Boston ? Is this the costume for natives of the global village now, a face mask?

In Hong Kong, a waitress and her customers are photographed wearing the same accessory, looped behind their ears. On sidewalks in that city people are buying masks in basic white or, if they prefer, in a Gucci print or a Burberry plaid. Meanwhile in airports, reluctant travelers on their way to Beijing or Toronto are packing N-95 respirator masks along with their passports.

It’s less than two months since the words “severe acute respiratory syndrome” first appeared in the daily newspaper. Now SARS has taken over the news like, well, a virus. We have now clocked 3,900 cases in 25 countries, a death toll over 218 and climbing.

Last year’s fear was the offspring of international bioterrorism: anthrax or smallpox. This year’s fear is the offspring of Mother Nature’s terror: a coronavirus never before seen in human beings.

Illnesses have always traveled in the human biological knapsack. The plague spread from one person to another until it killed one of every four Europeans in the 14th century. One out of every hundred people in the world died from the “Spanish Influenza” of 1918, a disease spread in part by soldiers on the move.

Now we are all on fast-forward. In 1955, 51 million people a year traveled by plane. Today 1.6 billion are airborne every year and 530 million cross international borders.

The Great SARS Tour once might have taken months or weeks to spread this far. Now it takes days. A flight attendant becomes the “index case” for 160 infections. A tourist infects seven others in a hotel. A globetrotter here and there brings it home like a biological souvenir.

The world has shrunk to the size of an airplane ticket. And germs don’t need a visa. You can have breakfast in Beijing, dinner in London and end up hospitalized in Toronto. And so, as the Singapore minister of health put it, SARS “gives new meaning to the word globalization.”

But before the cough heard round the world becomes a symbol of global vulnerability, let it also be said that the way the world has mobilized against this disease is an equal and opposite sign of the value of our connections.

It took centuries to identify the cause of cholera. It took two years to identify the virus that caused AIDS. It took five months to figure out Legionnaires’ disease.

But this time under the World Health Organization network, 13 labs in 10 countries put everything else aside. In a matter of weeks, an international community of scientists identified the coronavirus as the cause. Within a month, labs from Vancouver to Atlanta to Singapore mapped the genome. Soon we may have a diagnostic test for the virus itself. And after that, with luck, a treatment.

If the disease went international with unprecedented speed, so did the response. If oceans no longer can keep people or germs on their own side of the water, nor can they keep researchers apart. Health organizations and scientists also go global.

In describing the race between the bright and dark side of globalization, Julie Gerberding of the CDC wrote in the New England Journal of Medicine, “Speed of scientific discovery and speed of communication are hallmarks of the response to SARS.” Then, she added, “a very sobering question remains — are we fast enough?”

We don’t know the winner yet in this race. We don’t know whether this is the beginning or the end of a SARS pandemic. But we can be certain that SARS is not the last — nor the deadliest — virus to hitchhike across the world.

“You always read about the conquest of a disease,” says Howard Markel, a historian of medicine at the University of Michigan, “but we don’t conquer diseases. We wrestle them to a draw. So what happens in China or Zaire has an effect in Ann Arbor or Vancouver. Globalization has to include the globalization of good public health.”

We are in the adolescent stages of this new world, still lurching unevenly and living uncertainly in a time when diseases, like pollution and terrorism, cross the continents. We are discovering that neither biology nor ideology stays put.

In this epidemic, China, which suppressed bad news far too long, may finally learn that they can’t play in the global economy without a open and transparent public health system. America, for our part, may remember that we can’t meet every global threat alone.

This is a shrinking world in a perpetual rush hour. The way we deal with SARS may predict the way we face the global village — openly or behind a mask.

— Ellen Goodman is a columnist for Washington Post Writers Group.