XB, 3 Barber et al.: Malaria in the Philippines OPAL 
Both parasite and spleen indexes of children from 11 to 15 
years of age are higher than those of children from 5 to 10 years 
of age. Possibly if a larger proportion of older children had 
been included, we would have obtained a different ratio. Again, 
a very small proportion of children 5 years of age or younger are 
included. If all children from 1 to 10 years of age had been 
included, the parasite rate for the younger group probably would 
have been higher. In the third examination of Magdalena (see 
Table VI, No. 10) several groups of ages were considered sepa- 
rately. Here we find the highest rate, 69.9 per cent, among 
children from 1 to 5 years of age. 
As a rule, the number of parasites found in positive cases was 
small, as might be expected in latent malaria. The percentage 
of positives in which the parasites were approximately as numer- 
ous as or exceeded the number of leucocytes is given in Table 
VI. This gives a rough index of the proportion of more acute - 
cases occurring in a locality. An approximate estimate of the 
number of parasites was recorded for nearly all positives. For 
children of 15 years of age and under they are as follows: Only 
one parasite found after considerable search, 36 cases, or 6.3 
per cent; those marked “rare” (about 1 parasite to 10 or 15 
fields) , 244, or 42.9 per cent; “few” (about 1 parasite to 5 fields), 
109, or 19.2 per cent; “+” (1 or more per field), 122, or 21.4 
per cent; “1+” (1 or more per leucocyte), 58, or 10.2 per cent. 
All estimates, of course, are only approximate. 
As to the type of parasite, quartan occurred more frequently 
in these latent cases of children than has been our experience 
in acute cases of adults examined in the tropics. In 272 positives 
obtained by Walker and Barber in the examination of thin 
smears from acute cases at Canlubang, 54.4 per cent were sub- 
tertian, 41.5 per cent tertian, and only 4.1 per cent quartan. 
A frequent finding in the latent cases among children was a 
very few sporulating quartan. It is sometimes difficult to de- 
termine the species of parasite when only a very few can be found 
in the thick smear. Where plentiful enough they may be found 
in the thin smear and the identification confirmed. The error is 
probable in the direction of increase of subtertian at the expense 
of the other types, where only very scanty numbers of young 
rings can be found. 
Including only persons of 15 years of age and under, results 
were as follows: Subtertian, 291, or 49.6 per cent; tertian, 185, 
or 31.6 per cent; quartan, 108, or 18.4 per cent; mixed, 4, or 
0.3 per cent. Long search through all preparations would un- 
doubtedly increase the percentage of mixed infections. 
