MEXICO CITY — This sprawling capital was on edge Saturday as jittery residents ventured out wearing surgical masks and President Felipe Calderón published an order that would give his government emergency powers to address a deadly flu outbreak, including isolating those who have contracted the virus, inspecting the homes of affected people and ordering the cancellation of public events.
White-coated health care workers fanned out across the international airport here to look for ailing passengers, and thousands of callers fearful they might have contracted the rare swine flu flooded government health hot lines. Health officials also began notifying restaurants, bars and nightclubs throughout the city that they should close.
Of those Mexicans who did go out in public, many took the advice of the authorities and donned the masks, which are known here as tapabocas, or cover-your-mouths, and were being handed out by soldiers and health workers at subway stops and on street corners.
“My government will not delay one minute to take all the necessary measures to deal with this epidemic,” Mr. Calderón said in Oaxaca State during the opening of a new hospital, which he said will set aside an area for anyone who might be affected by the new swine flu strain that has already killed as many as 81 people in Mexico and sickened more than 1,300 others.
Mr. Calderón pointed out that he and the other officials who attended the ceremony intentionally did not greet each other with handshakes or kisses on the cheek, which health officials have urged Mexicans to avoid.
At a news conference Saturday night to address the crisis, Mexico’s health minister, José Ángel Córdova, said 20 of the 81 reported deaths were confirmed to have been caused by swine flu, while the rest are being studied. Most of the cases of illness were reported in the center of the country, but there were other cases in pockets to the north and south.
The government also announced at the news conference that schools in and around the capital that serve millions of students would remain closed until May 6.
With 20 million people packed together tight, Mexico City typically bursts forth on the weekends into parks, playgrounds, cultural centers and sidewalk cafes. But things were quieter than usual on Saturday.
The government encouraged people to stay at home by canceling concerts, closing museums and banning spectators from two big soccer matches on Sunday that will be played in front of television cameras, but no live crowd.
At street corners on Saturday, even many of the jugglers, dancers and musicians who eke out a living collecting spare change when the traffic lights turn red were wearing bright blue surgical masks.
The newspaper Reforma reported that President Obama, who recently visited Mexico, was escorted around Mexico City’s national anthropology museum on April 16 by Felipe Solis, an archaeologist who died the next day from flu-like symptoms. But Dr. Córdova said that it does not appear that Mr. Solis died of influenza.
White House officials said Saturday that they were aware of the news report in Mexico and that there was no reason to be concerned about the president’s health.
The Centers for Disease Control and Prevention in Atlanta said Saturday that it had sent a team of experts to Mexico to assist with the investigation of the outbreak, which has already been reported in Texas and California and possibly in New York, raising fears that it could spread into a global pandemic.
The possible New York cases were reported at a Queens high school, where eight students tested positive for a type of influenza that health officials suspect could be the new swine flu. Some of the school’s students had traveled to Mexico recently.
Still, the World Health Organization, which held a meeting on Saturday to discuss the outbreak, chose not to raise the level of global pandemic flu alert, which has been at a Level 3 because of the avian flu.
Epidemiologists want to know exactly when the first cases occurred in Mexico. Mexican health officials said they first noticed a huge spike in flu cases in late March. In mid-April, they began noticing that otherwise healthy people were dying from the virus. But it was only on Thursday night that officials first sounded an alarm to the population by closing schools, after United States health officials announced a possible swine flu outbreak.
The scene at the airport was alarming, with doctors stationed at the entrances to answer questions and to keep an eye out for obviously sick people. Regular public address announcements in English and Spanish warned travelers that anyone exhibiting any symptoms should cancel their flight and immediately seek medical attention.
Even Sunday Mass will probably be affected. The Roman Catholic Church gave worshipers the option to listen to Masses on the radio and told priests who decided to hold services to be brief and put Communion wafers in worshipers’ hands instead of their mouths.
Axel de la Macorra, 46, a physics professor at National Autonomous University of Mexico, said he became worried when he learned recently that a 31-year-man who played at a tennis club he once belonged to had suddenly died. “He got sick at the beginning of April and two weeks later, he was dead,” said Mr. de la Macorra, who was weighing whether to attend a First Communion with 200 guests on Saturday.
“My mother told me to wear it so I did,” said Noel Ledezma, 29, who had his mask pulled down so he could sip a coffee and eat a muffin as he walked to work. “Who knows who will be next.”
Sarahe Gomez, who was selling jewelry at a mall in the upscale Polanco neighborhood, spoke through a mask to the few customers who visited her kiosk. “I’m in the middle of all these people and one of them could have it,” she said. “The virus could be anywhere. It could be right here.”
She then took a half step back.