(CNN) -- Governments and health officials around the world continued to take steps Tuesday against the outbreak of swine flu that has killed scores of people in Mexico and spread to the U.S., Europe and possibly Asia.

International arrivals have their temperature checked as they pass a thermal scanner at Jakarta's main airport.

By early Tuesday, the swine flu outbreak in Mexico was suspected in 152 deaths and more than 1,600 illnesses, its health minister told reporters.

While authorities wait to verify whether the virus is responsible for all the deaths, the number of confirmed cases is sobering: 19 infected; seven others dead; and thousands flooding hospitals.

So far, at least 90 cases have been confirmed worldwide, including 50 in the United States; six in Canada; three in New Zealand; two each in Spain and the United Kingdom; and one in Israel. None has yet resulted in death. Read what steps countries are taking

With at least 11 other countries suspecting infections, the World Health Organization on Monday raised its alert level from three to four on its six-level scale.

The move means the U.N. agency has determined that the virus is capable of significant human-to-human transmission -- a major step toward a pandemic, but not necessarily inevitable, Dr. Keiji Fukuda said.

"In this age of global travel, where people move around in airplanes so quickly, there is no region to which this virus could not spread," said Fukuda, assistant director-general of the WHO.

Governments around the world scrambled to prevent further outbreak.

Some, like China and Russia, banned pork imports from the United States and Mexico. Several others, such as Japan and Indonesia, used thermographic devices to test the temperature of passengers arriving from Mexico. Watch how China is preparing for a possible outbreak »

The Philippines' health department urged people to avoid kissing and hugging in public.

U.S. President Barack Obama said the outbreak was a cause for concern, not for alarm. The government urged travelers to avoid non-essential travel to Mexico. Tell us what you think about the swine flu outbreak

Mexico has closed all schools until at least May 6 to help curb the spread of swine flu, officials announced Monday.

Armed police officers are also guarding hospitals in Mexico City while roads and schools in the city of 20 million people are deserted. Officials also have talked about shutting down the bus and subway systems.

Blue masks shield the faces of mothers and babies from a virus that doctors are still trying to understand, let alone bring under control. Read about what precautions people are taking

"I'm pretty nervous of this whole virus thing," Berta Hernandez said as she touched up her eyeliner inside a packed and humid subway car. She did not dare lift her surgical mask to put on lip gloss.

"I'm nervous of the people who aren't wearing masks. Maybe they will suddenly sneeze or cough," she said.

Some health experts fear the disease could become a pandemic, partly because it has killed young, healthy adults in Mexico.

The U.S. Food and Drug Administration issued emergency authorization for the use of two of the most common anti-viral drugs, Tamiflu and Relenza. The authorization allows the distribution of the drugs by a broader range of health care workers and loosens age limits for their use. The median age of all the U.S. cases is 16 years.

In Mexico City, however, there is a shortage of such medication. And the government ran out of surgical masks after handing them out to one out of every five residents.

Panicked citizens continue to flood in night and day at hospitals, only to be turned away by armed guards.

"I was looking for a mask at my local pharmacy, but they sold out," supermarket worker Rafael Martinez said as he rode the subway. "I know it's a risk, but I can't find one.'

Fuente: http://edition.cnn.com/2009/HEALTH/04/28/swine.flu.international/