RAY SUAREZ: The swine flu outbreak spread to more of the U.S. today. Health officials confirmed at least 93 cases and the first death on American soil.
That word came as an international health alert was raised higher still.
Health correspondent Betty Ann Bowser has our lead story report.
BETTY ANN BOWSER, NewsHour correspondent: The news was flashed this morning of a confirmed death in Texas. The victim was a toddler from Mexico who died Monday night at a Houston hospital.
Health officials said he traveled to Texas this month to visit family and was hospitalized a couple of weeks ago after falling ill.
DR. DAVID PERSSE, director, Houston Emergency Medical Services: Unfortunately, in spite of the best efforts, the child succumbed to the illness. And the CDC provided -- it was a laboratory confirmation, in which they announced this morning that the child did, in fact -- was, in fact, infected with the swine flu virus.
BETTY ANN BOWSER: And in Washington, President Obama took note of the child's passing.
U.S. PRESIDENT BARACK OBAMA: My thoughts and prayers and deepest condolences go out to the family, as well as those who are ill and recovering from this flu.
BETTY ANN BOWSER: A short time later, Texas called off all public high school athletic and academic events, at least until May 11th.
According to the Centers for Disease Control, at least 10 states, including Texas, have confirmed cases of swine flu. The others are New York, California, Kansas, Massachusetts, Michigan, Indiana, Ohio, Arizona, and Nevada.
And state officials in Maine also said they had confirmed cases, and several other states could join the list.
Some hospitals, like the Rose Medical Center here in Denver, have seen a spike in the number of people coming to the emergency room with flu-like symptoms. Just since Sunday, doctors have taken nasal swabs of more than 30 people and, when swine flu could not be ruled out in three of those cases, samples were sent to the CDC in Atlanta for testing.
One U.S. Marine was confirmed sick with the flu at Twentynine Palms Marine base in Southern California, and 30 other Marines were quarantined there.
To prevent further spread of the flu, the president today urged schools with confirmed or suspected cases to shut down temporarily.
BARACK OBAMA: If the situation becomes more serious and we have to take more extensive steps, then parents should also think about contingencies if schools in their areas do temporarily shut down, figuring out and planning what their childcare situation would be.
BETTY ANN BOWSER: And at a Senate hearing, Secretary of Homeland Security Janet Napolitano said the government was making ready for a worst-case-scenario.
JANET NAPOLITANO, secretary of Homeland Security: There is a lot we don't yet know about this outbreak, but we have been preparing as if we are facing a true pandemic, even though we don't know the ultimate scope of what will occur. We also have been preparing with the understanding that this will be a marathon and not a sprint. We're going to be at this for a while.
BETTY ANN BOWSER: Several lawmakers argued the administration should consider closing the border with Mexico, but Napolitano resisted that idea.
JANET NAPOLITANO: Making such a closure right now has not been merited by the facts, would have very, very little marginal benefit in terms of containing the actual outbreak of virus within our own country.
BETTY ANN BOWSER: Across the border, the mayor of Mexico City said the outbreak appeared to be stabilizing. There have been more than 150 deaths total, but only one since yesterday. He said he'd consider easing a citywide shutdown if that trend continues.
MAYOR MARCELO EBRARO, Mexico City (through translator): When we can confirm that the measures have achieved this objective and that the number of dead is decreasing, then we could pass from the maximum alert to the normal alert. We are following the international experience and the recommendation made by the World Health Organization.
BETTY ANN BOWSER: And in Egypt, the government ordered the slaughter of all 300,000 pigs in the country, despite repeated assurances the flu is not spread through consuming pork.
But the World Health Organization warned transmission from human to human is rising. It raised its alert status to level five, one stage below all-out pandemic.
MARGARET CHAN, director-general, WHO: WHO and health authorities in affected countries will not have all the answers immediately, but we will get them.
BETTY ANN BOWSER: The agency called for stepped-up action by governments and drug companies.
RAY SUAREZ: And for the latest on the outbreak and the government's efforts, we turn to the acting director of the Centers for Disease Control and Prevention, Dr. Richard Besser. He joins us from CDC headquarters in Atlanta.
Dr. Besser, welcome.
Just as you heard a few moments ago, we reported that the World Health Organization has raised its alert to the next-to-the-highest level. And here we are, in a world of 6 billion-plus people, a relative handful of cases outside of Mexico. Why does this situation require such a high level of alert?
DR. RICHARD BESSER, acting director, Centers for Disease Control: I was quite pleased to hear of the action taken recently by the World Health Organization.
Here in the United States, what we call this is not changing or will not change our approach. We have a very dynamic situation, and we're being very aggressive in our efforts to try and minimize the impact that this outbreak is having on people's health.
Today, we heard the very sad news of the child in Texas who passed away, and we know that influenza is a very serious infection. Each year, 36,000 people die in this country.
So as we move forward -- this is a new, emerging infectious disease; we don't know what the full picture will be -- we are taking bold and aggressive actions.
But if you look at the world as a whole, countries that have not been as fortunate in being able to plan as much as we have been planning over the past five years, this move to a level five, to phase five, is a wake-up call, to say this is a strain that appears to be spreading person to person.
It appears to be new and that people don't have immunity to this. It appears to cause disease, in Mexico, reported very significant disease, here quite a number of cases, but so far less severe disease.
This is a wake-up call to other countries that they have to be ready, they have to be planning and thinking about what they would do if this were introduced to their borders.
RAY SUAREZ: You used the phrase "wake-up call," and I'm wondering if this raising the alert level is more symbolic or, given the way viruses work, could we suddenly be awash in many more cases, now that there are people in many different locations who have been affected?
DR. RICHARD BESSER: Well, as you know, with global travel, this is a flat world. People are traveling all the time. Infectious agents don't respect borders. We've seen that with West Nile Virus and its introduction here. We saw that with the rapidity by which SARS spread around the world.
This is a world in which infections spread very quickly between countries. And so the fact that we see this in the United States, and Mexico sees this, and Canada sees this, and we're hearing reports and confirmed cases from European countries and other parts of the world, it's really telling us that it will be seen around the world, and countries have to be ready for that.
RAY SUAREZ: Earlier today, the secretary of homeland security rejected calls for closing the U.S.-Mexico border, but that's not just any border. It's one of the most busy land crossings on Planet Earth. She said the science doesn't support it. Why not?
DR. RICHARD BESSER: Well, if you look back to our planning for avian influenza, our initial approach was to -- that if an outbreak of a new strain of flu occurred outside our borders, we would work to join an international response, fly in there, try and quench that outbreak with antivirals and other measures, and hopefully prevent it from spreading around the world, prevent it from leaving that community.
That was phase one, or the initial approach to a potential pandemic. That no longer applies once you have an infectious agent that is within our country and in many other countries.
We've done a lot of modeling around what is the impact of border closing, border entry and exit screening. And what we have found is that, when you have an infection that is starting elsewhere, at quite a distance, by implementing stringent controls, you might be able to delay by a few weeks the entry into your own country.
And that, for many countries, might give them time to stand up and be ready. Here, we're in a situation where the initial detection was really here, and it was fortuitous. It was due to pandemic planning and development of a new test kit in San Diego that we identified the first strain of the 2009 H1N1 virus. That led to...
RAY SUAREZ: Let's talk a little bit more about that planning, if we could...
DR. RICHARD BESSER: Sure.
RAY SUAREZ: ... because several health authorities have cited the outbreaks of SARS and avian influenza as testing, as creating skills around the world and creating coordination. What did those outbreaks do that got us ready to handle this with an international response?
DR. RICHARD BESSER: Well, there have been incredible efforts in this country and around the world to plan for a pandemic. We had been very acutely aware that it had been a while since the last pandemic. We know that pandemics occur, because influenza viruses change over time.
And so there were enormous efforts underway. We were very concerned, and we still keep our eye on the H5N1 avian strain that's circulating.
There was tremendous work in Congress to promote preparedness for pandemic flu and, in this country, efforts in every state, at every level to build public health infrastructure, to look at how we respond within the government, how we coordinate, and we've been exercising and drilling for many years in -- for the eventuality of the next pandemic.
RAY SUAREZ: Now that we're a couple of weeks into this outbreak and scientists have had a chance to isolate that H1N1 virus that's making people sick right now, do we know anything more about it, how it sickens people, whether it's mutating? What you can tell us about what scientists have been able to figure out so far?
DR. RICHARD BESSER: Well, there are still a lot of unanswered questions. I think we're on day 11 right now. But there are a lot of people working on addressing the questions you just raised.
Some things we know, the virus that we identified here appears to be the same virus in every aspect that we've looked so far, as the Mexican virus.
There are questions that need to be answered. Does the virus change as it goes from person to person? Does it become more virulent, more severe, less severe, or not change at all? That's going to be a very important question as we look at control measures that we would like to implement.
We've looked at it in terms of resistance, and we know that the virus is susceptible to two of the antiviral agents, the oseltamivir and zanamivir. We know it's resistant to another class of antivirals.
But, thankfully, it is susceptible and can be treated by the primary antiviral that we have stockpiled in this country.
RAY SUAREZ: Let's talk a little bit about flu specifically. Scientists referred to it today as a "promiscuous virus," that it picks up genetic material easily. Does the fact that humans have caught it from somewhere else mean that the virus, in such a short time, has already changed, because now humans have it?
DR. RICHARD BESSER: Well, viruses do change very readily. And by nature, flu viruses change. Each season, we have to formulate a new flu vaccine for that very reason. We tend to see a drift in the components that are circulating in the community, and that requires a new vaccine.
What we see here is a virus that is a re-assortment of, really, four components. It has a human component. It has avian components. It has a domestic swine component and a swine component from Eurasia.
Those have reformulated into a virus that appears to transmit readily from person to person, and that has the makings of a virus that could cause a pandemic.
RAY SUAREZ: The acting director of the Centers for Disease Control and Prevention, Dr. Richard Besser, thanks for joining us.
DR. RICHARD BESSER: Thank you very much.