184 
Malaria in Malaya 
carriers is often so small as to make it improbable that an Anopheline will 
become infected by the carriers’ blood. In children, especially when young, 
both the rate of crescent-carriers and the number of gametes per carrier, are 
much higher. 
In regions of epidemic malaria, during the course of an epidemic, the 
spleen-rates in children and adults are equal, and often reach a figure not less 
than that of the splenic index in endemic regions; but in this case, the parasite- 
rates in children and adults are likewise equal. No difference is to be noted 
in the rate of infection with the three species of malarial parasites, or in the 
percentage of crescent-carriers, or in the number of crescents or rings per 
carrier. The total number of infections is also much higher than in endemic 
regions. 
Schiiffner (1919 a) explains this difference by the immunity that is generally 
supposed to develop in a population continually exposed to malarial infection. 
In endemic regions this immunity is attained by the adults; in epidemic 
regions it is not attained because serious epidemics are generally too infrequent 
to allow of a lasting immunity being acquired. 
The foregoing description of the relative parasitaemia in regions of endemic 
and epidemic malaria, is based on the most typical cases. It is obvious that, 
apart from these, numerous intermediate cases are to be met with, as may be 
gathered from the following table (Table I). 
Table I. 
Percentage of people examined 
showing infections of: 
Author and year of Children ,- A -^ 
Locality 
publication or de¬ 
livery of report 
or 
adults 
Simple 
tertian 
Quartan 
Sub¬ 
tertian 
Crescents 
Spleen- 
rate 
Tegal 
Swellengrebel, 1919 c 
child 
8 
3 
32 
15 
91 
(endemic) 
adult 
0 
0 
17 
1-7 
91 
Mandailing 
Schiiffner, 1916-1917 
child 
6 
11 
25 
9 
96 
(endemic) 
adult 
0-3 
1 
5-2 
0-9 
96 
Semarang 
Swellengrebel, 1918 d 
child 
8 
4 
15 
10 
80 
(endemic) 
adult 
2-7 
0-8 
7 
2-7 
74 
North Soendatar 
Swellengrebel, 1918 e 
child 
21 
9 
68 
48 
90 
(epidemic) 
adult 
11 
4 
53 
34 
87 
Naras 
Schiiffner, 1919 b 
child 
35 
3-5 
65 
40 
84 
(epidemic) 
adult 
24 
2-3 
55 
36 
70 
South Soendatar 
Swellengrebel, 1918 c 
child 
4 
2 
18 
13 
21 
(epidemic) 
adult 
4 
3 
18 
13 
29 
In regions of epidemic malaria, the number of carriers from which 
Anophelines can acquire infection is much greater, because of the many 
infected children and adults. In endemic regions the number of carriers is 
less, these being for the most part children alone. This should be taken into 
account when comparing the N. I. of the same species in different localities. 
Species usually exhibiting a very low N. I. may, in the epidemic regions, 
appear to be as heavily infected as good vectors in endemic regions. This is 
shown in the following table (Table II). 
