TOPOGRAPHICAL FACTORS IN EPIDEMIOLOGY OF MALARIA 
143 
mann 1934), and the malaria of this part of 
Mexico is restricted to sea-level conditions. 
A wide variety of climate and topography 
are provided in the Central American coun¬ 
tries of Guatemala, Salvador, Honduras, 
Nicaragua, Costa Rica, and British Hon¬ 
duras. For the most part, however, the flat 
coastal plains which flank the Pacific Ocean 
and the Caribbean Sea provide the most 
suitable breeding places for anopheline vec¬ 
tors, chiefly A. albimanus. Malaria occurs 
in the highlands of Guatemala at an alti¬ 
tude of 5000 feet (Raynal 1932) where A. 
pseudopunctipennis is the transmitter. A. 
albimanus, however, adapts itself to alti¬ 
tudes of 3280 feet or higher in Guatemala 
(Mira 1936). In a recent malaria survey 
of Costa Rica, Kumm and Ruiz (1939b) 
demonstrate that the most important areas 
of malarial endemicity lie in the coastal 
regions, at elevations less than 1000 feet. 
The accompanying maps (Figs. 3, 4 and 5) 
show the relationship of topography to the 
breeding areas of A. albimanus and likewise 
to the endemic centers of malaria. A. 
argyritarsis flourishes in the highlands but 
attains its maximum prevalence in places 
where malaria does not occur; thus it is 
not considered to be an important trans¬ 
mitter. 
The malaria problem in Panama centers 
chiefly around A. albimanus breeding sites 
provided by fluvial and coastal marshes, 
and by the low wet areas adjacent to the 
Chagres River. The lake systems provided 
for the Panama Canal serve as breeding 
places for A. albimanus, particularly Gatun 
Lake (Simmons et al. 1939). 
The basic physiography of the islands 
included in the West Indies is essentially 
the same, and, for the most part, the en¬ 
demic centers of malaria are coastal. The 
central portion of these islands is generally 
hilly or mountainous, and it is in the coastal 
marshes and river beds that anopheline 
breeding occurs. 
The coastal plains are often almost flat 
and their water tables are near the surface. 
The rivers, except for short periods of flood, 
are sluggish and not infrequently their 
mouths are blocked by wave action. These 
conditions make for poor drainage of the 
coastal lands and for the formation of 
marshes and swamps. Seepage areas occur 
frequently and each pool of water, however 
small, becomes a potential breeding place 
Fig. 5. Distribution of A. albimanus and A. argyritarsis in Costa Rica (from Kumm and Ruiz 1939b). 
