As London, Ont., deals with the fallout from the latest legionnaires’ outbreak, there’s a call for stricter regulations to help prevent mass spread of the bacteria that cause the respiratory infection.
On Tuesday, the Middlesex-London Health Unit (MLHU) said the likely source of a deadly outbreak this summer and one a year ago is the cooling tower at Sofina Foods Inc.
Over that time, there have been six deaths and over 120 infections.
Now, experts are looking to other jurisdictions for a blueprint to halt the disease’s return.
“There’s significant room for improvement,” said Vincent Brown, senior technical adviser at Magnus, a Quebec-based company that maintains cooling towers in the province and elsewhere. “If there were better protocols in place, more legislation, I think the risk would be a lot lower for the population.”
Part of Brown’s expertise lies in combatting legionella, including preventing it from multiplying. He said Ontario lacks some of the tools other provinces have to prevent such outbreaks.
Over the past 13 years, Quebec and New Brunswick introduced new regulations for the operation and maintenance of cooling towers following outbreaks in those provinces.
Legionella bacteria aren’t transmitted from person to person or through eating or drinking. But if the bacteria are aerosolized or misted into the air (via wind or fans), people may inhale them and become unwell.
The bacteria occur naturally in soil and water, and can contaminate and grow in environments including hot tubs, cooling towers, hot water tanks and parts of commercial air-conditioning systems, the MLHU says.
Most people exposed to legionella don’t get ill, but some may experience Pontiac fever, a mild, flu-like illness that commonly resolves itself.
The scope of the MLHU’s investigation to find the source of this summer’s outbreak was within a six-kilometre radius.
Brown said there’s no binding legislation in Ontario to ensure cooling towers are registered and maintained with stringent requirements, adding that Ottawa’s current guidelines only pertain to federal workplaces.
“I just hope that we pay attention to this a little bit more moving forward. I think there’s something to be done to actually help … without going overboard,” Brown said. “There are some reasonable improvements that can be made in the [Ontario] legislation, I think.”

In 2022, in the throes of an outbreak in Orillia, the Association of Local Public Health Agencies (ALPHA) asked the Ontario government to introduce a mandatory registry and mandate risk management plans for operators.
The ALPHA said the disease was underreported and likely to become an increasing issue within the context of climate change, but officials did not agree to meet with the organization to discuss the issue.
CBC asked the Ontario government if it will consider moving to establish regulations like those in other provinces, but the Ministry of Health didn’t provide an answer.
Instead, it issued a statement saying, “While local boards of health are responsible for monitoring and promoting preventative actions to reduce the spread of legionella … the Ministry of Health and Public Health Ontario (PHO) actively perform surveillance of legionellosis in Ontario.
“PHO is available to assist local boards of health with possible legionella outbreaks and investigations in community settings, including information on testing, case, and outbreak management,” the statement said.
Policy change required, says MLHU
Joanne Kearon, the MLHU’s associate medical officer of health, said the health unit operates a voluntary cooling tower registry and offers resources to help operators maintain their systems. However, Kearon added, the MLHU doesn’t have the authority to mandate rules for operators.
“We’re working with the city [London] to understand how we can create a list in the future, however, this does require policy change, potentially at the municipal and also the provincial level.”

Yves Leger, New Brunswick’s medical officer of health, said new rules are helping in the fight against legionnaires’ disease.
“With the registry, we’re now able to very quickly identify all the cooling towers in a specific area, which will help with investigations should it be needed,” Leger said. “We [also] want to try and prevent these outbreaks from happening in the first place. That aspect of the regulations is really focused on making sure that there are appropriate mechanisms in place to maintain the towers, to monitor the towers, including regular sampling for legionella.”
Kearon said the outbreak in London is still active, and the bacteria’s long incubation period likely means more cases will continue to emerge over the next two weeks.