24 
Following are the rates of infection in each age group with each 
species of parasite : 
Examined. 
Infections. 
Per 100 
persons 
Trichuris trichiura: 
Under 15 years 
123 
16 
13.01 
15 to 30 years 
572 
60 
10.49 
31 to 50 years 
1,341 
116 
8.65 
Over 50 years 
1,289 
60 
4.65 
Oxyuris vermicular is: 
. 
Under 15 years 
123 
2 
1.63 
15 to 30 years 
572 
10 
1.75 
31 to 50 years 
1,341 
14 
1.04 
Over 50 years 
1,289 
17 
1.32 
Hookworms: 
Under 15 years 
123 
1 
0.81 
15 to 30 years 
572 
16 
2.80 
31 to 50 years 
1,341 
9 
0.67 
Over 50 years 
1,289 
3 
0.23 
Ascaris lumbricoides: 
Under 15 years 
123 
1 
0.81 
15 to 30 years 
572 
3 
0.52 
31 to 50 years 
1,341 
6 
0.45 
Over 50 years 
1,289 
4 
0.31 
Strongyloides stercoralis: 
Under 15 years 
123 
0 
0.00 
15 to 30 years 
572 
1 
0.17 
31 to 50 years 
1,341 
3 
0.22 
Over 50 years 
1,289 
4 
0.31 
Hymenolepis nana: 
Under 15 years 
123 
6 
4.88 
15 to 30 years 
572 
0 
0.00 
31 to 50 years 
1,341 
4 
0.30 
Over 50 years 
1,289 
2 
0.16 
Tsema saginata: 
Under 15 years 
123 
0 
0.00 
15 to 30 years 
572 
0 
0.00 
31 to 50 years 
1,341 
1 
0.07 
Over 50 years 
1,289 
1 
0.08 
The results for Trichuris and for Ascaris are in accord with the 
results for total helminthiasis in that the percentage of infection 
decreased with increasing age of the patients, the decrease being much 
more marked, however, in the case of whipworms than in that of eel- 
worms. The frequency of pinworms showed little variation in the 
different age groups. The comparatively high frequency of hookworm 
infections in the second group (15 to 30 years) is perhaps explained by 
the large proportion of soldiers in that group who had returned from 
service in the Philippine Islands, over 12 per cent of whom were 
infected with this parasite. The figures for hookworms in the other 
three groups would seem to indicate a slight but consistent tendency 
to a decrease in frequency with increasing age of the patients. Cochin 
China worms, on the other hand, appeared to show some tendency to a 
