This section of the book is from the "Household Companion: The Family Doctor" book
This is, strictly defined, conveyance of disease by touch or contact.
But some (not all) disorders, which may be transmitted by actual
touch, pass also to a short distance through the air. This is true of
typhus, small-pox, chicken-pox, measles, scarlet fever, mumps, and
whooping-cough, certainly; perhaps, in rare instances, of
diphtheria. Hydrophobia, syphilis, and gonorrhoea are conveyed only by
contact and inoculation; that is, introduction of the virus of the
disease into the blood, or, at least, under the skin. These diseases,
are, in fact, the common diseases that are certainly contagious.