An outbreak of Legionnaires' disease in Toronto has highlighted the government's efforts to rebuild confidence in its public health system 
A mysterious respiratory illness killed more than a dozen elderly residents of a Toronto nursing home and infected staff and visitors last week. The deaths caused alarm in a city that has only recently recovered - at least economically - from the 2003 outbreak of severe acute respiratory syndrome. 

International media, including CNN and the BBC, reported "a deadly mystery in Canada" but public health officials played down the risks, and said tests had confirmed they were not dealing with Sars or avian flu. Still, the fact they could not identify exactly what was killing the nursing home residents did little to reassure the public.

On Thursday, there was widespread relief when David McKeown, Toronto's medical officer of health, announced the culprit was Legionnaires' disease. 
It is not unusual for legionella pneumophila to cause outbreaks of respiratory illness in nursing homes, and it had been suspected from the beginning. But urine from infected patients had tested negative and only a tissue sample collected during an autopsy of one of the residents showed the culprit was in fact the bacteria that cause Legionnaires' disease. In this case, officials believe it may have contaminated the nursing home's water system. 

The outbreak of the rare form of pneumonia wouldn't have received so much attention - both in Canada and around the world - if memories of Sars weren't so fresh. In 2003, Sars killed 44 people in Toronto and forced thousands of others into quarantine, decimating the tourism industry in Canada's largest city and shaking confidence in the public health system. 

A blue-ribbon panel charged with identifying what went wrong found that squabbling between different levels of government was a significant problem in controlling the outbreak. For example, the province of Ontario refused to share medical data with researchers who were trying to understand the spread of the disease. It was unclear who - if anyone- was in charge. 

David Naylor, chairman of the National Advisory Committee on Sars and Public Health, said the system lacked money and leadership, and called Canada's approach to public health an "international embarrassment". 

"People are chastened. We don't want to see this happen again," Dr Naylor said. 

The good news is that the report led to significant changes, changes that could save many lives in the event of the outbreak of another Sars-like virus, or a flu pandemic. 

The country now has a chief public health officer, and a new national agency to oversee infection control and disease prevention, as well as health promotion. The Public Health Agency of Canada has pushed the federal government to prepare for the threat of an avian flu pandemic. As a result, Ottawa has stockpiled 20m doses of anti-viral drugs. It has also prepared to produce a vaccine as soon as one is available. 

These steps might not have been taken if Sars had not exposed the weaknesses in the country's health care system. Still, Canadians are relieved the revamped system isn't facing the challenge of a deadly new respiratory bug. An outbreak of Legionnaires' disease, while tragic, can be easily treated and contained using antibiotics.