CAROL STREAM, Ill. (CBS) — DuPage County officials announced Saturday that they are investigating three cases of Legionnaires’ disease that have occurred since May of last year in a Carol Stream retirement community.

The Legionnaires’ cases have all been reported at the Windsor Park retirement community.

The DuPage County Health Department and the Illinois Department of Public Health are working with Windsor Park officials to collect information and further investigate. The state will be testing the facility’s water.

Windsor Park itself is also taking action with its own water management plan, and working to provide information to residents, employees, and visitors.

Legionnaires’ disease is a severe form of pneumonia caused by bacteria. It doesn’t spread from person to person; rather, it is born and spread through mist or water.

Outbreaks are most common in buildings with complex water systems, such as hospitals, hotels, long-term care facilities, and cruise ships.