Evening star. [volume] (Washington, D.C.) 1854-1972, 1913-03-07
Lethal Organisms.

Lethal Organisms.
A second type of communicable diseases
differs from the one just mentioned in
that the organism which causes the dis
ease must live for time in the body Of
some other animal to undergo certain
definite changes before it can again in
duce the disease in another individual.
The most important insect-borne diseases
belong to this type, for in the case or
man and domestic animals, certain insects
and ticks act as the secondary host ami
| mails for the organisms of many diseases.
Thus, yellow fever is spread only through
the agency of a certain mosquito. for in
its body alone can the yellow fever organ
ism live and undergo the changes that
are necessary before 1t can be introduced
| into another patient by the bite of an in
fected mosquito. Malaria belongs to the
same category, for it spreads only through
| the bite Of certain mosquitoes that ob.aln
the organisms with their meal of blood,
and then afterward inject into the blood
| of another person, later stage of the
malarial parasite which has developed
| meanwhile within the mosquito.
Diseases in which certain insects act as
specific carriers are most numerous and
prevalent in the warmer parts of the
world, although temperate regions are by
no means free from diseases of this KIND,
which may be referred to as the inOcula-
tive type.
Among insects which disseminate patho-
genie organisms without any specific as
ISOLATION. the common housefly Is without
doubt the most important. The rank OF
the fly in this unenviable profession is
due to several facts in its life history
which render it eminently suited to act
as vector for several diseases such as
typhoid fever diarrhOea, dysentery, sum-
mer complaint of children, etc. The eggs
of the house fly are laid preferably in
horse manure, upon which the larval
stages or maggots feed, but human ex-
crement serves equally well, and when
exposed is very likely to provide food for
brood of fly maggoss Less than two
weeks are required for the larvae to ma.
ture, and after short resting stage or
two or three days the adult flies emerge
from their bed of filth. At this time they
may quite possibly bear in their alimen-
tary tract bacteria derived from their
larval food. Usually, however. they are
quite clean when Matched. In spite OF the
surroundings whence they have come
They do not long remain so, however, for
they feed upon animal and human de-
jecta Of all sorts, garbage and other fer
menting material, and il still hungry IN
wade markets or houses. where they may
leave upon food any bacteria brought
upon their bodies. legs, mouth parts or
wings. In addition, their excrement de-
posted as NY specks" may contain yiru-
lent pathogenic bacteria, II they nave mad
access to matter from which these could
be obtained.
This, in brief, is the status of the house
fly as a disease carrier and it Is readily
seen why filth diseases are the ones nat
urally spread by this insect Attracted
to the nursing bottle or to the baby 8
mouth they may infect him with bacteria
OF any Of the numerous enteric troubles
known as summer complaint II they
have had access to the dejecta OF person
Of q chronic carrier of this disease, they
may deposit the virulent bacteria upon
food that later finds its way into our own
bodies. Bacillary dysentery may be
spread in the same fashion as well as
many other gastro-enteric infections.
The house fly occurs practically through
out the entire civilized world and under
all conditions is a continual menace to
public health. In rural communities.
however, where the proper disposal OF
waste matter Of all kinds is most difficult,
the Importance Of these insects is CORE
spondingly increased.
The house fly is not the only insect
which may act as q carrier OF typhoid.
that this may be spread by the bedbug.
These insects become infected through
feeding on the blood of person IN the
acute stage Of the disease and tor at
terra in a sufficiently virulent condition to
inoculate a second person whom they
may bite. That other biting insects such
as fieas and mosquitoes may act In the
same way Is as yet improved, out is D3
no means improbable.
Several other species Of flies appear
regularly in houses. but in far lesser
numbers. and none exhibit to such a
marked degree the peculiar tastes of the
house fly, which wanders back and forth
from filth to food, feeding on each in
turn. In this method of feeding lies the
danger Of infection by house flies; they
are equally fond of clean and filthy ma
teriaIs, and their frequent migrations
from one to the other multiply their oppor-
tuuities to pick up pathogenic organisms
| that may be later deposited upon foods.
Flea and the Bedbug.
The flea is another domestic insect
which was looked upon only as nui-
sance until it was shown that certain
kinds of fieas are agents in spreading bu-
bonic plague. The most terrible epi-
denies of which we have any historical
record have been those of plague. or
"black deatl" One swept from Egypt in
the sixth century before the Christian era
and invaded Europe and Asia, where it
ragged for sixty years. A similar one
spread through the whole known world
In the fourteenth century and Is thought
to have caused over twenty-five million
deaths before 1t subsided.