Evening star., 1935-12-19

Discovery of a new kind of yellow
feVer-for centuries one of the most
dreaded Of human pests and still an
eVer-threatening potentiality-has lust
been announced by the Rockefeller
Foundation.
The yellow fever which swept over the
southern half Of the United States early
in the nineteenth century is transmitted
from person to person only by certain
type of mosquito. This was proved def
nitely in one Of the most colorful med
ical experiments In history-that of the
Army doctor, Walter Reed. and his COL
leagues in Cuba. Protection against
mosquito bites was protection against
infection.
The new type. so far as can be deter
mined, does not depend on mosquitoes
for its transmission. Neither can it be
proved that 1t depends upon any other
animal or that it is transmittable from
person to person. 1t its general syn
drome it cannot be distinguished from
the old type of yellow fever. except that
it attacks sparsely settled districts rather
than centerS of population
At present the disease seems to be con-
fined to South America. The most
notable focus of it is in the emerald
mining district of Colombia where it
breaks out at sporadic intervals There
is every reason to believe, however, that
it occurs in Africa and in other sparsely
settled tropical areas, but has not yet
been found.
CuriouSly enough, this emerald mining
area in the watershed of the Magdalena
River is entirely free of mosquitoes, al
though there are plenty of other blood
sucking insects and an abundant animal
life. The disease also has broken out in
the primitive Matto Crosse region of
Brazil, where no other case of yellow
fever has been known during the present
century.
Rockefeller Foundation doctors are
making an intensive investigation of this
new threat lurking in the tropics.
I'm the present state of knowledge"
says the Rockefeller Foundation report
of the discovery, at appears there are
two forms of yellow fever. The first of
these, transmitted by the aedes aegyti,
or stegomyia mosquito, is the yellow
fever of classical type which occurs in
cities, towns and villages and which
disappears when this mosquito is sup
pressed. 1t may also occur in rural areas
with nigh Stegomy1a index and viii
disappear when this index is lowered.
Secondly, there is the yellow fever
which occurs in the absence of the
stegomyia mosquito. This is found in
two types of regions. First are non
urban areas in which there is a sufficient
density of human population to suggest
that the cycle of infection may be a
simple one-from man, the vector, and
back again. Second are rural, or jungle,
areas at isolated, sparsely settled points
along river banks, where there is SO little
movement of the human population that
it is difficult to see how the disease can
be carried direct from man to man. 1t
is possible that some animal host, at
present undiscovered, plays role in
keeping the disease alive in these iSo-
lated areas and that human cases are
accidental infections from this animal
reservoir.
This form of yellow fever always
occurs in places where the land has not
been completely cleared of forest or
jungle. It has appeared in places so
isolated as to suggest that it persists in
and of itself in those regions, and is not
secondary to infection in the endemic
urban centers of yellow fever. An i'm
mense amount Of work remains to be