GENEVA -- The World Health Organization declared an H1N1 flu pandemic Thursday -- the first global flu epidemic in 41 years -- as infections in the United States, Europe, Australia, South America and elsewhere climbed to nearly 30,000 cases.
The long-awaited pandemic announcement is scientific confirmation that a new flu virus has emerged and is quickly circling the globe. WHO will now ask drugmakers to speed up production of an H1N1 flu vaccine. The declaration will also prompt governments to devote more money toward efforts to contain the virus.
WHO chief Dr. Margaret Chan made the announcement Thursday after the U.N. agency held an emergency meeting with flu experts. Dr. Chan said she was moving the world to phase 6 -- the agency's highest alert level -- which means a pandemic, or global epidemic, is under way.
"The world is moving into the early days of its first influenza pandemic in the 21st century," Dr. Chan told reporters. "The (H1N1 flu) virus is now unstoppable."
On Thursday, WHO said 74 countries had reported 28,774 cases of H1N1 flu, including 144 deaths. Chan described the virus as "moderate." According to WHO's pandemic criteria, a global outbreak has begun when a new flu virus begins spreading in two world regions.
The agency has stressed that most cases are mild and require no treatment, but the fear is that a rash of new infections could overwhelm hospitals and health authorities -- especially in poorer countries.
Still, about half of the people who have died from H1N1 flu were previously young and healthy -- people who are not usually susceptible to flu. H1N1 flu is also crowding out regular flu viruses. Both features are typical of pandemic flu viruses.
The last pandemic -- the Hong Kong flu of 1968 -- killed about 1 million people. Ordinary flu kills about 250,000 to 500,000 people each year.
H1N1 flu is also continuing to spread during the start of summer in the northern hemisphere. Normally, flu viruses disappear with warm weather, but H1N1 flu is proving to be resilient.
The decision might have been made much earlier if WHO had more accurate information about H1N1 flu's rising sweep through Europe. Dr. Chan said she called the emergency meeting with flu experts after concerns were raised that some countries like Britain were not accurately reporting their cases.
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After Thursday's meeting, Dr. Chan said the experts agreed there was wider spread of H1N1 flu than what was being reported.
Dr. Chan would not say which country tipped the world into the pandemic, but said all countries and experts were agreed that it was time to declare a global outbreak.
WHO said it was now recommending that flu vaccine makers start making H1N1 flu vaccine. Drug giant GlaxoSmithKline PLC said they could start large-scale production of pandemic vaccine in July but that it would take several months before large quantities would be available.
The pandemic declaration will require all countries, including the dozens that haven't yet reported any cases, to launch pandemic-prevention plans.
Peter Cordingley, a spokesman for the WHO based in Manila, noted that the term pandemic was "a measure of the spread of the virus, not the severity of the virus." The virus's effects are moderate at the moment, he noted. "But it's still going to infect an awful lot of people."
Nearly half the world's confirmed cases, or 13,217, are in the U.S., including 27 deaths, according to the WHO.
In Australia, the number of the new disease, also known as swine flu, has more than tripled in the past week, reaching 1,263 on Thursday, when three new cases were confirmed in the state of Tasmania. It recorded its first case of the disease on May 9.
"Australia catches our eye particularly not because of the number of cases but because of strong evidence of community transmission," particularly in the southern state of Victoria and its capital, Melbourne, said Mr. Cordingley. He said the WHO is also focusing on similar evidence in the U.K., Spain, Japan and Chile.
More than 1,000 Australia's swine flu cases are in Victoria, which has been hit by the cold temperatures and dry conditions that flu viruses thrive in.
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Victorians now account for around 3.6% of total confirmed cases globally, and authorities are struggling to understand exactly why the virus has taken such a hold in the state, Victoria's acting chief health officer, Rosemary Lester, said Thursday.
"Perhaps we may never have a definitive answer on that," Lester told Australian Broadcasting Corp. radio. "We do know that we have had an extensive testing regime so we have uncovered a lot of cases that were there to be uncovered. And because the disease is so mild in the majority of people, that allowed it to spread undetected," she said.
Cases detected so far have been relatively mild, with no deaths from the virus yet recorded in the country. The majority of sufferers in Australia have been aged between five and 18, but the virus continues to strike healthy adults including several professional Rugby League players who competed in an interstate match in Victoria's capital, Melbourne, last week.
Those players were quarantined from their clubs, and earlier this week, authorities canceled a major swim meet due to be held in Melbourne. Victoria is on a higher level of alert than other Australian states.
On the streets of Melbourne there is little evidence of major concern among the city's nearly four million residents. Shops, bars and cafes -- while affected by the economic slowdown -- are still busy, and the city's public transport has shown no signs of reduced patronage.
Schools in the nation are no longer being closed if a student is reported as having the virus, although authorities have requested that school aged children at risk from the virus stay home for seven days.
In contrast, Hong Kong's government on Thursday ordered the closure of all nurseries, kindergartens and primary schools for two weeks after a dozen students at one school tested positive for swine flu.
Australian health authorities have stopped testing every suspected case of the virus -- drawing some condemnation from critics -- and Victoria is now focusing treatment on those most vulnerable to viral infections, such as the very old or very young.
New York City health officials say three more people have died from swine flu, bringing the city's total to 15. One victim was a child under the age of 5, one was a person between 5 to 24 years old, and another was between 30 to 39 years old.
The city health department says a telephone poll of over 1,000 residents found nearly 7% had flu-like symptoms in April and May. That suggests more than half a million New Yorkers were ill.
—Lyndal McFarland in Melbourne, Peter Stein in Hong Kong and the Associated Press contributed to this article.