Section 6. The department shall have the power to define, and shall from time to time define, what diseases shall be deemed to be dangerous to the public health, and shall make such rules and regulations consistent with law for the control and prevention of such diseases as it deems advisable for the protection of the public health. The department shall also have the power to define, and shall from time to time so define, what diseases shall be included within the term venereal diseases in the provisions of the laws relative to public health.