INTRODUCTION TO THE STUDY OF INFECTIOUS DISEASES 379 



case of children, epidemic spread is almost unavoidable if unsani- 

 tary, close association exists. Fortunately, in many of the diseases 

 so transmitted, namely, pneumonia, meningitis, diphtheria and a 

 number of others, the normal resistance . of the human being is 

 relatively high and epidemic occurrence takes place only when 

 unusual conditions prevail. 



(2) The intestinal group consisting very largely of typhoid and 

 the paratyphoid fevers, the dysenteries, cholera, the food poisonings, 

 and the simple diarrheas. In this group sanitation, apart from isola- 

 tion of the recognized case, focuses upon a constant vigilance in 

 regard to the distribution of dejecta from human beings, for every 

 infection signifies a sanitary defect in the transmission of the con- 

 tents of the bowels of one human being to the mouth of another by 

 any one of a variety of routes. Sanitation here requires proper 

 sewage disposal, the care of privies and latrines, and careful control 

 of water and food supplies, since naturally large epidemics can be 

 most easily brought about in this group by the contamination of 

 the daily diet of the community. In these diseases, wholesale infec- 

 tion with water and milk is constantly diminishing, as we are im- 

 proving in our sanitary organizations. But contact epidemics from 

 person to person becoming relatively more prominent. Kecent 

 studies are tending, for instance, to show more and more the in- 

 creasing importance of contact infection in typhoid fever. Schule 1 

 studying the reports of the German Laboratory at Trier for 1918, 

 states that of the typhoid cases occurring in the district controlled 

 by this laboratory during that year, 60 per cent were due to contact 

 with cases, 5 per cent were due to contact with carriers and only 

 1 per cent were due to water and milk each. Of 5,889 cases analyzed 

 at this laboratory, 71 per cent were contact cases. 



The manner of contact may vary, and Gay 2 summarizes in the 

 following way, the manner in which this may take place : 



1. Fingers or utensils mouth. 



2. Fingers food mouth. 



3. Fomites fingers food mouth. 



4. Flies food mouth. 



5. Fingers flies food mouth. 



In the case of the first route, more or less direct contact with 

 a case is implied. In each of the five routes it is easy to draw 



1 Schule, Mil. Surgeon, 45, 1919, 268. 



2 Gay, Typhoid Fever, Macmillan Company, N. Y., 1918. 



