176 INFECTIOUS AND PARASITIC DISEASES. 



disease. Furthermore, the movement of food-stuffs 

 from one part of a country to another, or from one 

 country to another, will be sufficiently dealt with to 

 show the possibilities of diseases being literally picked 

 up, carried hundreds of miles, and transplanted in 

 regions where they previously did not exist. 



Mention has been made of the manner in which 

 typhoid fever, cholera, dysentery, etc., are contracted 

 from drinking polluted water. Polluted water, how- 

 ever, although it may not be used for drinking purposes, 

 may nevertheless be a source of danger from certain 

 foods which grow in it and are consumed raw. This 

 danger has been realized a number of times in the case 

 of oysters and clams; and while water-cress has not 

 yet been definitely incriminated, there is no reason 

 why it may not be a menace to health in the same 

 way. 



Fruits and vegetables are sometimes polluted by the 

 fertilizer, especially where human excrement is used to 

 enrich the soil. In the United States this practice is 

 not so common as in certain European countries, nor 

 in the latter countries as in China, where it is the rule. 

 But the number of Chinese truck-farmers in the 

 United States and Cuba is not small, and steps should 

 be taken to illegalize the use of human excrement for 

 fertilizer unless it has been made innocuous by various 

 approved methods. Only a few years ago, during the 

 American occupation of Cuba, several Army Surgeons 



