TORONTO - An unknown respiratory illness has struck an Ontario nursing home, killing six elderly patients — including two announced Monday — and infecting at least 79 residents, employees and visitors. Toronto public health officials are monitoring 170 people connected to Seven Oaks Home for the Aged in Scarborough, a bedroom community just east of Toronto, including families and children who attend a day-care center in the building. Though Seven Oaks is not under quarantine, no visitors have been allowed for several days. The overnight deaths of two women, aged 95 and 79, brought to six the number of people who have died from the respiratory illness. Anxiety over the outbreak has been exacerbated by renewed fears of SARS — severe acute respiratory syndrome — which claimed 44 lives in Toronto from two outbreaks in early 2003. More than 8,000 people worldwide contracted the illness and some 774 people died. One of those who survived the SARS outbreak in Toronto was Dr. Allison McGeer, an infectious disease specialist at Mount Sinai Hospital. On Monday she ruled out SARS, avian flu, Legionnaires and influenza A and B, while emphasizing there was no cause for alarm. McGeer said the outbreak would not be ruled officially over until eight to 14 days after the last case was reported. "These are routine precautions for every respiratory outbreak; there is nothing different about this outbreak," McGeer said. "There no guarantees in medicine, so there's always an insurance period built in after the last case to make sure that things really have settled down definitely." Health officials have yet to determine whether the illness is a virus or bacteria — or possibly a combination — but they emphasized the outbreak was a "garden variety" respiratory illness that mostly targets the elderly, who typically are vulnerable to infections. Dr. David McKeown, Toronto's medical officer, said there have been 39 respiratory outbreaks at long-term care facilities in Ontario since Sept. 1. "I think it's more serious than average, but it's certainly well within the range of what we see in longer-term care facilities," he said. McGeer said she would not be surprised if this outbreak were due to a combination of factors and said she suspected a new rhinovirus was behind the illness. "A number of tests are ongoing; but there is an equal probability that we will never identify this particular virus," she said.