Legionella: How this lesser-known bacteria in water systems can impact your health

April 2, 2026.Reading time 9 minutes.

Stainless steel showerhead spraying water downward. Blue tile in the background.

In 2025, there were 33 cases of Legionella infections among King County residents compared to 8 cases in 2005. But there is good news: Legionnaires’ disease is preventable!

Patient at local hospital diagnosed with Legionnaire’s Disease

May 23, 2018.Reading time 4 minutes.

The University of Washington Medical Center (UWMC) has notified Public Health – Seattle & King County of one patient admitted to the Seattle Cancer Care Alliance hospital located at UWMC, was diagnosed with a serious type of pneumonia called Legionnaires’ disease caused by infection with Legionella bacteria. The patient’s medical history suggests that exposure to Legionella happened while hospitalized in […]

New cases of Legionnaires’ Disease at Local Hospital

August 25, 2017.Reading time 5 minutes.

The University of Washington Medical Center (UWMC) has notified Public Health – Seattle & King County of two patients who were diagnosed with a serious type of pneumonia called Legionnaires’ disease caused by infection with Legionella bacteria. The patients’ medical histories suggest that exposure to Legionella happened while hospitalized at UWMC. The first patient, a male in his 40’s, […]

Patient at Overlake diagnosed with Legionnaires’ disease

September 26, 2016.Reading time 6 minutes.

Update (10.14.16) Public Health – Seattle & King County confirmed that a King County resident who spent time in the Overlake emergency department on September 23 has tested positive for Legionella. The patient, a female in her fifties, experienced symptoms on September 29 and was hospitalized for Legionella pneumonia (Legionnaire’s disease) at another hospital. She has […]

Two patients at local hospital test positive for Legionnaires’ disease

September 8, 2016.Reading time 18 minutes.

Update 10.10.16 UW Medical Center (UWMC) has not detected any additional Legionella cases. To-date, water samples taken from the in-patient unit in Cascade Tower have tested negative for Legionella bacteria since UWMC completed the hyperchlorination process on September 20. Two scrub sinks in the operating room showed a very low level of Legionella bacteria; those […]