Toronto reports nine legionnaires' disease cases amid water safety concerns

Toronto public health officials have confirmed nine cases of legionnaires’ disease in the city. The serious respiratory illness, caused by legionella bacteria, can lead to pneumonia and spreads when people inhale contaminated water droplets. A report on the situation was first released on May 6, 2026. Legionnaires’ disease is triggered by legionella bacteria, which occur naturally in water. The infection does not pass between people but spreads through tiny water droplets containing the germs. Symptoms often include a high fever and chills.

Poorly maintained artificial water systems can allow the bacteria to multiply. As of Wednesday, the number of confirmed cases in Toronto remains unchanged.

Last summer, an outbreak in London, Ont., saw 94 cases, with 86 hospitalisations and four deaths. The recent Toronto cases have raised concerns about potential risks in water infrastructure. Health authorities continue to monitor the situation closely. The disease’s link to water systems highlights the importance of proper maintenance. Officials have not yet identified the source of the current outbreak.