Public Health investigating confirmed Legionellosis cases

HAMILTON, ON – Hamilton Public Health is investigating a cluster of confirmed cases of Legionellosis, an infection caused by a bacterium found primarily in warm water environments. 

There have been 13 cases reported to Hamilton Public Health since May 4, 2026. Hamilton Public Health is working to identify possible sources of exposure and is focused in East Hamilton/Stoney Creek. At this time, no common source has been confirmed.

“We have identified a cluster of legionellosis cases in the east end of the city and are focused on identifying potential sources of exposure,” said Dr. Brendan Lew, Associate Medical Officer of Health. “We are working closely with local partners and reminding residents and facility operators of the importance of properly maintaining water systems and mist-producing devices.”

Hamilton Public Health is investigating possible sources of exposure including nearby cooling towers and has notified hospital partners to be on alert for potential cases. 

Those who are experiencing symptoms including fever, chills, shortness of breath and cough should follow-up with their healthcare provider, and if severely unwell should seek immediate medical attention.

Quick Facts: 

• The bacterium that causes Legionellosis is commonly found in the environment. The disease is not spread person to person, but rather occurs through inhalation of droplets containing the bacterium.
• Legionellosis symptoms include high fever, chills, shortness of breath and a cough. Medical examination and testing are needed to determine whether someone has pneumonia caused by the bacteria.
• Legionellosis occurs more often in individuals aged 50 and over, individuals with weakened immune systems such as organ transplant patients and individuals with lung conditions, cancer, diabetes and smokers. 
• Residents are reminded to regularly clean and maintain household water systems such as humidifiers and hot tubs.

Additional Resources: 

• Web page: Hamilton Public Health
• Web page: Hamilton Public Health Legionnaires’ Disease