DISTRIBUTION OP MALARIA 
11 
Fig. 2. Annual malaria mortality rates by states 
for the Southern United States and average total 
rates for these states for the years 1929-1939. 
tory condition has resulted, at least in part, 
from extensive and intensive preventive 
measures directed against mosquito breed¬ 
ing and from antimalarial treatment of the 
human population is not known. 
Viewing the United States as a whole, we 
find definite evidence that malaria mortality 
has been greatly reduced in the past five or 
six years and that the heavily endemic foci 
have shown evidence of improvement over 
one or two decades ago. Nevertheless, ma¬ 
laria is more widespread and probably more 
prevalent today than in 1930. In the 
Southern States the infection is becoming 
dispersed radially from the heavily endemic 
centers. In the North, areas of endemicity 
a quarter of a century ago, but presumably 
free a decade ago, have provided the 
ground for reestablishment of the disease. 
While it is possible that this may have re¬ 
sulted from the reactivation of latent 
autochthonous strains, it is much more 
likely that new strains brought into poten¬ 
tial Northern and Western foci from the 
South and from Tropical America have con¬ 
stituted the source of the increasingly wide¬ 
spread distribution outside the South. 
Distribution of Malaria in Mexico, Cen¬ 
tral America and the West Indies 
Since no inclusive resume of the status of 
malaria in the countries south of the United 
States has ever been published, this com¬ 
pilation was undertaken with considerable 
hesitancy. It was realized that attempts to 
discover the distribution and practical im- 
Fig. 3. Estimated average malaria mortality rates for Mexico, Central America and the West Indies for 
the period 1929-1938, based on official reports and other available records. 
