Source of legionnaires’ outbreak elusive

Puzzled health officials search for link in eight Calgary cases

CALGARY – As the number of people hospitalized by an outbreak of legionnaires’ disease in southwest Calgary rose to eight, public health officials remain puzzled over the source of the potentially deadly infection.

Tests of possible sources in the workplaces and homes of the patients have come back negative, said Dr. Brent Friesen, Alberta Health Services medical officer of health.

“What we’ll be doing is continuing to monitor to see if any new cases occur. As those new cases occur, we continue to interview them to see if there’s anything particularly unique that comes up that would lead us to the possible source for the infection,” he said.

Tests of some of the most recent cases haven’t yet been completed, Friesen said.

Legionnaires’ disease is a form of pneumonia caused by bacteria and is contracted by breathing contaminated drops of water.

Among the Calgary patients are three men and five women, ages 51 to 78.

Earlier this month, Alberta Health Services reported a cluster of six cases involving people who live or work within 16 kilometres of one another in southwest Calgary. The two most recent patients, who also live or work close to the other cases, were reported Dec. 8 and Dec. 14, Friesen said.

All patients became seriously ill and required hospitalization — including, in some cases, treatment in intensive-care wards and ventilation to help with breathing, he said.

Two patients remain in hospital.

Friesen said seven of the cases appear to be linked to the same cluster. Health officials are still investigating whether the most recent case involves the same type of legionella bacteria as the others.

The disease isn’t spread person-to-person, so isn’t considered a risk to the general public. The chief concern is whether the bacteria is present in an aerosol-type spray, such as mist in public showers and water fountains.

Investigators are trying to determine whether common sources of aerosol spray exist among the eight patients, Friesen said. While it’s been two weeks since the last case was confirmed, it’s too soon to say whether the outbreak is over, he said.