Section 2314. County Agreements for Joint Contagious Disease Hospitals, Buildings, Wings and Units.--Whenever the county commissioners of two or more counties decide that a hospital or a building, wing or unit at a general hospital for the care and treatment of contagious diseases is necessary, they shall enter into an agreement for such purposes and therein provide how and in what proportions each county shall bear the expenses incident to the construction, operation and maintenance of the joint hospital, building, wing or unit for contagious diseases.