332 THE ALCALIGENES DYSENTERY TYPHOID 



rabbit's blood. They found that the typhoid bacilli localize them- 

 selves in the gall-bladders of the rabbits, and that they may from time 

 to time invade the blood stream. In a more recent communication 1 

 they have shown that the carrier state occurs much less frequently 

 if the animals are immunized with their dried sensitized vaccine. 



Antibody Production. Animals may be immunized by repeated 

 injections of typhoid bacilli to such a degree that they will successfully 

 resist several times the original fatal dose of these organisms. 2 Suc- 

 cessive injections of typhoid bacilli stimulate antibody formation 

 in horses, rabbits, guinea-pigs, and other animals. Of these anti- 

 bodies, the lysins and agglutinins may be produced in high potency 

 if the injections are continued long enough. Other antibodies, opsonins 

 and precipitins particularly, are also produced. Gay and Claypole 3 

 have produced experimental evidence indicating that the titre of the 

 specific agglutinins which develop during the process of immunization 

 of rabbits affords no indication of the degree of protection attained by 

 the immunizing process. 



Protective Immunization. As a rule, one attack of typhoid fever 

 confers immunity; subsequent attacks are unusual. 



During the last few years definite progress has been made in the 

 protective immunization of human beings, both by the use of killed 

 cultures of typhoid bacilli and by live cultures. The vaccine treat- 

 ment for typhoid fever is the best known and the most widely prac- 

 ticed. The procedure is to grow typhoid bacilli on agar slants, wash 

 them off with sterile physiological salt solution, kill them by heating 

 to 60 C. for an hour, standardizing the suspension of typhoid bacilli, 

 and injecting as a first dose five hundred million killed typhoid organ- 

 isms. After an interval of seven to ten days a second injection of a 

 billion killed typhoid bacilli is made, and after an equal interval a 

 third and last injection of a billion killed typhoid bacilli is made. 

 In about 20 per cent, of the cases injected general symptoms which 

 consist of a febrile reaction and malaise develop, accompanied by 

 local symptoms of pain, redness, and swelling at the site of inoculation. 

 These symptoms may appear after the second or even after the third 

 injection. It is customary to make the inoculation about four o'clock 

 in the afternoon, so that the patient in the majority of cases sleeps 

 through the general symptoms. 



* Arch. Int. Med., 1914, xiv, 671. 



2 See Gay and Claypole, Arch. Int. Med., 1914, xiv, 671, for essential details. 



3 Loc. cit. 



