Evening star. [volume] (Washington, D.C.) 1854-1972, 1953-03-23
Dreaded Yellow Fever
Threatens Once More
Tiny Treetop Blue Mosquito
Corryine.Virus Northwurd
By Thomos R. Henry

Corrying, Virus Northword
By Thomos R. Henry
Five Panamanian farmers died in
November and December, 1948, Of
disease which had all the symptoms Of
yellow fever.
All came from a narrow area Of rain
forest on the Pacific side of the isthmus.
Panama doctors at the Santo Tomas
Hospital in Panama City diagnosed the
deaths as due to "infective hepatitis."
They didn't dare make the absurd dag
nosis Of yellow fever because everybody
knew that yellowjack had been ban
ished from Panama for about 80 years.
"Infective hepatitis" and yellow fever
have some Of the same symptoms. Then
a few more died-and then a few more.
1t finally became impossible both for
Panamanian and American doctors not
to recognize that what couldn't happen
had happened. Yellow fever was back.
1t was like bolt from the blue. A
supposedly quiet reservoir of the yellow
fever virus in Amazon jungles had
overf1own and was moving northward.
The Magyar prophecy Of the return
OF "xekik" was coming true.
Already the wave has moved through
Costa Rica and into Central Nicaragua.
1t Is travelling north at steady rate.
approximately Is miles a month. It
is carried by a tiny blue mosquito of
the high treetops which it is almost
impossible to eliminate. In three or
four years at the most, If the wave
continues at its present speed, it will
have passed beyond the northern limit
OF blue mosquitoes and bowler monkeys.
whose blood is the reservoir Of the virus.
theoretically that should be the end of
it. The virus cannot move without
hosts and carriers.
OpOSsums Are New Threat.
But within the past year, another
serious possibility has developed. The
northern limit of the monkeys overlaps
the range Of opossumS. There are
about 10 varieties of these treetop
animals in the rain forest. Three or
four closely related varieties extend
northward as far as Maryland and
Virginia. Now, it has been found, the
tropical opossums are susceptible to
yellow fever The virus, however, doesn't
XIII these primitive creatures. It prob
ably doesn't even make them sick.
But they may carry it in their blood
throughout their lives. They provide a
Vector by which the disease may be
carried far north OF its supposed limit.
The blue mosquito is quite susceptible
to cold. 1t probably cannot go much be-
yond the tropics, but it can go far
enough to pass on the malady to north
ward ranging opossums and some other
mosquito may be able to act as a
transmitter.
Any great epidemic in the United
States now is almost out of the cues
ton. 1t will not be difficult, although
quite costly, to get rid of the stegomyia
mosquito, traditional carrier of the
virus. which is especially sensitive to
DOT sprays. But, as has been the case
with almost every other insect, it lately
has shown tendency to develop i'm
munity to this poison.
Mountains May Be Barrier.
But Col. Norman w. Elton of the
Army Medical Corps, the foremost cpl
Neurological authority on sylvan yellow
fever, isn't much worried at present
over any threat to the United States.
1t is possible that barrier may be
thrown up against the advancing wave.
short Of the desert country Of northern
Mexico or the Gulf Coast. Col. Elton
believes he has found a weak spot in
the line along the so-called interior
mountains" Of northern Honduras.
There, at one point, the high jungle
narrows to about Is miles, east and west.
It constitutes a funnel to the north
through which the majority of the blue
mosquitoes would be expected to pass.
Within this 25-mile stretch the forest
is broken by three mountains from
5000 to 5000 feet high. These attitudes
are altogether too great for the blue
mosquito.
So. it now is proposed that the jungle
tops be given super-intensive spray
ing from the air. It will be, as Col. Elton
says. costly gamble with not much
more than fair chance of success. If
the attempt fails, he says, "the disease
is more than likely to creep onward
towards Mexico, becoming more and
more complicated in its pattern and
behavior as it progresses. The threat
will be Of serious proportions for the
Central American republics wherever
infected mosquitoes Of the jungle can
opy come down to ground level, as in
agricultural clearings, roadways and
riverways, or wherever the trees Of the
forest are felled. Much Of the food
crops Of Central America and Mex
leo are cultivated in such localities.
Should the wave reach the provinces
of Izabal and Peten in Guatemala
and the lowlands of Yucatan in Mex
leo cataclysmic effects may be ex-
pected, due to the almost insuperable
difficulties attending vaccination cam
paigns in these hard-to-reach regions.
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