What to know about legionnaires’ disease during the London, Ont., outbreak – CBC

Severe lung infection comes from inhaling contaminated water spray

Jul 08, 2025

Legionnaires’ disease is in the headlines this week after public health officials in southwestern Ontario declared an outbreak of the severe respiratory illness.

What is legionnaires’ disease?
Legionnaires’ disease is a respiratory infection caused by the Legionella bacteria.

Early symptoms include fever, chills and a dry cough.

It can lead to a serious chest infection or pneumonia, with symptoms that may include high fever. The symptoms usually develop days after being exposed to the bacteria — and can be fatal.

The name of the disease comes from an outbreak of pneumonia that killed 29 people at an American Legion Convention in Philadelphia in 1976.

Read more: https://www.cbc.ca/news/health/legionnaires-disease-explainer-1.7580254