46 
the prevalence of the disease in AVashin^on. but with the increase 
of cases on t^e watershed in the snnnner there may be. in spite of 
the dilution, enough typhoid infection in the water to occasion a 
marked increase in the prevalence of the disease hi AVashington. In 
this connection reference should be made to Kober's observations on 
the effects of the typhoid epidemic of 1889-1890 at Cumberland. Md.. 
upon the prevalence of the disease in T\hishington.® 
TTe have noted that in dry and warm seasons the present system 
of storage and filtration of the Potomac Eiver water will give a water 
of good sanitary cpiality, but in periods of high turbidity, especially 
in winter, fine silt in the river water does not settle so well, nor is 
it all retained by the sand filters. IVith the increased amount of this 
silt in the effluent is an increased number of bacteria. 
MILK. 
Tlie 523 cases considered as having contracted the infection in the 
District of Columbia gave the following history as to the use of 
milk during the thirty days prior to illness : 
As a beverage 200 
On fruits or cereals, but not as a beverage US 
In bot tea or coffee only U 
As ice cream only 2S 
’In no way 38 
Not determined 5 
Total 523 
Of the cases using milk as a beverage or on fruits and cereals 6 
used boiled milk exclusively. 
One distinct milk outbreak occurred. This was among the cus- 
tomers of milk dealer Xo. 163. There were in the course of this 
outbreak 31 cases with the onset of illness between June 8 and 
August 17. (See Chart Xo. 4.) Of these cases 2 gave a history 
of having used boiled milk only during the thirty days prior to onset, 
and for one other infection by contact seemed more probable. Elimi- 
nating these 3 cases there are left 28. considered as being cpiite defi- 
nitely attributable to milk infection. 
The evidence that these cases were due to milk infection Avas not 
absolutely positive, but it seemed sufficiently strong to justify at- 
tributing these cases to milk. Thus, there was a sudden and marked 
increase in the number of cases among the customers of this dealer. 
The number of cases among his customers was far in excess of the 
rate of j^revalence among persons living in the same neighborhoods 
® Report on the pollution of rivers, by Henry Talbott. Chairman of Committee 
on River Pollution, to the Game and Fish Protection Association of the District 
of Columbia. Government Printing Office, Washington, 1S9S, p. 32. 
