Flu stalks Olympians

The Olympics are on a collision course with a Sydney influenza epidemic, and athletes and spectators have been warned they should be vaccinated before heading for the Games.

Alan Hampson, deputy director of the World Health Organisation Collaborating Centre for Influenza in Melbourne, said Olympic fever may have become an unhealthy reality when the Games open on September 15 in Sydney.

"The Sydney virus peaked in about July last year but this year it's still increasing, and increasing fairly dramatically over the last week or so," Hampson told Reuters.

"What we really hope is all the Olympic athletes have been vaccinated so they don't come down with it. You've trained for four years and then take the chance of being wiped out by a virus -- not good news."

Officials warned months ago that holding the summer Olympics in Australia, where winter is just finishing, was risky because the flu season would be in full swing.

"This is unique, really, in terms of the summer Olympics, as we call them, because they are usually held in the summer in northern hemisphere countries, well outside the traditional flu season," Hampson said.

Three flu strains are active in the Olympic city, Hampson said, with the worst, dubbed A Sydney, particularly virulent. It has caused severe outbreaks in Europe and the United States in the last three years.

The strain is characterised by a rapid onset of symptoms -- including fever, chills, muscle aches and pains, headache and sore throat -- within 24 to 48 hours of exposure, Hampson said.

Most victims are severely affected for three to five days, with lingering symptoms lasting for several weeks or more.

The Olympics are a perfect incubator for the virus, he said.

"That's a great time to spread the flu. The virus just loves crowds, loves schools and places like that -- stadiums would be brilliant," he said.

Hampson said there was still time to arm against the virus.

"If you had a flu shot today, within a week or less you'd have gained some resistance. So it's not too late."