Sars fear comes back to Toronto

Canada is reeling from the shock of discovering it may have at least 20 new cases of severe acute respiratory syndrome (Sars), less than a month after health experts gave it the all clear for foreigners travelling there.

A woman patient who went into a Toronto hospital for a hip replacement had the virus but was not diagnosed at an early stage. This weekend it emerged that, unwittingly, she may have infected her neighbours, healthcare workers, other patients and their family members as long as four weeks ago.

Hundreds of people who have come into contact with her or the other suspected cases have been advised to go into a 10-day quarantine. Emergency departments have also been put under special access restrictions.

Toronto health officials said that they were investigating a new cluster of at least 20 potential Sars cases. The disclosure came hours after US health experts reissued a warning about travel to the city.

The news is a setback to the city's efforts to control the disease, which has already killed 24 Canadians. Officials were furious last month when the World Health Organisation issued a travel warning about Toronto, which it rescinded less than a week later.

Word of the city's new outbreak came as the WHO announced that it was rescinding its travel warning for Hong Kong and Guangdong province in China, where the disease first appeared late last year.

Sars has spread to more than 8,100 people around the world and killed at least 696 people, the vast majority of them in Asia.

Despite the decline of the disease worldwide, Asia has remained the focus of the outbreak because of sharp increases in the number of Sars victims in Taiwan. Some experts expect the WHO to reinstate its advisory against unnecessary travel to Toronto, but such a decision will not be made before Tuesday.

Dr Donald Low, a microbiologist in Toronto heading the anti-Sars efforts, said he could not give precise figures for the number of patients being investigated. 'It's so fluid right now,' he said. 'It's unfair to put a number on it, but we're talking low 20s.'

Low said authorities were investigating two deaths as possibly Sars-related. Canada had not announced a new Sars case since 18 April.