The World Health Organization (WHO) on Saturday urged countries to be alert for unusual flu outbreaks after a deadly swine flu virus has claimed dozens of lives in Mexico and infected at least 11 people in the United States.

A woman wears a mask to prevent from being infected by the swine flu virus in the Mexico City, capital of Mexico, April 25, 2009. The World Health Organization (WHO) on Saturday declared the swine flu outbreak in Mexico and the United States a "public health emergency of international concern" and urged countries to be alert. (Xinhua Photo)

North America: Dozens killed

On Saturday, Mexican Health Minister Jose Angel Cordova raised the probable death toll from the outbreak of the swine flu to 81, including 20 already confirmed, and said more than 1,324 had been suspected to be infected since April 13.

Mexico City has closed schools, museums and other public gathering places, and the Army has been distributing face masks to the population. The health minister said classes in the capital, the neighboring Mexico state and the northern state of San Luis Potosi will resume on May 6.

Mexican President Felipe Calderon has issued an emergency decree giving the government special powers to run tests on sick people and order them to be isolated.

In the U.S., two more cases of swine flu were confirmed on Saturday in the state of Kansas and one case in California, bringing the total number of people infected to 11. Eight more cases have been reported in Texas and California.

Eight schoolchildren in New York City were found to be infected with a type A influenza virus that was likely to be the swine flu.

Mexican Federal Policemen wear masks in Mexico City April 25, 2009. (Xinhua/Reuters Photo)

WHO issues alert

WHO says the virus from 12 of the Mexican patients is genetically the same as a new strain of swine flu, designated H1N1, which is also seen in eight people in California and Texas.

The H1N1, a mixture of swine, human and avian flu viruses, is still poorly understood by scientists.

Based on the advice of a WHO emergency committee, Director-General Margaret Chan "has determined that the current events constitute a public health emergency of international concern," the UN agency said in a statement on Saturday.

WHO urged all countries to boost their surveillance for any unusual outbreaks of influenza-like illness and severe pneumonia.

But the Geneva-based UN agency left the alert status at "Phase 3" denoting none or very limited human-to-human transmission on its scale of one to six. The alert status "Phase 4" would indicate evidence of an increase in human-to-human infection.

"It has pandemic potential because it is infecting people," Chan said in Geneva. "However, we cannot say on the basis of currently available laboratory, epidemiological and clinical evidence whether or not it will indeed cause a pandemic."

Precautionary measures

Precautionary measures have been taken around the world against a possible global flu pandemic which could deal another blow to the world economy already knocked into a deep downturn by the financial turmoil.

According to WHO, no other countries have reported suspicious cases so far.

Up to now, no countries or global bodies have issued travel bans to Mexico, but some countries alerted travelers to learn about the information on the flu outbreak.

Costa Rica's Health Minister Maria Luisa Avila said Saturday that her country has issued a flu alert throughout the country and asked the Pan American Health Organization for a supply of antiviral drugs, especially Oseltamivir by the brand name of Tamiflu, to combat a possible outbreak spread from neighbouring Mexico.

In Honduras, Health Minister Carlos Aguilar said Saturday it may quarantine passengers with flu-like symptoms. The capital Tegucigalpa and San Pedro Sula, two main port cities in the country, will be the main area of surveillance, the minister said.

Chile ordered a sanitary alert that included airport screening of passengers arriving from Mexico. Those showing symptoms will be sent to a hospital for tests.

In Peru, authorities will monitor travelers arriving from Mexico and the U.S., and people with flu-like symptoms will be evaluated by health teams, Peru's health ministry said.

Brazil will "intensify its health surveillance in all points of entry into the country," the Health Ministry said in a statement. Measures will also be put in place to inspect cargo and luggage, and to clean and disinfect aircraft and ships at ports of entry.

The Stockholm-based European Center for Disease Prevention and Control on Saturday expressed concerns about the swine flu cases, saying it stood ready to lend support in any way possible.

A British Airways cabin crew member was taken to a London hospital after developing flu-like symptoms on a flight from Mexico City, which was the first such reported precautionary measure in Britain.

In France, a government crisis group began operating Saturday. The government has already closed the French school in Mexico City and provided French citizens there with detailed instructions on precautions.

The Netherlands has advised any traveler who returned from Mexico since April 17 and develops a fever over 38.5 Celsius degrees within four days of arriving in the country to stay at home.

The Polish Foreign Ministry has recommended that Poles postpone any travel plans to regions where the outbreak has occurred until it is totally contained.

Some Asian countries and regions have also stepped up checks on passengers with flu-like symptoms.

Japan has stepped up health surveillance in its international airports, while the Philippines said it will quarantine travelers with fevers who have been to Mexico. Health authorities in Thailand and China's Hong Kong said they were closely monitoring the situation.

Health experts have advised people to wash hands frequently, stay away from people with flu-like symptoms and avoid large gatherings.

Editor: Yan