One person has died and over 40 are ill in London, Ontario, as health officials investigate a Legionnaires’ disease outbreak linked to contaminated water systems.
Ontario Health Officials Probe Deadly Legionnaires’ Outbreak
A public health alert has been issued in London, Ontario, after an outbreak of Legionnaires’ disease left one person dead and more than 40 others sick. The outbreak, declared by the Middlesex-London Health Unit, is concentrated in the city’s southeast and has renewed concerns about building water systems and cooling towers during Canada’s warmer months.
Officials are currently working to identify the exact source of the outbreak, though initial investigations suggest that contaminated mist from local cooling systems may be responsible.
What Is Legionnaires’ Disease?
Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria. Common early symptoms include high fever, dry cough, chills, and, in some cases, nausea or confusion. If untreated, it can lead to life-threatening respiratory complications and organ failure.
The illness develops after inhaling contaminated water droplets, typically from man-made systems like industrial cooling towers, hot tubs, or plumbing. The disease is not contagious and cannot spread person-to-person, according to the Public Health Agency of Canada (PHAC).
How the Disease Spreads
Legionella bacteria thrive in warm, stagnant water—particularly in systems maintained between 20°C and 50°C. Cooling towers, which are used to regulate temperatures in large buildings, can release contaminated aerosols into the air. Wind can then carry these droplets across a broad area, unknowingly exposing people nearby.
Outbreaks are more common in summer, when cooling systems are most active. Experts believe warm weather creates optimal growth conditions for the bacteria.
Local Impact and Ongoing Investigation
So far, the majority of cases in London are concentrated in one part of the city, and the health unit is analyzing environmental samples from various water and cooling systems.
“We know people want answers about where this is coming from. So do we. Unfortunately, we don’t yet have a confirmed source,” said Dr. Joanne Kearon, associate medical officer of health for the Middlesex-London Health Unit.
A similar outbreak occurred in London in 2024, causing two deaths and 30 illnesses. The source was never identified, but officials suspect the outbreak ended when cooling systems were deactivated for the season. It’s unclear whether this year’s cases are connected to the same location.
Who Is Most at Risk?
While the general public faces low risk, certain individuals are more vulnerable. These include people over 40, smokers, and those with chronic lung conditions, kidney disease, diabetes, or weakened immune systems. Recent travel or hospitalization can also increase susceptibility.
Patients with severe cases may require hospitalization or intensive care, as the infection can affect multiple areas of the lungs.
Treatment and Prevention
Legionnaires’ disease is typically treated with antibiotics, though severe cases may require respiratory support and intensive care. Doctors note that while common pneumonia medications are often effective, a patient’s immune response and the extent of lung damage can complicate recovery.
To reduce risk, health officials recommend maintaining and disinfecting all mist-producing devices in homes—like humidifiers, hot tubs, and showerheads. In larger buildings, especially those with cooling towers, consistent monitoring and sanitation are essential.
Past Canadian Outbreaks Offer Cautionary Lessons
Canada has witnessed several significant Legionnaires’ outbreaks in recent decades. In 2012, Quebec City saw 14 deaths and 200 infections traced to a rooftop cooling tower. That incident led to new provincial regulations and mandatory maintenance plans for tower operators.
In Toronto, a 2005 outbreak at a long-term care home resulted in 23 deaths. Public health traced the cause to a cooling tower on the building’s roof. Since then, multiple provinces have called for cooling tower registries and stricter oversight.
Public Health Monitoring Continues
According to PHAC, Canada sees an average of 620 confirmed cases of Legionnaires’ disease annually. Most are isolated, but periodic outbreaks highlight the need for constant vigilance—particularly in warmer months.
As investigators in London continue testing and analysis, residents are advised to stay informed and seek medical attention if symptoms arise.
For continuous coverage and real-time updates, keep following Maple News Wire.
