TYPHOID FEVER 83 



Thanks largely to the work of Wright, much has been 

 done to prevent infection with typhoid bacilli by pro- 

 tecting the individual through antityphoid vaccination. 

 For this purpose a bacterial vaccine is used, the typhoid 

 bacilli being very carefully killed by heat. The vaccina- 

 tion should consist of three injections a week apart. 

 The first one contains 500,000,000 bacilli, and the second 

 and third each 1,000,000,000. The results of such pro- 

 tective vaccinations have been excellent; very few cases of 

 typhoid fever develop among those so vaccinated, and the 

 cases that do occur run a milder course. 



Treatment of developed cases of typhoid fever by means 

 of these vaccines or by specific sera has proved to be with- 

 out value. 



