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Mexico's official swine flu count went up over the weekend to nearly 600 confirmed cases and more than 20 deaths. Still, that's fewer deaths than many health experts feared just a few days ago. The new flu virus has so far spread to around 20 countries, and there is a new concern that humans might start passing the virus on to pigs.
NPR's Richard Knox has more on why top officials expect a flu pandemic of some sort is upon us.
RICHARD KNOX: Yesterday on CBS's "Face the Nation," Janet Napolitano, the secretary of Homeland Security said it straight out: A pandemic has begun. The World Health Organization hasn't declared it yet. In the past week, the WHO pushed up the needle on its flu pandemic alert meter from 3, to 4, to 5. Five means a pandemic is imminent. Napolitano says people need to understand what that means.
Secretary JANET NAPOLITANO (Department of Homeland Security): When the World Health Organization goes from 3 to 4, or 4 to 5 and so forth, that doesn't associate with the severity of the disease. What it means is how widespread it is. So when you talk about level 6 - which they very well could go to this week - all that means is it's widespread throughout the world.
KNOX: Indeed, it is. It's a textbook case of how a new flu virus can spread all over the globe in the jet age. What's happening in Spain might trigger the declaration of a pandemic. Cases there now number 40. Thirty-eight of them involve people who apparently got the virus in Mexico, but the other two raise the question of whether it's spreading in Europe as it is in North America. In the daily update from the Centers for Disease Control and Prevention, Dr. Anne Schuchat says the virus has probably found its way to every corner of the United States.
Dr. ANNE SCHUCHAT (Center for Disease Control and Prevention): When I say that this virus is widespread, I mean that it is in many places, that virtually all of the United States probably has this virus circulating now. That doesn't mean that everybody's infected, but within the communities, the virus has arrived.
KNOX: Schuchat doesn't share Mexican officials optimism that a corner has been turned on swine flu.
Dr. SCHUCHAT: The time course here in the United States is later. We believe we're just on the upswing here and that in several parts of Mexico, cases began quite a while ago, several weeks ago. From what I know about influenza, I do expect more cases, more severe cases and I do expect more deaths.
KNOX: The severity of this new disease is the biggest unknown. At least 30 Americans are hospitalized with severe cases of the new flu, which officials call H1N1 of 2009. That's a small number compared to the hundreds of thousands hospitalized by regular flu. But, Schuchat says…
Dr. SCHUCHAT: One important difference between what we're seeing in hospitalizations here in the U.S. so far is that, in general, they're not in the age groups that typically are hospitalized for seasonal flu.
KNOX: Seasonal flu mostly puts infants and elderly people into the hospital, not young adults. Still, the other 200 or so cases are mild, says Dr. Marc Lipsitch of the Harvard School of Public Health.
Dr. MARC LIPSITCH (Epidemiology, Harvard School of Public Health): That's certainly good news for suggesting that severity is lower than it might have appeared. We still don't know for sure where it falls out in terms of comparisons to seasonal flu or prior pandemics.
KNOX: Experts are disturbed about something that happened recently in Alberta, Canada. A worker at a pig farm came back from a Mexican trip, and suddenly 220 pigs caught the flu, apparently from the human. Tests on some pigs reveal the same virus that's been infecting humans. Scientists say the virus originated in swine. Joan Nichols is an expert on swine flu viruses at the University of Texas in Galveston. She says the Canadian episode is alarming to animal health people.
Professor JOAN NICHOLS (Internal Medicine, University of Texas): They're going to really move to a higher level overall.
KNOX: What does that mean? What would they be saying, you suspect?
Prof. NICHOLS: Evaluating whether or not we're seeing more in pigs and then more careful precautions for people who work around pigs, to make sure they don't transfer the virus to the pigs as they work with them, nor do we transmit back again from the pigs back to people.
KNOX: That's not just a problem for pig farmers. Because pigs can get infected with both animal and human flu viruses, they create ideal conditions for mixing up viral genes. Nichol says once these viruses starts circulating, they usually become more easily transmitted over time. But nobody knows whether they also become nastier. Not much is known, she says, about the genes that do that in human flu viruses.
Richard Knox, NPR News. Transcript provided by NPR, Copyright NPR.
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