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Legionnaires’ disease is caused by legionella bacteria, a germ that exists in the environment. Most people contract the illness by inhaling water or soil that contains the bacteria.

“This is one of these bacteria that is everywhere in the environment, particularly in damp places,” Summers said. “They are great at forming films on pipes and stuff like that and often as human beings we can be exposed to this at many different points during the year.”

Elderly people, and ones with compromised immune systems, are most vulnerable to a legionella infection, Summers said. Legionnaires’ disease causes severe pneumonia, fever and muscle aches and can be fatal.

Sometimes legionella bacteria triggers Pontiac fever, a condition less severe than legionnaires’ disease that does not typically include the pneumonia symptoms, Summers said.

In a typical year, the health unit would see about six cases of legionella infections, Summers said. To date, the London-area public health authority has encountered 15, six of which they believe are linked.

Public health officials investigate legionella infections, paying special attention to cases where a link is suspected, Summers said.

“We want to make sure there is no common source in the environment that is exposing people,” Summers said. “We’ve had classic outbreaks from things like cooling towers for air conditioning units . . . or fountains or hot tubs, water parks.”

Legionnaires’ disease was named after a 1976 outbreak of the bacterial infection among attendees of an American Legion convention in Philadelphia. More than 220 people were sickened and 34 people died.

So far, public health officials have not found the source of the bacteria behind the six linked cases, Summers said.

Public health officials are making a report to the board of health Thursday evening on the progress of the investigation.

While legionella bacteria is cause for concern, Summers said the outbreak should not

“Legionella can certainly cause severe illness . . . but we don’t want to frighten people,” he said. “We are taking action, we are intervening and we are certainly optimistic that we will make progress on this.”

jbieman@postmedia.com

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