Mexico shut down schools, museums, libraries and state-run theaters across its overcrowded capital Friday in hopes of containing a swine flu outbreak that authorities say killed at least 20 people — and perhaps dozens more. World health authorities worried openly that the strange new virus could become a global epidemic.
The U.S. Centers for Disease Control and Prevention said tests show some of the Mexico victims died from the same new strain of swine flu that sickened eight people in Texas and California. Of the 14 samples tested from Mexico, seven were matches, said the CDC's acting director Dr. Richard Besser.
Mexico put the confirmed toll at 20 dead, but 40 other fatalities were being probed, and at least 943 nationwide were sick from the suspected flu, the health department said.Scientists said the virus combines genetic material from pigs, birds and humans in a way researchers have not seen before.
“We are very, very concerned,” World Health Organization spokesman Thomas Abraham said.
“We have what appears to be a novel virus and it has spread from human to human,” he said. “It’s all hands on deck at the moment.”
President Felipe Calderon cancelled a trip and met with his Cabinet to coordinate Mexico’s response. The government planned to administer its remaining 500,000 vaccines from the flu season to health workers, the highest risk group, although it is not known how effective they are on swine flu. It said it also has enough oseltamivir, the generic name of Tamiflu, to treat 1 million people, but the medicine will be strictly controlled and handed out only by doctors.
The CDC says Tamiflu and Relenza do seem effective against the new strain. Roche, the maker of Tamiflu, said the company is prepared to immediately deploy a stockpile of the drug if requested. Both drugs must be taken early, within a few days of the onset of symptoms, to be most effective.
Authorities urged people to avoid hospitals unless they had a medical emergency, since hospitals are centers of infection.
They also said Mexicans should refrain from customary greetings such as shaking hands or kissing cheeks, and authorities at Mexico City’s international airport were questioning passengers to try to prevent anybody with possible influenza from boarding airplanes and spreading the disease.
But the CDC said Americans need not avoid traveling to Mexico, as long as they take the usual precautions, such as frequent handwashing.
“We certainly have 60 deaths that we can’t be sure are from the same virus, but it is probable,” said Health Secretary Jose Cordova. He called it a “new, different strain ... that originally came from pigs.”
Epidemiologists are particularly concerned because the only people killed so far were normally less-vulnerable young people and adults. It’s possible that more vulnerable populations — infants and the aged — had been vaccinated against other strains, and that those vaccines may be providing some protection.
All eight U.S. patients recovered from symptoms that were like those of the regular flu, mostly involving fever, cough and sore throat, though some of them also experienced vomiting and diarrhea.
Scientists have long been concerned that a new flu virus could launch a pandemic, a worldwide spread of a killer disease. A new virus could evolve when different flu viruses infect a pig, a person or a bird, mingling their genetic material. The resulting hybrid could spread quickly because people would have no natural defenses against it.