22 
every 348; while in 1906 the morbidity rate was 3.45 per 1,000. or 
one in every 289. 
The number of deaths from typhoid fever in the District of Colmn- 
bia during 1907 was 114, being a death rate of 34.5 per 100,000 of 
population, as against 49.3 for 1906. The percentage of deaths to 
cases (mortality rate) for the two years was as follows: 
Year. 
White. 
Colored. 
Total. 
1907 _ 
1906 
- - - 10.4 
10.3 
17.6 
24.2 
12.0 
14.4 
Thus the mortality rate was higher in 1906 than in 1907, and as 
the rate for the whites was slightly lower in 1906 than in 1907, the 
higher rate in 1906 was due to the higlier rate among the colored. 
As the mortality rate for the whites was about the same for the 
two years, it does not seem probable that the lower rate for the col- 
ored in 1907 was due to the occurrence of a milder type of infection 
in lYashington during that year. From what we know of the facts 
the difference was not due to improvement in the treatment of cases 
in 1907. Therefore it seems that the different rates among the col- 
ored for the two years may have been due to difference in percentage 
of error in diagnosis and report of cases. 
The mortality rates for the other three years of which there is 
record were as follows : 
Year. 
White. 
1 
Colored. Total. 
1903 _ - — — 
10.69 
19.35 12.98 
1904 _ - - - - - - 
190:> 
10.89 
11.66 
22.42 14.01 
16.33 12.94 
The rate among the whites during the five years is seen to be fairly 
constant, while among the colored it varies considerably from year 
to year. Probably the lower figures more nearly approach the actual 
mortality rate among the negroes, and in those years in which the 
figures are high it is likely that the proportion of cases reported to 
the 'number which actually occurred was relatively low. This is 
based on the assumption that typhoid fever may not show marked 
variations in virulence from year to year among the colored people 
in an endemic area. 
