14 
CONTACTS. 
Association 30 clays prior with patients in febrile stage, . 
Association with suspected cases, . 
Association with persons who have had typhoid within 6 months, ; 
1 year, ; 2 years, ; 3 years, ; 4 years, ; 5 years. 
Association 30 days prior with persons in contact with patients in febrile 
stage, . 
Treatment of stools and nrine of patients, — ^ . 
Other precautions, . 
Itemarks : . 
Summary : . 
(Signature of investigator.) 
IMPORTED CASES. 
In detennining the number of cases in which the infection was con- 
tracted out of the District of Columbia the same method, but with a 
little more detail, was adopted as in our study of. the cases reported 
from June 1 to Xovember 1, 1906, and as published in our previous 
report.® 
The cases fall under the following heads : 
Cases. 
(a) Infection undoubtedly contracted out of the District of Columbia 117 
(&) Infection probably contracted out of the District of Columbia 30 
(c) Infection contracted in or out of the District of Columbia, chances 
about equal 40 
(d) Infection undoubtedly contracted in the District of Columbia 363 
(e) Infection probably contracted in the District of Columbia 120 
Total 670 
Considering the cases on the percentage of chances of the infection 
having been contracted out of the District of Columbia, they are as 
follows : 
Cases. 
(a) 117 cases, chances 100 per cent 117 
(&) 30 cases, chances 75 per cent 22 
(c) 40 cases, chances 50 per cent ^ 20 
(d) 363 cases, chances 0 per cent 0 
(e) 120 cases, chances 12.5 per cent 15 
670 cases. Total 174 
On this estimate, about 26 per cent of the cases investigated con- 
tracted the infection out of the District of Columbia, as against about 
15 per cent of the cases studied by us in 1906. 
In estimating the chances of contracting the infection out of the 
District, the time element was given the greatest consideration, but 
the prevalence of typhoid fever in the communities visited and known 
exposure of the person to infection while away were also taken into 
® Bulletin No. 35, Hygienic Laboratory, P. II. and M. H. S. Report on the 
Origin and Prevalence of Typhoid Fever in the District of Columbia, 1906. 
