Passersby could have breathed in legionnaires' bacteria from air conditioner

TORONTO (CP) - An outbreak of legionnaires' disease that killed 17 elderly people could have been spread by a roof-top air conditioner that sent bacteria through a nursing home, adjoining buildings and to passersby on streets below, health officials said Thursday.

Toronto's medical officer of health, Dr. David McKeown, said investigators are trying to determine just how widespread the infection is, after two middle-aged men contracted the pneumonia-like illness despite having no connection to a cadre of sick seniors at Seven Oaks Home for the Aged.

McKeown said it's possible for air conditioners to spread bacteria through water droplets produced as part of the cooling process.

"That aerosol, including the bacteria, could get sucked into a building's air conditioning system or could float down on the street in front of a building and be inhaled by someone passing by," McKeown said.

"This is the kind of thing that we are looking at in the investigation at this point."

The actual source of infection has yet to be determined and there is no threat to the community, McKeown stressed repeatedly at a news conference broadcast live to a city still trying to shed bad publicity from the SARS epidemic that killed 44 people in the spring of 2003.

"There is no indication that I can see that there is an ongoing risk of transmission in the community or in the vicinity," McKeown said.

"We're seeing two cases associated with the original cluster."

Both patients fell ill about two weeks ago at the peak of the outbreak and were part of the original investigation but initially tested negative for the disease.

One of the men is a resident at what's known as the Shoniker building, a nearby apartment complex for 126 seniors; the other works at a hospital across the street from Seven Oaks.

Reg Ayre, manager of health environments for Toronto public health, said the air conditioning units at the Shoniker building and the hospital have been decommissioned and that officials were examining all buildings within a 1 1/2-kilometre radius of the nursing home, located in the eastern suburbs of Toronto.

"We're certainly going back and looking at logs, we're speaking to the maintenance staff, and the service companies, looking at what actually took place, what activities are involved in the decommissioning," Ayre said.

The result of tests conducted on water and environmental samples are expected in the next week or so.

The outbreak includes more than 100 cases of legionnaires' disease involving 71 nursing home residents, 23 staff, 14 visitors, one hospital worker and the Shoniker resident.

McKeown said that a small number of people remain in hospital but most everyone was improving.

The pneumonia-like illness is not a communicable disease and is usually spread through water supplies or ventilation systems.