25 
The proportion of cases among persons living at residences of 
which all the sanitaiw conditions were good was considerably smaller 
during the 190T period than during the 1906 period; but again this 
year a majority (about 62 per cent) of the cases occurred among 
persons living at residences of good or fairly good sanitary condition. 
DISPOSAL OF SEWAGE. 
Of the 523 cases, 462 were among persons living at residences con- 
nected with the city sewerage system and at which there vrere water- 
closets, 56 at residences not connected with the city sewerage system 
and at which there were box privies, 1 at a residence from which the 
water-closet discharged into a subsoil cesspool, 1 at a residence hav- 
ing neither water-closet nor privy, and 3 at institutions not connected 
with the city sewerage system but having water-closets which dis- 
charged into local sewerage s^'stems. 
Of the 462 cases occurring at residences connected with the city 
sewerage system, 212 were at residences having water-closets in the 
house only, 163 at residences having water-closets in the yard only, 
and 87 at residences having water-closets in both house and yard. 
As in the 1906 period, there was no unusual prevalence of the disease 
among persons living at residences not connected with the city sew- 
erage system and at which privies or other local means of disposing 
of sewage were in use. Thus, in the 1907 period 88.3 per cent and 
in the 1906 period 90 per cent of the cases were at residences connected 
with the city sewerage system and supplied with water-closets. 
Of the 56 cases occurring at houses at which privies were in use, 15 
were secondary cases and attributed to personal infection from cases 
in the same house or in a house nearby. 
The danger of the spread of the infection by flies, etc., necessarily 
is greater where the excreta of the typhoid fever patients are de- 
posited in privies, and it is therefore important to abolish privies as 
speedily as the extension of the city's sewerage system makes possible. 
WATER. 
Of the 523 cases, 492, or about 94 per cent, gave a history of having 
used unboiled Potomac water supplied through the regular city sys- 
tem as the sole, principal, or occasional source of water for drinking 
during the thirty days prior to the onset of illness. Of the cases 
investigated during the 1906 period, 96.54 per cent gave a history of 
having used the unboiled Potomac water. 
