Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-11-22
ACCIDENT REVEALS
! PLAGUE IMMUNITY
Chilled Yellow Fever Virus
HaItS Disease-White Mice
Found Susceptible.
BY THOMAS r. HENRY.

BY THOMAS II. HENRY.
A laboratory accident may have
opened the way to make man immune
to yellow fever.
The United States Public Health
Service. now greatly concerned with
this ancient scourge because OF the
possibility revealed by recent expert
rnents that it can be brought into the
United States by airplane, has just
received a report of this accident from
the international Office of Public Hy-
giene in Paris, of which organization
It is a member.
Search for a yellow fever vaccine has
been conducted with intensity in Ia
boratories all over the world during
the past few years with INDIFFERENT re-
suits. Among the cooperating labora-
tories is that of the Institute OF Iropl-
cal Medicine in Amsterdam.
Cold Induces Immunity.
The most common carrier OF yellow
fever is the mosquito Aedes Aegytl. IN
the Amsterdam laboratory some OF
these insects had bitten monkey SUI
ferinp from yellow fever. In the course
~ +he eyneriments these mosquitoes
a. were kept at the tropical temperature
believed most favorable for them-from
"a to 80 degrees Fahrenheit. AT the eno
of a month they were again allowed 70
bite monkeys. The animals died OF
yellow fever in five days.
{ Then the experimenter went on ms
annual vacation. The laboratory az
tendants neglected his mosqulvoeS, ~
J lowing the temperature of the room 10
fall to go degrees Fahrenheit. Wnen
the doctor returned he found his mos
ouitoes still alive. They were all ne
: had to continue his experiments. he
turned them loose with some healUiiy
monkeys, but the animals refuseo 20
''take'' the disease. There was only q
slight elevation OF temperature alVeA
the mosquito bites.
low fever bearing mosquitoes kept at
the proper temperature and let tnem
bite the monkey colony. The two mon
KEYS who had been bitten by the cold
MOSQUITOES" previously showed no signs
of the disease. All the other monkeys
which had been bitten died.
Mice Found Susceptible.
It has long been known that yellow
fever its a hot weather disease IN tem-
perate climates. The great epldem-
les of a century ago in the southern
United States, presumably started py
MOSQUITOES brought in on ships, SUD
. sided with the coming of cold. Now,
it appears, the deadly virus, subjected
to cold. acts as an immunizing agent
against itself. It is stressed in the re-
mort that the experiments thus lar ex-
tend only to monkeys and the same
effect may not be obtained with nu-
man beings.
with experiments which have resulted,
according to the International Public
Hygiene Office report, in a means OF
finding what parts of the world are
yellow fever reservoirs, from Whlch cpl
denies can be expected to spread. Inc
inhabitants of such regions have &C
uuired an immunity 10 the disease, 80
that they suffer from 1t only in milo
and unrecognizable form. They are
carriers who, through the medium OF
mosquitoes, can spread the malay 10
others.
DR. Max TT1ieIer. of the Amsterdam
laboratory found that white mice, IN
oculated with the yellow fever virus,
developed specific brain disease Whicn
killed them in short time. ms
could be passed on from mouse to
mouse by injections into the brain. But
when the virus was mixed with the
blood serum of a person who had re-
covered from yellow fever the brain
disease did not appear. Hitherto the
only animal considered susceptible to
yellow fever was the Fhesus monkey,
which Is too scarce and valuable to be
used in such wholesale investigations
as would be necessary to determine
whether there is latent yellow fever IN
the locality.
Clue to Danger Spots Barred.
White mice can be had by the thou
sands. If they die when inoculated
in the brain with the virus mixed with
blood serum of the population Of a dis
trict 1t means that yellow fever is not
present. If they show no i'll effects it
means a definite danger spot on the
health map of the world.
Great yellow fever reservoirs are be-
lieved still to exist in the interior jun
giles of West Africa and Eastern South
America. For the most part they are
kept from overlooking by the extreme
precautions against mosquitoes main
tanned in the coast settlements, but
. they are constant source of danger
while they remain unknown. The ex-
periments, according to the Interna-
{ fional Office report, also open up the
J possibility Of developing an anti-yel-
low fever serum from the blood of per-
sons who have recovered from the dis
ease.
The Rockefeller Foundation, the re-
port says, has expressed its willingness
to cooperate on the difficult and ex-
!. tensive job of mapping the virus areas
' and 1t is proposed to use the white rat
method to determine the existence of
anti-bodies in the blood of children I'M
der 10 years old in the suspected local
tiles. In this way, it is believed, It
will be possible to delimit rather ex-
actly the places where the virus is
stored up between outbreaks.