Canadian health officials meanwhile vowed to maintain a vigilant SARS watch after being burned by a recurrence once before.

The Geneva-based UN health agency said the last probable case of Severe Acute Respiratory Syndrome had been detected in Toronto on June 12 and was immediately isolated.

Two incubation periods -- 20 days -- without a new case of SARS have now passed, meaning the chain of human-to-human transmission is considered broken, WHO said in a statement posted on its website.

"This is a great achievement for public health in what we hope is the final phase of the global emergency," said David Heymann, WHO executive director for communicable diseases.

"Toronto faced an especially challenging outbreak. As we have learned, SARS is a difficult disease that produces many surprises and setbacks," he added.

Canada -- the country hardest hit by SARS outside Asia -- has seen 39 people die from the disease, including 14 linked to a second outbreak which emerged on May 22, according to health officials.

"Obviously we're pleased that Toronto's been removed from the list of affected areas," said Tanya Cholakov, a spokeswoman with Ontario's ministry of health.

"That being said, we recognize that it is likely that we will have to deal with this disease -- with SARS -- for some time. We are going to continue to take SARS very seriously."

Twenty-one people are still being treated for the disease in the Toronto area. Twenty of them are so-called "probable cases" and considered more serious. Eleven of those are in critical condition and on ventilators.

The WHO advised travellers against non-essential visits to Toronto on April 23, though the warning was lifted a week later after Canada promised to introduce better screening for travellers leaving the country.

But Toronto found itself back on the WHO's list of areas with recent local transmission on May 26 after the virus surfaced in the second SARS outbreak.

A 96-year-old man, who died May 1, contracted the flu-like illness after surgery, unwittingly spreading it to hospital workers and other patients.

Canadian health officials were smarting from relaxing safeguards too early after the decline of the first outbreak and vowed to be vigilant throughout the summer.

"We really let down our guard. Nobody asked the difficult question: 'When do we know it's over?'" said Doctor Donald Low, chief microbiologist at Mount Sinai Hospital here and part of the city's SARS investigation team.

"The lesson we learned after the first wave is we have to be a lot more vigilant. That's what we'll be doing over the summer," Low said in an interview.

Cholakov stressed: "We're not going back to how it was pre-SARS. We're taking the lessons learned and we're keeping the precautions in place to make sure that we can ... contain" the disease.

Precautions like double gowns, gloves and masks are still standard in Toronto hospitals.

Toronto has reported a total of 252 SARS cases, the WHO said, adding that the city was among the first areas affected after the virus moved out of southern China in late February and began to spread internationally.

Taiwan now remains the last area in the world to be on the UN health body's list of areas with recent local transmission for which it recommends exit screening for international travellers.

But WHO spokeswoman Christine McNab said that if no new SARS cases were reported, Taiwan was expected to follow Toronto in being crossed off the list of areas with local transmission on Saturday.

Hong Kong and Beijing were delisted last month.

Worldwide, more than 800 people have died from the pneumonia-like epidemic in 10 countries, and nearly 8,500 have been infected in 32 countries or regions.

TERRA.WIRE