TOKYO - The spread of the new H1N1 virus in Asia showed no signs of slowing Thursday as the Philippines recorded its first case and new infections were confirmed in Japan, China and Taiwan.
In the United States, authorities reported the country's ninth death from the virus; a 13-year-old boy in Arizona.
The H1N1 flu strain is a never-before-seen mixture of swine, bird and human viruses that spreads easily between people. It has killed 85 people and infected more than 11,000 in 41 countries, according to the World Health Organisation.
Most of the deaths have been in Mexico, occurring mostly in people with underlying medical problems.
While it has killed nobody so far in Asia, its grip appeared to tighten on a region that has battled the H5N1 bird flu virus and the SARS virus over the past 10 years.
The Philippines said a 10-year-old girl, who had returned from a trip to the United States and Canada, had the illness but was recovering. The government was contacting people who were on the same flight and asked the girl's family to put themselves in quarantine until they are declared free of the virus.
There is no community level outbreak in the country, and measures are being taken by the government to prevent transmission, said Health Secretary Francisco Duque.
The number of cases in Japan rose to 272, including a 16-year-old female high school student in Tokyo who had recently returned from New York.
About 4,500 schools, mostly in the western prefectures of Osaka and Hyogo about 400 km (250 miles) from Tokyo, have closed until the end of the week and more schools may follow suit.
In China, authorities confirmed its fifth case, a 21-year-old Chinese-Canadian student in Beijing, while there was also a jump in infections in Australia to eight.
Taiwan also reported two more cases of the new flu, bringing the number of people with the virus on the island to three.
Elsewhere, Chile has become one of the most affected countries in South America. Sixteen children and adults have tested positive for the H1N1 virus.
Margaret Chan, head of the World Health Organisation, said Thursday she would raise the global pandemic alert to the top of the six-point scale if the H1N1 flu was spreading globally.
When I see more signals coming from the virus itself or the spread of the disease, including severity, I would not shy away from making a very difficult decision, she said, adding health experts were now monitoring carefully for signs the virus has taken hold in the southern hemisphere.
Chan said progress was being made on an agreement on how to share drugs, vaccines and the viruses needed to make them.
She said collaboration between governments and drug makers gave hope for conciliation between rich and poor countries.
We have seen something that we have never seen before: the total commitment to countries affected to transparency, to timely reporting, sharing of information, sequences, viruses, diagnostic kits, laboratory equipment, and the list goes on.
So far the symptoms of the new virus appear to be mild, but it is starting to cause more severe effects as it spreads.
Japanese Health Minister Yoichi Masuzoe said a study on 43 cases in Kobe city suggested it was behaving like seasonal flu, and not everyone affected needed hospitalisation.
But U.S. federal health researchers said the seasonal flu vaccine provides virtually no protection against the new flu.
Their study also supports an intriguing theory that people over the age of 60 have some immunity to the new H1N1 strain, perhaps because it resembles an older version of seasonal flu.
They say an unusually high proportion of those being infected and hospitalised with serious disease are young adults, teenagers and older children. Seasonal flu, in contrast, is usually far more severe in very young children, people over the age of 65 and people with chronic disease.
Japan is considering winding down strict health checks at international airports at the end of the week, which had been imposed to try to buy time before an outbreak in the country.
But for the poorest of countries, there is hardly any protection to speak of.
In Afghanistan, a medical centre has been set up at Kabul airport to deal with possible cases, but the country cannot afford temperature screening equipment and relies on other countries to scan outbound passengers.
The WHO has donated $500,000 (320,000 pounds) worth of the antiviral drug Tamiflu, still effective in fighting the new virus. That amount, however, covers only 30,360 people -- a mere fraction in a country of 26 million people and where the most basic of medical facilities and drugs are wanting even in the best of times.