President Barack Obama said Monday the rising numbers of swine flu cases is a cause for concern but "not a cause of alarm," as the State Department warned Americans not to travel to Mexico, and New Jersey became the latest state to report suspected cases of the virus.
The number of confirmed U.S. cases rose to 50 although none were fatal. Twenty-eight cases have been reported in New York, 11 in California, six in Texas, two in Kansas and one in Ohio. Unlike in Mexico where the same strain appears to be killing dozens of people, cases in the United State have been mild -- and U.S. health authorities can't yet explain why.
New Jersey health officials say they've identified five probable cases of swine flu in people who recently traveled to Mexico and California, with confirmation results of tests expected by Wednesday.
The New Jersey Department of Health and Senior Services said Monday that all have mild forms of the flu and none has been hospitalized.
The patients include residents of several counties. Four recently traveled to Mexico; the fifth had traveled to California.
Meanwhile, the State Department warned U.S. citizens Monday to avoid nonessential travel to Mexico and those who live in Mexico to avoid hospitals or clinics there unless they have a medical emergency.
The department says those who fall ill in Mexico should stay home and call their doctors to avoid exposure to swine flu infection at hospitals.
Earlier, the World Health Organization raised its pandemic alert by one level, two levels short of declaring a full pandemic. A phase 4 alert means there is sustained human-to-human transmission in at least one country, WHO said. The highest alert level is 6.
"The change to a higher phase of pandemic alert indicates that the likelihood of a pandemic has increased, but not that a pandemic is inevitable," the agency said in a statement.
Dr. Richard Besser, the head of the Centers for Disease Control and Prevention warned Americans to brace for the problem to become more severe -- meaning "possibly deaths."
But President Obama tried to tamp down concern that the flu would reach pandemic levels in the U.S. He said his administration is "closely monitoring" the flu and that he was getting regular updates.
"This is obviously a cause for concern and requires a heightened state of alert," Obama said. "But it's not a cause for alarm."
The U.S. began border screening for exposure to swine flu as the European Union advised citizens against travel to the United States -- while China, Russia and Taiwan moved to quarantine visitors as fears of a global pandemic spreads.
Officials began "passive screening" at the borders where border agents would be "asking people about fever and illness, looking for people who are ill," said acting head of the Centers for Disease Control Richard Besser said.
The U.S. declared a public health emergency Sunday in response to the burgeoning swine flu epidemic -- a rare move that lets the government prepare for the illness in much the same way it braces for hurricanes.
The declaration allows the federal and state governments easier access to flu tests and medications, and frees up funding for other public health resources.
At a White House news conference, Homeland Security Secretary Janet Napolitano and Dr. Besser sought to assure Americans that health officials are taking all appropriate steps to minimize the impact of the outbreak.
"As we continue to look for cases, we are going to see a broader spectrum of disease," predicted Besser. "We're going to see more severe disease in this country."
Napolitano called the emergency declaration standard operating procedure — one was declared recently for the inauguration and for flooding. She urged people to think of it as a "declaration of emergency preparedness."
"Really that's what we're doing right now. We're preparing in an environment where we really don't know ultimately what the size of seriousness of this outbreak is going to be."
Napolitano says roughly 12 million doses of the drug Tamiflu are being released from a federal stockpile so that states can get it if needed.
President Obama's press secretary, Robert Gibbs, issued a statement that said the president's health was fine after having visited Mexico a little more than a week ago.
Obama was received at an anthropology museum in Mexico City by Felipe Solis, a distinguished archaeologist who died a week later.
Mexico's health secretary, Jose Cordova, said Solis had a pre-existing illness and died of pneumonia unrelated to influenza.
Swine flu spreads globally
Nations from New Zealand to Spain have reported suspected cases of swine flu, and some warned citizens against travel to North America while others planned quarantines, tightened rules on pork imports and tested airline passengers for fevers.
The Health Ministry in Spain confirmed the country's and Europe's first case of swine flu Monday and said another 20 people are suspected of having the disease
In Mexico, a strain of the swine flu has killed 20 but is suspected in 149 other deaths. The flu is suspected of sickening more than 1,995 across Mexico, where authorities have extended school closures in the capital and two neighboring states with outbreaks.
Canada became the third country to confirm human cases of swine flu Sunday as global health officials considered whether to raise the global pandemic alert level.
The six Canadian cases in Nova Scotia and British Columbia all had links to people who had traveled to Mexico, and all are the same swine flu strain. The six people have recovered, said Dr. David Butler-Jones, Canada's chief public health officer.
In Scotland, two people who had returned from Mexico tested positive for swine flu and were being put in isolation, the Washington Post reported.
A senior World Health Organization official said the agency's emergency committee will meet for a second time Tuesday to examine the spread of the virus before deciding whether to increase the alert for a possible pandemic, or global epidemic.
The same strain of the A/H1N1 swine flu virus has been detected in several locations in Mexico and the United States, and it appears to be spreading directly from human to human, said Keiji Fukuda, WHO's assistant director-general in charge of health security.
WHO's emergency committee is still trying to determine exactly how the virus has spread, Fukuda said
"Right now we have cases occurring in a couple of different countries and in multiple locations," he said. "But we also know that in the modern world that cases can simply move around from single locations and not really become established."
Swine flu is a respiratory disease of pigs caused by type A flu viruses, the CDC's Web site says. Human cases of swine flu are uncommon but can happen in people who are around pigs and can be spread from person to person. Symptoms of the flu include a fever of more than 100 degrees, body aches, coughing, a sore throat, respiratory congestion and, in some cases, vomiting and diarrhea.
Top Obama administration health positions vacant
The White House meanwhile brushed off questions about whether a lack of top health officials was making more difficult President Barack Obama's response to the flu outbreak.
Gibbs said the administration's response was competent even though the Senate has yet to confirm a secretary of human services, a surgeon general or a director of the Centers for Disease Control and Prevention.
"We are doing fine," Gibbs said.
Obama's first pick to run the Health and Human Services Department, Tom Daschle, withdrew amid tax problems. The second pick, Kansas Gov. Kathleen Sebelius, has faced delays in her Senate confirmation because of her support for abortion rights.
White House officials say they expect Sebelius to be confirmed shortly, given the urgency of the flu outbreak that started in Mexico and spread to the United States. They also say work at the departments is being done even though the top jobs have gone unfilled.
Obama's team tried to recruit CNN's Dr. Sanjay Gupta to be the surgeon general, the nation's top public health spokesman. Gupta took himself out of the running for the post, and Obama hasn't settled on a second choice.
Swine Flu Across the U.S.:
View H1N1 Swine Flu in a larger map
Pink markers are suspect, Purple markers are confirmed, Deaths lack a dot in marker, Yellow markers are negative