Public health officials are investigating whether Northwestern Medicine Central DuPage Hospital was the source of three cases of Legionnaires' disease.
Three patients could have acquired the infection at the Winfield hospital, but they also had other possible sources of exposure during the 10 days before they started showing symptoms, the Illinois Department of Health said in a news release Friday.
One person was an inpatient, and the second and third had outpatient visits.
Northwestern Medicine spokesman Christopher King referred questions to IDPH. Melaney Arnold, a spokeswoman for the agency, did not respond to inquiries about when the patients developed Legionnaires'.
"We are working closely with IDPH while also conducting an internal review to determine if these cases are related to hospital services," King said in statement. "The safety and health of our patients is our top priority. We will have no additional comments until the review is completed."
The Centers for Disease Control and Prevention recommends health officials conduct a full investigation into the source of Legionella bacteria in a health care facility after identifying two or more cases possibly associated with the facility within 12 months of each other.
IDPH is working with the DuPage County Health Department and the hospital to further investigate the cases. IDPH will conduct another on-site visit to test the hospital's water. The agency also has recommended the hospital conduct surveillance to identify other potential cases.
"Central DuPage Hospital is working with IDPH to strengthen its water management plan and implement multiple control measures. The hospital has also taken actions outlined in its water management plan, including flushing the plumbing system," the news release stated. "The hospital is working to provide information to potentially impacted patients and employees about Legionella."
Legionnaires' disease, a serious lung infection, is not passed from person to person. People can develop the illness after breathing in small droplets of water containing Legionella bacteria.
Symptoms -- including a fever, chills, muscle aches, cough and shortness of breath -- usually develop up to two weeks after exposure.
Outbreaks are most commonly associated with buildings that have complex water systems such as hotels, hospitals, long-term care facilities and cruise ships, according to the state health department.