MEXICO CITY (AP) Churches stood empty Sunday in heavily Roman Catholic Mexico City after services were canceled, and health workers screened airports and bus stations for people sickened by a new strain of swine flu that experts fear could become a global epidemic.
President Felipe Calderon has assumed new powers to isolate people infected with the deadly swine flu strain that Mexico's health minister says has killed up to 81 people and likely sickened 1,324 in the country since April 13.
The flu has spread beyond Mexico's borders with confirmed cases in the United States and suspected cases as far away as New Zealand.
New York Mayor Michael Bloomberg said Sunday that the Centers for Disease Control and Prevention confirmed that students at a city high school were infected with swine flu.
New York officials previously had said they were eight "probable" cases, but tests later confirmed it was swine flu. Bloomberg stressed that the cases were mild and many are recovering.
About 100 students complained of flu-like symptoms at the school. Some students went to Cancun, Mexico, on a spring break trip two weeks ago. Mexican authorities have not said whether swine flu has been found in the Caribbean beach resort.
In Mexico, soldiers and health workers patrolled the capital's subway system on Sunday handing out surgical masks and looking for possible flu cases. People were advised to seek medical attention if they suffered from multiple symptoms which include a fever of more than 100 degrees, body aches, coughing, a sore throat, respiratory congestion and, in some cases, vomiting and diarrhea.
Hundreds of public events from concerts to sports matches to were called off to keep people from congregating and spreading the virus in crowds. Zoos were closed and visits to juvenile correction centers were suspended.
About a dozen federal police in blue surgical masks stood in front of Mexico City's Metropolitan Cathedral, which was nearly empty after a measure canceling services to avoid large concentrations of people.
Johana Chavez, 22, said she showed up for her confirmation only to find a sign advising that all Masses, baptisms and confirmations were canceled until further notice.
"We are all Catholic so this is a big step, closing the cathedral," she said, cradling a squirming infant in her arms. "The flu must be bad. I guess I'll have to come back later."
Markets and restaurants were nearly empty. And throngs of Mexicans some with just a fever rushed to hospitals.
Mexico appears to have lost valuable days or weeks in detecting the new flu strain, a combination of pig, bird and human viruses that humans may have no natural immunity to. Health officials have found cases in 16 Mexican states. Two dozen new suspected cases were reported in the capital on Saturday alone.
At least 11 cases of swine flu have been confirmed in California, Texas and Kansas, in addition to the New York students.
The first death was in southern Oaxaca state on April 13, but Mexico didn't send the first of 14 mucus samples to the Centers for Disease Control and Prevention until April 18, around the same time it dispatched health teams to hospitals looking for patients with severe flu or pnuemonia-like symptoms.
Those teams noticed something strange: The flu was killing people aged 20 to 40. Flu victims are usually either infants or the elderly. The Spanish flu pandemic, which killed at least 40 million people worldwide in 1918-19, also first struck otherwise healthy young adults.
The World Health Organization on Saturday asked all countries to step up reporting and surveillance of the disease, as airports around the world were screening travelers from Mexico for flu symptoms.
On Sunday, New Zealand reported that 10 students "likely" have swine flu after a school trip to Mexico, though Health Minister Tony Ryall said none of the students was seriously ill and there was no guarantee they had swine flu. Israel's Health Ministry said there is one suspected case in that country and France is investigating four possible cases.
WHO Director-General Margaret Chan said the outbreak of the never-before-seen virus has "pandemic potential." But she said it is still too early to tell if it would become a pandemic an epidemic that spreads in humans around the world.
WHO guidance calls for isolating the sick and blanketing everyone around them with anti-viral drugs such as Tamiflu. Too many patients have been identified in Mexico's teeming capital for such a solution now. But some pandemic flu experts say it's also too late to contain the disease to Mexico and the United States.
"Anything that would be about containing it right now would purely be a political move," said Michael Osterholm at the University of Minnesota.
Mexican authorities ordered schools closed in the capital and the states of Mexico and San Luis Potosi until May 6.
A team from the CDC was in Mexico to help set up detection testing for the swine flu strain, something Mexico previously lacked.
Health authorities noticed a threefold spike in flu cases in late March and early April, but thought it was a late rebound in the December-February flu season.
Testing at domestic labs did not alert doctors to the new strain. Health Secretary Jose Cordova acknowledged Mexican labs lacked the profiling data needed to detect the previously unknown strain.
Even though U.S. labs detected the swine flu in California and Texas before last weekend, Mexican authorities as recently as Wednesday were referring to it as a late-season flu.
But mid-afternoon Thursday, Mexico City Health Secretary Dr. Armando Ahued said, officials got a call "from the United States and Canada, the most important laboratories in the field, telling us this was a new virus."
Asked why there were so many deaths in Mexico, and none so far among the U.S. cases, Cordova noted that the U.S. cases involved children who haven't been among the fatal cases in Mexico, either.
"There are immune factors that are giving children some sort of defense, that is the only explanation we have," he said.
Another factor may be that some Mexican patients may have delayed seeking medical help too long, Cordova said.
Others are forced to work and leave their homes despite health concerns.
Wearing two dirty, blue surgical masks she says she found and a heavy coat, Daniela Briseno swept garbage early Sunday morning from the streets in Mexico City.
"This chill air must be doing me harm. I should be at home but I have a family to support," the 31-year-old said.
Scientists have warned for years about the potential for a pandemic from viruses that mix genetic material from humans and animals.
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.
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