Evening star., 1931-04-21
HEALTH DIRECTORS
I STUDY FEVER PERIL
Pan-American Group Told
\ Yellow Scourge Still
4 Menaces Nations.

Bere told at their conference here to-
day, while recent studies tend to under
mime the sense Of security, which came
b generation ago with the American dis
covery that the disease was spread only
person to person.
Procedure Is Explained.
Development Of a procedure for locat-
ing these yellow fever reservoirs, which
hitherto has been very expensive and
difficult, was explained to the health
directors by DR.. Wilbur Sawyer of the
Rockefeller Institution.
The yellow fever virus, 1t was ex-
planned, apparently spreads from def
mite foci in the tropical countries. Some
of these exist in Brazil presumably linn
tied in area. For some unknown reason
neighboring areas with the same phys
acal conditions are free of the disease.
But in the foci, it was explained, the
virus will persist for long periods. In
habitants of such foci develop an i'm
munity against the virus so that the
disease appears among them only as
very mild illness which may not even
require the services of a physician.
How Disease Spreads.
But when a mosquito which has
Etung one of these mildly i'll persons
stings somebody else n n non-lmmune
area, yellow fever appears in its full
yirulence.
Monkey Injected.
Hitherto the only means OF locating
such a foci has been with single va
riety of monkey which was found to
share mans susceptibility to yellow
fever. The monkey was injected with
q fixed poison" serum made from
the blood of yellow fever victim. This
was concentrated by passing it through
the blood of generations OF monkeys
until standard potency was reacneo,
which would kill monkey in known
time With the fixed poison" was
mixed some of the blood of a. person
in the suspected focus area. If the
person happened to have had yellow
fever his blocd conferred on the monkey
such immunity against the virus that
the fixed poison had no bad effects. II
was necessary to perform many such
experiments in a suspected area. If
the monkeys lived it indicated a yellow
fever focus. If they died suspicion was
removed.
Process Was Expensive.
But one monkey could only be used
once. If he did not die Of yellow fever
from the mixed poison, he acquired
that he was not again susceptible. Nu-
merous tests were necessary. The mon
KEYS were expensive, required much care
and were delicate. 1t was an extremely
expensive and slow way TO make the
yellow fever maps.
The Rockefeller Institution doctors
have found DR. Sawyer said, that white
mice answer the same purpose If small
amount of starch Is injected into the
brain at the same time that the liked
poison and blood mixture Is injected
into the peritoneum. If the blood con-
fers nc protection against the virus
the rat dies within flve days. The mice
are cheap, hardy and can be obtained
in almost any quantities, so that large
sampling can be taken from the popula-
ton of any suspected area. 1t Is ex-
pected that they will make possible
yellow fever map OF the world.
Foci in Brazil.
This is particularly important, 1t was
explained. for South America, where
II is known that there are foci in Brazil
and where there have been recent out
breaks in other countries. The great
yellow fever reservoir, 1t is believed, is
the interior of the African continent.
While these foci exist and remain un-
known and unguarded, It was explained,
the civilized world is not safe from the
scourge. Even the Southern United
States, despite the efficiency OF Ameri-
can sanitation methods, is not entirely
safe.
One Of the jobs before the health di-
Tectors is to frame a sanitary code for
air transport over national boundaries.
The extreme speed OF the alrplane
makes 1t possible for them TO transport
either yirus-bearing mosquitoes them
selves or persons who have been Stung
by them, who will later be stung by 10
cal mosquitoes around the landing port
during the yellow fever termination pc
riod. A few such cases might start an
epidemic.
Planes Cause Menace.
At present airplanes in international
transport are subject to the same sani-
tary regulations as ships. But an air
plane travels so much faster that spe-
cial rules Of quarantine, airport SANTA
ton, etc, are considered essential. The
airplane unlike the ship, may set out
from a real, but unknown virus focus,
make a forced landing in such place,
or land in another part of the world
passenger who has been infected, but
has not had time to develop any overt
symptoms Of the disease. Such a code
for the world is being considered by
the League of Nations and the pan
American directors will examine this
and propose such alterations as they
consider necessary to meet new world
conditions.
Recent work indicates, members OF
the conference explained that the virus
may be carried by more than one spe-
cies Of mosquito and that 1t can he
transmitted from mosquito to mosquito
without man as an Intermediary.
Scourge Hard Hit.
The work OF Walter Reed and the
American and Cuban army doctors,
which resulted in largely eliminating
yellow fever as Scourge of the civilized
world, seemed to show that the disease
could be transmitted by only one va
riety which first stung victim of the
disease and then a well person. Thus
by eliminating this mosquito as far as
possible and affording adequate protec-
ton an epidemic was made impossible.
But that was before the days of the air.
plane and the discovery Of probable
virus foci.
At present much OF the yellow fever
country is unknown-especially such as
may exist in the deep Brazilian Jungles
and the interior Of Africa. But the ex-
treme specihcity of the white rat test
is expected TO enable medical explorers
70 mark off such foci on the map in
short order.
Tested in Virginia.
It's specihcity, DR.. Sawyer explained.
twas tested in Virginia, where few
survivors of the last great American
yellow fever epidemic still survive. An
old gentleman who had had yellow
fever was found and small amount OF
his blood mixed with the fixed poison
The injected rat survived. Then blood
from the generation born since was
used and all the injected rats died on
schedule.