45 
The locations of the water-closets in relation to the houses connected 
with the city sewerage system and in which the cases occurred were 
as follows: 
Location of water-closets. 
Number of cases. 
’ 1908. 
1907. 
1906. 
In house only 
' 198 
212 
240 
In yard only 
' 190 : 
163 
257 
In both house and yard 
95 ’ 
87 
174 
Total 
483 1 
462 
671 
Of the 56 cases occurring at houses at which privies were in use, 16 
had direct contact with cases in the febrile stage in the same house 
or house near by, 1 had direct contact with a suspected case, and 8 
had indirect contact by persons or flies vdth patients in the febrile 
stage. This relatively high contact infection shows that when cases 
occur in houses at which privies are in use, the chances of infection 
being conveyed to other members of the household are much greater 
than when the houses are connected with the city sewerage system. 
WATER. 
Of the 542 cases, 515, or about 95 per cent, gave a history of having 
used unboiled Potomac River water supphed through the regular 
city system as the sole, principal, or occasional source of water for 
drinking purposes during the thirty days prior to the onset of illness. 
Of the 523 cases investigated in 1906, 96.54 per cent gave a history 
of having used the unboiled Potomac water. 
The following table gives the source of water used for drinking 
during the thirty days prior to onset of illness by the 542 cases inves- 
tigated : 
Raw tap: 
Solely 
Principally 
Occasionally 
Occasionally (?) 
Boiled tap: 
Solely 
Principally 
Occasionally . . . 
Filtered tap: a 
Solely 
Principally 
Occasionally 
Water. 
Number of 
cases. 
346 
112 
57 
3 
1 
30 
2 
1 
3 
0 
a By “filtered” tap water is meant water filtered after it is drawn from the tap. 
