3 hospitalized, 17 cases in legionnaires' outbreak as health unit looks to find source

Since this story was first published on July 30, the health unit identified 3 additional cases. The story has been updated to reflect that finding.

Three people are being treated in hospital after a legionnaires' disease outbreak in London that has led to 17 confirmed cases. 

The Middlesex-London Health Unit first became aware of a cluster of cases on July 24 when employees of a single workplace came forward with reports of illnesses. 

However Dr. Joanne Kearon, the health unit's associate medical officer of health, said the investigation has now widened beyond that original location and is now focused on a specific London neighbourhood. 

 "Our investigation has now expanded to the broader community," said Kearon.

Kearon said health unit won't publicly identify the workplace where the reports first came from, because she said releasing that information won't lead to an increase in public safety. 

"We can't confirm that there is any workplace that's actually linked to the outbreak," she said. "Providing the public with the specific workplace wouldn't be informative necessarily of their risk."  

She said there are now different locations tied to the 17 confirmed cases. 

Kearson said staff are collecting samples from the people who are sick and looking through a specific neighbourhood to identify the source of the legionella, the bacteria that causes the disease. 

On Friday, July 26, two days after the first cluster of cases was identified, the health unit declared an outbreak of legionella.

Legionnaires' disease is a respiratory illness that can cause high fever, chills and dry cough.

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. 

The disease is not transferred from person to person, Kearon said.

"There is no broad risk to the public," the health unit's statement said. 

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. 

However the disease can be serious, even fatal, particularly to the elderly or people with compromised immune systems. 

The health unit said it will work with Public Health Ontario and the Public Health Ontario Labs to develop a sampling plan in an attempt to identify the source of the bacteria.

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

"More information will be released following further investigation," the health unit's statement said.