The outbreak of Legionnaires’ disease in Montreal, Canada’s worst outbreak to date, has finally been confirmed to be over. Following a city-wide campaign to ensure all cooling towers were disinfected as a matter of emergency, no new cases have been reported within the last 15 days. The incubation period for the disease is between 2 and 15 days and as the last person known to have developed the symptoms of the disease was on 29th August, city officials are now sure that the outbreak is at an end.
Being a naturally occurring bacteria, legionella can develop in any type of water system, which is why it is important to prevent water stagnating and to keep plant such as cooling towers and hot and cold water systems properly cleaned and disinfected. Cooling towers we immediately identified as the cause in Montreal, as new cases were identified across the city, rather than being confined to one particular building, as would be the case if a domestic hot or cold water system were to blame.
By not maintaining and cleaning a cooling tower in Montreal, an as yet unidentified building owner has caused the deaths of a total of 13 people and has caused varying degrees of illness to 176 others, who have inhaled droplets of affected water.