Mo. Rev. Stat. § 192.260
The county commissions of the several counties of this state may appoint a duly licensed qualified physician as a county health officer for a term of one year, and in the event a vacancy is created in the office of the county health officer, such commission may appoint a duly licensed qualified physician for the unexpired term. If the county commission of any county decides to appoint a county health officer as empowered in this law, it shall agree with the officer as to the compensation and expenses to be paid for such service, which amount shall be paid out of the county treasury of the county. Nothing contained herein shall be construed to require the county commission of any county to appoint a county health officer in any county.
§ 192.260, RSMo