WASHINGTON, May 8 (Xinhua) -- The United States has 1,639 confirmed human A/H1N1 cases in 43 states, including two deaths, overtaking Mexico as the country having the most confirmed cases in the world, the U.S. Centers for Disease Control and Prevention (CDC) said Friday.
The update registered a sharp increase from the case count on Thursday when confirmed cases were 896.
The CDC said because there is a backlog of likely cases that need to be confirmed through extra testing, the number of cases may jump quickly day to day as more suspected cases are confirmed.
However, the jump "does not reflect a speed-up of the epidemic," said Dave Daigle, a spokesman for the CDC. The official said as more places were now able to test for the virus, "we do expect to see the numbers climbing."
About 3.5 percent of the cases have been sick enough to be admitted to hospitals and health officials said the rate will continue to fall as more screening is done in the community.
According to the CDC, the state of Illinois has 392 confirmed cases of A/H1N1 flu, followed by 240 of Wisconsin, 174 of New York, 131 of Arizona and 107 of California.
Acting Director of the CDC Richard Besser has said they expect A/H1N1 flu to spread to all 50 states.
U.S. President Barack Obama on Friday urged Americans to take persistent precautions on A/H1N1 flu, even though he said the virus is not as virulent as first feared.
"I want to assure everybody that we're seeing that the virus may not have been as virulent as we at first feared," Obama told a town-hall meeting with members of Hispanic communities at the White House.
"But we're not out of the woods yet. We still have to take precautions," he said.
The president said that the CDC recommends Americans to keep taking precautions.
"We may have to prepare for an even worse flu season sometime in the fall," he cautioned.
Obama also said the flu provides a chance for Americans to hold even closer together.
"We're one country, we're one community. And when we help to make everybody well, one person well, then everybody has the potential to get well. We can't be divided by communities," he said.
The president also pledged to provide people all over the country with information on flu, saying that "government at every level has to make sure that good information is getting out to every part of the broader American community."
Obama noted that "one of the things that we have to understand is public health issues like this -- not only is it important for all communities within the United States to be working together, it's also important to be working internationally together."
The president said that A/H1N1 flu has hit Mexico much more badly than it has hit the United States, and he's been working very closely with the Mexican government on this issue.
"I spoke to (Mexican) President Calderon last weekend to ensure that we were providing Mexico with the assistance that it needed," he said.
Obama made the remarks during a brief surprise appearance at the event for the Hispanic community on the virus, which was conducted mostly in Spanish.
With the rapid growth of confirmed cases, U.S. citizens begin to change their behavior, a study released Friday showed.
According to a study by the Harvard School of Public Health, two-thirds people reported they or someone in their household have washed their hands or used hand sanitizer more frequently because of the outbreak. About 55 percent had made plans to stay home with children or work from home if they became sick, if school closed or if a family member got sick.
About one in 10 Americans have stopped hugging and kissing close friends or relatives because of concerns about swine flu. About the same number have stopped shaking hands, said the study.
"This outbreak has permeated a lot of American life," said Robert Blendon, the Harvard School of Public Health researcher who led the study based on a survey on 1,000 U.S. adults.
On Tuesday, the Texas Department of State Health Services said a woman, who died earlier this week, has been the first death of a United States resident with A/H1N1 flu.
On April 29, the CDC said a 23-month-old toddler in Texas became the first fatality from A/H1N1 flu in the United States . The child was a Mexican who had traveled to Texas for medical treatment. He was also the first person to have died of A/H1N1 flu outside of Mexico .