Swine flu virus could still mutate – WHO

GENEVA – The new H1N1 flu virus could still mutate into a more virulent form and spark an influenza pandemic that could be expected to circle the globe up to three times, the World Health Organisation said yesterday. The impact of any pandemic would vary, as a virus that causes only mild illness in countries with strong health systems can become ‘devastating’ in those with weak health systems, shortages of drugs and poorly equipped hospitals, it said.

The new virus, commonly referred to as swine flu, ‘appears to be more contagious than seasonal influenza’ and nearly the world’s whole population lacks immunity to the new disease, the WHO said in a document issued overnight entitled ‘Assessing the severity of an influenza pandemic’. ‘It attempts to explain different aspects of severity, not just the pathogenicity of the virus but its impact on health and social systems,’ WHO spokesman Thomas Abraham told Reuters. ‘It is in response to questions from the public and media.’
The United Nations agency’s pandemic alert level is at 5, its second-highest level on a scale of 1 to 6, he said.
This means that the virus shows no signs of sustained person-to-person spread outside North America.
Some 5 251 people have been infected in 30 countries, according to WHO’s tally yesterday, which includes 61 deaths. Hardest hit are Mexico with 2 059 cases, including 56 deaths, and the United States with 2 600 cases including three deaths. So far, with the exception of the deadly outbreaks in Mexico, the virus has tended to cause very mild illness in otherwise healthy people, it said.
But influenza viruses mutate frequently and unpredictably and ‘the emergence of an inherently more virulent virus during the course of a pandemic can never be ruled out,’ the WHO said.
‘The overall severity of a pandemic is further influenced by the tendency of pandemics to encircle the globe in at least two, sometimes three, waves,’ the WHO said.
‘For many reasons, the severity of subsequent waves can differ dramatically in some or even most countries,’ it said. The 1918 influenza pandemic – which killed tens of millions of people – began mild and returned within six months in a much more lethal form, it said. The 1968 pandemic began relatively mild, with sporadic cases prior to the first wave, and remained mild in its second wave in most, but not all countries, it said.