HOST-PARASITE RELATIONS! INTESTINAL PROTOZOA 



a very adequate idea of the incidence of infection on the 

 basis of one or two examinations of each person. The 

 results of the examinations of the soldiers are of par- 

 ticular interest. They are as follows. 



Soldiers that did not go to Europe (1.3 examinations 

 each). 



2584 individuals, 93 positive = 3.5 per cent positive. 

 Soldiers after their return from Europe (i.i examina- 

 tions each). 



3536 individuals, 100 positive == 2.8 per cent posi- 

 tive. 

 Soldiers of unknown military history (1.5 examina- 

 tions each). 



362 individuals, 1 1 positive = 3.0 per cent positive. 



These results indicate that soldiers who may have come 



into contact with other soldiers, some of whom had come 



from the tropics, were no more frequently infected than 



those who remained in the United States. 



An attempt was also made to determine by means of 

 questionnaires whether the return of about 3,000,000 

 soldiers from overseas had had any effect upon the num- 

 ber of cases of clinical amoebiasis. The data are as fol- 

 lows (Stiles, 1922) : 



Letters of enquiry were sent to 607 hospitals and 115 



medical schools. 

 Replies were received from 468 hospitals and 71 medi- 

 cal schools, representing all but 4 states. 

 190 negative replies were received from 28 states. 

 174 negative replies, 8 indefinite, and 24 positive re- 

 plies, were received from 13 other states. Three 

 states gave negative or indefinite replies. 

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