Public health officials in London, Ont., have declared that an outbreak of legionnaires' disease is over, but a search for the source of the bacteria continues after three people died and dozens were hospitalized over the course of a month.
The Middlesex-London Health Unit says there were 70 confirmed cases of the respiratory illness in the region between July 8 and Aug. 6.
It says three died during the outbreak of the respiratory illness and 64 people were hospitalized, while one remains in hospital.
The health agency says that because no new cases have developed symptoms since July 9, the outbreak is now considered over and the risk of exposure has decreased.
It says it has not identified the source of the legionella bacteria, despite collecting 126 environmental samples from 26 cooling tower sites close to the geographic centre of the cases.
The health agency says the reason the source hasn't been identified could be that bacteria are hard to find, people may have been exposed to more than one source or cleaning may have happened before testing.
It says the search for the source will continue with further environmental sampling.
This report by The Canadian Press was first published Aug. 6, 2025.
The Canadian Press
