With the number of confirmed U.S. swine flu cases double the 20 it was yesterday, the government says that it is closely monitoring the swine flu outbreak and is preparing for further spread.

"This is obviously the cause for concern and requires a heightened state of alert, but it's not a cause for alarm," President Obama said today at the National Academy of Sciences (NAS).

In the U.S., 40 cases have been confirmed by the U.S. Centers for Disease Control and Prevention (CDC) in five different states: New York, California, Texas, Ohio and Kansas. All individuals have recovered, including the one that was hospitalized, Richard Besser, acting director of the CDC, said in a press conference today. Twenty of the cases have stemmed from a New York City preparatory school. Although that's more than twice the number originally reported, the additional cases were a result of further testing rather than continued spread of the flu, Besser noted. The CDC is distributing kits to test for swine flu in affected states, and as testing ramps up, Besser said, "I expect we will see other cases across the country."

New cases are being reported in Canada and across the Atlantic, according to a report by the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota. As of April 26, six confirmed cases of swine flu in Canada and one in Israel had been reported. An informal map of cases worldwide is being collected by a biomedical researcher in Pittsburgh.

Meanwhile, the European Union has issued a travel warning to citizens, urging them to avoid nonessential travel to the U.S. or Mexico, reports The New York Times. The CDC will be distributing information cards at U.S. ports of entry to inform travelers about the flu's symptoms and precautions that should be taken to avoid it. Later today, the CDC will also issue a travel advisory recommending that all nonessential travel to Mexico be avoided.

"This is a serious event, and we're taking it seriously," Besser said. "This situation is evolving very quickly," he said, and a clear picture of how the disease is spreading may not be available for another week or two. 

Although a vaccine for the flu strain, which is similar to those responsible for the 1918 and 1957 outbreaks, is likely months away, biotechnology companies are anxious to get to work, notes FierceBiotech, a biotech industry newsletter. The CDC is discussing whether to include strains of this flu in next year's flu vaccines.

By dubbing the outbreak a public health emergency yesterday, the government authorized states to release 25 percent of their antiviral drugs from the Strategic National Stockpile, which means that 11 million courses of the drugs are en route to the affected states, said Besser.

Although the drugs could help treat those infected with the virus, Besser noted that, "there's no single action that will control an outbreak… It starts with personal responsibility, but it doesn't end there." He recommended that people take standard precautions such as frequent hand washing, covering coughs and sneezes and staying home from work and school if feeling ill.

At the speech to the NSA, Obama concluded, "If there was ever a day that reminded us of our shared stake in science and research, it is today."

For more on swine flu and other influenza outbreaks, see our In-Depth Report.

Image courtesy of Laurel Fan via Flickr