Outbreak of Legionnaires’ Disease in London Sparks Health Investigation

The Middlesex-London Health Unit is currently looking into an outbreak of Legionnaires’ disease in the city.

This rare respiratory illness is caused by the legionella bacteria, which typically hide out in warm water sources like hot water tanks and air conditioning systems. So far, since July 24, 20 cases of Legionnaires’ disease have been reported, starting from a business in the south end of London and spreading nearby to a neighborhood in the southeast.

Half of those infected have been hospitalized, according to Dr. Joanne Kearon, an associate medical officer of health with the Health Unit. She explained that it’s serious, particularly for those with existing health issues.

Legionnaires’ disease isn’t contagious between people, but can hit vulnerable groups hard. Symptoms often include high fever, chills, and a dry cough that can escalate into severe illness, particularly among older adults and smokers.

“It’s not very infectious at all; most people exposed will not develop any symptoms,” Kearon mentioned. She explained that the bacteria thrive in water but become a risk when they get aerosolized and are inhaled.

The Health Unit noted that while sporadic cases occur each summer due to warmer weather, this outbreak is unusual, as many individuals have likely been exposed but might not show symptoms.

On July 24, local health officials noticed the cases were clustered together more than usual, prompting this investigation. The current focus covers a sizable area in southeast London—about a five-kilometer radius.

The Middlesex-London Health Unit and Public Health Ontario are working together to track down where the bacteria might be coming from. Luckily, they stressed there is no risk to the drinking water.

Dr. Kearon added, “If people do become infected, typically their symptoms are mild. We often don’t see those cases at hospitals because they don’t require emergency care.”

As the investigation continues, health officials are urging people to maintain their cooling systems properly to prevent future outbreaks.