An unidentified illness has claimed four more lives at a nursing home near Toronto in Canada. In total, 10 people have died since the mystery infection first surfaced last week at the Seven Oaks Home for the Aged. Forty residents have been admitted to hospital. Doctors say the outbreak has been contained, but the death toll could rise.“It would not surprise me if there were some additional deaths,” Toronto’s Medical Officer David McKeown said in a press conference. However he said there was little risk to public safety because the infection was mainly within the retirement home. While testing for the cause continues, public health officials have said it may never be possible to determine the exact type of virus or bacteria responsible for the illnesses. They have already ruled out influenza, avian flu, SARS and Legionnaire’s disease. Anxiety over the outbreak has been exacerbated by fears of SARS – severe acute respiratory syndrome – which claimed 44 lives in Toronto during two outbreaks in 2003.