Mexico started a five-day shutdown of most offices and businesses on Friday to try to halt the spread of a deadly flu strain, and officials said they were encouraged by signs the number of new cases was dropping.

Health Minister Jose Angel Cordova said the public hospitals that treat roughly half the country admitted 46 patients with severe flu symptoms on Thursday, down from 212 patients on April 20. This is encouraging, he said.

Cordova said tests of samples sent to laboratories in the United States, Canada and Mexico had confirmed only 12 out of 176 deaths blamed on the H1N1 swine flu virus. The number of confirmed fatalities will probably rise, he said.

Normal seasonal flu kills between 250,000 and 500,000 people around the globe in an average year, including about 36,000 in the United States.

Worldwide, 11 countries have reported confirmed cases of the H1N1 strain, with the Netherlands the latest to join the list. A further 17 countries were checking possible cases.

New confirmed cases were reported in Canada, the United States and Europe. Almost all infections outside of Mexico have been mild and only a handful of patients have required hospital treatment. Only one person has died outside Mexico -- a toddler from Mexico who was visiting the United States.

The World Health Organization said the current alert level would remain one step below full pandemic and that it would no longer refer to the H1N1 virus as swine flu to appease outraged meat producers. But WHO did not offer another name to distinguish the new virus from other H1N1 strains.

Mexico's peso was hammered on Thursday and its stock market slid. But most global markets were taking the flu news in stride as traders focused on hopes that a deep U.S. recession may be nearing an end.

The information that we have at this stage is it is a relatively minor (economic) event, International Monetary Fund chief economist Olivier Blanchard said, although he warned that some countries and sectors could see fallout from the outbreak.

MONGREL VIRUS

The WHO and flu experts say they do not yet know enough about the new strain to say how deadly it is, how far it might spread and how long any potential pandemic may last.

But the first detailed analysis, published in the journal Eurosurveillance, showed it was a mixture related to two known swine viruses, one itself a triple mixture of bird, human and swine viruses.

The closest relatives to the virus we have found are swine viruses, said Paul Rabadan of New York's Columbia University.

U.S. Health and Human Services Secretary Kathleen Sebelius said the United States would spend $251 million to buy 13 million more courses of flu medicine. The United States began sending 400,000 doses of treatment to Mexico

The U.S. government has stockpiled about 50 million courses of antiviral drugs and state stockpiles across the country include an additional 23 million courses.

Both Roche AG's Tamiflu, known generically as oseltamivir, and GlaxoSmithKline's Relenza, known generically as zanamivir, work against the new virus.

Mexican President Felipe Calderon has asked Mexicans to stay home May 1-5 over the long Cinco de Mayo holiday beginning on Friday and urged businesses to close.

There is no safer place than your own home to avoid being infected with the flu virus, Calderon said.

Japan's Bridgestone Corp said it was suspending production at its four tire plants in Mexico for five days. Of 23 Japanese expatriate staff, 14 would return to Japan on Saturday along with all 15 family members of expatriate staff.

In the United States, retailers reported strong sales of medical items to combat the flu.

Sales are brisk for items such as hand sanitizers, anti-bacterial soap and protective masks and gloves, CVS Caremark Corp spokesman Mike DeAngelis said.

He said there was increased demand for Tamiflu, particularly in markets where there are confirmed cases of H1N1 flu virus.

Similar increases in demand are being seen in Canada, according to spokesmen for Shoppers Drug Mart chain and Wal-Mart Canada.

(Additional reporting by Helen Popper, Bill Berkrot, and Deborah Charles; Writing by Maggie Fox and Andrew Marshall; Editing by Bill Tarrant)

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