8
Exits of Bacteria from Body

From the standpoint of defensive hygiene or prevention it is im
portant to know the mode of exit of the disease producing bacteria from

the body of the infected individual.

{a} Nose and throat

(b) Bowels or bladder

{c) Mucous membranes {fenital)
(a) Blood (indirect by insects)

Fate of Bacteria in the Body

Every human being is constantly taking micro-organisms into his body.
The fate of these orgenisms within the body has a vital relationship to
defensive hygiene. They may:

(a) Live; multiply and produce disease
(bv) Live, multiply without producing disease-—"carriers"
(c) Killed by defensive mechanisms of body.

Determiners of Infection

Whether an individual who takes micro-orgenisms into his body will
develop disease or not depends upon a number of factors:

{a) Type of organism
(bv) Virilence or strength of organism

(c) Number of organisms
(a) Degree of resistance or immmity possessed by the individual.

Course of Infection

A brief outline of a typical infection will serve as a basis for a
better understanding of what is happening in disease caused by micro~-

orgenisms .

(a) Cause--e specific bacteria or protozoa taken into the bodys _
(bo) Incubation period--a battle of resisting forces with infecting

organism. |
(c) Symptoms:
1. Premonitary
2. Onset
5. Fully developed
(d) Results:
1. Recovery
2. Degeneration of organs
3e Death

Mechanism of Infection

We must remember that they,
conditions are favorable
{a} res-

How do micro-orgehisms cause disease?
being living organisms, cannot survive unless
for then: They must carry out their fundamental cycles of life:
piration, {b) nutrition, {c) excretion, (d) reproduction.