Legionnaires’ Disease in London, Ontario: How the KRAKEN System Could Help Prevent Future Outbreaks
London, Ontario is once again facing a Legionnaires’ disease outbreak. After several weeks without new cases, the Middlesex-London Health Unit (MLHU) has redeclared the outbreak following 25 additional cases. Investigators have confirmed that multiple cooling towers at nine separate locations tested positive for live Legionella bacteria, with further testing linking the outbreak to a specific subtype.
Despite routine cleaning and disinfection, trace amounts of Legionella bacteria can survive and regrow in cooling towers under hot, humid conditions — a reminder of how persistent and challenging this pathogen can be.
This 2025 outbreak has now affected at least 94 residents, resulting in 86 hospitalizations and 4 deaths, making it one of the largest Legionnaires’ outbreaks in Canada in recent years (MLDU, 2025).
Why Legionella Is So Difficult to Control
Legionnaires’ disease is a severe form of pneumonia caused by breathing in tiny water droplets containing Legionella bacteria. The bacteria thrive in man-made water systems like cooling towers, hot tubs, decorative fountains, and large plumbing systems.
Even when water systems are treated, bacteria can sometimes persist in biofilms — slimy layers that protect microbes — and re-emerge when environmental conditions favor growth. Outbreaks like this highlight the limitations of traditional surveillance, which often depends on waiting for cases to appear, then investigating water systems after the fact.
The KRAKEN Advantage: Proactive Water Monitoring
The KRAKEN system, developed by Kraken Sense, provides a solution that shifts the approach from reactive outbreak response to proactive outbreak prevention.
Here’s how KRAKEN could help London:
1. Continuous Cooling Tower Monitoring
Instead of periodic manual testing, KRAKEN units can continuously monitor water samples from cooling towers for Legionella DNA. This provides a near real-time alert if bacteria begin to regrow, enabling faster remediation before people get sick.
2. Rapid, On-Site Results
Traditional Legionella testing can take several days because cultures need time to grow in a lab. KRAKEN’s qPCR-based detection delivers results in hours, dramatically reducing response time.
3. City-Wide Surveillance
Multiple KRAKEN units can be deployed across high-risk facilities — cooling towers, large plumbing systems, hospitals, food processing plants — and connected to a central dashboard. Public health officials can view trends across the city and quickly identify hotspots.
4. Early Warning for Public Health
When a facility shows a rise in Legionella levels, health authorities can respond immediately with disinfection measures, cooling tower shutdowns, or public advisories, potentially preventing an outbreak entirely.
From Outbreaks to Prevention
The current situation in London underscores the need for more real-time, data-driven monitoring. The KRAKEN system could transform how cities manage waterborne pathogens by catching problems early and providing actionable data for public health teams.
With continuous surveillance, London — and other cities worldwide — could prevent Legionnaires’ disease outbreaks, protect vulnerable residents, and save lives.
