294 THE PRINCIPLES OF IMMUNOLOGY 



duced. Lustig and Galeotti used nucleoprotein extracted from the 

 organisms and Kitano and others have employed organisms grown in 

 Bengal isinglass medium. Kitano and Sukegawa employed sensitized 

 vaccines and are of the opinion that these give better results than the 

 usual heated vaccine. They gave in the first dose 2 mg. of the sensi- 

 tized organism and in the second dose 4 mg. of the sensitized organism. 

 If haste is essential, 6 mg. may be given at one dose. 



Experimentally, it has been established that vaccinated animals dis- 

 play an increased resistance against the disease. The Indian Plague 

 Commission reported that vaccination in man diminishes the incidence 

 of the disease, but that it does not furnish absolute protection. Appar- 

 ently the duration of immunity lasts from a few weeks to a few months, 

 but immune bodies are not demonstrable until ten days have elapsed. 

 In spite of the fact that numerous investigators have reported favorably 

 on vaccination against plague, Flu has stated that an analysis of the 

 statistics fails to furnish evidence that sufficient attention has been 

 given in the earlier studies to the prevalence of infected rats or to 

 other hygienic conditions which prevailed. 



Vaccination Against Typhus Fever. Vaccination against this 

 disease has been attempted with the serum of convalescent patients, but 

 the results have not been highly satisfactory. Plotz, Olitsky and Baehr 

 employed a vaccine composed of fifteen strains of bacillus typhi exan- 

 thematici. Of a series of 5251 vaccinated individuals where typhus was 

 epidemic only Ihree contracted the disease, and in another series of 

 8420 cases only six contracted the disease. Although the work of Plotz 

 with this organism has been carefully done there is still doubt as to its 

 exact etiological relationship. In statistics concerning this disease, 

 the presence of infected lice should be taken carefully into considera- 

 tion. It cannot be stated that vaccination in typhus has any great value 

 until further investigations have been conducted. 



Vaccination Against Pertussis (Whooping-Cough). The dis- 

 covery of the bacillus of whooping-cough by Gengou almost immediately 

 led to investigation as to vaccination. Luttinger has summarized the 

 results obtained in a large whooping-cough clinic and by over 180 private 

 physicians and health officers. The results were sufficiently encouraging 

 to justify the recommendation of this procedure. Conditions of ex- 

 posure and the nature of surroundings, as well as the variability of the 

 disease, even in a single epidemic, makes the interpretation of statistics 

 extremely difficult. 



Vaccination Against Dysentery. Prophylactic vaccination against 

 dysentery has encountered great difficulties because of the extreme tox- 

 icity of the cultures, Shiga attempted to overcome this by employing 

 mixed active and passive immunization. He used a bacterial vaccine to 

 which was added immune serum. Experiments on 10,000 individuals 

 showed a definite decrease in the rate of mortality. Others have em- 

 ployed toxin-antitoxin mixtures with apparent success, but Hoffmann 

 found that this type of vaccination failed to have any effect on the control 

 of a dysentery epidemic which he studied. Whitmore and Fennel and 



