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.
So are there better ways to scan passengers?
There's a term called risk-based border screening. What that basically means is that you're going to rank passengers into "no risk," where people are fine, "low risk," which requires additional testing, and "high risk," which basically means "we're isolating you here." In the screening, what will happen is travelers will be asked about where they've been, how do you feel, have you been coughing… The [U.S.] federal government has designed a risk-based border screening strategy that hasn't been used, so we don't know how effective it is. It might work, but we don't know the answer.
And what about on the airplane? How can airlines prevent diseases from spreading?
I'd love to see hand sanitizers throughout the cabin or an alcohol-based gel handed out with the peanuts. Anything that really encourages people to be washing their hands. Also, there have been some papers looking at ventilation within confined spaces, specifically from a flu outbreak in 1979 … which found there was a benefit to increasing the ventilation rate. So there might be a benefit if, whenever WHO declares an outbreak of public-health importance, airlines were required to increase their ventilations. We don't know for sure it would work, but it's one thought.
What do passengers need to be thinking about when they're traveling on airplanes? Any precautions they should take?
The risk of infection within any confined space is dependent on three things: the strength of the source strand [how contagious or lethal it is], proximity to exposure and ventilation. You can't change the lethality and you don't have control over who you're seated next to. However, unless you've come in very close contact, basically within two rows of a contagious person, you don't have much to fear in terms of contracting an illness … so if you're seated in row 12 and you're hearing somebody coughing in row 30 you don't have to worry.
What if you're in row 29?
The good news is you can still minimize risk by practicing very good hand hygiene, not touching eyes or nose and using alcohol-based hand sanitizers. The second important thing to think about is ventilation. You can actually increase the ventilation at your seat a little bit more, through the overhead air releaser. What I recommend people do is turn it on to a low stream and position it so the flow goes in front of your face. That will increase the ventilation, at minimal, create a turbulence of air in front of your face. If a particle is coming by, that might be enough to push it out of the way.
The final thing is to keep yourself well hydrated. The mucus membrane is one of the body's first barriers and inside there are a lot of enzymes our body uses to destroy viruses and bacteria. When mucus membranes get dehydrated, it's postulated they're not going to work as well. So drinking plenty of nondehydrating fluids could be good.