In all counties of class one, except counties of the first class not having a charter form of government, and in any county of the second class in which the circuit court sits in more than one city and which has a population of at least fifty-eight thousand but not more than sixty-five thousand, the county commission of such county may appoint such deputies or assistants to or for the county health officer of such county, and when appointed shall fix a reasonable compensation, including expenses of such deputies and assistants, all of which shall be paid out of the county treasury.