(c) 2009, Los Angeles Times
MEXICO CITY -- An outbreak of swine flu that may have killed up to 60 people prompted authorities Friday to close schools throughout this sprawling city of 20 million people and order emergency health measures in an attempt to contain the disease.
Meanwhile, U.S. officials said they had found one new case in San Diego, bringing the total number of cases in the United States to eight. All have recovered fully. In Geneva, the World Health Organization said the strain in Mexico was identical to the one that has shown up in California and Texas. In Mexico City, nervous parents, some wearing surgical masks and carrying toddlers, formed long lines at clinics Friday morning. They were full of questions, about symptoms, how they can stay home from work to care for the sick, where to obtain the medicines.
"We are monitoring the evolution of the epidemic and, so far, it is under control," national Health Secretary Jose Angel Cordova said Friday. He said the rate of deaths is slowing and there are no plans to close the country's borders because of the outbreak.
Of the deaths believed linked to the outbreak, he said, 20 have been confirmed as being caused by swine flu; 40 are being investigated. A total of 1,004 people are reported to be ill with flu symptoms, including a high fever, severe headache and persistent cough, Cordova said.
International health officials said they were considering whether to raise the alert for a possible pandemic or global outbreak.
But researchers at the U.S. Centers for Disease Control and Prevention have so far found no links among the U.S. victims or any common behaviors, acting director Dr. Richard Besser said Friday in a telephone news conference. That suggests "there has been transmission through several cycles" -- meaning several intermediaries passed it among themselves before the virus reached the identified victims.
If that is the case, Besser added, many people have already been exposed to the virus and it is too late to contain a potential outbreak in the United States. The good news is that none of the intermediaries appear to have developed serious illness, suggesting that the disease is not especially virulent.
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None of the American victims has had any contact with pigs, and only one has traveled to Mexico recently, he said. Six of the eight U.S. cases were in San Diego and Imperial counties in California and two in Texas' Guadeloupe County.
"It's really critically important we learn what is happening in Mexico," Besser said. "Sorting out which of the cases are caused by swine flu is an important public health question. ... There is much uncertainty, more than anyone would like."
The CDC has been testing samples from Mexico and found that half of 14 samples proved positive for swine flu with "similarity" to the strain that appeared in the United States, he said. "It's safe to say it's the same virus, from what we know."
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Investigators are analyzing why the disease is so much more severe in Mexico, Besser said, adding that a CDC team would travel to Mexico.
U.S. health experts noted, meanwhile, that deaths from influenza are common. In an average year in the United States, about 35,000 people die of the flu, and in bad years nearly twice that number. Such deaths are most often among the very young and the elderly.
Cordova, the Mexican health secretary, said the virus was "different" because it wasn't striking the most vulnerable populations, but young adults and people who were otherwise healthy. That is potentially alarming because the 1918 influenza epidemic also struck the young and healthy.
"We have confirmation that this is a mutant of a virus that comes from pigs that ... never had provoked an epidemic, that is, had never spread among humans," Cordova said.
The new swine virus is unlike any that researchers have seen. It appears to be a combination of segments from four viruses from three continents, including a human segment, an avian segment and pig segments.
Government officials took the rare step of a national synchronized television broadcast late Thursday night to order parents to keep children home from school in Mexico City and the surrounding State of Mexico. It was possible that schools will remain closed next week, officials said, adding they were examining whether it would be necessary to shut down businesses and offices as well as a precaution.
Museums, theaters and movie houses will be closed for the weekend, and Mexico City Mayor Marcelo Ebrard also canceled all public events, including concerts and sports matches.
Most of the flu cases have been reported in Mexico City, but a small number of cases have appeared in six other states, the government said.
By closing schools in Mexico City and the State of Mexico, nearly 7 million students -- from pre-school through university -- had the day free from classes. The Mexican press said it was the first general closure of schools since the 1985 earthquake that leveled parts of the capital and killed 10,000 people.
^Wilkinson reported from Mexico City, and Maugh from Los Angeles. Times staff writer Julian E. Barnes in Washington contributed to this report.