Two patients at Seattle-based University of Washington Medical Center have contracted Legionnaires' disease, and one of those patients has died, according to a Public Health-Seattle King County blog post.
Legionnaires' disease, a serious type of pneumonia caused by Legionella bacteria, contributed to the death, according to the department of public health.
Both affected patients were in the hospital's cardiac unit, but no source has been identified yet, according to a Seattle Times report. The hospital is working with the public health department to track down the source.
A statement from UW Medical Center released to KIRO says the hospital reported the death as required by law and is cooperating with the ongoing investigation. "We continue our internal investigation to identify the source of the infection and are taking steps to protect the health and safety of our patients," the statement reads.
Legionella bacteria exist naturally in water environments, but become a concern when in human-made water systems, according to the CDC. The bacteria can cause Legionnaires' disease when aspirated by people at risk for infection. Roughly 5,000 people get Legionnaires' disease in the U.S. each year, and about one in 10 people with the illness will die.