The local outbreak of Legionnaires’ Disease, declared by the Middlesex-London Health Unit in July, is over.

Between May 1 and September 26, 2024, a total of 30 confirmed legionella cases met the criteria for inclusion in the outbreak. The individuals infected by the legionella bacteria ranged in age from 37 to 87 and more than half (20) were males. All 30 have been hospitalized at some point, nine were admitted to the Intensive Care Unit, and two cases have died. One case remains in hospital.

The date of symptom onset of the most recent case (the date when the last case started feeling unwell) was September 14. Now that 24 days have passed since any new cases have developed, the outbreak is considered over.

Despite collecting environmental samples from 18 cooling tower sites, all close to the geographic centre of the cases, no samples have yet detected legionella bacteria that is a match for that identified in the cases. However, results of the most recent round of tests are still with the Public Health Ontario lab, and it remains possible that a source could be found. If the source is found the community will be informed that the source has been found and sanitized.