BACILLUS TYPHOSUS 529 



As a rule the injections particularly the primary one 

 are followed by a red, tender, swollen area at the site of 

 puncture. This may be accompanied by headache, fever, 

 general malaise and sometimes by a chill with vomiting 

 or diarrhea. In the majority of individuals the reactions 

 are mild and disappear in from thirty-six to forty-eight 

 hours. 



In the later use of this vaccine it was found possible to 

 secure the desired protection by one single injection, instead 

 of three. In from one to three persons out of every thousand 

 vaccinated the reaction may be severe, though they are 

 not dangerous. No ill effects of a permanent nature have 

 thus far been noted in the thousands of civilians and millions 

 of soldiers inoculated during the war, nor have the vaccina- 

 tions been seen to influence unfavorably the course of other 

 diseases from which the individual may be suffering. 



It should be needless to say that strict aseptic precau- 

 tions are to be taken in performing the operation. The 

 resistance that is excited by the vaccination is an "active 

 immunity" that is, it is an immunity identical in nature 

 with that acquired by an individual who has recovered from 

 an attack of typhoid fever. In so far as can be stated now, 

 however, the immunity is not permanent. All indications 

 point to its gradual diminution and possible disappearance 

 often in two to three years, so that revaccination after the 

 lapse of this time is advisable. 



NOTE. Obtain a pure culture of typhoid bacilli, and 

 from this make inoculations upon a series of potatoes of 

 different ages and from different sources. Do they all 

 grow alike ? 

 34 



