The department is authorized, with the consent of the boards of health and the county authorities of the counties involved, to establish health districts comprised of one or more counties. The county boards of health of the constituent counties shall, at the call of the commissioner, meet in joint session to approve the selection of a director appointed by the commissioner to serve such boards in common. A county board of health is authorized to appoint one of its members to represent the board at a joint meeting for this purpose. The director shall be a physician who is licensed to practice medicine under Chapter 34 of Title 43 and who otherwise meets the requirements of the State Merit System of Personnel Administration. The district director shall have the same powers, duties, and responsibility as a director serving a single county board of health. To further the purposes of this Code section, county boards of health may contract with each other for the provision of multicounty services and also exercise any additional powers as authorized by paragraph (7) of Code Section 31-3-4; and in the performance of such contracts a county board of health may utilize its employees in other counties.