Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-02-14
CAUSAT|VE AGENT.
FOR TYPHUS FEVER
IS DETERMINED.
Virus of Disease Obtained
From FIeas Collected
From Wild Rats.
PROBLEM HAS PUZZLED
PHYSICIANS FOR YEARS
Discovery Held One Of Most NOta-
BILE Recent Developments in
Medical Science.
BY THOMAS r. HENRY.

BY THOMAS r. HENRY.
Determination of q causative agent
for typhus fever in the United States
was announced today by the Public
Health Service.
The virus of this dreaded disease was
obtained from fleas collected from wild
rats. This discovery goes far toward
solving a problem which has puzzled
medical science for years.
The Old World typhus-which from
the Middle Ages until the coming of
modern sanitation was the great scourge
of city slums, crowded prisons and
armies in the field, and which almost
wiped out the French Army during the
Crimean Warts spread by the human
body louise. 1t always can be traced to
filthy and overcrowded living condi-
tionS- Thorough delousings keep it in
check, which was one potent reason for
the frequency of such ordeals for Amert-
can soldiers in France.
Many Theories Tested.
In the United States there has
broken out from time to time localized
epidemicS of fever which differs from
European typhus only in having a
slightly milder course. and is only diff
ferent strain of the same disease. But
1t has been impossible to associate It
with body lice, hitherto considered the
only carrying agent, and there has been
a constant search for some other organ
ism. Theory after theory has been
tested, with negative results.
Scientists of the National Institute Of
Health, research branch of the Public
Health Service, got clue to the mys-
terry through the outbreak OF endemic
typhus, as the American strain is
known, in the neighborhood of several
81 no ND HI IN
more last November. They found the
premises infested with rats. Many of
these were trapped and combed for
fleaS. These f1eas then were ground
up in salt solution and injected into
guinea pigs. The deaS themselves were
identified by entomologists.
Within week one of the animals had
developed fever and soon died. His
companion showed evidences of fever
q few days later, was killed, and his
brain prepared as an emulsion with salt
solution. This was injected into fresh
guinea pigs. Both developed. fevers.
One was killed, and prepared emulsions
of both his brain and heart blood were
injected into still other guinea pigs. In
this way the fever strain was carried
/ successfully through seven sets of these
animals. with the development in each
generation of the characteristic symp-
toms. A disease strain had been eStab-
hshed, but it remained to be determined
whether it was typhus fever, although
the symptoms shown by the animals
were similar to those previously eStab-
hshed for guinea pigs for known en-
demic typhus virus injections.
Monkeys Develop Fever.
From the fifth generation" of the
guinea pigs-that is, those five times re-
moved from the original rat flea injec-
tion-the strain was passed on to mon
keys and rabbits. Two injected mon
keys developed fever, and so did third
kept in the same room with them but
not given any of the virus. It later de-
veloped, however, that this monkeys
sickness probably was incidental, since
tests Of his blood did not show the
characteristic typhus reaction obtained
from the other animals. Blood Of in
Jected rabbits also met the required tests
for typhus.
Then came a series of laborious
"croSS tests" The endemic typhuS
virus builds up its own immunity in
the blood. Guinea pigs inoculated with
1t and allowed to recover did not show
any symptoms when given injections of
the solution prepared from the bodies
of the rat fieas. Thus was established
what Public Health Service physicians
consider one of the most notable re-
cent developments in medical science.
The rest&tS do not necessarily indicate,
it was pointed out, that there is no
other agent in nature for the spread Of
endemic typhus.
Potential Source Of Danger.
The finding is of special significance
because Of the almost universal diStri-
button of wild rats in the United States.
These, it is assumed. get the virus into
their blood from the bites of f1eas.
There it remains, to be passed on to
another generation of f1eaS, which pass
it to other rats. But the rat f1ea ac-
cidentally may get on a man in a rat
infested building, thus passing on to
human being the submicroscopic ell
terable virus" another of those strange,
extremely minute Lying things which
can be detected only through the fact
that 1t will pass through porcelain
filter. More and more animal, and plant
disease is being traced to these viruSeS.
Endemic typhus, it was pointed out,
is not now a serious factor in Ameri-
can sickness ard mortality tables, but
always is potential source of danger
To the populace so long as 1t turks In
the background. In the fact that it Is
carried by an insect from the body Of
a wild animal, it is similar to the dread
ed spotted fever Of the Rocky Noun
tains, which is spread by mammal ticks
with restricted range, but which al
ready has come in contact over wide
frontier with the common Eastern dog
tick which. it has been. Demonstrated in
the laboratory, can carry the virus. The
syndromeS Of spotted fever and endemic
typhus also are quite Similar. but the
later does not bring such high NOR
tally. ',''..
The work was carried on by Surg.
r. z. Dyer and Passed Asst. Surgs. r.
Rumreich and L. F. Badger of the staff
Of the National Institute Of Health.