Homeland Security Secretary Janet Napolitano, press secretary Robert Gibbs, center, and Richard Besser, acting director, U.S. Centers for Disease Control and Prevention, outline the government’s swine flu response at a White House briefing. Photo by Alexis C. Glenn/UPI/Landov

President Obama Tuesday sent a letter to Congress asking for $1.5 billion to fight the swine flu outbreak, a request he said he was making “out of an abundance of caution,”  as U.S. officials confirmed 64 cases of swine flu, including five individuals who had to be hospitalized.

In the letter, the president suggested adding to U.S. stockpiles of antiviral medicines and assisting international efforts to stem the outbreak.

Meanwhile, Gov. Arnold Schwarzenegger declared a “state of emergency” in California, a move that will allow the state to beef up its Department of Public Health. State officials say they have confirmed 13 cases of swine flu and are investigating two deaths that may be linked to the illness. No fatalities have been confirmed in the United States so far in cases in New York, Texas, Kansas and Ohio.

The United States is acting swiftly to "stay ahead" of the swine flu, Richard Besser, M.D., acting director of the Centers for Disease Control and Prevention said at a Tuesday press conference. Besser said of the five people hospitalized, three were in California and two in Texas. They ranged in age from 7 to 54.

In Mexico, where the outbreak is centered, more than 1,900 people are believed to have contracted the flu virus, and the death toll there has climbed to 152, Mexican officials said. The government there has canceled school, banned large gatherings of people for sporting events and recommended that Mexicans wear surgical masks outdoors.

"What we see in the United States is milder, less severe, than what had been reported out of Mexico," Besser said.

But he predicted that there will be deaths in the United States from swine flu. "I expect we will see deaths in this country," from the flu Besser said. The swine flu is apparently spreading from person-to-person as other influenza strains do.

Still, U.S. officials sought to reassure the public about the outbreak, while warning people to take precautions. The CDC recommends that people stay home if they feel sick and have coughing, fever, headaches and body aches. Officials say to check with a doctor if the symptoms don’t improve in a day or two. Antiviral drugs Tamiflu and Retenza can be given to those who need them, the agency says.

Homeland Security Secretary Janet Napolitano, making the rounds of television news shows, said the government is prepared to take more drastic measures, but for now monitoring people coming in at the borders for sickness and recommending normal hygiene procedures is enough.

"We think that what we're doing now at the land ports and airports makes sense," she said, adding that the government would have to look at the cost of more draconian measures.  She added that the usefulness of such measures would be "marginal" in containing the virus.

She also said that the United States will not wait for a World Health Organization declaration of a pandemic to respond. The WHO lifted the pandemic threat status worldwide to a level 4 on a 6-figure scale, as more cases were discovered around the world. That figure means the flu is spreading within communities.

Napolitano said earlier that the U.S. government has freed up and can distribute 12.5 million doses of antiviral drugs.

WHO officials say the picture of the disease is just now evolving. It is hard to predict the course the swine flu virus will take over the next few weeks, experts say, because they are not even certain at this stage whether the infection is mild or serious. “If this were something other than swine flu, it might not even have made the news,” says Gabor Kelen, M.D., director of the Johns Hopkins University Office of Critical Event Preparedness and Response. “On the other hand, some epidemics have started with sort of mild versions.”

The CDC’s guidelines for preventing swine flu are similar to those for preventing other strains of flu. The U.S. flu season runs from fall through the winter months and scientists here are already at work on next winter’s flu vaccine, which could be modified to protect against the swine flu strain if necessary, officials say.

While flu usually poses the greatest threat to infants, older people and those with compromised immune systems, most of the illnesses linked to swine flu have been among young adults, both here and in Mexico.

Swine flu cases have been reported in Canada, Brazil, New Zealand, France, Israel and Scotland, and some nations have issued travel warnings for Mexico and the United States.

Some U.S. airlines are waiving “change fees” for ticket holders who want to change their reservations to Mexico because of the flu outbreak. Those fees typically total around $125.

Elaine S. Povich writes about health and political issues.