(Brennan Linsley ~ Associated Press)
Mexican officials said the epidemic was waning at its epicenter, announcing that Wednesday will conclude a five-day closure of nonessential businesses they credit for reducing the spread of the new virus.
President Felipe Calderon said higher education classes would resume Thursday and all other schools and government-run day care centers would reopen by May 11.
Global health officials urged countries to remain vigilant because the outbreak's spread around the world remains in its early stages, but there were no imminent plans to raise the pandemic alert level.
Raising the alert level to 6, the highest, would mean that a global outbreak of swine flu is underway. The World Health Organization uses the term pandemic to refer to geographic spread rather than severity. Pandemics aren't necessarily deadly. The past two pandemics -- in 1957 and 1968 -- were relatively mild.
"We do not know how long we will have until we move to Phase 6," said Margaret Chan, head of the WHO. "We are not there yet. The criteria will be met when we see in another region outside North America, showing very clear evidence of community-level transmission."
WHO declares a level 5 alert when it thinks a global outbreak is "imminent." Though Mexican authorities think the outbreak may have peaked there, WHO says it is too early to tell if the outbreak is slowing down.
While Mexico began its first steps toward normalcy, the virus spread to Colombia in the first confirmed case in South America, where the coming winter means flu season is about to begin.
More cases were confirmed in North America and Europe -- including Portugal's first.
A total of 1,276 swine flu cases have been confirmed worldwide, according to health and government officials.
Many questions remain about this virus -- a new blend of genetic material from humans, birds and pigs -- leading a number of countries to take urgent measures against arriving Mexicans or those who have recently traveled to Mexico.
In China, 71 Mexicans have been quarantined in hospitals and hotels, Foreign Secretary Patricia Espinoza said. Arriving Mexicans were taken into isolation, said Mexico's ambassador, Jorge Guajardo. Even the Mexican consul in Guangzhou was briefly held after returning from a vacation in Cambodia.
And in Hong Kong, 274 people remained isolated in a hotel Monday after a Mexican traveler there was determined to have swine flu.
China's Foreign Ministry denied it was discriminating against Mexicans. But Calderon complained of the backlash, and sent a chartered plane to China Monday to pick up Mexican citizen wanting to return home.
"I think it's unfair that because we have been honest and transparent with the world some countries and places are taking repressive and discriminatory measures because of ignorance and disinformation," Calderon said.
Mexico also criticized Argentina, Peru and Cuba for banning flights. Argentina sent a chartered plan to Mexico to collect Argentines wanting to return home, and set up a field hospital at its airport in Buenos Aires to handle incoming passengers with symptoms.
WHO flu chief Keiji Fukuda said quarantines were a "long-established principle" that makes sense in the early phases of an infectious disease outbreak, but not once a full pandemic is under way.
"As we get later on into Phase 6 then these sorts of measures will become less useful because there will just be more infections around and you can't quarantine everyone in the world," he said.
A group of 25 Canadian university students and a professor also have been quarantined at a hotel in China since the weekend over swine flu fears. Canada has 140 confirmed cases of swine flu. The group does not have any flu symptoms, University of Montreal spokeswoman Sophie Langlois said Monday.
Mexico had 727 cases of swine flu and 26 deaths from the virus, Health Secretary Jose Angel Cordova said Monday. There has been one other death worldwide -- a Mexican toddler who died in Texas.
The U.S. caseload grew to at least 300 confirmed cases in 36 states, reflecting streamlined federal procedures and the results of tests by states, which have only recently begun confirming cases.
The U.S. Centers for Disease Control and Prevention's acting chief, Dr. Richard Besser, said swine flu is spreading just as easily as regular winter flu.
"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."
In Alberta, Canada, officials quarantined about 220 pigs infected by a worker who 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 is no danger in eating pork.
Associated Press writers Christopher Bodeen in Beijing, Bradley S. Klapper in Zurich and Alexandra Olson, Paul Haven and E. Eduardo Castillo in Mexico City, John Heilprin at the United Nations, Rob Gillies in Toronto and Min Lee in Hong Kong contributed to this report.