17 
Children drink more milk than adults, so that where milk is a 
frequent source of infection a relatively large number of cases among 
children may be expected. 
In considering the number of cases among children in a commu- 
nity where typhoid fever has prevailed extensively for a number of 
years, we have to take into account that a proportionately larger 
number of adults have been rendered partially or completely immune 
by previous infection. 
Contact between child and child and between child and adult is of 
a close and intimate nature, and such as to favor the spread of the 
infection of hqDhoid fever. Considering this fact, along with the 
known extensive prevalence of the disease among children, we have 
a possible explanation of the spread of the infection to many of the 
cases unaccounted for by epidemiological investigations, thus robbing 
the general problem of some of its mystery. Koch found that 49 of 
the 64 unrecognized cases of typhoid fever at Trier occurred among 
children. (Die Bekampfung der Typhus, Berlin, 1903.) The large 
number of cases among children emphasizes the importance of keep- 
ing this factor in mind in carrying out practical measures to prevent 
the spread of the infection. 
NATIONALITY. 
In the following table is given the nationality of the cases along 
with the number of foreign born in the District of Columbia for 1900, 
according to the United States Census reports. For some of the 
nationalities the population no doubt has changed considerably since 
1900, so that the figures in the table are not strictly comparable. 
Nationality. 
Number 
of cases. 
Number of 
foreign- 
born in 
District of 
Columbia, 
census of 
1900. 
American - _ _ 
495 
Danish-- 
1 
88 
English-- - - - - . _ - ----- 
3 
2,299 
German -- - _ i - 
5 
5,857 
Hungarian- _ _- - 
1 
48 
Irish - — _ - — - 
5 
6,220 
Italian-- _ — _ 
11 
930 
Russian 
1 
807 
Swedish — -- 
1 
234 
Tnf.al 
523 
40219 - 08 - 
