Southern part of the World, braces for the worst

SAO PAULO, Brazil — The Southern Hemisphere has been mostly spared in the swine flu epidemic. That could change when winter starts in coming weeks with no vaccine in place.

So far, the most affected nations have been in North America and Europe, which are heading into summer. But flu is spread more easily in the winter, and it’s already fall down south. Experts fear public health systems could be overwhelmed — especially if swine flu and regular flu collide in major urban populations.

"You have this risk of an additional virus that could essentially cause two outbreaks at once,” Dr. Jon Andrus said at the Pan American Health Organization’s headquarters in Washington.

There’s also a chance that the two flus could collide and mutate into a new strain that is more contagious and dangerous.