WASHINGTON — Confirming at least 40 cases of swine flu in the U.S., the Obama administration said Monday it was responding aggressively as if the outbreak would spread into a full pandemic. Officials urged Americans against most travel to Mexico as the virus that began there spread to the United States and beyond.
Of the 40 U.S. cases, only one person has been hospitalized and all have recovered, said Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention.
NEW YORK — Twenty-eight people connected to a private New York City high school have confirmed cases of swine flu, and 17 more probably have it, Mayor Michael Bloomberg said Monday as officials tried to assure residents that the situation was far less serious than Mexico's deadly outbreak.
Nearly all of the students are feeling better, and the one or two who aren't are feeling the same, Health Commissioner Thomas Frieden said.
St. Francis officials learned that something was wrong there on Thursday when students started lining up at the nurse's office complaining of fever, nausea, sore throats and achy bones.
Some of the infected students said they had recently returned from a spring break trip to Mexico. Frieden said most of the students who had become ill had not traveled recently, meaning most had passed on the infection within their community.
Bloomberg said the St. Francis infection doesn't appear to match the flu strain in Mexico.
President Barack Obama urged calm, saying there was reason for concern but not yet "a cause for alarm."
Yet just in case, administration officials said that they were already waging a vigorous campaign of prevention, unsure of the outbreak's severity or where it would show up next.
U.S. customs officials began checking people entering U.S. territory. Millions of doses of flu-fighting medications from a federal stockpile were on their way to states, with priority given to the five already affected and to states along the Mexican border. Federal agencies were conferring with state and international governments.
"We want to make sure that we have equipment where it needs to be, people where they need to be and, most important, information shared at all levels," Janet Napolitano, head of the Homeland Security Department, told reporters.
Her briefing came shortly before the World Health Organization raised the severity of its pandemic alert level to four from three on a six-point scale. Level four means there is sustained human-to-human spread in at least one country. Level six is a full-fledged pandemic, an epidemic that has spread to a wide geographic area.
"We are proceeding as if we are preparatory to a full pandemic," Napolitano said.
She said travel warnings for trips to Mexico would remain in place as long as swine flu is detected.
Besser said that so far the disease in the United States has seemed less severe than the outbreak in Mexico, where more than 1,600 cases had been reported and where the suspected death toll had climbed to 149. No deaths had been reported in the U.S.
"I wouldn't be overly reassured by that," Besser told reporters at CDC's headquarters in Atlanta. He raised the possibility of more severe cases — and deaths — in the United States.
A European Union official warned against travel to parts of the U.S. as well as Mexico, but Besser said that seemed unwarranted.
State Department spokesman Robert A. Wood said the EU commissioner's remarks were his "personal opinion," not an official position, and thus the department had no comment. "We don't want people to panic at this point," Wood said.
Still Besser said of the situation, "We are taking it seriously and acting aggressively. ... Until the outbreak has progressed, you really don't know what it's going to do."
The U.S. stepped up checks of people entering the country by air, land and sea. Federal health officials can send someone to the hospital if they suspect a case, but no one was being refused entry.
The United States also issued a new travel advisory suggesting "nonessential travel to Mexico be avoided."
The confirmed cases announced on Monday were double the 20 earlier reported by the Centers for Disease Control. Besser said this was due to further testing — not further spreading of the virus — in a New York City school. Besser said other cases have been reported in Ohio, Kansas, Texas and California. Some schools in the affected areas have closed as a precaution.
The CDC reported 40 cases: 28 in New York, seven in California, two in Texas, two in Kansas and one in Ohio. Other information suggested three cases in Texas and eight in California, bringing the total to 42.
While there presently is no vaccine available to prevent the specific flu strain now being seen, there are anti-flu drugs that do work once someone is sick.
Countries across the globe increased their vigilance amid increasing worries about a worldwide pandemic. Obama told a gathering of scientists that his administration's Department of Health and Human Services had 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."
"This is obviously a cause for concern and requires a heightened state of alert, but it's not a cause for alarm," Obama said. He said he was getting regular updates.
Obama went to Mexico earlier this month, but the White House said Monday the president has shown no symptoms of swine flu and that his health was never in danger.
U.S. customs officials began checking people entering U.S. territory. Officers at airports, seaports and border crossings were watching for signs of illness, said Customs and Border Protection spokesman Lloyd Easterling.
While the borders are open, Easterling said officials were "taking a second look at folks who may be displaying a symptom of illness."
If a traveler reports not feeling well, the person will be questioned about symptoms and, if necessary, referred to a federal health official for additional screening, Easterling said. The customs officials were wearing personal protective gear, such as gloves and masks, he said.
Napolitano urged Americans to take "common sense" precautions.
"Common sense means washing hands, staying home from work or school if you feel sick, covering your mouth if you cough or sneeze. These are straightforward and simple measures, but they can materially improve our chances of avoiding a full-fledged pandemic," she said.
Authorities were not recommending that people in the U.S. put on masks in the workplace to protect against swine flu infection.
Associated Press writers Mark Stevenson and Olga R. Rodriguez in Mexico City; Frank Jordans in Geneva; Mike Stobbe in Atlanta; Maria Cheng in London and Eileen Sullivan and Robert Burns in Washington contributed to this report.