694 ACTIVE IMMUNIZATION 



TYPHUS FEVER 



Preliminary studies upon prophylactic immunization of persons with 

 Bacillus typhi exanthematici, a Gram-positive pleomorphic bacillus 

 secured in blood-cultures from persons suffering with typhus fever by 

 Plotz, Olitsky and Baehr, 1 seem to indicate that a vaccine of this bacillus 

 is capable of reducing the incidence of the disease, although it does not 

 produce an absolute immunity to typhus fever (Plotz, Olitsky, and 

 Baehr). 2 The vaccine is polyvalent and is sterilized by heating to 58 

 to 60 C. for from half an hour to one hour. The suspension is so diluted 

 that each cubic centimeter contains about 2,000,000,000 bacteria, and 

 is preserved with 0.5 per cent, phenol or tricresol. Three injections con- 

 sisting of 0.5, 1, and 1 c.c., respectively, have been given in five- or six- 

 day intervals. The subject is in the experimental stage. 



PNEUMONIA 



In the prophylaxis of lobar pneumonia by active immunization 

 Wright 3 has had an unusually rich experience in the Rand mining 

 district of South Africa where a severe type of pneumococcus pneu- 

 monia has claimed a high morbidity and mortality among the natives. 

 After a considerable amount of experimentation the administration of 

 a single large dose of stock vaccine containing 1,000,000,000 cocci was 

 generally employed. Wright thinks that this vaccine reduced the inci- 

 dence of pneumonia among the natives during the first three months 

 following inoculation. Later reports of this work have failed to establish 

 the efficacy of active immunization in preventing the development of 

 pneumonia or materially lowering the mortality. Since, however, re- 

 cent investigations by Lister 4 have shown the existence of different 

 serologic types of pneumococci on the Rand, an improvement in the 

 efficiency of Wright's vaccine may have been made by using a mixed 

 vaccine of these special strains; if a vaccine is employed as a prophy- 

 lactic measure in pneumonia, it should be prepared of a number of 

 strains belonging to types I and II at least and several injections should 

 be given at intervals of five or seven days. The protection is likely to be 

 of short duration, but the method would appear worthy of trial under 

 these conditions and particularly during the seasons when pneumonia 



is prevalent. 



PLAGUE 



% In view of the frightful infectiousness and mortality of plague, 

 prophylactic measures are highly desirable. Extermination of rats and 



1 Jour. Infect. Dis., 1915, xvii, 1. 2 Jour. Amer. Med. Assoc., 1916, Ixvii, 1597. 



3 Drugs and Vaccines in Pneumonia, 1915, Paul B. Hoeber, New York. 



4 South African Inst. for Med. Res., Johannesberg, Dec. 22, 1913. 



