527 
Latent wmfection in the adult native-—I was unable to examine the 
blood of more than 45 adults, of which 28, or 62.2 per cent, were infected ; 
of these 5 were due to the tertian plasmodium and 23 to the tertian wstivo- 
autumnal variety. It is very probable that a further study of the blood 
of a larger number of adult natives would materially reduce this great 
percentage of infected cases, but from the above it is evident that the 
adult Filipino is more often infected than is the negro in Africa or 
the native of India. 
Both Koch in Africa and James in India, have ascertained that the percentage 
of infected adults is very small. In the planting districts of the Duaro, James 
stated that he discovered no adults with plasmodia in their blood, although 65 
to 75 per cent of the children were found to be infected. 
Therefore, it is evident that the adult Filipino possesses little or no 
relative immunity to malaria, despite the fact that in malarial districts 
such adults have from childhood suffered repeated attacks of malarial 
disease. I have notes on several adult natives who, within two years, 
were admitted to the hospital from 8 to 16 times, suffering from attacks 
of malarial fever. 
Latent infection in native children.—The blood of 180 children was 
examined, of which 87 or 48.3 per cent showed the presence of malarial 
plasmodia. Of these 34 were due to the tertian plasmodium, 6 to 
the quartan one, and 44 to the estivo-autumnal variety; of the latter, 
40 were infected with the tertian estivo-autumnal and 4 with the 
quotidian estivo-autumnal plasmodium. There were 3 cases which had 
the tertian and the tertian estivo-autumnal plasmodium combined. 
The infections in the children diminished in number with advancing 
age; thus, between the ages of one month and five years, among 40 
children, 79 per cent; of 54 individuals between five and ten years, 37 
per cent; and of 53 between ten and fifteen years 24.5 per cent of those 
examined were infected. These results agree with those of Koch, Ste- 
phens and Christophers, James and others, who invariably found that 
the younger the child, the more susceptible it was to malarial attack. 
The following table illustrates the relationship between malarial infec- 
tion and the age of the individual as observed in native children in the 
barrios about Camp Stotsenberg; it gives the number of children exam- 
ined, the number attacked, arranged in five-year periods, the percentage 
of those infected, and the type of infection: 
Beate | | 
| Number ; | Estivo- | 
Age. infected. Per at Tertian. UATERE | autumnal. | 
| | 
| —<—_—___|—________|- aes 
eee | | 
Pe a aie et ear Sh acres. 10 4| 16 
d | | | 
| 5 to 10 years \ 20 37 | $| 1| on 
hone | 
10tol5 years ' } | | rs 
| 53 } 13 24,5 | 5 1 | 7 
| 
aCombined, 1. 
