(Brennan Linsley ~ Associated Press)
The virus spread to Colombia in the first confirmed case in South America, worrisome because flu season is about to begin in the Southern Hemisphere. More cases were confirmed in Europe and North America; the World Health Organization said at least 787 people have been sickened worldwide.
Dr. Richard Besser, acting chief of the U.S. Centers for Disease Control and Prevention, said swine flu is spreading just as easily as regular winter flu, with 226 confirmed cases in 30 U.S. states.
"The good news is when we look at this virus right now, we're not seeing some of the things in the virus that have been associated in the past with more severe flu," Besser said. "That's encouraging, but it doesn't mean we're out of the woods yet."
Mexican Health Secretary Jose Angel Cordova said the virus that has killed 19 people in Mexico and sickened at least 506 apparently peaked here between April 23 and April 28. A drastic nationwide shutdown appears to have helped prevent the outbreak from becoming more serious, he said.
"The evolution of the epidemic is now in its declining phase," Cordova declared.
He said officials would decide today whether to extend the shutdown or allow schools and businesses to reopen on Wednesday.
Pablo Kuri, an epidemiologist advising Cordova, said tests have confirmed a swine flu death in Mexico City on April 11, two days earlier than what had been thought to be the first death.
He also said there have been no deaths among health-care workers treating swine flu patients in Mexico, an indication that the virus may not be as contagious or virulent as initially feared.
In Mexico, Sunday marked the official start of campaigning for July 5 congressional elections -- but all public campaigning was banned to prevent gatherings where the virus could spread.
Gabriela Cuevas Barron of the conservative National Action Party, giddily claimed she was launching Mexico's first virtual campaign, promising in a webcast to work for a cleaner and safer Mexico City -- for now, through Twitter, Facebook and YouTube. Meanwhile, the leftist Democratic Revolution Party was already up with a Facebook page for its candidates.
Still a threat
In the Canadian province of Alberta, officials quarantined about 220 pigs that became infected from a worker who had recently returned from Mexico.
It was the first documented case of the H1N1 virus being passed from a human to another species. Canada stressed that pigs often get the flu and there's no danger in eating pork.
Health officials around the world cautioned that despite encouraging signs, swine flu still poses a threat.
"Most experts would agree that the current outbreak that we are experiencing is mild to moderate in severity," Dr. Jon Andrus of the Pan American Health Organization said in a teleconference from Washington. "That is not to say that things cannot change very rapidly and very dramatically."
Under one scenario, the virus could peter out now, only to re-emerge in the fall when flu seasons begins.
"Certainly, maybe, this current round of activity has peaked, but we are only 10 days into this outbreak," WHO spokesman Gregory Hartl said. "I think we would want to wait awhile before making a definitive decision."