TYPHOID FEVEP IN DISTRICT OF COLUMBIA. 
15 
children makes it probable that many cases are not recognized, as 
typhoid is especially mild and irregular in children. The prevalence 
of the disease among children may have an important bearing upon 
the subject of the spread of the disease by direct and indirect contact. 
IMPORTED CASES. 
One hundred and twenty-nine of the 866 cases studied, or about 
15 per cent, contracted their infection outside of the District of 
Columbia. Sixty-six of these imported cases were taken directly 
to hospitals and 15 more were taken to hospitals after a stay of a 
few days at private houses. The fact that this large number was 
treated in the hospitals shows that the chances of dissemination of 
the infection by the imported cases was correspondingly diminished. 
SEASONAL PREVALENCE. 
There was a sudden rise in the number of cases early in July, 
reaching its maximum early in August, and then a marked falling 
off about the middle of August, which decline continued through 
September. It is a striking fact that the marked rise occurred with 
the advent of the hot weather, but the disease declined while the 
weather continued hot and moist. 
The seasonal prevalence for this year is very similar to that for 
previous years. In other words, typhoid fever is largely a summer 
disease in Washington. In some years, however, the disease con- 
tinued throughout the late fall. (See chart No. 4.) 
The secondary rise, which occurred in October, 1906, was largely 
a milk outbreak. (See chart No. 1.) 
GEOGRAPHICAL DISTRIBUTION. 
During the period covered by our investigation the disease was 
quite uniformly distributed throughout the inhabited portions of 
the District of Columbia. This widespread and uniform distribu- 
tion suggests some common factor as one of the principal means of 
disseminating the infection. In no instance was anything approach- 
ing a local focus noted. There was no unusual grouping of cases 
about shallow wells, in crowded and insanitary courts and alleys, or 
in districts where privies are numerous. It is interesting that there 
were no such local outbreaks in these localities where the conditions 
seemed favorable for the spread of the disease by direct contact and 
flies. 
It is interesting to note that at the Government Hospital for the 
Insane, with a population of about 3,000, most of them of a suscep- 
tible age, there were no cases of typhoid fever in 1906, while around 
the institution the disease prevailed in about its normal distribution. 
For details as to isolation, water and milk supply of this institution, 
see page 298. 
