The times., 1901-04-13
INSECTS AND DISEASES.
DIR. WardelI Stiles Tells of the Dis
scmination nf Germs

oT- W Narue'i Sttfes Tetis OF the Dis
scmination Of Germs.
The second of the new series of Toner
lectures given under the auspices of the
School of Medicine Of Georgetown Uni
versity. was delivered before a large au-
dieuce by Prof. Ch, Wardell Stiles, a. NJ,
III. D., at Georgetown College last night
His subject of discussion was insects as
Idsseminators of Diseae'' and by means
OF a number of fine lantern slides the
lecture was made Particularly interesting
DIR. Stiles said in the course of his lee
tuTe;
1T is sometimes charged that scientists
make public too many facts concerning
microbes. and that at the present rate
the laity will soon either become dis
Susted with hygienic research or will come
to the belief that death turks in every
thing we eat. drink. touch, or breathe.
That wild hygienic theories and specula-
tions have at times been launched upon
the public cannot be denied, and some
men have undoubtedly laid themselves
open to censure by rushing into print
with unjustitied conclusions based upon
scientific dreams. Let US recall. how
ever that until the cause and method of
dissemination of a given disease are
known, the flygienist. whose duty it is to
guard against that malady, must take
into consideration ali imaginable possibili-
ties. When, on the other hand. the cause
and source are once matters of positive
knowledge effort may he intelligently con-
centrated and the preventive measures
given a definite direction.
Insects must be looked upon as among
our best friends and worst enemies. Some
insects are instrumental in the spread
of the pollen by which certain plants are
fertilized, and they are thus important
factors, not only in beautifying our sur
roundings. but also in the economies of
the country. Destroy all of the bees and
you will destroy one of the important
forage plants. namely, clover. Other in
sects are injurious to plants or animals.
1t is estimated, for instance, that certain
flies cause an annual loss of about $780,,
000, 900 to the cattle industry of the United
States.
other insects are active In the dissent
nation of disease germs. A certain mos
quito in Italy is the normal carrier of
malady which causes that country 1000
deaths and about 100000 cases of disease
per year When we consider the aggre-
gate human suffering involved and the
economic loss brought about by this mos
quito. our imagination is almost stag
gered. Assume, for instance, that these
3.0D00G patients average loss of 81
surely very low estimate-in time taken
from work, in doctor bills, in drugs, fu-
neral expenses, etc, and we obtain the
total of s. 900 600, in addition TO the pain
endured and the economic loss through
death.
The insects which come more especial
~ into consideration in connection with
the diseases of man are mosquitoes, flies,
and feas, and when we turn to the dis
eases of animals we must add TO TINS list
the ticks and crustaceans, two groups of
arthropods closely related to insects"
DR.. Stiles distinguished between two
general classes of diseases-drst, those
which must necessarily be transmitted by
insects, and secondly, those in which in
sects are only acci9eutaJ, though in many
cases important factors. Thus malaria,
Dr. Stiles continued, lis normally trans
mittcd by mosquitoes. and is dependent
upon them. Kill eff mosquitoes and ma
iaria will disappear typhoid fever, on
the other hand, may BE transmitted by
them. XIII OFF alt hiesIand you win un-
doubtedly decrease typhoid. but since in
Sects are only accidental and not neces-
sary spTcaders of this nIal-dy, such meas
urcs viii not eradicate 1t.
We may lay down twn general biologic
rules, which | believe are enHnciated to-
night for the first time, The first rule, TO
W hich at present q few exceptions are
known. is that diseases which are acct
dentally spread by insects are caused by
parasitic plants, particularly by bacteria.
/ ne second ruif 70 zWnlcn no exceptions
are as yet known is that those diseases
which are dependent upon insects or
other arthropods for their dissemination
are caused BY parasitic animals. particu-
larry by spOrOZOa and worms -
Concluding his interesting lecture DR.
Stiles said: Not every germ is danger
Gus and not every insect disseminates dis
ease Many germs aud many insects are
positively useful to us. The dangerous
germs and the insects which transmit
them should. however, be guarded against
and destroyed, and although the Wash
ington Humane Society in placing itself on
record as opposing the protection of life
and property by the dehorning OF cattle
we may confidently hope that active and
well intending body of esteemed fellow
quitoes aies. 1eas. and bedbugs. not only
in order TO increase our comfort but in
order to save human life"