At Least 20 Dead, Hundreds Ill in Swine Flu Outbreak in Mexico

April 24 -- FRIDAY, April 24 (HealthDay News) -- Mexican officials took extraordinary steps Friday to try to contain a swine flu outbreak that has killed as many as 20 people, and possibly dozens more, and sickened more than 900 other people in recent weeks.

World Health Organization officials worried that it could mark the start of a flu pandemic, according to published reports, although several infectious disease experts in the United States said that was unlikely.

Officials from the U.S. Centers for Disease Control and Prevention said Friday that tests showed some of the Mexico victims died from the same new strain of swine flu that sickened eight people in Texas and California. It's a worrisome new strain that combines genetic material from pigs, birds and humans. All eight U.S. patients have recovered.

The World Health Organization said that at least 57 people have died in the outbreak in Mexico, but it wasn't yet clear if this larger number of deaths was due to swine flu, the Associated Press reported.

"The United States government is working with the World Health Organization and other international partners to assure early detection and warning and to respond as rapidly as possible to this threat," Dr. Richard Besser, acting director of the CDC, said during a Friday afternoon press briefing.

"We do not know if this swine flu virus or some other influenza virus will lead to the next pandemic," he added. "However, scientists around the world continue to monitor the virus and take its threat seriously."

Thomas Abraham, a spokesman for the World Health Organization, said, "We have what appears to be a novel virus and it has spread from human to human." If international spread is confirmed, that meets WHO's criteria for raising the pandemic alert level, he added.

Besser said the CDC has issued an outbreak notice for travelers to central Mexico and Mexico City, alerting people to the flu outbreak. "At this time there are no recommendations for U.S. travelers to change, restrict or alter their travel plans to Texas, California or Mexico," he said.

In response to the outbreak, Mexico City closed schools -- from kindergartens to the university level -- as well as museums, libraries, and state-run theaters across the metropolis of 20 million people on Friday, and urged people with flu symptoms to stay home from work, according to published reports.