When Flu Flies

As the number of confirmed swine-influenza cases rises, so does global concern over the role aircraft could play in the disease's spread. The Centers for Disease Control and Prevention recommend all Americans cancel any nonessential travel to Mexico. The European Union made the same recommendation for citizens flying to both Mexico and the United States. Passengers coming from Mexico have been greeted with great caution in some locations. At Tokyo's airport, passengers were thermoscanned to check for fevers; at London's Heathrow, passengers waited aboard their plane for 45 minutes as health officials checked for signs of the disease.

"Certainly this outbreak has shown us again that the aircraft is a vehicle of infectious disease that spreads very rapidly throughout the world," says Mark Gendreau, an assistant professor of emergency medicine at Tufts University and vice-chairman of emergency medicine at Lahey Clinic in Burlington, Mass., who has written extensively on aviation medicine. NEWSWEEK's Sarah Kliff spoke with Gendreau about travel safety, why scanning passengers for fevers doesn't work and what every traveler can do ensure a healthier flight. Excerpts:

NEWSWEEK: What role do airplanes and air travelers play in international flu pandemics?
Mark Gendreau: One of my favorite quotes on this is [from Nobel laureate] Josh Lederberg ... He said, "The microbe that felled one child in a distant continent yesterday can reach yours today and seed a global pandemic tomorrow." This swine situation was brought to us by tourists who traveled to Mexico and then came back. Air travel is enormously important in terms of spreading infectious disease very rapidly.

So should we be cutting down on air travel? Or even barring travel from certain parts of Mexico completely?
Airport closures aren't going to stop this. Bottom line is the cat is already out of the bag, so it probably wouldn't make a big impact at this time. There was an observational study, published shortly after the terrorist attacks in 2001. They found that, since air travel largely came to a halt, there was a two-week delay in the flu season. It made the authors postulate that the two-week delay was a result of the markedly decreased air travel that occurred shortly before the flu season. What that tells us is that restricting travel won't stop it, although it might give us time to help mobilize resources and prepare a little bit better.

Tokyo's airport has begun screening passengers  arriving from Mexico for swine flu, using thermoscanners to detect high body temperatures. How well does that work for preventing the spread of flu?
There was a meta-analysis of thermoscanner use that shows it didn't work well during the SARS outbreak because it had a lot of false negatives. It wasn't getting people who were symptomatic. Airport screening is going to get done, I guarantee it, but it typically doesn't work particularly well with flu. With flu, there's a time frame between when you get infected and become contagious. In that area, you don't know you're sick even though you're contagious. Thermoscanning in airports is not effective in picking up the people you want to.