Infection

The growth of a parasitic organism within the body.

(A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a 'germ') growing within him, drawing its nourishment from the person.

The term 'infection' has some exceptions.

For example, the normal growth of the usual bacterial flora in the intestinal tract is not usually considered an infection.

The same consideration applies to the bacteria that normally inhabit the mouth.