CHICAGO (CBS) — State health officials are investigating two new cases of Legionnaires’ disease in the western suburbs.

The Illinois Department of Health has confirmed two cases of the disease in Batavia, about 40 miles west of Chicago.

This is in addition to 12 other cases reported since August at a Batavia retirement home.

Officials believe cooling towers might be the source of the recent outbreak.

“Cooling towers emit water plumes, and if there is Legionella bacteria in those water plumes, they are aerosolized. And people can inhale it, and those plumes can extend a mile or two,” said Dr. Ngozi Ezike, director of the Illinois Department of Health.

State health officials say there have been 285 cases of the disease so far this year.