Evening star., 1939-03-29
Typhoid Vaccine
OF Higher Potency
Developed
Army Medical Corps
Advances Revealed
By Col. SiIer
By THOMAS r. HENRY.

BY THOMAS r. HENRY. >.
A typhoid vaccine which appears
nearly twice as potent a protective
agent as that given 100000 World
War soldiers has been developed by
the United States Army Medical
Corps.
1t is made from very virulent
strain of the typhoid organism OBJ
tanned from a carrier" in Panama,
and has been tested with volunteers
from the student bodies of the medi-
cal schools of Georgetown and
George Washington Universities and
the University of Pennsylvania.
The new vaccine takes the place
of that developed from organisms
recovered from a soldier nearly 35
years ago, which in successive gen.
erations have lost much Of their
virulence. Experience with other
maladies has shown that. generally
speaking. the more virulent the or
ganisms, the more potent is the vac
ClIlc plcpdlcu
Cuts c. C. C. Rate.
The vaccine was described last
night by Col. j. F. Siler, director OF
the Army Medical School here, in
the annual Kober lecture at George
town University. Already, he said
the typhoid rates in the Civilian
Conservation Corps, where it has
been used since January. 1887, have
dropped so per cent. While part OF
this gain can probably be attributed
to improved environmental protec-
tive measures" and some of it to
luck, the Army medical authorities
believe that the new vaccine has
played major part. If the ground
gained is held for the next
two or three years. Col. Siler said,
there will be no doubt as to the
much greater protection conferred.
The protective value OF the new
vaccine now is being assayed on the
oasis of mouse immunization tests
The ability of the animals to with
stand doses of living typhoid organ
sms in many times the numbers
which ordinarily would prove fatal
after injections of the blood serum
If the inoculated medical students.
This involves, he explained, giving
fatal doses of an extremely virulent
strain of typhoid organism to an ex-
;remely susceptible strain of mice
especially bred for the purpose.
New Facts Developed.
In the experiments undertaken
to develop this new vaccine, Col.
Siler explained, considerable new
light has been thrown on the actual
of immunization in hu-
man beings.
Through employment of the
mouse protection test" he said, lit
las been possible to demonstrate that
the concentrations of protective
in the blood of individuals
after initial immunization with a
strain gradually decline, but
that even two and a half years
afterward a large proportion of
individuals still are well
protected. The evidence also indi-
Gates that if immunization is re-
peated two or three times most in
dividuals build up hign concentra-
ions of protective substances in theil
blood and this high level is main
tanned for indefinite periods.
1T was demonstrated also that
in practicing reimmunization to
typhoid fever it is possible to stimu-
late the defense mechanism of the
body by the use of a single small
dose of vaccine administered intra-
with the result that
large quantities of protective sub
stances reappear in the blood
this reaction is an evanes-
cent one or of some permanency can
be determined only by further
studies. If eventually it can be dem
onstrated that single small dose
will suffice for reimmunization pur-
poses it will be greatly superior to
the procedure now followed of CIV
ing three large doses.
Rarely Causes Disability.
"The reactions observed to single
small dose are mild in character
and of short duration. Only very
rarely do they disable the individual
to any extent whatsoever. The local
reaction consists of an area of red
ness around the site of the injection
Usually the systemic reaction is of
no moment. though occasionally
there may be mild malaise, head
ache and slight elevation of tenn
perature, so mild in character as
to cause no disability"
The small dose immunization. Col
Siler said. should prove a great aid
to public health authorities in keep
ing large numbers of the population
protected from typhoid. Faced with
the prospect of three separate in
EQUATIONS several days apart. each
followed by some degree of sickness,
the average citizen sometimes per-
fers to take chance on the ty-
phoid.
At the conclusion of the lecture
the Very Rev. Arthur A. OLeary,
president of Georgetown, presented
Col. Siler with a $500 check. pro-
vided under the terms of the Kober
Foundation. DR.. Eugene r. Whit
more, professor of pathology, intro
iuced the lecturer.