INFECTION AND IMMUNITY. 553 



had been killed after heating to a moderate temperature. 

 The dead organisms when injected bring about a reac- 

 tion in the body as shown by a marked increase in the 

 agglutinative and bactericidal properties of the blood 

 serum against the particular organism. The favorable 

 results following the use of the Haffkine fluid in pre- 

 venting plague have already been given. 



Wright has introduced a similar method of vaccina- 

 tion against typhoid fever. The prophylactic treatment 

 consists of one or two injections of dead cultures of 

 bacillus typhosus. Caiger l gives the results obtained 

 in the British regiments serving in India. Amongst 

 1 5,384 inoculated men the incidence of typhoid fever 

 was 0.8 percent., as against 1.5 per cent, in the uninocu- 

 lated. The case mortality amongst the inoculated was 

 15.6 per cent., as against 26.6 per cent, in the uninocu- 

 lated. The results obtained in the military hospitals in 

 South Africa show that the case mortality was 8.2 per 

 cent, among the inoculated, as against 15.1 per cent, 

 among the uninoculated ; a reduction in the mortality 

 of about 50 per cent. In the staffs of three of the mili- 

 tary hospitals the reduction in the mortality was nearly 

 threefold. 



Bresredka 2 sought to find a method of immunization 

 against plague, cholera, and typhoid. For this purpose 

 he places a culture of bacillus typhosus into typhoid 

 immune serum until it is completely agglutinated. The 

 bacteria are then removed from the serum by centrifug- 

 ing and subsequently washed with sterile physiological 

 salt solution in order to remove all trace of the serum. 

 The bacteria are then heated to 60 C. for several 



1 Caiger : The Lancet, 1904, vol. ii., p. 1467. 



2 Bresredka : Annals of the Pasteur Institute, 1902, T. 16. 



