By Anita Manning, USA TODAY

The only thing that seems more contagious than the mystery disease SARS, severe acute respiratory syndrome, is the fear of SARS.

"It's not a panic yet, but it's getting there," says John DiScala, a travel expert in Los Angeles.

"People flying, especially to Asia, are nervous," he says. But "I've had e-mails from people on the East Coast asking, 'Should I go to the Caribbean?'"

It's no wonder. The messages coming from health authorities have been distinctly ominous. Surgeon General Richard Carmona said Friday that a quick health screening for passengers before boarding international flights from SARS-affected countries might be a good idea, and President Bush gave U.S. health officials the power to involuntarily quarantine people suspected of having the disease.

The disease continues to spread. Kuwait announced its first suspected case on Saturday. The World Health Organization reports 2,416 cases, including 89 deaths, as of Sunday. No deaths have occurred in the USA among 115 suspected cases, but health officials in Canada have reported 217 cases, most of them in the Toronto area, and nine deaths.

"We've seen it spread rapidly and dramatically to a number of countries," James Hughes of the Centers for Disease Control and Prevention said in a briefing Friday. "We're not totally on top of this by any means."

For reasons not understood, most of the American cases have been milder than those in other countries, but concern is high just the same. Airplanes have been grounded while passengers are evaluated for possible symptoms. Colleges and church choirs have postponed or are reconsidering trips to Asia. Last week at a school in Connecticut, students and teachers recently back from a China trip were sent home for a few days even though they all seemed healthy.

Three days before the start of its annual meeting Saturday in Toronto, the city most affected by SARS outside Asia, the American Association of Cancer Researchers canceled the event, citing the need to "minimize the risk of spreading SARS, especially for those whose immune system is already compromised from their fight with cancer." Officials said they had expected 16,000 people to attend, but thousands had pulled out, so they had no choice but to cancel.

Among those most concerned about SARS are flight attendants, says Pat Friend, president of the Association of Flight Attendants, which urged the Federal Aviation Administration last week to issue an emergency order requiring airlines to offer gloves and surgical masks to airline attendants, or at least allow them to bring their own. Some airlines already are making them available to passengers and crew on Asian flights.

SARS, Friend says, "is particularly frightening because of the nature of the disease, the fact that it has been reported to be communicable by inhalation or by coming in contact with used food or beverage items the infected passengers have had."

CDC experts say that although much is still unknown about SARS, they believe it is passed most often through direct exposure to "droplets" expelled when an infected person speaks or coughs. But there is some evidence that the virus — thought to be a new bug in the family of germs that causes colds — can live for hours on objects and may even spread through the air.

About 85% of passengers on flights from Asia are wearing masks, Friend says. The CDC is advising people to reconsider non-essential travel to Hong Kong, China, Vietnam and Singapore, but "that's not an option for us," she says. "It's our job."

SARS, first diagnosed in Vietnam in February, has raced around the world, carried by international travelers to at least 19 countries. Many of the early cases involved hospital workers who cared for patients before it was known how contagious the disease was.

San Francisco internist Hans Yu, whose practice is about 80% Chinese and Chinese-American, says he has been getting calls daily from patients who have returned from China or have relatives visiting from there.

WHO's advice to travelers to postpone non-essential travel to Hong Kong and China's Guangdong Province has rattled the Chinese community.

Yu says that surgical masks have sold out of stores in Chinatown and that he has had requests from friends in Hong Kong to send some because they're in short supply.

He has posted a sign outside his office asking patients whether they have symptoms of SARS — fever, dry cough — and have traveled recently to SARS-affected areas.

"If so, we say 'Don't come into the office. Go home and call me,' " he says. "It's to protect the staff and waiting room. By doing that, if a case does come up, we don't want it to spread."

With few exceptions, most people seem to be reacting with an appropriate mix of calm and caution, says Arthur Reingold, professor of epidemiology at the University of California-Berkeley and head of the California Emerging Infections Program. He says the advice and precautions being taken by public health officials make sense.

"This is, if not unprecedented, certainly a highly unusual and scientifically interesting new disease," he says. In the USA, "we don't have evidence of transmission in the general public, and at the moment things appear to be well-controlled in Canada," where the disease does not appear to be spreading broadly in the community.

Still, uncertainty is the word of the day, says travel expert DiScala, who runs a travel Web site, www.johnnyjet .com. DiScala says he gets a "Should I go?" e-mail every day.

He won't make decisions for others, he says, but he would not hesitate to go to the Caribbean, for example, or to other unaffected parts of the world. He wouldn't wear a face mask while traveling, either, he says, unless he were heading to Asia.

At this point, DiScala says, he doesn't see travelers going to extremes.

"I just came through an international terminal the other day, and not one person was wearing a mask. Right now it's not panic time. It's time to find out what the facts are so we can go forward."