The southern sentinel. (Winnfield, La.) 1883-1910, 1903-07-03
HOUSE FLY CARRIES DISEASE
Investigation by Illinois Nor..,
school Students Proves Tha
ConcIusiseiy.

The house fly appears as dangerou.
and vicious insect, il the light of IN.
Investigations and experiments which
have been made by Miss Eva May Shoe.
maker and Alvin Waggoner, TWO stu
dents of the eastern Illinois state For
NAL school, working under the Gree
ton of W. II. Manwaring, of Johns
Hopkins university.
Their experiments seem 10 prove
the charge against the ny tia,
il is a carrier of disease. They hays
shown how the fly, captured abou.
houses and in the open air, carries bac-
terra and how it can spread disease, re.
ports the Chicago Tribune.
Their endeavor was to determine the
part the fly plays in the transmission
of bacteria.
To do this they constructed piece
of apparatus consisting OF box d.
vided into two compartments. In the
first compartment they exposed food
material infected with an easily rec
ognizable species OF bacteria-ham-
less bacteria, of course, being used
and in the second compartment they
placed an open Petri dish containing
sterile nutriment-agar, culture me-
dunn for bacteria. Flies were placed
in the first compartment, and as soon
as a number of them had been seen to
walk upon or eat the infected mate
rial they were allowed to pass through
small door into the second compart-
ment, where they had chance to come
into contact with the agar in the Petn
dish. Bacteria, deposited On the sur
face of the agar, multiply there ard
form characteristic colonies.
In the preliminary experiment. per-
formed July 16, yellow bacteria was
lsed Molasses mixed with a growth
of this bacterium was spread on
plate in the first compartment, and
dozen flies put into the apparatus
Half an hour later the door between
the two compartments was opened and
the flies allowed to pass through. As.
soon as six of them had been seen 10
come in contact with the agar in the
Petri dish the dish was covered and
put away to develop. A few days later
there had grown on the agar over >
hundred colonies of yellow bacteria.
They repeated this experiment with
red and violet bacteria, and obtained
Characteristic red and violet colonies.
To prove that the germs from which
= he,
fected material in the first compare
ment and not from accidental sources,
control experiments were made with
other groups of flies, but with no in
fected material in the first compart-
ment. In no case, however, did the
Petri dishes used in these control ex-
periments develop yellow, red or violet
colonies. To prove that the flies were
the only means Of transmitting the
bacteria, experiments were made with
infected material in the first compart-
ment. but with no flies in the appara-
tus. The Petri dishes from these ex-
periments also developed no colonies
The germs that grew into colonies in
the first experiments, therefore, came
from the infected material in the first
compartment and were carried to the
dishes by flies. From these results
they drew the more general conclu-
sion that flies are capable of carry
ing bacteria from one place to another
il they have a chance to come in con-
tact with material containing these or
ganisuns.
They next undertook to determine
whether flies in nature actually do
carry bacteria with them" ITO de-
termine this, test tubes of sterile agar
were melted and then cooled to 40 de
grees c.. a temperature a little above
that of the human body. Atthis tenn
peTature the agar still remains liquid,
but is not hot enough to kill bacteria.
Flies were caught with sterile forceps
and washed in this melted agar. The
agar was then poured out into sterile
Petri dishes, where it. soiidified. 1t
is reasonable to suppose that if bac-
terra were present on the flies some OF
them at least would be washed off by
this process into the agar, where they
would multiply and form colonies"
The dishes obtained from these ex-
periments varied greatly, but all OF
them developed colonies ranging from
so to over 1000. Flies in nature, there
fore, probably always do carry bac-
terra with them.
From the standpoint'of public by
giene these conclusions. are signif-
cant; for, admitting that flies can
carry harmless bacteria, there seems
to be no reason why they cannot carry
disease producing bacteria as well. In
fact, it has been general belief among
scientists for humber of years that
they are active agents in the trans
mission of many diseases. Recent
studies by DIR. L. o. Howard on the
breeding habits of these insects fur
nish good evidence that they OCCASION
ally play an important role in the
transmission of typhoid fever 1t is
proba bic that they can, and do. carry
the germs of any disease which offers
them an opportunity to come in con-
tact with infected material.