BACILLUS TYPHOSUS 117 



but yet set up some resistance to it comparable to that 

 acquired by passing through a spontaneous attack. 

 The bacilli are prepared like the vaccines or bacterins 

 described on p. 82, and injected under the skin. A 

 slight fever may result but no further bad effects have 

 been noted. All symptoms are over in twenty-four 

 hours after each injection. The bacteria are intro- 

 duced three times. The immunity resulting is sup- 

 posed to last about two years. This vaccine method 

 is well adapted for and most used by armies going into 

 camps. The results in our army and that of Great 

 Britain have been very encouraging. It should be 

 taken by nurses doing army nursing or seeing many 

 typhoid cases. 



Major Russell, U. S. A., concludes his investigations 

 into the theory and practice of antityphoid vaccination 

 as a prophylactic as follows : 



1. Antityphoid vaccination in healthy persons is a 

 harmless procedure. 



2. It confers almost absolute immunity against 

 infection. 



3. It is the principal cause of the immunity of our 

 troops against typhoid in the recent Texas maneuvers. 



4. The duration of the immunity is not yet deter- 

 mined, but is assuredly two and one-half years and 

 probably longer. 



5. Only in exceptional instances does its administra- 

 tion cause an appreciable degree of personal discomfort. 



6. It apparently protects against the chronic bacillus 

 carrier and is at present the only means by which a 

 person can be protected against typhoid under all 

 conditions. 



