Legionnaires’ outbreak in London ends after 70 cases, 3 deaths

A heat map provided by the Middlesex-London Health Unit shows the general area of confirmed cases (home addresses) of Legionnaires’ disease reported to the Middlesex-London Health Unit in 2025.

The outbreak of Legionnaires’ Disease in London has been declared over.

Between July 8 and Aug. 6, 2025, three people died and there were a total of 70 confirmed legionella cases, 64 of which had to be hospitalized.

According to the Middlesex-London Health Unit, enough time has passed since the last reported case, that the outbreak is considered over.

At this time, the health said it can’t say where the bacteria came from, despite collecting 12 environmental samples from 26 cooling tower sites — the search for a source will continue.

The health unit said there are a few reasons the bacteria may not be found, including, people may have been exposed to more than one source, or cleaning of sites may have happened before testing.