Evening star., 1940-12-12
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henry.

And Study
By Thomas r. Henry.
An attack Of influenza, presumably
identical with the war disease which
swept America in 19ls-1919, builds up .
limited resistance to q second attack
within a short period.
This Is the finding, just reported to
the United States Public Health Service
by Drs E. r. Rickard, Edwin H. Len
nette and Frank L. Horsfall, jr., OF the
city of Yorktown, N. Y, in which tests
were made of the blood of nearly 1000
persons over a period of two years.
DR.. Rickard is health oflicer of West
chester County. Drs. Lennette and Hors-
fall are on the stan Of the Rockefeller
Foundation, and the recent discoverers
of an influenza vaccine which promises
to give a high degree of protection
against this scourge. True influenza
they point out, is caused by virus and
can be sharply differentiated by various
tests against other respiratory diseases.
AS is the case with other virus maladies.
antibodies against the enthusiastically
minute organisms are built up in the
blood sera of the victims. The amount
of these can be determined by tests
with mice.
Yorktown was selected as commu-
nifty with a settled, fairly homogeneous
population which would be fairly repre-
sentative of the country in general.
Samples of blood were taken from tine
population early in January, 1898. when
there had been no cese reported there
for year and no notable world epidemic.
Other blood samples were taken from
time to time to determine If the degree
of resistance was rising or falling.
In 1899 there was a small epidemic in
Yorktown, giving the investigators an
opportunity to determine whether there
was any correlation between the previ-
ously demonstrated degree Of immunity
and like, ,ihood of contracting the disease.
The post-epidemic tests also enabled the
investigators to determine whether an
attack of the malady increased the i'm
munity.
1fle llIlOlIlSS are Su!IlIHdTllcO Us lCl-
lows:
The "titers." or amounts of antibodies
found in the blood serum, differed great
ly from person to person. The greatest
resistance was found IN adolescents. 1t
remained at an approximately constant
level during adult life and dropped of
sharply with old age.
Among persons who did not have an
attack of influenza the degree of resist
ance found on the first tests remained
fairly constant for one year but showed
a tendency to decline during the second
unusually high at first.
In a flu epidemic which broke out in
the winter Of 1899 it was found that
most of those who contracted the di-
sease were persons with low resistance.
as shown by their previous blood anti
bodies tests In some cases, however.
persons with high 'titers" fell sick Of
the malady.
Significant increases in neutralizing
antibodies were found in the blood sera
of 63 persons who lived in the commu-
nifty during the epidemic but who gave
no history of having been i'll with symp-
toms suggestive of influenza. These
cases were classified as "subclinical in
fections" The individuals actually had
influenza but never knew 1t.
The pre-epidemic titers Of these peo-
pie and those who had severe cases Of
flu were almost identical. thus showing
that the degree of resistance alone was
not responsible for the severity of the
symptoms
Great variation among different indi-
vidusls was noted both in the increase
and in the subsequent decrease Of anti
bodies after infection The titers Of
some persons during convalescence were
lower than the titers Of the pre-epidemic
sera of other individuals with proven
cases. After one year the titers of 19
per cent of those who had been sick had
returned to their pre-epidemic levels. In
another % per cent, however, the con-
yalescent levels were maintained for one
decline, but not to the pre-epidemic
level.
A comparison Of the average titers of
the one-year post-epidemic sera Of per-
sons who had been infected to the aver
age pre-epidemic sera of these same
individuals and to that Of the popula-
tions in general demonstrated that after
a lapse Of IL months there was con-
siderable average increase in immunity
both among persons who had been Ill
and among those who had suffered from
flu without knowing it,
The survey, it is pointed out, gives lit
tie promise that a high degree of i'm
munity to influenza can be built up by
an epidemic. Persons who have the
disease, however, are much less likely
to contract 1t again for the next few
months.
Quotes King George vi