Omaha daily bee., 1905-10-08
YELLOW JACKS TROLLEY LINE
Pr Played BY Tropical Insects in Spread
ing Yellow Fever.
MOSQUITOES OLE HOST OF DEATH
Facts Established by Prolonged study
of Microbes and Insects which
HarbOr Reconsideration
Of the MicrObe.

The Rois Of Insects In the Transmission
Of Disease" IL the title Of a timely paper
contributed ny Or. Mlilard Langfeld OF
Omaha 70 the October number Of the
Trained Nurse and Hospital Review OF
New York. Or. LanEfeld IL professor OF
bacteriology In the John A. Creighton Med
ical college and also bacteriologist Of the
Omaha Board Of Health. His paper fol-
lows:
The recent appearance OF yellow fever
In Louisiana draws attention again to
the part that a certain mosquito plays In
this disease. II also suggests the inquiry
why yellow fever, when It invades the
United States. has of late years been
confined 10 the southern and gulf states.
consideration Of the role OF insects In
the transmission OF diseases In general
furnishes us most excellent reasons for
this peculiar locallzation. The word trans
mission Is used advisedly, namely, in the
sense OF transferring or passing on of the
cause OF the disease by insects, in contra
distinction to such Insects as are them
selves the actual cause. For example:
The so-called yellow fever mosquito is not
the primary cause of yellow fever; 1t is
only when this mosquito harbors the para
site Of yellow fever that II can convey the
disease. II is an accessory factor only,
the accidental host of a death-dealing
microbe on the other hand, the itch mite
is the primary cause OF the disease we call
itch" the manifestations OF which are
the direct result of the female burrowing
into the skin to lay her eggs
The Investigations which successfully
solved the problem of the part that In
sects play in the transmission OF disease
incriminated not only the mosquito but
the fly, the bedbug, the ant, the flea the
tick, and probably the body massachusetts
which have the greatest opportunity for
contact with both food and human beings.
The diseases spread by these insects make
quite a~formidable list, a few of the more
common ones being yellow fever, malaria,
typhoid fever, cholera, tuberculosis and
bubonic plague.
Incidental TO, but not less important than
these invaluable discoveries, are the many
other interesting phenomena brought tc
light in the course of these studies. Chief
among them is the fact that all animals
both aquatic and terrestrial, cold-blooded
and warm blooded, also suffer from dis
cases conveyed by insects. OF biological
interest are the many curious and unex
pected data concerning the life history. Of
cycle of development of very low forms
of animal life,
As a rule diseases communicated through
the agency of insects are caused by thu
lowest forms of animal and vegetable life
the organisms being so small as to be in
visible to the unaided eye. To this clas
of micro organisms the vegetable kingdom
has given the bacteria; the animal king
dom the protocol, hlaria and the like
Some diseases are caused. by microbes 81
minute that an instrument has not we
been devised to make them visible, ye
we are aware of their presence through
tests evolved from the study OF form
which the microscope has revealed.
Insects as Disease Carriers.
mlcro-organism, microbe or germ of
disease is carried by an insect either acci
dentalTy or as host. In the former in
stance some portion of the insects bod
becomes soiled by disease germs which, 4
turn, are transferred to food or person
during the creatures flight. In this wa
many diseases may be carried, among ther
typhoid fever, cholera and tuberculosis:
Or the insect may imbibe the germs wit
Its food and then contaminate persons Q
food with its excrement. the germ passin
through It, Still another possibility is til
contamination of wounds either durin
flight or by a person crushing the inseC
and then scratching the spot where it ha
set up an irritation through biting. Plagu,
lock jaw, etc, may be conveyed in thi
way.
When the insect acts as a host for III
germ, an entirely different condition
presented; the insect is not only the carrie
II the germ, but is an incubator for it, d
Il were. during one phase of It's life hstor!
In the host the microbe finds all the cond
tions favorable TO it's growth and multi
plication, and coincidentally, for the IN
crease in virulence of its specific viru
rhe germ is, in this case parasite on IL
insect. There exist in the world numerol
genera OF animal and vegetable life tn,
always live upon other genera as parasites
that is to say, they live at the expeni
IF other organisms by sharing their foo
or by drawing nourishment directly fro
heir bodies. The organism that supper
he parasite is called the host. Anon
ow forms of life parasitism is almost Il
'ule. Many OF the parasites require tW
losts TO successfully carry out their III
welcome host to support their baby
arval form, another the mature or adu
'orm, In each host development can on