Legionnaires’ disease: One dead, infections rise in London outbreak

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One person has died and the infection toll has risen from a rare outbreak of legionnaires’ disease in London.

The number of confirmed cases of the respiratory illness has risen to 22, up from 20 reported a day earlier, the Middlesex-London Health Unit said Friday as public health officials continue to investigate how the outbreak began and spread.

The public health office said one person had died but provided no other information about that individual. Six of the 22 people infected are now being treated in hospital and “all identified cases were hospitalized at some point over the course of their illness,” the office reported.

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Most of the cases detected so far have been in people who either live or work, or both, within a five-kilometre radius of one another in London’s southeast, said the health unit, which hasn’t publicly specified the area beyond that.

Patients in hospital are receiving varying degrees of treatment, from intravenous antibiotics to intubation, Joanne Kearon, the health unit’s associate medical officer of health, has said.

Those most at risk include are older, have lung problems or are immune-compromised, the public health office said Friday.

The Middlesex-London Health Unit was notified July 24 about a cluster of cases that first appeared to be pneumonia. But after two days of investigation, the health unit declared an outbreak of legionella, the bacteria that causes legionnaires’ disease.

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

Legionella bacteria can be found in warm water sources such as air-conditioning systems, hot water tanks and heaters and plumbing systems.

Though not considered contagious in person-to-person transmission, legionnaires’ disease can be spread when the bacteria is aerosolized by fans or wind and people breathe it in.

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Symptoms of  legionnaires’ disease usually begin two to 10 days after a person is infected.

The health unit says its investigation into the source of the illness will likely be “lengthy” and may not be conclusive. The probe includes sampling warm-water systems within a five- to 10-km radius of an area in southeast London. Samples are sent to Public Health Ontario for testing.

“With many cooling towers and other types of cooling equipment in a region of this size, it will be a lengthy investigation,” the health unit said Friday, adding it “it may take weeks before the source is identified and confirmed as the cause of the outbreak.”

In some cases, in investigations like the one in London, “the source of the bacteria is never definitively found, though the outbreak may naturally end,” the health unit said.

Outbreaks of legionnaires’ disease are rare. The last one in London in 2019 sent six people to hospital.

The health unit urges operators of warm-water sources to make sure they sanitize those systems, and encourages anyone who has symptoms to see their health care provider.

Legionnaires’ disease got his name in 1976 following an outbreak of pneumonia that occurred among delegates to an American Legion convention at a Philadelphia hotel. Twenty-nine people died in that outbreak.

The health unit has said there is no “broad risk” to the public in the outbreak, and it is not recommending any changes in behaviour.

HRivers@postmedia.com
@HeatheratLFP

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