Its most recent figures show 506 people have been infected in Mexico and 160 people have been infected in the United States, the two countries most affected by the virus widely known as swine flu. There has also been one U.S. death, identified by authorities there as a Mexican infant.

Earlier on Sunday, WHO had said there were 397 infections in Mexico and 16 deaths there. The U.N. agency said its figures changed because of “ongoing testing of previously collected specimens” and not new reported infections.

Mexico has revised down its estimate of as many as 176 suspected H1N1 deaths after receiving dozens of negative test results. Mexican authorities said on Saturday out of more than 100 suspected deaths from the strain, 19 have been confirmed.

The WHO has also confirmed flu infections, without deaths, in the following countries:
Austria (1),
Canada (70),
Hong Kong – China Region (1),
Costa Rica (1),
Denmark (1),
France (2),
Germany (6),
Ireland (1),
Israel (3),
Netherlands (1),
New Zealand (4),
South Korea (1),
Spain (13),
Switzerland (1),
Britain (15).

Mexico was approved for $3 billion in international loans to fight the swine flu crisis, as the country began a five-day shutdown on Friday to try to halt the spread of the virus. As nations worldwide stepped up safety measures following a World Health Organization, or WHO, warning that a global pandemic may be imminent, Mexican officials said the rapid spread of the H1N1 virus could be slowing, reported Agence France-Presse.

But Mexico’s chief epidemiologist accused the WHO of being slow to respond to the country’s warning about a health crisis that turned into a global swine flu scare. He called for an investigation.Dr. Miguel Angel Lezana told The Associated Press late Thursday that his center alerted the Pan American Health Organization on April 16 about alarming occurrences of flu and atypical pneumonia in Mexico. But no action was taken until eight days later when the World Health Organization said it was “very, very concerned” the outbreak could grow into a pandemic.

“It seems it should have been more immediate,” Lezana, director of the National Epidemiology Center, told AP in a telephone interview.

13 confirmed cases

WHO officials said Friday the health body had been informed on about April 9 of unusual cases of “suspicious influenza” from Mexico that had begun in late March, but that U.S. and Canadian laboratories identified the virus on April 24, when the organization responded rapidly. Health authorities said they have confirmed 300 swine flu cases and 12 deaths due to the virus. Worldwide, 13 countries have confirmed cases. The latest were Denmark and Hong Kong – where a traveler from Mexico accounted for the first verified case on the Asian continent. Canada, New Zealand, Britain, Germany, Spain, Switzerland, the Netherlands, Israel and Austria also have confirmed cases.

Across Mexico’s border, the number of confirmed swine flu cases in the United States rose to 130 Thursday. Hundreds of schools shut their doors. The only confirmed U.S. swine flu death so far was a Mexican toddler who succumbed in Texas. The swine flu outbreak penetrated over a dozen states and even touched the White House, which disclosed that an aide to Energy Secretary Steven Chu apparently got sick helping arrange President Barack Obama’s recent trip to Mexico but that the aide did not fly on Air Force One and never posed a risk to the president. The Washington Post identified the aide as Marc Griswold, a former Secret Service agent who was doing advance work for Chu. It said that Griswold has complained about the infection placing his family in an awkward position with family and neighbors.

U.S. authorities were pledging to eventually produce enough swine flu vaccine for everyone who needs it but the shots couldn’t begin until fall at the earliest. The U.S. swine flu caseload passed 100, and nearly 300 schools closed in communities across the country. Federal officials had to spend much of the day reassuring the public it’s still safe to fly and ride public transportation after VP Joe Biden said he wouldn’t recommend it to his family. “There’s not an increased risk there,” Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, said Friday. “If you have the flu or flu-like symptoms, you shouldn’t be getting on an airplane or you shouldn’t be getting in the subway, but for the general population that’s quite fine to do,” he said.

$3 billion in loans

In Washington, the Inter-American Development Bank said it would approve $3 billion in loans for Mexico, which was already struggling from the global financial crisis. Mexican authorities, meanwhile, cancelled the traditional gatherings of workers to celebrate May Day, as the restaurants, bars, tourist sites and other public venues remained closed in the capital and elsewhere. “Stay at home with your family,” President Felipe Calderon said in an address to the nation.

The WHO said it would not as yet invoke the highest health threat level – what it calls Phase 6, meaning a worldwide pandemic is under way – but kept it at phase five, indicating a pandemic is imminent. The WHO’s acting assistant director Keiji Fukuda said the virus was behaving like a typical influenza virus, meaning there could be an increase in cases in the southern hemisphere, which is about to enter winter. Elsewhere authorities tightened travel restrictions and took other measures to keep the virus from spreading. Singapore invoked health orders not used since the SARS crisis, ordering anyone arriving from Mexico to be quarantined for one week, as Israel began airport health inspections for those coming from Mexico. Argentina and Cuba have suspended flights to Mexico.