29 The Philippine Journal of Science 1915 
As a rule, where considerable numbers of parasites were 
found, more than one stage of development occurred. This is 
what would be expected in latent cases, the majority of whom 
had undoubtedly been infected a long time. 
Of 641 positives of 15 years of age or under, 376, or 58.7 
per cent, were males and 265, or 41.3 per cent, were females. 
The town of Magdalena, third examination, gave of 194 males 
104, or 53.7 per cent, positive and of 177 females 92, or 52.0 
per cent, positive. Examinations of 23 localities including Mag- 
dalena gave: Males, 1,360; positive 194, or 14.3 per cent; females, 
991; positive, 173, or 17.5 per cent. 
While a single survey can give approximately the percentage 
’ of persons harboring parasites at any one time, repeated exam- 
inations would be necessary to show the number parasitized at 
some time during childhood, or even during a single year. In 
the town of Magdalena three surveys were made; the first, 
March 28; the second, July 22; and the third in late October 
and early November. About four months intervened between 
the first and the second and about three months between the 
second and the third. A record was kept of the name of each 
person examined. Fifty-eight children came for all three exam- 
inations. An analysis of the results of these 58 cases may be 
of interest (Table VII). 
TABLE VII.—Children of Magdalena examined on three separate occasions. 
| Number. Per cent. 
= ee ee = | 
Positive at all 3 examinations_________ ef eee a OE] 4! 6.9 
IPositiveatiziexaminavions Mera chy Gat ieee oe ee eee ae 17 | 29.3 



Positiveratiltexamination, ener alu vie jet tices setae | 21 | 36.2 
Nevativelatalligiexaminablon sasees= sees es sae She te cern eee Se Ses Ss | 16 27.6 
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Positive atwirstiexaminationgs=2 ese -—-- se = eee aaa eee eee ne ee 9 | 15.5 | 
Positiyerat second examination oo. <4. 255c—s = Bee ee 35 60.3 | 
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Positive:at.at.least: lexamination = 42-2 2.602 ok oe ee eee | 42 | 72.4 



The highest percentage, 60.3, obtained at the second examina- 
tion was brought up to 72.4 by the additional positives obtained 
at the other examinations. It is probable that repeated exam- 
inations of the children of this town during two years would 
give nearly 100 per cent of positives, and that few of the children 
of this town escape malaria at some time during childhood. 
None of the 58 of this group were under 6 years of age. A 
