MEXICO CITY - Mexican President Felipe Calderon told his people to stay home from Friday for a five-day partial shutdown of the economy, after the World Health Organization said a swine flu pandemic was imminent.

Calderon ordered government offices and private businesses not crucial to the economy to stop work to avoid further infections from the new virus, which has killed up to 176 people in Mexico and is now spreading around the world.

There is no safer place than your own home to avoid being infected with the flu virus, he said in his first televised address since the crisis erupted last week. [ID:nN29466276]

Twelve countries have reported cases of the H1N1 strain, with the Netherlands the latest to join the list. It said a three year-old who had recently returned from Mexico had contracted the virus.

Switzerland also confirmed its first case on Thursday in a man returning from Mexico. Peru reported what appeared to be the first case in Latin America outside Mexico, also in someone who had been to the country.

On Wednesday, Texan officials reported the first swine flu death outside Mexico, a 22-month-old visiting Mexican boy.

The World Health Organization (WHO) raised its alert level to phase 5, the last step before a pandemic.

Influenza pandemics must be taken seriously precisely because of their capacity to spread rapidly to every country in the world, WHO Director General Margaret Chan told a news conference in Geneva on Wednesday.

The biggest question is this: how severe will the pandemic be, especially now at the start.

WHO later issued guidance recommending all countries track any suspect cases and ensure medical workers dealing with them wear protective masks and gloves.

The organization has stopped short of recommending travel restrictions, border closures or any limitation on the movement of people, goods or services.

WORLD STOCK MARKETS RALLY

Mexico's peso currency weakened sharply after the government called for chunks of the economy to close. The peso fell 1.6 percent to 13.83 per dollar.

But world stocks hit a four-month peak on economic optimism, showing little sign of fears over the flu.

Earlier in the week they fell on worries that a major outbreak could hit the struggling global economy.

Almost all those infected outside Mexico have had mild symptoms, and only a handful of people have been admitted to hospital.

In Mexico City, a metropolis of 20 million, all schools, restaurants, nightclubs and public events have been shut down to try to stop the disease from spreading, bringing normal life to a virtual standstill.

Several countries have banned pork imports, though the World Health Organization says swine flu is not spread by eating pork. Egypt started confiscating and slaughtering pig herds despite criticism from the United Nations.

There is no reason to do that. It's not a swine influenza, it's a human influenza, said Joseph Domenech, the U.N. Food and Agriculture Organisation's chief veterinary officer. The FAO is lobbying for a name change for the virus.

President Barack Obama said on Wednesday there was no need for panic and rejected the possibility of closing the border with Mexico.

At this point, (health officials) have not recommended a border closing, he said. From their perspective, it would be akin to closing the barn door after the horses are out, because we already have cases here in the United States.

Obama also praised his predecessor for stockpiling anti-viral medication in anticipation of such an outbreak.

EXPERT SAYS VIRUS RELATIVELY WEAK

Masato Tashiro, head of the influenza virus research center at Japan's National Institute of Infectious Disease and a member of the WHO emergency committee, told Japan's Nikkei newspaper it appeared the H1N1 strain was far less dangerous than avian flu.

I am very worried that we will use up the stockpile of anti-flu medicine and be unarmed before we need to fight against the avian influenza. The greatest threat to mankind remains the H5N1 avian influenza.

The WHO's Chan urged companies who make the drugs to ramp up production. Two antiviral drugs -- Relenza, made by GlaxoSmithKline and Tamiflu, made by Roche AG and Gilead Sciences Inc -- have been shown to work against the H1N1 strain.

Guan Yi, a microbiologist at the University of Hong Kong, said the swine flu virus could mix with avian flu, or H5N1, to become a very powerful and transmissible virus. Then we will be in trouble, it will be a tragedy.

Mexico's central bank warned the outbreak could deepen the nation's recession, hurting an economy that has already shrunk by as much as 8 percent from the previous year in the first quarter.

The United States, Canada and many other countries have advised against non-essential travel to Mexico. Many tourists were hurrying to leave, crowding airports.

European Union health ministers were due on Thursday to discuss coordinating possible restrictions on travel to and from Mexico and Southeast Asian health ministers will hold emergency talks to coordinate their fight against swine flu next week.

Japan's Masato Tashiro said the possibility of an overreaction to the outbreak was a concern. Excessive curbing of corporate activity will be a problem. The best course of action is to adopt rational measures.