288 



THE PRINCIPLES OF IMMUNOLOGY 



Prophylactic Value of Vaccination. It can readily be understood 

 that the control of individuals in armies offers excellent facilities for 

 determination of the prevalence and mortality of infectious disease. 

 Consequently, much of the statistical evidence favorable to typhoid 

 vaccination has been collected in armies. The following table, taken 

 from Gay, "Typhoid Fever," illustrates the prevalence of typhoid fever 

 in Great Britain and her colonies before vaccination was introduced : 



MORBIDITY AND MORTALITY FIGURES FROM TYPHOID FEVER PER 100,000 OF ENGLISH 

 TROOPS IN THE YEAR 1898 IN DIFFERENT LOCALITIES. 



Locality Morbidity Mortality 



Great Britain 120 24 



Gibraltar 420 132 



South Africa 3290 577 



India 3600 1000 



Egypt 8100 2340 



Gay states that even greater rates of typhoid morbidity have been en- 

 countered. The results of anti-typhoid vaccination are splendidly 

 summarized in another table from Gay's work : 



RESULTS OF ANTI-TYPHOID IMMUNIZATION IN THE ENGLISH ARMY. MORBIDITY 

 AND MORTALITY PER 100,000. 



The results obtained in the United States Army under the direction 

 of Colonel Russell and his staff have been most impressive. In Decem- 

 ber of 1919 Colonel Russell summarized the results in a paper in the 

 Journal of the American Medical Association. He gives an analysis 

 of a water-borne epidemic in Hawaii as follows : 



TYPHOID EPIDEMIC IN HAWAII, H. T., IN THE FALL OF 1917. 



Population No. of 



on Castner cases 



water of 



system typhoid 



Vaccinated 4087 55 



Unvaccinated 812 45 



Cases 

 per 



thousand 



1345 



55-41 



Deaths 

 Number Per cent. 



74 

 15-5 



Mortality 



rate 



per 

 thousand 



0.97 

 8.62 



It is of importance to note in reading this table the large number 

 of vaccinated as contrasted with the Unvaccinated. It is apparent that 

 the vaccinated show not only a reduced morbidity percentage, but also 

 a diminished mortality rate. Colonel Russell gives the following table 

 of figures from the United States Army for nineteen years : 



