MORTALITY AND INCIDENCE 17 



necessity for interpretation of their language, may well have 

 resulted in inaccuracies in certain instances. It was often only 

 after much questioning that the duration of illness before ar- 

 rival in our Division could be determined even though the 

 symptoms of onset were well described and seemed to have 

 appeared abruptly. Some instances of apparently abnormally 

 long or abnormally short courses may have been due to error in 

 statements of duration on admission. In general, however, the 

 facts were obtained as accurately as careful questioning could 

 effect, and it is probable that in the combined statistics such 

 errors as were unavoidable largely offset one another. 



2. MORTALITY 



It may also be mentioned that, as will be seen from the statis- 

 tics, the epidemic with which we were dealing was one of the 

 disease in a mild form. The mortality among the recent total 

 admissions of the St. Stanislaus Hospital and of other typhus 

 hospitals in the neighborhood was estimated as not over 7 per 

 cent. The mortality of 13.26 per cent of our cases, even though 

 they were selected largely for signs of dubious prognosis, is low 

 as compared with the mortality of many typhus fever epi- 

 demics. 



3. INCIDENCE 



Our series of cases included 181 patients, 86 men and 95 

 women. The great majority were residents of the city of War- 

 saw although some were refugees from a distance. Nearly all 

 were from the lower classes; many were Hebrews. There were 

 frequent instances of infection of two or more members of the 

 same family. 



The ages are not typical of the age-incidence of the disease 

 because we selected older patients for our work. The increas- 

 ing mortality with advancing age is well illustrated in the table 

 of deaths (see p. 32) for each decade. 



