59 
To contrast with the above figures we reprint the following sum- 
mary of our findings in 1906 from Hj^gienic Laboratory Bulletin No. 
35, page 57 : 
SUMMARY FOR 1906. 
Eight hundred and sixty-six cases investigated June 1 to vwA’Pmber 1, 1906: 
( 
1 
Cases. 
Percent- 
age. 
Infection contracted out of District of Columbia-- - _ _ _ 
Infection attributed to milk or ice cream _ _ 
Infection attributed to contact _ _ _ ' 
Accounted for — _ - _ _ - . 
Unaccounted for ' 
129 
85 
54 
14.89 
9.81 
6.23 
268 
598 
30.93 
69.07 
Total— - - - - _ - • _ _ -i 
836 
1 
200.00 
1 
Or, considering only the TdT cases, of which 681 undoubtedly and 
66 probably contracted the infection in the District of Columbia, we 
h.aye — 
Attributed to infection by milk or ice cream. 
Attributed to infection by contact 
Accounted for 
Unaccounted for 
Total 
Ca.ses. 
Percent- 
age. 
85 
11.30 
54 
7.30 
139 
18.60 
608 
81.40 
747 
100.00 
The aboye figures are necessarily not exact, l)iit are apiiroximations 
based on the findings. 
CONCLUSIONS. 
1. jNIuch of the typhoid feA^r in the District of Columbia is im- 
ported. 
2. Many cases in the District of Columbia are contracted through 
contact with persons, or with articles handled or soiled by persons 
in the febrile stage of the disease. The especial preATilence of the 
disease among children in the District of Columbia probably has an 
important bearing on the spread of the infection by contact. 
3. Infected milk is one of the important knoAvn factors in the 
spread of the disease in the District of Columbia. 
4. The filtered Potomac KiA^er water during the typhoid season of 
1907 (May to September) was according to present bacteriologic 
standards of good sanitary quality and so far as could be ascertained 
Avas not responsible for the spread of the infection. 
In the typhoid season of 1907 there Avere about 200 cases less than 
in the 1906 period. This improA^ement in the situation suggests that 
