Public health has declared a Legionnaires outbreak in London, Ontario, with one person dead and 43 confirmed cases in 2025.
The Middlesex-London Health Unit stated that up to 35 those 43 cases that were reported last week are within six kilometres of each other in Southeast London, marking the second Legionnaires outbreak of 2025.
Legionnaires’ disease is a rare respiratory disease caused by Legionella bacteria that may lead to pneumonia, with numerous symptoms, including high fever and chills.
According to the health unit, the bacteria are discovered in water sources such as water tanks and cooling towers, and the team is currently working to detect the actual source of the ongoing outbreak.
In 2024, a similar outbreak of Legionnaires’ disease was reported in London which infected up to 30 people, with two people dead.
Public Health Ontario stated that most of the cases of legionellosis in the province occur between June and September.
In addition, Legionella bacteria are “ubiquitous” in the environment, and many of the cases in Ontario are “sporadic and not linked to an identified outbreak.”
Are legionnaires contagious?
Individuals can contract the infection by breathing in tiny droplets of contaminated water that were aerosolised by air. Notably, it’s not a contagious disease and is not transmitted through person-to-person contact.
