By Steven Reinberg
TUESDAY, April 28 (HealthDay News) -- The number of confirmed cases of swine flu in the United States has doubled to 40, U.S. health officials said Monday, with all the new cases coming from a New York City high school that had previously reported eight cases of the infectious disease.
Some news reports Tuesday were listing the number of U.S. cases at 50, but the World Health Organization was still reporting 40 confirmed cases.
The Associated Press reported Tuesday that the epidemic had crossed new borders, with the first cases confirmed in the Middle East and the Asia-Pacific region. Meanwhile, the number of deaths in Mexico -- thought to be the source of the outbreak that continues to reach around the world -- surpassed 150. Mexico is the only country to report deaths caused by the never-before-seen strain of flu. Cases in all other countries have been described as mild.
Despite the reports out of Mexico, there was a glimmer of good news. The number of new swine flu cases reported by Mexico's largest government hospitals has been declining the past three days, government officials said, from 141 on Saturday to 119 on Sunday and 110 Monday, the AP reported.
Still, on Monday, U.S. officials said they were tightening their travel advisory to Mexico, recommending that all nonessential travel to that country be avoided.
And late Monday, the World Health Organization raised the alert level over swine flu from 3 to 4, two levels shy of declaring a pandemic. A level 4 alert means there is sustained human-to-human transmission of the virus causing outbreaks in at least one country.
"This situation is evolving very quickly, it is changing quickly," Dr. Richard Besser, acting director of the U.S. Centers for Disease Control and Prevention, said during a Monday afternoon teleconference. "We are officially reporting 40 confirmed cases in the United States. The only change from yesterday is 20 confirmed cases in New York City. These are associated with the same school outbreak and really represent additional testing in that group and not an ongoing spread."
All 40 U.S. patients -- 28 in New York, seven in California, two in Texas, two in Kansas and one in Ohio -- have either recovered or had mild infections, Besser said.
"Later today, we will be releasing a new travel advisory for Mexico," he added. "This is out of an abundance of caution, and we will be recommending that nonessential travel to Mexico be avoided."
Mexico on Monday was reporting as many as 1,900 possible swine flu infections and as many as 149 deaths.
Earlier Monday, President Barack Obama said the threat posed by the swine flu outbreak was a cause for concern but "not a cause for alarm."
"The Department of Health and Human Services has declared a public health emergency as a precautionary tool to ensure that we have the resources we need at our disposal to respond quickly and effectively," Obama told a gathering of scientists at the National Academy of Sciences, amid increasing worries worldwide about a possible pandemic.
Besser said that he "expects that we will see [swine flu] cases in other parts of the country, and I would fully expect that we will see a broader range in terms of the severity of infection. Thankfully, so far we have not seen severe disease in this country as has been reported in Mexico."
Besser said the United States will step up checks of people entering the country by air, land and sea, looking for signs of infection, and the CDC will begin distributing "yellow cards at ports of entry."
"These will provide information on swine flu, so that people coming into the United States will have information about this outbreak -- what to do if they become sick, what things they can do to prevent the likelihood that they will become sick," he said.
He also said U.S. officials were questioning border visitors about their health, looking for signs of possible infection.
The fast-unfolding events in the United States -- where all 40 cases have been relatively mild and there have been no deaths -- came in response to some 1,900 swine flu infections and as many as 149 deaths in neighboring Mexico.