The county health officer, elected as provided in Section 22-3-2, shall devote all of his time to official work and shall, under no circumstances, engage in private practice. He shall, under the direction of the State Health Officer and the county board of health, have sole direction of all sanitary and public health work within the county, including incorporated municipalities, and shall employ for his assistants, subject to the provisions of the appropriate merit system, such number of physicians, nurses, clerks, inspectors and other employees as are found necessary to accomplish the work. The county health officer may remove from office any assistant or employee, subject to the rules of the appropriate merit system.