'3 



INFECTION AND I MM UNITY 



lengthened about six years. During the first thirty- 

 five years of the past century, the vital statistics of the 

 city of London showed a mortality of about 29 per 

 thousand. At the present time the mortality in that 

 great city has been reduced to from 17 to 19 per 

 thousand. 



No doubt a considerable proportion of this reduc- 

 tion in the rate of mortality in London and in other 

 large cities in this country and in Europe is due to a 

 diminished typhoid-fever rate. Indeed, sanitarians 

 at the present day depend largely upon this factor of 

 the general mortality rate of cities as an index of their 

 sanitary condition. The following table showing the 

 typhoid death-rate of cities, compiled by the Register 

 of Vital Statistics of the New York Health Depart- 

 ment, is given in a recent publication. 



AMERICAN CITIES 



