360 
MALARIA 
TABLE I 
Malarial Bates of Employees of the Panama 
Canal, the United Fruit Company and the 
Tropical Oil Company of Colombia 
Years 
Panama 
United Fruit 
Company 
Tropical Oil 
Company 
Average employ¬ 
ees (thousands) 
Malarial rate 
per thousand 
Average employ¬ 
ees (thousands) 
Malarial rate 
per thousand 
Average employ¬ 
ees (thousands) 
Malarial rate 
per thousand 
1906 
26.5 
821 
1907 
39.2, 
424 
1908- 9 
45.5 
248 
1910-12 
50.2 
160 
1913-15 
45.3 
70 
30.7 
208 
1916-18 
30.4 
16 
30.4 
120 
1919-21 
19.8 
22 
50.1 
153 
1922-24 
11.0 
17 
56.8 
160 
3.0 
500 
1925-27 
12.8 
17 
54.1 
163 
3.3 
623 
1928-30 
15.3 
.20 
62.9 
71 
4.6 
312 
1931-33 
13.2 
20 
51.5 
58 
2.4 
38 
1934-36 . 
12.4 
14 
59.2 
73 
3.1 
59 
1937-39 
14.5 
12 
62.5 
82 
3.9 
43 
Fruit Company and of the Tropical Oil 
Company. The reduction in incidence is 
most evident among those living in the 
Canal Zone, but it is also apparent, after 
1927, in the personnel of the United Fruit 
Company and after 1930 among those of 
the Tropical Oil Company. 
In a recent letter Dr. D. P. Curry, who 
has. for many years directed the mosquito 
control work in the Panama Canal Zone, 
says, “I would stress that, in spite of all 
our sanitation, we still insist on screened 
living quarters and screened offices for those 
working at night. Even temporary build¬ 
ings of construction camps are screened 
throughout. This includes rooms for sleep¬ 
ing, recreation, dining, bath, toilet and any 
other space. We require all contractors 
to do the same. More and more confirmed 
is our belief here in the extremely long- 
range of flight of A. albimanas from vast, 
far away, uncontrolled, and economically 
uncontrollable areas. ’ ’ 
Dr. Curry wrote last October that the 
1940 malaria morbidity rate to that date 
was 18.3 based on an average of 24,028 em¬ 
ployees. New construction was being 
pushed both night and day on a 24 hour 
basis, so that there was more exposure at 
night outside screened quarters than in nor¬ 
mal times. 
The rate for employees of the United 
Fruit Company in 1937 was 55, but rose 
to 95 in 1938-39 because of new banana 
developments on the Pacific Coast of the 
Republics of Guatemala and Costa Rica. 
During the construction days of the Pan¬ 
ama Canal, anopheline breeding was largely 
controlled by the extensive use of larvicides, 
but with the advent of more stable condi¬ 
tions permanent drainage was introduced. 
The precast sectional inverts, which. were 
first developed by Curry for paving drain¬ 
age ditches in the Canal Zone (Panama 
Canal Health Department 1933) are now 
being used in many of the neighboring- 
countries. 
Simmons et al. (1939) gave an excellent 
description of the methods in use for the 
control of malaria in the Canal Zone. They 
discussed cement pipe for subsoil drainage 
and the types of molds used in Panama to 
make inverts, tiles and wall slabs. Several 
photographs are presented in this paper to 
illustrate these phases of the work. 
At the present time the Health Depart¬ 
ment of the Panama Canal is making 150 
three-foot inverts every other day, or over 
a mile of inverts per month. Even at that 
rate, Curry writes that he can hardly meet 
the demand for them by the Health Depart- 
Fig. 1. Inverts for lining drainage ditches, pro¬ 
duced by the Health Department of the Panama 
Canal. 
