Experts probe ‘milder Sars’

A mild illness which has swept through a nursing home in Canada may have been caused by a new version of the Sars virus.

However, health officials are keen to play down the “mystery infection”, which appears far less lethal than Sars itself. While the respiratory infection has contributed to six deaths among elderly residents of the home in Vancouver, it has none of the powerful symptoms and high mortality rates of the Toronto outbreak earlier this year. An expert from the World Health Organization has travelled to Vancouver to try to work out why the virus found in patients is so similar to the Sars coronavirus – yet the disease is so much milder. One theory is that the virus has mutated slightly and lost some of its virulence. Most of the 150 residents and staff members at Kinsmen Place Lodge have recovered completely, and the six who died showed signs of a “typical” pneumonia rather than the distinctive and overwhelming Sars pneumonia symptoms. What is it?Dr Katrin Leitmeyer, a virologist with the WHO, is studying samples from the patients at Canada’s national disease laboratory. WHO spokesman Iain Simpson said: “The question is – was this indeed the coronavirus that causes Sars? “We know that this could be a mutated Sars coronavirus that has lost virulence, and that’s the favourite hypothesis among many people”Dr David Patrick, BC Centers for Disease Control “If so, how come it hasn’t caused Sars as we understand it in this case, and if not, how come the test results came back positive? “As far as we are concerned, there are no cases of Sars currently in Vancouver or indeed anywhere else.” Dr David Patrick, director of epidemiology at the British Columbia Centre for Disease Control, said that the “pattern of illness” was different. He said: “We know that this could be a mutated Sars coronavirus that has lost virulence, and that’s the favourite hypothesis among many people.” A total of 44 people died in an outbreak of Sars in Toronto earlier this year – the biggest outbreak outside Asia. However, Toronto has been officially Sars-free for some months, and is more than 1,000 miles from Vancouver. (Source: BBC, 21 August 2003)