688 ACTIVE IMMUNIZATION 



being about 10 per cent, in spite of the intensive treatment, and about 

 40 to 60 per cent, without treatment. 



When symptoms of rabies have appeared, the treatment is unavail- 

 ing. Antirabic serums have been prepared by immunizing animals, 

 such as sheep and horses, and these should be tried in human patients 

 presenting symptoms, but the results in general have not been uniformly 

 encouraging. 



TYPHOID FEVER 



Our knowledge of vaccination in typhoid fever begins with the work 

 of Pfeiffer and Kolle. 1 These observers, in 1896, immunized two volun- 

 teers with heat-killed cultures, and by complete laboratory investiga- 

 tions demonstrated the identity of the immunity following an attack of 

 the disease with the artificial immunity produced by inoculation. At 

 about the same time Wright, 2 of London, inoculated two men with 

 killed cultures, and a year later published the results of the successful 

 vaccination of 17 persons. In 1898 be continued the work in India, 

 where 4000 soldiers were inoculated, with encouraging results. Later, 

 during the Boer war, Wright and Leishman treated 100,000 men, and 

 the results, while good, were not encouraging, due, as pointed out later 

 by Leishman, 3 to the fact that the vaccine was damaged during its 

 preparation by overheating. Since 1904 an improved vaccine has been 

 used among the British troops in India in ever-increasing quantities, 

 with uniformly good results. 



Antityphoid vaccination was begun in the United States army in 

 1908, the vaccine being prepared by Major Frederick F. Russel. Its 

 value has been established so clearly that vaccination is now compulsory. 

 The results obtained in the army have had considerable influence in 

 establishing a wide-spread general confidence in antityphoid inoculation. 



Preparation of Typhoid Vaccine. Based upon general principles, 

 the vaccine should be prepared of typhoid bacilli as little changed by 

 heat or chemicals as possible. Russel has prepared the army vaccine 

 with a single avirulent culture which proved by animal experiments 

 and laboratory methods capable of producing large quantities of immune 

 agglutinins and bacteriolysins. As a general rule, however, the vaccine 

 should be polyvalent, and particularly in view of the experiments of 

 Hooker, 4 who has shown by complement-fixation tests consistent anti- 

 genie differences among some strains of Bacillus typhosus. 



1 Deutsch. med. Wchnschr., 1896, xxii, 735. 



2 The Lancet, London, September 19, 1896, 907; Brit. Med. Jour., January 30, 

 1897, 16. 



3 Jour. Roy. Inst. 4 Jour. Immunology, 1916, 11, 1. 



