3rd Texas student has swine flu...

SAN ANTONIO -- A Texas high school where two students are confirmed to have swine flu is temporarily closing after a new possible case of swine flu was identified there, state health officials announced Saturday.

Carrie Williams, a state Department of Health Services spokeswoman in Austin, confirmed Saturday that another student in Guadalupe County near San Antonio is now believed to have the illness.

Williams said lab tests have not confirmed the potential case.

Because of the outbreak, Williams said officials were temporarily closing Byron Steele High School in Cibolo for classes next week. She did not give any other details.

The illness sickened two high school students at the school and a 10-year-old boy from San Diego who visited Dallas before his diagnosis. All three have recovered and are fine.

As many as 81 people in Mexico have died of swine flu, while at least 1,000 others have become ill.

Gov. Rick Perry announced Saturday that because of the outbreak he was asking the Centers for Disease Control and Prevention to give Texas 37,430 courses of antiviral medications from the Strategic National Stockpile to prevent the spread of swine flu.

"As a precautionary measure, I have requested that medication be on hand in Texas to help curb the spread of swine flu by helping those with both confirmed and suspected cases of this swine flu virus, as well as health care providers who may have come in contact with these patients," Perry said in a statement.

"We will continue to work with our local, state and federal health officials to ensure public safety is protected." With 24 new suspected cases reported Saturday in Mexico City alone, schools were closed and all public events suspended in the capital until further notice -- including more than 500 concerts and other gatherings in the metropolis of 20 million.

A hot line fielded 2,366 calls in its first hours from frightened city residents who suspected they might have the disease. Soldiers and health workers handed out masks at subway stops, and hospitals dealt with crowds of people seeking help.

World leaders may declare global emergency

On Saturday evening, the swine flu outbreak forced Mexico to extend school closures in the capital and two more states.

The World Health Organization’s director-general, Margaret Chan, said the outbreak of the never-before-seen virus is a very serious situation and has “pandemic potential.” But she said it is still too early to tell if it would become a worldwide outbreak.

"The situation is evolving quickly," Chan said in a telephone news conference in Geneva. "A new disease is by definition poorly understood."

This virus is a mix of human, pig and bird strains that prompted WHO to meet Saturday to consider declaring an international public health emergency — a step that could lead to travel advisories, trade restrictions and border closures. Spokesman Gregory Hartl said a decision would not be made Saturday.

Scientists have warned for years about the potential for a pandemic from viruses that mix genetic material from humans and animals. Another reason to worry is that authorities said the dead so far don’t include vulnerable infants and elderly. The Spanish flu pandemic, which killed at least 40 million people worldwide in 1918-19, also first struck otherwise healthy young adults.

This swine flu and regular flu can have similar symptoms — mostly fever, cough and sore throat, though some of the U.S. victims who recovered also experienced vomiting and diarrhea. But unlike with regular flu, humans don’t have natural immunity to a virus that includes animal genes — and new vaccines can take months to bring into use.

But experts at the WHO and the U.S. Centers for Disease Control and Prevention say the nature of this outbreak may make containment impossible. Already, more than 1,000 people have been infected in as many as 14 of Mexico’s 32 states, according to daily newspaper El Universal. Tests show 20 people have died of the swine flu, and 48 other deaths were probably due to the same strain.

The CDC and Canadian health officials were studying samples sent from Mexico, and airports around the world were screening passengers from Mexico for symptoms of the new flu strain, saying they may quarantine passengers.

But CDC officials dismissed the idea of trying that in the United States, and some expert said it’s too late to try to contain spread of the virus.

They noted there had been no direct contact between the cases in the San Diego and San Antonio areas, suggesting the virus had already spread from one geographic area through other undiagnosed people.

“Anything that would be about containing it right now would purely be a political move,” said Michael Osterholm, a University of Minnesota pandemic expert.

Mexican President Felipe Calderon said his government only discovered the nature of the virus late Thursday, with the help of international laboratories. “We are doing everything necessary,” he said in a brief statement.

Public demands answers

But the government had said for days that its growing flu caseload was nothing unusual, so the sudden turnaround angered many who wonder if Mexico missed an opportunity to contain the outbreak.

“Why did it break out, where did it break out? What’s the magnitude of the problem?” pizzeria owner David Vasquez said while taking his family to a movie Friday night, despite warnings to stay out of theaters.

Beginning in late March, when the flu season usually starts to taper off, health officials began recording a spike in cases — three times the normal number.

On April 16, Assistant Health Secretary Mauricio Hernandez noted “an unusual transmission period” of regular, seasonal flu.

Starting two days later, health teams were sent to hospitals looking for patients with severe flu or pnuemonia-like symptoms. They noticed something strange: The flu was killing people aged 20 to 40, though flu victims are either infants or the elderly.

This Wednesday, Hernandez said testing was being carried out in Mexican labs, and hospitals were alerted to watch out for cases. But testing at Mexican labs did not alert doctors to the new strain — even though U.S. authorities had detected cases in California and Texas by April 19.

Mexico City Health Secretary Dr. Armando Ahued said it wasn’t until mid-afternoon Thursday that authorities received a call “from the United States and Canada, the most important laboratories in the field, telling us this was a new virus.”

“That was what led us to realize it wasn’t a seasonal virus ... and take more serious preventative measures,” federal Health Secretary Jose Cordova said.

Across Mexico’s capital, residents reacted with fatalism and confusion, anger and mounting fear at the idea that their city may be ground zero for a global epidemic.

Authorities urged people to stay home if they feel sick and to avoid shaking hands or kissing people on the cheeks.

Outside Hospital Obregon in the capital’s middle-class Roma district, a tired Dr. Roberto Ortiz, 59, leaned against an ambulance and sipped coffee Saturday on a break from an unusually busy shift.

“The people are scared,” Ortiz said. “A person gets some flu symptoms or a child gets a fever and they think it is this swine flu and rush to the hospital.”

He said none of the cases so far at the hospital had turned out to be swine flu.

Jose Donasiano Rosales, 69, got nervous on the subway and decided to get out one stop early.

“I felt I couldn’t be there for even one more station,” Donasiano said as he set up a rack to sell newspapers on a busy thoroughfare. “We’re in danger of contagion. ... I’m worried.”

The local Roman Catholic Church recommended that priests shorten Mass; place communion wafers in worshippers’ hands, instead of their mouths; and ask parishioners to avoid kissing or shaking hands during the rite of peace. The Archdiocese also said Catholics could fulfill their Mass obligation by radio.

Ahued, the capital’s health secretary, said Mexico City may not be the epicenter of the outbreak — and could be appearing to the brunt simply because it is home to the most sophisticated medical centers.

“The country’s best health care facilities are concentrated in the city,” he said. “All the cases here get reported, that’s why the number is so high.”

The same virus also sickened at least eight people in Texas and California, though there have been no deaths north of the border, puzzling experts at the U.S. Centers for Disease Control and Prevention.

A “seed stock” genetically matched to the new swine flu virus has been created by the CDC, said Dr. Richard Besser, the agency’s acting director. If the government decides vaccine production is necessary, manufacturers would need that stock to get started.

The CDC says two flu drugs, Tamiflu and Relenza, seem effective against the new strain. Roche, the maker of Tamiflu, said the company is prepared to immediately deploy a stockpile of the drug if requested. Both drugs must be taken early, within a few days of the onset of symptoms, to be most effective.

Mexico’s Health Secretary Jose Angel Cordova said the country has enough Tamiflu to treat 1 million people — only one in 20 people in greater Mexico City alone — and that the medicine will be strictly controlled and handed out only by doctors. 

Associated Press Writers Mark Stevenson, David Koop and Peter Orsi in Mexico City; Frank Jordans in Geneva; Mike Stobbe in Atlanta; Malcolm Ritter in New York; and Maria Cheng in London contributed to this report.