15 
account. *It should be borne in iiiiiid that the number of imported 
cases in a city is probably ^Yholly or partly offset by the number of 
cases which contract the infection in the city and develop the disease 
elsewhere. 
Xo detailed epidemiological investigations Avere made of the cases 
Avhich were considered as certainly or almost certainly haA'ing con- 
tracted the infection out of the District. Therefore, most of the 
data in this report refer to the 523 cases comprised under c, and e 
of the above classification. 
SEX. 
Of the 523 cases. 301 occurred in males and 219 in females. Males 
compose about 18 per cent and females about 52 per cent of the popu- 
lation of the District of Columbia: 58.12 per cent of the cases Avere 
among males, .shoAving, as Avas the case in the group studied by us in 
1906, a relatively slightly higher typhoid fever morbidity rate among 
the males. 
Tavo conditions, perhaps, contribute to tlie higher rate among the 
males; first, due to habits of occupation, etc., men are more exposed 
to infection, and, secondly, during the summer months, Avhen the 
disease is most preA^alent in IVashington, a relatively larger num- 
ber of women than men leave the city. 
RACE. 
Three hundred and eighty-seven, or 71 per cent, of the cases were 
among Avhites, and 136, or 26 per cent, among negroes. According 
to the police census for the spring of 1907, the population of the Dis- 
trict of Columbia consists of 233.103 whites and 96,188 negroes, a 
total of 329,591. Thus negroes compose 29.18 per cent of the popu- 
lation, while the cases of typhoid fever among them composed 26 
per cent of the total number investigated, shoAving a relatively some- 
what loAver morbidity rate among negroes than among Avhites. A 
discussion concerning the marked decrease in the morbidity and 
mortality rates in the negroes during the calendar year 1907 Avill be 
found on page 22, under Prevalence.'' 
AGES. 
The folloAving table gives the cases classified by age and sex, along 
Avith the population of the District of Columbia in 1900 (U. S. Cen- 
sus Eeport) : 
Ages, years. 
Xumber of eases. Population, 1900. ! Ratio of 
Alale. 
Female. 
Total. Alale. 
1 1 lu 
Female. ! Total. 
1 
0-4 . 
‘A 
11 
2-1 11,683 
11,467 23,150 1-1,052 
5-9__ 
.48 
33 
81 11,708 
12,023 23,731 1- 293 
10-14-_ . . . 
47 
50 
97 1 10,953 
11,781 22,734 1- 234 
15-19 
41 
33 
74 1 21,362 1 
1 13,452 24,814 . 1- 335 
