The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1918-09-29

THAT the rat is the great cause, IL
not the only cause, of the dreadful
y disease called infantile paralysis,
is suggested By Dr. Mark W. Richardson,
a distinguished Boston physician, in a
paper read BY him before the Association
of American Physicians recently and en-
bodied in the American Journal Of Public
Health. Dr.. Richardson's suggestions are
based upon wide experimentation since
the terrifying New York City epidemic
of 1916.
DR.. Richardson caused much interest in
the medical world in 1916 by presenting
evidence against human contact, direct
or indirect, as the determining factor In
the spread Of the disease. At the same
time he suggested that the facts OF the
epidemic could be better harmonized IL
the cause was assumed as antecedent
and underlying the infection OF rodents
transmitted to human sufferers by means
of the rat flea
objection was made at the time that
DIR. Richardson's argument against the
role of human contact was much stronger
than that in favor of the rat as the DOM
inant factor of infection. 1t was to
strengthen, by additional data, the new
hypothesis that rat epizootic must and
does precede human infantile paralysis,
and secure further evidence that in the
transfer Of the disease human beings are
not themselves important, directly or
Indirectly. as FAR as infectious secretlons
or excretions are concerned, that Dr.
Richardson's address was made. 1t is ad-
mitted, of course, that healthy third per
sons as carriers Of infected heas may be
of very great importance.
DR. Richardson gives credit in great
mart to Professor Charles T. Brues, who
is the consulting entomologtst who IN
yestigated the New York epidemic OF
1916. for the new evidence as to human
transmissability.
Professor Brues," says Dr. Richardson.
was able under what would be generally
considered as unfavorable conditions 10
develop some facts of great Importance
For instance, whoever has seen city
slum street in Summer time cannot I'm.
agine more intimate personal contact
than is enjoyed by the tenement chlloren
playing in the crowded, hot, dusty THOR
oughfare, and yet it appeared that cases OF
fnfantile paralysis might be numerous In
the tenements on one side Of the street
opposite.
THE contagion appeared therefore, to
he quite sharply localized in the quad
rangIe formed by the tenements bounding
a city block, and did not travel across
the street in spite Of all the human
migrations and opportunities for direct
and indirect contact If human carriers
could not carry the infection across the
street, then it is equally improbable that
the cases in the same block were trans
ferred one TO the other by human
agency. On the other hand. the unre-
stricted migration of infected rats over
the back yard enclosed by such tenement
uuadrangles would explain quite ade-
quately the sharp locsliEation Of the
human cases A somewhat parallel
phenomenon has been seen in plague con-
ditions in India. where people of different
castles never associate with each other.
In spite of this absence Of human contact,
plague spreads from caste to caste. The
explanation is, in the end, simple: AL
though personal association is forbidden,
the houses, fronting oftentimes on diff
ferent streets, have adjacent back yards
over which rats travel freely.
"In this connection it may be noted
that in India the distribution Of rats has
been found to be very irregular. The
general character of a building is no
index OF its rat population. In a con-
siderable collection of old ramshackle
buildings, perhaps only one or two will
be found to be rat infested. On the other
hand, buildings apparently well built and
we'll kept and occupied by the well-todo
class are not infrequently overrun with
rats.
"a study of secondary cases by Profes-
sor Brues showed, furthermore, that a
large percentage occurred in other famL