THE STEPS IN DISEASE ONSET
An infectious disease can begin
when the causative organism, microscopic in size, gains entry through a wound
or natural body opening. Under suitable conditions, microorganisms can
reproduce at fantastic rates. In 30 minutes, one may divide to become two; in
another 30 minutes, the two double again; at that rate, it takes only about 12
hours for the multiplication process to produce an army of more than 16 mil-
lion organisms.
There is no warning when a disease process begins. It takes
many organisms to produce symptoms. And the incubation period-the time between
entry of an organism and your awareness of being sick-may extend for several days,
weeks, even months.
There are great variations in multiplication rates among
disease organisms and in the numbers needed to cause symptoms. For some
diseases, the incubation period may be a day or two; for others, far longer.
The rabies virus, for example, may multiply in some instances for several
months before producing symptoms. Organisms are specific, each producing its
own kind of disease-diphtheria, tuberculosis, boil, pneumonia.
They are
specific, too, in terms of site of attack-lungs, brain, nervous system,
kidneys, skin, etc. In some diseases, symptoms result from destruction of
tissue by the organisms. Thus, polio virus destroys nerve cells, producing
paralysis. Tuberculosis bacteria destroy lung, bone, or other tissue. In other
dis- eases, the symptoms arise from the production of toxins, or poisons, by
the organisms.
Thus, toxins produced by streptococcal bacteria may cause
rheumatic fever, heart damage, or kidney disease even though the organisms
themselves do not directly attack the joints, heart, or kidneys. Their toxins
get into the bloodstream and are carried to these areas. Five types of
microorganisms cause communicable diseases. Knowing something about them will
help make it easier for you to avoid trouble with them.
