MEXICO CITY — Mexico’s president assumed new powers Saturday to isolate people infected with a deadly swine flu strain that health officials warned could become a global epidemic.
New cases of swine flu were confirmed in Kansas and California and suspected in New York City. But officials said they didn’t know whether the New York cases were the strain that has killed up to 81 people in Mexico and likely sickened 1,324 since April 13, according to figures updated Saturday by Mexico’s health secretary.
Authorities ordered schools closed until May 6 in the capital and the states of Mexico and San Luis Potosi.
Soldiers and health workers patrolled airports and bus stations to corral people who may be infected with the swine flu.
The government may have been slow to respond to the March outbreak of the combination of swine, bird and human influenza that people may have no natural immunity to. Now, even detaining the ill may not keep the strain from spreading, epidemiologists say.
The World Health Organization on Saturday asked countries to step up reporting and surveillance of the disease and implement a coordinated response to contain it.
Two dozen new cases were suspected in Mexico City, where authorities suspended public events until further notice. More than 500 concerts, sporting events and other gatherings were canceled in the metropolis of 20 million.
President Felipe Calderon can invoke special powers letting the Health Department isolate patients and inspect homes, incoming travelers and baggage.
At Mexico City’s airport, health workers passed out questionnaires seeking to identify passengers with flu symptoms. Surgical masks and brochures were handed out at bus and subway stations.
A team from the U.S. Centers for Disease Control and Prevention traveled to Mexico to work with its counterparts to limit the outbreak.
A U.S. Embassy statement said the United States has not imposed travel constraints to and from Mexico but is suspending the processing of visas and other services through Wednesday to avoid creating crowds. It also issued a message advising U.S. citizens to avoid large crowds, shaking hands, greeting people with a kiss or using the subway.
With confirmed swine flu cases in at least six Mexican states, and possibly as many as 14, the efforts seemed unlikely to stop the spread of the disease.
Particularly difficult in a metropolis as crowded as Mexico City was the embassy’s advice that maintaining “a distance of at least 6 feet from other persons may decrease the risk of exposure.”
WHO Director-General Margaret Chan said the outbreak of the never-before-seen virus has “pandemic potential.” But she said it is too early to tell if it would become a pandemic.
“The situation is evolving quickly,” Chan said. “A new disease is by definition poorly understood.”
WHO lays out three criteria necessary for a global epidemic to occur: The virus is able to infect people, can readily spread from person to person, and the global population has no immunity to it. The agency held off raising its pandemic alert level, citing the need for more information.
Early detection and treatment are key to stopping any outbreak. WHO guidance calls for isolating the sick and blanketing those around them with antiviral drugs such as Tamiflu.
Health authorities started noticing a threefold spike in flu cases in late March and early April, but they thought it was a late rebound in the December-February flu season.
Testing at domestic labs did not alert doctors to the new strain, although U.S. authorities detected an outbreak in California and Texas earlier this month.
Mexico sent 14 mucous samples to the U.S. Centers for Disease Control and Prevention on April 18 and dispatched health teams to hospitals looking for patients with severe flu or pneumonialike symptoms.
Those teams noticed that the flu was killing people aged 20 to 40. Flu victims usually are 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.
As recently as Wednesday, authorities were referring to it as a late-season flu.
But Thursday afternoon, Mexico City Health Secretary 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.”
“That was what led us to realize it wasn’t a seasonal virus … and take more serious preventative measures,” Health Secretary Jose Cordova said.
Hospitals dealt with crowds of people seeking help. A hot line fielded 2,366 calls in its first hours from city residents who suspected they might have the disease.
Doctors reported that anti-viral medications and even steroids were working well against the disease, noting no new deaths had been reported in the capital in the past day.
Airports around the world were screening travelers from Mexico for flu symptoms. But containing the disease may not be an option.
Ahued said Mexico City may not even be the epicenter of the outbreak.
“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.”
Scientists have warned for years about the potential for a pandemic from viruses that mix genetic material from humans and animals.
This swine flu and regular flu can have similar symptoms: mostly fever, cough and sore throat. But some U.S. victims who recovered also experienced vomiting and diarrhea.
Unlike with regular flu, humans don’t have natural immunity to a virus that includes animal genes.
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. New vaccines can take months to bring into use.