THE MYSTERY AILMENT SPREADS.

It was not what health-care officials had hoped for, to say the least. Only a week earlier, one of Health Canada's leading authorities on infectious diseases had speculated that SARS -- severe acute respiratory syndrome -- might actually be "easy to control." How quickly things change. By last week, the numbers had more than tripled, and SARS had infected hospital workers who worked far away from the departments where patients were being treated. While it still looked as if only close contact spreads SARS, health authorities directed more than 1,000 people possibly exposed to the mysterious virus in Toronto to be quarantined in their homes. Don't panic -- that was the word from just about every health official who had anything to say. The progress of a potentially fatal disease with no known cause and no cure created fertile ground for public apprehension, not to mention a run on sales of surgical masks. Canada was definitely a hot spot in the world outbreak of SARS, its confirmed cases reaching 28 in and around Toronto, and one in Vancouver. There have been three deaths from SARS, all in Toronto. Still, doctors in Ontario stressed that last week's surge in numbers was among health-care workers who tended SARS patients before anyone knew they should be taking precautions -- wearing a mask, gloves and a surgical gown. Health Canada noted that all Canadian patients had travelled to Asia or had contact with SARS cases in the household or in a health-care setting. Health Canada toughened its travel advisory, recommending that Canadians not fly to affected regions, particularly around southern China. Ottawa was also considering a request from the World Health Organization to screen all passengers flying out of the country for SARS. International efforts to identify what is believed to be a viral agent behind the outbreak continue, with Hong Kong researchers suggesting the bug belongs to the coronavirus family, known for causing the common cold.