Planes, Cruise Ships, and Germs

Boost your chances of healthy travel by taking a few preventive steps.

Medically Reviewed by Louise Chang, MD on October 31, 2007

Flying to great-aunt Erma's house for Thanksgiving? Or taking a leisurely wintertime cruise along the shores of the Mexican Riviera? Boost your chances of healthy travel by taking a few preventive steps. That way, you'll cut your risk of catching cold and flu from other plane passengers. And you won't be confined to your cabin on the cruise ship, battling a nasty case of gastroenteritis while other passengers are off enjoying the sights.

Flu Season Coming

As winter approaches, "the concern right now is influenza," says William Schaffner, MD, a professor at Vanderbilt University School of Medicine and vice president of the National Foundation for Infectious Diseases.

Many people worry that they're more susceptible to cold and flu germs while sitting inside a plane for hours with hundreds of other travelers. But there's no strong evidence to show that we're more vulnerable in the air than on the ground, says Gary Brunette, MD, MS, a medical epidemiologist who serves on the CDC Travel Health Team. "Certainly, [on a plane] people are in close contact for long periods of time, and one would think that there's a higher likelihood of coming in contact with somebody who's sick. But there's nothing to show that it happens any more often than in a normal working environment."

To trap viruses, bacteria, and fungi most newer airplanes filter the air with HEPA filters similar to those used in hospital respiratory isolation rooms, according to the CDC.

"The planes have very good filtration systems, and they also introduce fresh air into circulation. So any microbes that might be in the air would possibly be filtered out pretty quickly," Brunette says.

Still, filtration isn't foolproof. "It's not 100% air exchange all the time, just as it is not in any of our buildings. The fresh air intake is incremental over time, so there's a fair amount of air sharing over time in the airplane," Schaffner adds.

And you can still catch a cold or the flu if someone near you coughs or sneezes infected droplets that directly enter your eyes or nose. Or you might touch a contaminated armrest or tray table and transfer the germs to your eyes or nose by hand.

Also, the air within planes is usually very dry, with 10%-20% humidity, according to the CDC. When your mucous membranes dry out as a result, you're more susceptible to infection.

So what can you do to stay one step ahead of cold and flu germs while flying? Experts offered these tips.

1. Wash hands frequently. To cut down on viruses that hitch a ride on your hands, "frequent hand washing or using hand gels is very important," Schaffner says. An alcohol-based gel hand sanitizer that contains 62% ethanol does the best job at killing germs. After you wash with soap and warm water, you can use some gel to get your hands even cleaner. Avoid hand contact with your face.

2. Stay hydrated. "Keep up your fluids," Schaffner says. Avoid or limit caffeine and alcohol, because both can cause dehydration. If you want to indulge in an alcoholic drink or a cup of java, make sure you drink plenty of water before and during the flight. You can also keep your eyes and nasal passages moist with saline eye drops and saline nasal spray.

3. Ask a flight attendant for new seating if a passenger nearby is coughing, sneezing or appears ill. "Proximity matters," says Schaffner, who once developed a cold within a couple of days after sitting by a sneezing, sniffling plane passenger. "Being very close to the source -- in the same row or two seats in front or back -- those are the folks who are at greatest risk," he says. "After that, the risk tails off very remarkably."

The reason? Large aircraft are designed so that air doesn't blow from the front to the rear of the cabin, but instead, air circulates "segmentally," from ceiling to floor. "You're really in your own kind of air zone, with about two rows in front and two in back," Schaffner says.

The longer you're seated near an ill passenger, the greater your risk of exposure, Schaffner adds. "The longer you're together, the more apt you are to talk with each other, perhaps even touch the same things, and the longer you share the same airspace."

4. Consider getting a flu shot before you travel. Some experts like Schaffner worry that this year's flu season may be harsher than in the last three years.

It takes two weeks to get maximum immune protection from the flu shot, Schaffner says. But getting the shot late can still confer some protection. "From the moment you get the inoculation, your immune system begins to rev up in response to the vaccine."

"Although colds are a bother," Schaffner adds, "influenza is the viral infection that will put you into the hospital. It's the one that can get complicated by pneumonia, it's the one that year in and year out, on average, causes 36,000 deaths each year. It's the serious one. Get vaccinated. Protect yourself. Then you'll be a good citizen on the airplane and at home. You won't transmit influenza to anyone else, either."

What Doesn't Help?

Does wearing a mask help to protect you from colds and flu on planes? "I think that's going a little overboard. I don't think that's going to make a difference," Brunette says. "It doesn't seem realistic to me that people should be wearing masks on an airplane."

Schaffner doesn't believe that blankets or pillows transmit germs, either. "It's never been shown, and it's highly unlikely," he says. If so, "we would be in a hard place. We would be anxious about staying at hotels and being in any kind of group circumstance, if that were the case."

What about taking popular over-the-counter products, such as Airborne? This herbal cold remedy claims to help prevent colds by boosting the immune system. Its ingredients include vitamin C, zinc, and echinacea.

No need to buy these remedies, according to Schaffner. He says that he's "skeptical" of these types of products because they lack good studies to show effectiveness. "The quip is: 'In God we trust. All others must provide data.'"

Battling Noroviruses on Cruise Ships

If you're on a cruise, don't ruin your trip with much concern about germs, experts say. But realize that in the semi-confined quarters of a cruise ship, contagious illnesses can spread fast, particularly noroviruses. These viruses cause what many call the "stomach flu." Typical symptoms of nausea, vomiting, diarrhea, and stomach cramping last for one to two days, according to the CDC.

Noroviruses flourish in the winter, but also year round, says Jaret Ames, chief of the CDC Vessel Sanitation Program, which partners with the cruise industry to promote sanitation and minimize the risk of gastrointestinal illness on ships.

Since 2001, more outbreaks of gastrointestinal illness have been reported, including those from noroviruses, according to the CDC's web site. The reasons? More passengers, more ships and an average cruise length of seven days -- ample time for people to mingle and come in contact with infectious germs. However, the risk of gastrointestinal illness is still small: less than 1% during an average week-long cruise, the CDC says.

Once noroviruses contaminate surfaces, some may remain after routine cleaning. "If anything, the importance of hand washing is greater than ever on a cruise ship," Schaffner says. "You may think you're in an idyllic, somewhat protected environment -- you don't have to be as careful. Au contraire. We'd like you to be even more careful than you are at home."

Passengers can fall ill if they touch objects or surfaces contaminated with norovirus -- among them, doorknobs, railings, elevator buttons, or counters -- and then place their hand in their mouth. People can also be infected if they have direct contact with a sick person or consume food or drink that is contaminated with norovirus. If an ill person vomits or has diarrhea in a whirlpool bath or swimming pool, others who come in contact with the water can be infected, too.

Some tips to reduce the risk of gastrointestinal illness on a cruise ship:

  • Wash your hands for at least 20 seconds before eating or smoking. Also wash hands after using the restroom, returning to your cabin, changing a diaper, helping a sick person, or touching surfaces that a lot of other passengers have touched, such as doorknobs and railings.
  • After you've washed your hands in a restroom, dry your hands with a paper towel and use the towel to turn off the faucet and open the door.
  • Washing with warm water and soap is best, but if you can't do so during an excursion, use an alcohol-based gel hand sanitizer that contains 62% ethanol.
  • Notify cruise staff about sick passengers.

Show Sources

SOURCES: William Schaffner, MD, professor, Vanderbilt University School of Medicine; vice president, National Foundation for Infectious Diseases. Gary Brunette, MD, MS, medical epidemiologist, CDC Travel Health Team. Jaret Ames, chief, CDC Vessel Sanitation Program. CDC Health Information for International Travel 2008.

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