World eyes deadly flu risk
Mexicans huddled in their homes while US hospitals tracked patients with flu symptoms and other countries imposed health checks at airports as the World Health Organization warned the virus had the potential to become a pandemic.
A global outbreak would deal a major blow to a world economy already suffering its worst recession in decades.
While all the deaths so far have been in Mexico, the flu is spreading in the United States. Eleven cases were confirmed in California, Kansas and Texas, and eight schoolchildren in New York City caught a type A influenza virus that health officials say is likely to be the swine flu.
The flu outbreak has snowballed into a huge headache for Mexico, already grappling with a violent drug war and economic slowdown, and has become one of the biggest global health scares in years.
Residents of Mexico City, home to some 20 million people, hoarded bottled water and canned food. Millions stayed home over the weekend and worshipers were told to follow Sunday church services on television.
Convenience stores were open as normal on Sunday but some residents abandoned the capital, a rambling, chaotic city.
Michelle Geronis, 22, a film student, took a bus to be with her family in the central state of Aguascalientes.
"My parents heard the news and said, 'You know what? You'd better get here,'" she said. Others escaped to the Pacific resort of Acapulco after the capital's schools were closed for 10 days and bars, restaurants, cinemas and churches shut down.
In Spain, doctors checked three people who had returned from visiting Mexico and reported flu-like symptoms.
In New Zealand, 10 pupils from an Auckland school party that had been in Mexico were being treated for influenza symptoms in what health authorities said was a likely case of swine flu, although they added none was seriously ill.
The WHO declared the flu a "public health event of international concern." WHO Director-General Dr. Margaret Chan urged greater worldwide surveillance for any unusual outbreaks of influenza-like illness.
"(We are) monitoring minute by minute the evolution of this problem across the whole country," Mexican President Felipe Calderon said as health officials counted suspected infections from the tropical south to the arid northern border.
International experts will convene on Tuesday to advise the WHO whether to declare a pandemic -- a global outbreak of serious disease.
MAJOR RISK
The new flu strain, a mixture of various swine, bird and human viruses, poses the biggest risk of a large-scale pandemic since avian flu surfaced in 1997, killing several hundred people.
A 1968 "Hong Kong" flu pandemic killed about 1 million people globally.
New flu strains can spread quickly because no one has natural immunity to them and a vaccine takes months to develop. Flu is characterized by fever, muscle aches, sore throat and dry cough. Victims of the new swine flu have also suffered vomiting and diarrhea.
US Homeland Security Secretary Janet Napolitano and other administration officials will address a special White House briefing on Sunday on the outbreak.
Authorities across Asia, who have had to grapple with deadly viruses like H5N1 bird flu and SARS in recent years, snapped into action. At airports and other border checkpoints in Hong Kong, Malaysia, South Korea and Japan, officials screened travellers for any flu-like symptoms.
In China, officials assured people that efforts in place were adequate to contain the new threat.
"The measures we've been taking against bird flu are effective for this new type of disease," said Wang Jing of the China Inspection and Quarantine Science Research Institute.
Mexican Health Minister Jose Angel Cordova said the swine flu had killed at least 20 and possibly as many as 81 people in Mexico, and more than 1,300 people were being tested for suspected infection.
Most of the dead were aged 25 to 45, a worrying sign because a hallmark of past pandemics has been high fatalities among healthy young adults.
In Brussels, the European Commission said no cases of the new flu had been reported so far in Europe but in France two people returning from Mexico who had flu-like symptoms were being tested, public health director Didier Houssin said.