Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1919-05-11
infectious Agents in Disease.

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there Is no disease which a single in
fictitious agent acting alone can pro-
duce; that is to say, one micro-or
ganism of certain species, how
ever virulent it may be, is incapable
OF provoking disease. EXperim emit
ally it has been found that even In
animals very susceptible to them, it
takes large numbers of a particular
germ to bring about characteristic
results. In diseases occurring among
persons we have no way of determine
ing the number of germs that pri-
marily enter the body, yet wealth
of facts cleaned through expert
ments upon animals leads us to con-
clude their numbers must be large.
Clinical observations also furnish
some data in support of this view.
In cases where long and tedious OPP
erat1ons are performed a wound is
often exposed to the air for hours
without i'll effects following. Cel-
tainly none believes that during the
time OF exposure and manipulation
bacteria do not soil the wound. On
the contrary, we know they do; but
the reason harm only occasionally
results from those that enter Is at
tributed to the fact that either they
are present in insufficient numbers
and are of low virulence, or the
vital forces of the patient are suffi-
cient to destroy them. Similar OBJ
servations are made by physicians
in the repair of injuries In which
either aseptic or antiseptic precau-
tons are utterly Impossible. Thus
in the practise of midwifery for
example, although such unfortunate
surroundings are quite common,
cases of puerperal fever (child-bed
fever) are so infrequent as to ex-
cite comment. Indeed, puerperal
fever occurs occasionally under con-
ditions in which the surroundings
are ideal, probable through the full
fillment of the third condition above
given, viz, extraordinary virulence
of the germs.
Portal of Entry.
singular popularity of patho-
genie ro-organisms is that in
order to provoke disease, they must
find Judgement in or upon that por-
ton of the body which offers the
least resistance to their attack. The
tissues of the body vary in suscep-
tibility to microbic invasion, the diff
ference having relation to the
species of organism. Thus, there
are certain bacteria which can ex-
ert specific action only when they
gain entrance into the intestinal
tract; to this class belong the
typhoid bacillus and the spirillum
of Asiatic cholera. There are bac- !
terra, on the other hand. such as
the tetanus bacillus, the gas bacillus, |
and the common bacteria Of pus,
which may be swallowed with i'm
punity, in fact often are, their |
efforts being produced |
only by entrance into a wound of |
the skin or mucous membrane. The |
channel of entry, therefore, occupies
an important position when the SUBJ
iect of an organisms pathogenicity
is under consideration, since upon it |
will depend the result of the pres
ence of a pathogenic agent whether |
the latter does or does not satisfy
every other condition necessary for
it's specific action.
,ViruIence.
The real power of every species
Of micro organism which produces
disease lies in, it's ability to secrete
one or. more poisons Cor toXins).
When it has this power it is said
to be virulent. That virulence in
bacteria is an essential phenomena
in disease production has been
confirmed by the find
ing on it's propitious channel of en-
try various pathogenic micro-or-
sanisms in perfectly healthy indi-
vidpals, the organisms so found be- !
ng commonly non-virulent varie-
ties. Now all pathogenic bacteria
vary in respect to virulence. and
are on this account divided into
hose which are virulent and those
which are non-virulent. However, it
should be remembered that nom
virulent bacteria are not without
LANCER to individuals who carry
hem, and to other persons to whom
hey may be conveyed, since theyN
nay acquire virulence either before
Or after transference and provoke
disease