Swine Flu: 'Encouraging Signs' But 'We Cannot Lower Our Guard'

May 3, 2009— -- The top U.S. public health official said today there are encouraging signs that the swine flu virus seen in this country will be less deadly than previous flu strains -- but nevertheless, the number of cases of the H1N1 flu virus continues to grow around the globe.

The Centers for Disease Control and Prevention officially confirmed 226 cases in 30 states this morning, but during the day, North Carolina, Pennsylvania, Oregon and Louisiana joined the list for a total of 34 states and 245 cases.

Globally, officials in 19 countries have confirmed at least 917 cases -- slightly more than the 898 in 18 countries confirmed by the World Health Organization.

Officials in Mexico said there have been more than 500 confirmed cases of the disease and reported three swine flu deaths late Saturday, bringing the death toll in that country, believed to be the epicenter of the outbreak, to 19. In the United States, the virus claimed the life of a toddler in Texas last month.

Mexico's Health Minister Jose Angel Cordova said today that "the evolution of the epidemic is now in its phase of descent," but officials in the United States and at the World Health Organization in Geneva said that the world must remain vigilant.

WHO epidemic and pandemic diseases spokesman Gregory Hartl said today that though the current epidemiology in Mexico might show a slowdown, history must be considered when evaluating the virus' potential to come back.

"I also would like to remind people that in 1918, the Spanish flu showed a surge in the spring and then disappeared in the summer months only to return in the autumn of 1918 with a vengeance, and we know that killed eventually 40 to 50 million people," Hartl said. "So I think while tracing these kind of curves of activity, increasing, decreasing activity, we cannot lower our guard."

On "This Week," acting CDC director Dr. Richard Besser said that "we're seeing encouraging signs" that H1N1 is less virulent than past strains.

As for the CDC's analysis if the H1N1 virus, Besser said, "what we've found is that we're not seeing the factors that were associated with the 1918 pandemic, we're not seeing the factors that are, were associated with other H1N1 viruses, and that's encouraging."

But though officials are cautiously optimistic, whether the virus will reemerge when the typical flu season starts in the fall is still unclear.

"Every virus is new," Besser cautioned. "And what it will do is different. And so you're hitting a critical point: What will happen this spring and summer?"

He reiterated that the virus is spreading "quite easily," and that he expects to see reports of more confirmed cases in this country.