Infection and
Disease - These terms are often mistaken for each other, as they are closely
related even though not the same.
Infection is a growth of
microorganisms in the host''s body and will not neccesarily cause an illness. Animal intestins, animal skin and other parts are routinely infected with colonies of many different types of germs and only rarely do these turn into a real illness.
Disease is defined as actual damage caused to the host due to the presence of microorganisms (as a result of an infection). The situation is, of course, dinamic, and there are many infection that can persist for a long while without causing a disease, and then due to a change in the
Microorganism or host the infection might turn into a disease. Changes that cause a disease can be ones of the microorganism (mutation, change in life cycle) or in the host: change of temperature, moisture, acidity, another illness, the weakening of the immune system, etc., including
anti-immunic diseases (AIDS, certain cancers, etc) which harm the ability of the host to deal with the microorganism''s tendency to grow and annex new areas. For a microorganism to cause a disease the microorganism must be pathogenic (Virulent) to the host.