By William Lee Adams/London

Fearing that their vacations could comprise of surf, sand and swine flu, potential travelers are turning to health organizations for guidance on whether to pack their bags or stay home. And while opinions from health officials have come thick and fast, their often contradictory advice doesn't make it any easier to decide whether to fly or not to fly. 

On Monday, the European Union's health commissioner Androulla Vassiliou told reporters in Luxembourg that she was "not worried at this stage" about a pandemic sweeping across Europe, but she urged travelers to avoid Mexico and the United States anyway. That prompted a swift rebuke from Richard Besser, the acting director of the Centers for Disease Control and Prevention (CDC) in Atlanta, who rejected her advisory as "quite premature." Even so, the CDC website "recommends that U.S. travelers avoid all nonessential travel to Mexico." As for the World Health Organization, it's calling on nations to keep their borders open and to avoid restricting international travel, and emphasizes that a pandemic is not inevitable. Despite that plea, Argentina and Cuba have suspended all flights from Mexico, and tour operators and airlines across the globe — including some based in Canada, Germany and the U.K. — have canceled flights and holiday packages to sunshine destinations like Cancún and Cozumel. (See pictures of thermal scanners hunting for swine flu.)

So much for a relaxing summer break. Andrew Nolan, 30, a lawyer living in London, had planned to fly to Los Angeles on April 30. But the conflicting travel advisories left him so uneasy that he decided to stay put. "If these large international bodies are having difficulty deciding where it's safe to travel, I thought it was better to cancel," he says of the trip he started planning two months ago. "I'm in no way assured that they understand the full extent of the epidemic, or that they have it under control."

Those concerns will take center stage on Thursday when health ministers from the 27 E.U. states convene at an emergency conference in Luxembourg to define and coordinate a response — and a unified travel advisory. "During these meetings we will ask our European colleagues to consider the suspension of flights going to Mexico," France's Health Minister Roselyne Bachelot told reporters after meeting with French president Nicholas Sarkozy to discuss the flu scare. But France won't advocate suspending flights returning from Mexico, as that would strand thousands of passengers, leaving them in a scramble to find other ways out of the country and potentially increasing their risk of exposure to the virus. (Read a brief history of the flu vaccine.)

For those in the tourism industry, discussing restrictions simply doesn't fly. The world travel sector is already experiencing its first contraction since 2003, when the outbreak of SARS in Asia decimated tourism revenues. Michael O'Leary, chief executive of discount airline RyanAir, drew criticism on Tuesday for publicly suggesting that only the world's poorest people will succumb to swine flu, despite the fact that two middle-class Scottish newlyweds have been isolated in a hospital for several days after having tested positive for the H1N1 virus. "It is a tragedy only for people living in slums in Asia or Mexico. But will the honeymoon couple from Edinburgh die? No. A couple of Strepsils will do the job," he said, suggesting that all they have to do is suck on the popular candy-flavored, over-the-counter throat lozenges.

Geoffrey Lipman, assistant secretary-general of the United Nations World Tourism Organization, has a less inflammatory take. "We know from the past that restrictions don't actually serve to hold back the spread of this kind of virus," he says. "It's already out there around the world in different places."

That's not just hot air. According to Dr. Meirion Evans, an epidemiologist with the U.K.'s Faculty of Public Health, the government body that sets public health standards, "If we start seeing countries reporting contractions from person-to-person, then visiting anywhere in the world would be as risky as visiting Mexico." And despite the high number of swine flu cases reported in Mexico — over 2,000, with more than 150 deaths so far — that number may stabilize or fall, suggesting that Mexico "could be over the worst of its problems, whereas other countries have the worst to come."

Even so, countries continue to take precautions. Officials at Tokyo's Narita International Airport have installed a device at the arrival gate for flights from Mexico to measure the temperature of disembarking passengers, and passengers flying into the Philippines who report fevers have been quarantined in government hospitals. (Read "Battling Swine Flu: The Lessons from SARS.")

As the threat of travel restrictions spreads, it's those kinds of inconveniences — not health concerns — that put some people off their vacation plans. Yvonne Worth, 50, a freelance editor in London, says she's debating whether to travel to New York and Massachusetts to visit old friends because she worries the airline will cancel her flight. "If I book a ticket and end up losing it because of travel restrictions, I may not get my money back," she says. "Maybe I'll go see somebody in Amsterdam instead." Apparently not even a deadly virus can kill the travel bug in some folks.