55 ILCS 5/5-25009
Any city, village or incorporated town, or combination thereof or any public health district which maintains its own independent health department may abandon the same and become integrated in the county or multiple-county health department. The method of abandonment, unless otherwise prescribed by law, shall be the same as the method of adoption. Abandonment shall become effective at the end of the fiscal year of the city, village, incorporated town or public health district.
Any county which establishes a county health department may unite with other counties to organize a multiple-county health department, in which event the county health department shall be dissolved as soon as the multiple-county health department is organized and all of its records shall be transferred to the multiple-county health department.
55 ILCS 5/5-25009