New-York tribune., 1916-07-14

they are called, Indicate kressoi 80"
eral susceptibility than has always
been recognized, and their discovery
promises to have far-reaching conse'
quences in respect to the means en-
ployed to limit the spread or eradicate
foci Of the disease.
Period of Incubation.
Like all other infectious diseases,
infantile paralysis does not arise ~
once after exposure, but only after an
intervening lapse Of time called the
period of incubation. This period Is
subject to wide limits Of huctuation:
In certain instances 1t has been as
short as two days, in others II mas
been two weeks or possibly even
longer. But the usual period does not
exceed about eight days.
Period of Infectivity.
Probably the period at which the
danger of communication is greatest
is during the very early and acuter
stage of the disease. This statement
must be made tentatively since 1t de-
pends on inference. based on general
knowledge of infection rather than
on demonstration. Judging from expert
ments on animals, the virus tends not
to persist in the body longer than four
or five weeks except in those excep-
tional instances in which chronic car.
riage is developed. Hence cases OF
infantile paralysis which have been
kept under supervision for period OF
six weeks from the onset of the symp-
toms NAV be regarded as practically
free of danger.
Protection BY Previous Attack.
Infantile paralysis is one of the In
fectious diseases in which insuscepu-
bility is conferred by one attack. Inc
evidence derived from experiments on
MONKEYS is conclusive in showing that
an infection which ends in recovery
piyes protection from a subsequent IN
oculation. Observations upon human
beings have brought out the same TACT,
which appears to be generally true, and
IN include all the forms of infantile
paralysis, namely the paralytic, menin-
real. or abortive, which all confer I'M
munity.
Basis OF the Immunity.
The blood Of normal persons and
monkeys Is not capable Of destroying
or neutralizing the effect OF the virus
of infantile paralysis. The blood OF
persons or monkeys who nave reco' .
cred from the disease IS capapie OF
DESTROYING or neutralizing the effect or
the virus The insusceptibility or i'm
munity 10 subsequent Infection,
whether occurring in human beings
after exposure or monkeys after IN
oculation, rests on the presence OF the
DESTROYING substances, the so-cailed I'M
L oh ~ N
ternal organs and are yielded to the
blood. So long as these immunity
bodies persist in the body, protection
is afforded; and their presence has
been detected twenty years or even
longer after recovery from infantiie
paralysis. Experiments have shown
that the immunity bodies appear IN the
blood in the course OF even the mlldest
attack of the disease, which fact ex-
plains why protection is afforded IT.
respective of the severity Of the case.
Active Immunization.
Protection has been afforded mon
KEYS against incubation with enectVe
quantities of the virus Of infantlIe
paralysis by previously subIectlng
them to inoculation with sub-effectlve
quantities or doses of the virus. by
this means and without any evident
illness or effect of the protective IN
oculation, complete Immunity has been
achieved. But the method Is not per-
feet since in certain instances not
only was immunity not obtained, put
unexpected paralysis intervened. IN
the instances in which protection was
accomplished, the immunity bodies ap-
peared in the blood.
Passive Protection.
By transferring the blood OF I'M,
mune monkeys TO normal or untreated
ones, they can be rendered insusceptt,,
ible or immune, and the immunity VIII
endure for relatively short PERIOD
during which the passiveiy trans
ferred immunity bodies persist. inc
accomplishment of passive immuniza-
tion is somewhat uncertain, and It's
brief duration renders it useless for
purposes Of protective immunization.
Serum Treatment.
On the other hand, measure OF
success has been achieved in the ex-
detrimental serum treatment Of inocu-
lated monkeys. For this purpose blood
serum derived either from recovered
anu pTOleCltu VI ~
ings has been employed. The serum
is injected into the membranes about
the spinal cord, and the virus is in
oculated into the brain. The injection
of serum must be repeated several
times in order to be effective. Use
of this method has been made in a
few instances in France, where the
blood serum derived from persons who
had recovered from infantile paralysis
has been injected into the spinal mem
branes of persons who have just be-
come paralyzed. The results are said
to be promising. Unfortunately. the
quantity of the human immune serum
is very limited, and no other animals
than monkeys seem capable of yield
ing an immune serum and the monkey
is not a practicable animal from which
to obtain supplies.
Drug Treatment.
The virus of infantile paralysis at
tacks and attaches itself to the CEN
tral nervous organs. Hence il is
reached not only with difficulty be-