Legionella outbreak in Montreal is under control, public health says

This 2009 colorized 8000X electron micrograph image provided by the Centers for Disease Control and Prevention shows a large grouping of Gram-negative Legionella pneumophila bacteria.Fountains and hospitals don't mix, a new study suggests. The water features may be a source of calming negative ions, but they can also be a source of legionella, the bacteria that causes Legionnaire's disease.THE CANADIAN PRESS/AP-Janice Haney Carr

Eight people had to be hospitalized in Montreal recently in connection to a probable outbreak of Legionella, but public health says the situation is now under control. 

Legionellosis is a respiratory infection that can be caught by breathing in fine droplets of water - suspended in the air - contaminated with the Legionella bacteria.

At the end of September, Montreal public health indicated that seven cases had been reported between Sept. 9 and 22 among residents of the LaSalle borough.

The DRSP then asked the health network to be vigilant in order to identify other cases, and an eighth was added to the list. The eighth was reported in the same area on Sept. 30, but the person became sick as early as Sept. 15.

All those who caught the infection had to be hospitalized, but none died.

Public health has been trying to identify the source of the contamination ever since it became aware of the first cases. It has examined water cooling towers, the water parks in the area, construction sites and aqueducts.

A public health team was also deployed to the field to find other potential sources and to contact citizens – but they never managed to identify where the bacteria came from.

Since the last documented infection dates back to Sept. 15, “it is therefore likely that the source has been controlled,” health authorities said. They figure the eight cases were exposed to the same source.

“The lack of new cases since leads us to believe the outbreak is over, but we are continuing to monitor the situation,” they said.

Every year, about 50 Montrealers contract the infection.

During a Legionellosis outbreak in Quebec in 2012, 181 people were infected and 14 died.

This report by The Canadian Press was first published Oct. 13, 2020.

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