STATISTICAL STUDY OF UNCINARIASIS. 255 



presence of an intestinal parasite was unsuspected until the stool exam- 

 ination showed ova. This is in accord with my experience at New 

 Orleans, where uncinariasis was found extensively among men apparently 

 in perfect health. 



The few differential leucocyte counts which have been recorded at the 

 Division Hospital in uncinariasis confirm my observations at New Orleans 

 that an eosinophilia of over 5 per cent is the rule, but that figures as low 

 as 1, 2, or 3 per cent are by no means infrequent and are valueless in 

 excluding the diagnosis of hookworm disease (7). 



WHERE THE AMERICANS 1ST THE PHILIPPINE ISLANDS CONTRACT THEIR 

 INFECTIONS WITH UNCINARIA. 



About a year ago, in reporting my work in the United States, I ex- 

 pressed the opinion that when soldiers with uncinariasis (species not 

 mentioned) returned from the Philippine Islands it was unsafe to assume 

 that the infection had occurred in the Islands, as there was quite as 

 much likelihood that these men had taken the worms from the United 

 States and had returned with them still in" the intestine. With the 

 view of establishing or disproving this theory, I have investigated the 

 residences of the 90 cases covered by this report. As the histories did 

 not record the various places of residence of each patient, I obtained from 

 the sick and wounded report cards and from the descriptive lists of the 

 soldiers, whenever possible, the following data which I shall term "res- 

 idential factors." 



1. Place of enlistment or acceptance for enlistment. 



2. Birthplace, giving State of the United States, or country, if not in United 

 States. 



3. Residence of the man's nearest relative. 



4. Residence of the man himself as given at the date of enlistment. 



In the cases of the soldiers at Port William McKinley and most of the 

 civilians, only the birthplace could be determined. 



An analysis of these data shows that among the 90 cases of uncinariasis 44 

 were born in the southern portion of the United States, 41 elsewhere, and in 5 

 there is no record. In the case of each of the 44 men born in the Southern 

 States for whom other "residential factors" could be obtained, it was found 

 that at least one, and usually two, other factors designated the South. Therefore, 

 it seems fair to assume that these 44 southern-born men, constituting 49 per 

 cent of the cases of uncinariasis, were so definitely identified with the South 

 that the infection of the majority of them with hookworm, while in that region, 

 was highly probable. 



In connection with southern birth and residence it is necessary to consider 

 also length of service in the Army, because, under the good sanitary conditions 

 prevailing in the military service within the limits of the United States, I 

 assume that reinfection with hookworms must be extremely rare, and that, under 

 such sanitary conditions, after five years' service the greater part of the soldiers 

 who were infected at the date of their enlistment will have become free from 

 the parasites by reason of the natural death of the worms. Looking over Tables 



