A total of 160 human A/H1N1 cases have been confirmed in 21 U.S. states, the U.S. Centers for Disease Control and Prevention (CDC) said Saturday.

The only person that has so far died of the H1N1 flu virus is a Mexican toddler who was visiting relatives in Texas, said Anne Schuchat, the CDC's interim deputy director for science and public health programs.

Most U.S. cases of the new flu strain have been mild with New York having the highest tally of 50 which has remained the same for several days and about one-third of the confirmed cases are people who had been to Mexico, according to the official. That suggests a substantial portion of the U.S. cases may have picked up the infection in Mexico. Thirteen patients of the confirmed cases were hospitalized.

Although there are reports that the outbreak in Mexico may be stabilizing, Schuchat warned that "We can't afford to let down our vigilance."

"We have information that this novel virus continues to spread with increasing cases and increasing states affected. And we are acting, as President Obama said this morning, actively and aggressively," she told a news conference.

"I will not be surprised if we find additional cases or additional deaths," she said.

U.S. President Barack Obama outlined the "quick and aggressive" steps on Saturday for the federal government to take to respond to the A/H1N1 flu virus that has left more than 140 cases in the country.

"Unlike the various strains of animal flu that have emerged in the past, it's a flu that is spreading from human to human," Obama said in his weekly address. "This creates the potential for a pandemic, which is why we are acting quickly and aggressively."

Although the strain has not been as potent or as deadly in the United States, Obama warned that the country still has to take all necessary precautions in case the virus turn into "something worse. "

As part of precautions, the CDC has recommend that schools and child care facilities with confirmed cases of the virus close for up to 14 days, and employers are also urged to do the same.

The president also urged parents and businesses to think about contingency plans if children have to stay home.

"We have asked every American to take the same steps you would take to prevent any other flu: keep your hands washed, cover your mouth when you cough, stay home from work if you're sick, and keep your children home from school if they're sick," he said.

The White House has launched pages in social network like Facebook, MySpace and Twitter to support the ongoing efforts to update the public as quickly and effectively as possible, he added.

On the other hand, the Unite States will continue to invest in "every resource" necessary to treat the virus and prevent a wider outbreak.

"It is my greatest hope and prayer that all of these precautions and preparations prove unnecessary," the president said. "I would sooner take action now than hesitate and face graver consequences later."

(Xinhua News Agency May 3, 2009)