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The World Health Organization is likely to raise its alert for the H1N1 swine flu outbreak to the highest level and declare a pandemic, its director indicated in an interview published on Monday.

"Level six does not mean, in any way, that we are facing the end of the world. It is important to make this clear because (otherwise) when we announce level six it will cause an unnecessary panic," Reuters reported WHO Director General Margaret Chan told Spanish newspaper El Pais.

"Flu viruses are very unpredictable, very deceptive... We should not be overconfident. One must not give H1N1 the opportunity to mix with other viruses. That is why we are on alert," she reportedly told the newspaper.

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Chan warned against over-confidence following a stabilization in the number of new cases of H1N1 because the southern hemisphere was about to enter winter, when flu cases naturally spike.

"We have to be very careful. No one can predict what is going to happen when countries in the south have flu peaks and this new one arrives — which it is going to do, without a doubt."

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"It is true that the number (of cases in people who have not been to Mexico) is small but because of that I would say that we have not seen the full situation or the whole picture of what is happening. The situation is evolving and the virus is changing".

She said it was too early to predict what proportion of the population would catch the new influenza strain after the European Union predicted 40 percent of the population would become infected.

Meanwhile, Mexico decides today whether to reopen businesses and schools or extend a shutdown that has helped choke off the spread of swine flu but caused untold economic harm. The virus continued to spread around the world, with new cases in Europe and North and South America.

President Felipe Calderon said a nationwide shutdown and an aggressive informational campaign appeared to have helped curtail the outbreak in Mexico. His health secretary said the government is starting preparations for the return to classes and work, and plans to give safety recommendations to businesses and disinfect schools on Monday.

"We have succeeded in detaining or at least slowing the spread of the virus precisely because the measures have been the correct ones," Calderon said in an interview with state television broadcast Sunday night.

Health Secretary Jose Angel Cordova said the virus had killed at least 22 people in Mexico, raising the toll from 19, adding that the last confirmed death occurred April 29. He said the virus had sickened at least 568 people and apparently peaked in Mexico between April 23 and April 28.

While Mexico began its first tentative steps toward a return to normalcay, 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 North America and Europe, with the total number sickened worldwide rising to at least 1,001 people, according to health and government officials.

Health officials raised the number of confirmed U.S. swine flu cases to 245 in 35 states late Sunday. The new number, up from 160 on Saturday, reflects streamlining in federal procedures and the results of tests by states, which have only recently begun confirming cases, said Dr. Anne Schuchat of the U.S. Centers for Disease Control and Prevention.

Officials in New Mexico announced that 14 schools in four towns were being closed for at least a week after the state's first swine flu case was confirmed, and the New Mexico Activities Association suspended all athletic and activity programs until further notice at member schools across the state. California officials suspended all visitations at prisons pending results of tests on an ill inmate at Centinela State Prison.

In Alberta, Canada, 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 is no danger in eating pork.

In Trinidad, crew aboard a Mexican tanker had been isolated since Friday at the Point Lisas Port. The Ministry of Health said Sunday that they were tested and cleared of any flu infection and that the vessel was expected to be released.

Hong Kong isolated 350 people in a hotel after a Mexican traveler there was determined to have swine flu.

China quarantined more than 70 Mexican travelers in hospitals and hotels there, and Mexicans on arriving flights were being 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, Guajardo said.

Calderon complained of the backlash against Mexicans abroad.

"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. "There are always people who are seizing on this pretext to assault Mexicans, even just verbally."

The president did not single out any country. But the Foreign Relations Department said afterward that Mexico was sending a chartered jetliner Monday to bring back any citizens who wanted to leave China. A statement said the plane would go to several Chinese cities "where Mexicans have expressed their intention to return to Mexico."

China's Foreign Ministry denied it was discriminating against Mexicans.

The CDC'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."

Cordova said late Sunday that Mexico's government would start distributing swine flu safety recommendations to businesses, but warned the national lockdown would not be lifted in one fell swoop.

The reopening "will not happen just like that," Cordova said at a news conference. "There will have to be training, preparations for teachers and parents."

Possible safety recommendations would be that there be a 2-meter (6.5-foot) distance kept between people in restaurants or theaters and that workers be urged to wear masks on the subway. He said a decision on whether to extend or end the business and school shutdown was expected Monday.

Cordova presented the most comprehensive description yet of the dead in Mexico, although no conclusions have yet ben drawn about how their characterics may have contributed to their deaths.

He said 15 were female and seven were men. One possible explanation could be that women get poorer health care in Mexico because of its male-dominated culture, he said.

Cordova also said only 4 percent were unemployed; the rest either had jobs or were housewives and students. More than 50 percent had not graduated from high school and only 11 percent had university education.

Pablo Kuri, an epidemiologist advising Cordova, told The Associated Press on Sunday that tests have confirmed a swine flu death in Mexico City on April 11, two days earlier than what had been believed to be the first death.

Kuri 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.

According to tallies by the CDC, World Health Organization and governments, there were 101 confirmed cases of swine flu in Canada; 40 in Spain; 18 in Britain; eight in Germany; four in New Zealand and Israel; two each in Italy and France; one each in Colombia, Costa Rica, Ireland, Switzerland, South Korea; Austria, Hong Kong, Denmark and the Netherlands.

The Associated Press and Reuters contributed to this report.

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