First Published: May 7, 2009
PARIS: Preventing the swine flu that is spreading across the globe from infecting patients sick with the deadly H5N1 avian flu should be a top priority, especially in Asia, top experts said Thursday.
If both viruses wind up in the same individual, they could mix genes and mutate into a form that is both very pathogenic and easily transmitted among humans, said John Oxford, a virologist at London Queen Mary's School of Medicine and Dentistry.
"We don't want a situation where you have a virus with the spreadibility of the pig virus with an H5 stuck on it. That is something we worry about, to put it mildly," he said in a phone interview.
On an influenza "Richter scale" of concern, if an ordinary seasonal flu rates a level three and the swine flu a level five, then bird flu on its own would be a six and "an H5N1 virus swapping genes with a pig virus would be the highest of all, at least a seven," Oxford said.
Since 2003, the H5N1 strain of bird flu has killed more than 250 people in a dozen countries, according to the World Health Organization (WHO).
More than 80 percent of the deaths were in East and Southeast Asia, with 115 in Indonesia, 56 in Vietnam, 25 in China and 17 in Thailand. There have also been 26 fatal cases in Egypt, the most recent two weeks ago.
But while the strain has killed almost 60 percent of those infected, it does not spread easily — virtually all its victims had extensive, direct contact with poultry.
By contrast, the swine flu that erupted in Mexico this spring has moved across the globe much more quickly, but thus far has not proved especially lethal. Mexican officials report 42 deaths, with two more registered in the United States.
All told, the WHO has verified some 1,900 cases in 23 countries.
The nightmare scenario for virologists is a mutated virus combining high infection potential and virulence.
"The danger of a genetic recombination is real, in animals and in humans — this is something we fear," said Pierre Duplessis, Special Envoy for pandemic influenza at the International Federation of Red Cross and Red Crescent Societies.
"We know that in the current genome of the [swine] flu, there is a sequence that comes from birds, so it is possible that the virus could take on more aggressive attributes and become more virulent," he told AFP.
Duplessis and other experts caution that it is far too early to "declare victory" against the swine flu, even though its spread appears to have slowed.
All three of the great pandemics of the 20th century, they point out, began with mild "herald waves" in the spring that were followed by far more deadly attacks later in the year. –AFP
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