376 TYPHOID FEVER 



dermically will kill a guinea-pig of from 350 to 400 grammes. 

 Vaccination can be accomplished by such a culture emulsified in 

 bouillon, and killed by heating for five minutes at 60 C. For 

 use, from one-twentieth to one-fourth of the dead culture is 

 injected hypodermically, usually in the flank. The vaccine now 

 used, however, actually consists of a portion of a bouillon culture 

 similarly treated (see p. 133). The effects of the injection are 

 some tenderness locally and in the adjacent lymphatic glands, 

 and it may be local swelling, all of which come on in a few 

 hours, and may be accompanied by a general feeling of restless- 

 ness and a rise of temperature, but the illness is over in 

 twenty-four hours. During the next ten days the blood of the 

 individual begins to manifest, when tested, an agglutination 

 reaction, and further, Wright has found that usually after the 

 injection there is a marked increase in the capacity of the blood 

 serum to kill the typhoid bacillus in vitro. These observations, 

 there is little doubt, indicate that the vaccinated person possesses 

 a degree of immunity against the bacillus, a conclusion borne 

 out by the results obtained in the use of the vaccine as a 

 prophylactic against typhoid fever. Extensive observations 

 have been made in the British army in India, and in the South 

 African War the efficacy of the treatment was put to test. 

 Though in isolated cases not much difference was observed 

 among those treated as compared with those untreated, yet the 

 broad general result may be said to leave little doubt that on the 

 one hand protective inoculation diminishes the tendency for 

 the individual to contract typhoid fever, and, on the other, if the 

 disease be contracted, the likelihood of its having a fatal result 

 is diminished. Thus, in India, of 4502 soldiers inoculated, '98 

 per cent, contracted typhoid, while of 25,851 soldiers in the 

 same stations who were not inoculated, 2 '54 per cent, took the 

 disease. In Ladysmith during the siege there were 1705 

 soldiers inoculated, among whom 2 per cent, of cases occurred, 

 and 10,529 uninoculated, among whom 14 per cent, suffered 

 from typhoid. Wright has collected statistics dealing in all 

 with 49,600 individuals, of whom 8600 were inoculated, and 

 showed a case incidence of 2 '25 per cent., with a case mortality 

 of 12 per cent. ; in the remaining 41,000 uninoculated the case 

 incidence was 5 '75 per cent, and the case mortality 21 per cent. 

 The best results seemed to be obtained when ten days after 

 the first inoculation a second similar inoculation was practised. 

 Weight has found that in certain cases immediately after 

 inoculation there is a fall in the bactericidal power of the blood 

 (negative phase), and he is of opinion that this indicates a 



