10 now hospitalized in legionnaires' outbreak as health unit continues search for source

There are now ten people in hospital after a legionnaires' disease outbreak in London with an additional ten people sick with the air-born illness.

The Middlesex-London Health Unit said Thursday it continues to investigate the source of the legionella bacteria, which causes high fever, chills and a dry cough.

It said it first learned it was circulating when employees at a workplace got sick on July 24. The health unit won't disclose the location of the workplace, but says the disease has now spread to a neighbourhood. 

"We are currently sampling cooling towers and units that are in the area that we suspect the source is," said Dr. Joanne Kearon, the health unit's associate medical officer of health.

"These investigations with legionella are difficult, they are complicated," Kearon said. "They tend to last some time because we may actually find sources of legionella that aren't related to this outbreak."

The health unit declared an outbreak last Friday, two days after the first cluster of cases was identified. 

Legionella is typically found in warm water sources such as hot water tanks, large plumbing systems, cooling towers, or air conditioning systems. The bacteria are then aerosolized by wind or fans which can cause people to breathe it in and become sick with legionnaires' disease.

A Legionnaires' disease outbreak in London

11 months ago

Duration 2:30

Ten people have been hospitalized following an outbreak of the respiratory illness Legionnaires' disease in London this week. Dr. Joanne Kearon, the associate medical officer of health for the Middlesex-London Health Unit, joined London Morning to talk about the situation.

Kearon said the bacteria that causes the disease is quite common in the environment and that many people never know they're exposed to it. 

"Most people who are exposed won't be infected, they won't develop symptoms," Kearon said.

She said that the disease cannot be transmitted from person to person. However, legionnaires' disease can be serious, even fatal, particularly to the elderly or people with compromised immune systems. 

Kearon said there have been 27 cases of legionnaires' disease in London since April 1 and that the investigation could reveal more information about which cases are related or unrelated to the latest outbreak.

London last had a legionnaires' outbreak in 2019.

Anyone who develops symptoms is advised to see their healthcare provider.