CONTROL OF MALARIA IN PANAMA WITH DRUGS 
277 
TABLE IV 
Parasite Index. Three Survey Groups. All Villages 
Years* 
1 to 5 surveys 
6 to 11 surveys 
12 surveys 
No. ex¬ 
amined 
No. 
posi¬ 
tive 
Per 
cent 
posi¬ 
tive 
No. ex¬ 
amined 
No. 
posi¬ 
tive 
Per 
cent 
posi¬ 
tive 
No. ex¬ 
amined 
No. 
posi¬ 
tive 
Per 
cent 
posi¬ 
tive 
1935-36 
789 
152 
19.2 
379 
197 
52.0 
230 
134 
58.2 
1936-37 
623 
133 
21.3 
426 
230 
54.0 
190 
82 
43.1 
1937-38 
689 
100 
14.5 
410 
156 
38.0 
171 
63 
36.8 
1938-39 
694 
123 
17.7 
383 
155 
40.5 
142 
61 
43.0 
1939-40 
583 
155 
26.6 
407 
226 
55.5 
71 
43 
60.6 
Totals 
3378 
663 
19.3 
1805 
964 
53.4 
804 
383 
47.6 
* The intervals are from Sept. 1 to Aug. 31 of the following year. 
has motor-boat transportation, and often 
visits all towns even outside of the regular 
treatment periods following blood-surveys. 
Our medical staff visits the towns on an 
average of 4 times a month. Yet with all 
these opportunities to collect blood-films 
from those not present on regular survey 
days, we found it impossible to secure 
blood-films from every individual for 12 
successive months. Some of this difficulty 
may be explained by the habits of the popu¬ 
lation. Some of the inhabitants move from 
the towns, and others take their places; 
others have residences in the towns, but 
divide their time between these homes and 
their farms, which may be several miles 
from the villages; other persons examined 
are transient visitors over a period of 
weeks or months. The persons examined 
in 6 to 11 surveys and in 12 surveys per 
year, a total of 2,609 individuals, formed 
the permanent population of the area dur¬ 
ing the period of the survey. The re¬ 
mainder, 3,378 individuals, were transients 
who made satisfactory treatment of the 
persons examined very difficult because 
their presence in the villages increased the 
chances that mosquitoes would become in¬ 
fected, for many of them were untreated 
carriers of sexual forms of the malarial 
parasite. 
For the past 3 years a steady diminution 
in the population of our towns has been 
taking place. However, enough inhabi¬ 
tants remain to show the benefits of drug 
control of malaria. In August, 1940, the 
atabrine-treated towns had a parasite rate 
of 11.5 per cent; the quinine-treated town 
a rate of 12.7 per cent; the Madden High¬ 
way untreated control group, mostly school 
children, a rate of 32.7 per cent; and Rio 
Pescado, another untreated group, a rate 
of 65.1 per cent. The number of heavy 
infections found was also much higher in 
the control areas than in our treated towns. 
The age group from 5 to 10 years and 
from 10 to 20 years always have the high¬ 
est rates, proving the importance of ma¬ 
laria in young adult labor force. 
Both Tables Y and VI show that inci- 
TABLE V 
Cumulative Incidence of Malaria by Age 
Groups for Ten Years in the Treated 
Villages. Migratory and Perma¬ 
nent Inhabitants 
Age in 
years 
Atabrine- 
Plasmochin 
Quinine- 
Pla8moehin 
Examined 
Positive 
Per cent 
positive 
Examined 
Positive 
Per cent 
positive. 
0-5 
665 
162 
24.3 
635 
190 
29.9 
5-10 
397 
177 
44.6 
388 
173 
44.6 
10-20 
712 
293 
41.1 
618 
274 
44.3 
20-40 
855 
237 
27.7 
811 
215 
26.5 
40-60 
452 
146 
32.3 
336 
60 
17.8 
Over 60 
122 
40 
32.7 
140 
21 
15.0 
Totals 
3203 1055 
32.9 
2928 
933 
31.8 
