Health officials are investigating four cases of Legionnaires' disease at Advocate Christ Medical Center, reports the Chicago Sun-Times.
The Illinois Department of Public Health said three patients and a staff member have contracted the illness since 2018. Two cases occurred within the past two months.
Health officials visited the hospital this week to test the facility's water supply.
Advocate Christ is working with the health department "to strengthen its water management plan and implement multiple control measures," according to a statement from IDHP.
"Our top priority is to provide the safest and highest quality care for the patients and communities we serve, and we are working closely with the Illinois Department of Public Health on its review," Advocate Christ said in a statement cited by the Chicago Sun-Times. "Our facility is safe for our patients, visitors and team members."