Güncelleme Tarihi:
Although most of those now affected are not thought to be in serious danger, the flus spread from
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Nations from Asia to Europe to the
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Margaret Chan, the head of the WHO, said the warning level was being raised to phase five on a 1-6 scale -- meaning the threat of a pandemic was imminent and that time was "short" for nations to put emergency plans into action.
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"All countries should immediately now activate their pandemic preparedness plans," Chan said. "The biggest question right now is how severe the pandemic might be."
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Officials in
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Some experts have suggested that the virus has weakened as it was carried elsewhere. The only confirmed swine flu death outside
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"Unfortunately I would anticipate that we will see additional deaths," said Richard Besser, the acting head of the US Centers for Disease Control (CDC).
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"It would be akin to closing the barn door after the horses are out, because we already have cases here in the
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Since the outbreak in the past few weeks, swine flu has quickly made its way around the world, and nations have stepped up checks at airports and distributed flu medicines to try to halt the spread of the disease.
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However, several of the high school students who were initially believed infected following a trip to
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The WHO’s phase five alert means widespread transmission from person to person, and with no vaccine against the swine flu strain, authorities are dependent on reducing human contact to fight the spread of the virus.
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In a televised address President Felipe Calderon urged Mexicans to help fight the disease by staying put over the forthcoming five-day holiday weekend.
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"There is no place as safe for protecting yourself against swine flu as your own home," he said.
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The government said the ultimate cost to
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In addition to the airline and travel sectors, which were already suffering from the global economic downturn, pig farmers in many places have been hit hard by the swine flu crisis.
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But a student who asked not to be named told Reuters he believed there were two gunmen.
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"As far as I know there were two terrorists," he said. "One of them committed suicide and another was arrested by police."
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He said the shooting started shortly after classes began at 9:00 a.m.
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