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Worry grows about swine flu

By Laura Elder — April 29, 2009

As the number of confirmed U.S. swine flu cases continued to rise Tuesday, epidemiologists and health organizations worked to quell the spread of panic but were troubled by similarities between this outbreak and deadly influenza epidemics of the past.

The Galveston County Health District had no reports of anyone locally contracting swine flu, which is suspected of killing more than 150 people in Mexico and infecting at least 64 U.S. residents.

But U.S. deaths from swine flu were likely, federal officials said. One newspaper was reporting two people who died in Southern California had swine flu symptoms.

While urging calm, researchers at the University of Texas Medical Branch's Galveston National Laboratory joined the World Health Organization in noting this swine flu outbreak had similarities to the 1918 influenza epidemic that killed 50 million people worldwide.

Meanwhile, Carnival Cruise Lines, with two ships that sail from the island, announced it had suspended until May 4 stops at Mexican ports over concerns about the virus. The cruise line, which had no reported cases of swine flu, had not canceled cruises and would adjust itineraries and attempt to call at alternative ports, official said.

Most of the cases in Mexico have been in Mexico City, not port cities. Still, the hundreds of people who visit Mexico on cruise ships and return to Galveston was a potential issue, some researchers said.

'We Should Be Concerned'
Experts were unwilling to make predictions about a widespread outbreak in Texas or locally of a virus strain no one had seen before and for which there are no known vaccines.

Flu outbreaks are difficult to predict, said Dr. James LeDuc, who last year left the U.S. Centers for Disease Control and Prevention to become director of the Program on Global Health at the medical branch's Institute for Human Infections and Immunity.

But government and health agencies should be ready, he said.

"I think we should be prepared for it," LeDuc said. "But I certainly wouldn't want to predict it; the situation is such that we should be concerned."

What's so troubling about swine flu, a respiratory disease caused by influenza Type A, which until now had typically infected pigs, is that it's new, easily transmitted between humans and no one has immunity, LeDuc said.

LeDuc and other authorities on emerging diseases also are concerned about the number of serious illnesses and deaths in Mexico, where officials have closed schools and other public gathering places.

While LeDuc and other epidemiologists said they don't yet have enough information about the people who died from the flu, they worry about initial reports the virus had killed healthy people, not just typical vulnerable populations of the very young, elderly and people with compromised immune systems.

Such were the characteristics of the 1918 flu, also known as the Spanish flu, which killed 675,000 in the United States and more than 50 million worldwide. To put those deaths in perspective, the influenza virus kills about 36,000 people in a normal year.

But unlike in 1918, health and governmental officials have been preparing for a flu pandemic for years by stockpiling antiviral drugs to manage outbreaks, LeDuc said.

Gov. Rick Perry on Saturday asked the Centers for Disease Control and Prevention for 37,430 courses of antiviral medications from the Strategic National Stockpile as a precaution after several cases of swine flu were confirmed in Texas, according to reports.

No Need For Panic
While there are similarities between this swine flu outbreak and the 1918 Spanish flu pandemic, there's no reason to panic, said Joan Nichols, associate director of research at the medical branch's newly opened Galveston National Laboratory, a biodefense laboratory where researchers will develop drugs and vaccines to battle infectious diseases.

Far from being widespread in the United States, swine flu outbreaks are occurring in small clusters and the spread is tightly localized, Nichols said.

The swine flu virus isn't necessarily targeting people with healthy immune systems, Nichols said. The common denominator among most of the people around the world who have been infected is that they had traveled to Mexico, Nichols said.

And most people infected in the United States are showing only mild symptoms, Nichols said.

"Confirmed cases outside of Mexico have not caused serious disease," Nichols said.

It's too early to tell whether the swine flu would spread quickly and how virulent it might be, said Lauren Ancel Meyers, an associate professor and evolutionary biologist at the University of Texas at Austin. Meyers is working with members of the National Institutes of Health's Models of Infectious Disease Agent Study to better understand swine flu.

Still, based on preliminary data, the world is a much better position to deal with swine flu than it was the pandemic of 1918, Meyers said.

"The rate of the spread outside Mexico is not explosive so we may have time on our side," Meyers said. Should it become a pandemic in late summer or fall, researchers would have enough time to develop and distribute a vaccine, she said.

The 1918 flu began as a mild pandemic, but by the fall had become one of the most severe infectious disease episodes ever recorded, said Keiji Fukuda, an assistant director-general of the World Health Organization, according to Reuters news service.

"We may have to time to ramp up an effective response," Meyers said. "I would expect in a few days we'll have a better idea how virulent and deadly it is."

Researchers at the Galveston National Laboratory will be able to test some experimental vaccines against swine flu once they obtain a sample of the strain, LeDuc said.

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