholera, and Pasteur 

 used the term vaccination for such inoculations. To-day the simple 

 term vaccine is loosely applied and should be restricted to cowpox 

 vaccine. Suspensions of bacteria such as typhoid bacilli or pyogenic 

 cocci should be designated bacterial vaccines. Wright defines a bac- 

 terial vaccine as follows : " Bacterial vaccines are sterilized and enumer- 

 ated suspensions of bacteria which furnish, when they dissolve in the 

 body, substances which stimulate the healthy tissues to the production 

 of specific bacteriotropic substances (or antibodies) which fasten 

 upon and directly or indirectly contribute to the destruction of the 

 corresponding bacteria." 



Perhaps the first serious attempt to apply practically a bacterial 

 vaccine in the treatment of human disease was that of Koch, who in 

 1890 employed tuberculin in the treatment of tuberculosis. In 1893 

 Frankel treated thirty-seven cases of typhoid fever with subcutaneous 

 injections of killed typhoid bacilli. He reported that the course of 

 the disease was favorably modified and in a few instances terminated 

 by rapid lysis. Rumpf treated a series of cases of typhoid fever with 

 bacillus pyocyaneus and obtained equally favorable results, thus throw- 

 ing doubt upon the specific character of the treatment and leading into 

 the newer field of non-specific therapy. Wright and Douglas soon 

 after the discovery of opsonins demonstrated their method of treatment 

 by bacterial vaccines under the guidance of the opsonic index. Wright 

 stated that a patient who had become infected by an organism such as 

 the staphylococcus aureus or the tubercle bacillus would be found to 

 have a lowered resistance against these organisms; that this degree 

 of want of resistance could be accurately determined, and that the 

 resistance could be stimulated and controlled by measured doses of 

 a vaccine of the causative organism. Wright's method of treatment 

 was based on the principle of strict specificity. It was soon pointed out 

 that opsonins are only one link in the defensive chain of the host, and 

 the use of the method has been somewhat restricted. The measure of 

 opsonins in a given instance was subsequently found not to be a measure 

 of the existing degree of total immunity. In the majority of diseases, 

 therapeutic vaccination has not withstood the test of time. Wright 

 himself, after experiences in the World War, stated that it has been 

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