Mo. Rev. Stat. § 192.280

It shall be the duty of the county health officers to enforce the rules and regulations of the department of health and senior services throughout their respective counties outside of incorporated cities which maintain a health officer. The health officers for incorporated cities of less than seventy-five thousand population shall enforce the rules and regulations of the department of health and senior services within their respective cities. Any county health officer who neglects or refuses to perform his duties as required by this chapter shall be deemed guilty of a misdemeanor. In case of dereliction of duty or refusal to act on the part of the county health officer of any county, the department of health and senior services may at its discretion declare the office of county health officer for that county vacant.