No matter the destination, travelers often come home with more than pictures and T-shirts. They pick up a malady - a cold or a stomach ailment, or worse.
But as the summer travel season gets under way, those in the business of keeping people healthy say good planning and some vigilance can increase the odds of keeping illness at bay.
They say that for most people traveling domestically by car, train or plane, the most important steps to staying healthy - or at least reducing the severity of a cold - are simple. Get plenty of rest and proper nutrition leading up to the trip and drink extra fluids to stay hydrated, particularly on a plane filled with dry air. Frequent hand-washing is also crucial.
If Mary Barton of Baltimore was making a list, she'd tell travelers to avoid touching germy surfaces with bare hands.
"The door knobs, the railings, the earphones on the plane," she said. "I don't touch anything. I don't use airplane blankets. And I won't eat airplane food that's not packaged. My husband might say I'm a bit fanatical."
But this mantra, as well as drinking orange juice instead of dehydrating caffeinated drinks, meant Mary and Red Barton recently returned to BWI Marshall Airport from their vacation in Orlando, Fla., without so much as a sniffle.
The experts say that as trips get longer and more exotic, there are also some other steps to consider.
On flights longer than two hours, travelers need to walk up and down the aisle or at least stretch. This staves off deep vein thrombosis, or potentially deadly blood clots, said Dr. Michael P. Zimring, director of the Center for Wilderness and Travel Medicine at Mercy Medical Center and the author of Healthy Travel.
For overseas trips, he said, it's also important to check which immunizations are necessary or recommended. The Centers for Disease Control and Prevention (cdc.gov) issues advisories. Recent warnings include a yellow fever outbreak in Brazil and Paraguay and measles in Israel.
For foreign trips in general, Zimring recommends shots for hepatitis A, which is contracted through contaminated food, and hepatitis B, which comes from blood and bodily fluid. An up-to-date tetanus shot is also a good idea.
He also says travelers might want to consider an extra medical policy. Medicare and some private health care policies are not good outside of the United States or require an upfront cash payment at foreign hospitals. Some countries are also unable to provide adequate emergency care, and evacuation may be necessary.
In other cases, finding an English-speaking doctor may be difficult. U.S. embassies and hotels may be able to offer referrals.
Zimring advises travelers to carry prescriptions in their original bottles onto the plane to show authorities. And he said to pack commonly needed over-the-counter medications like Pepto Bismol and aspirin, and even an antibiotic for travelers' diarrhea. For the opposite problem, constipation, travelers should be prepared to drink extra fluids, eat fruit and, if necessary, take a tablespoon of Milk of Magnesia.
"In general, travelers should be prepared and informed," said Zimring. "For those big international trips, they should see an experienced travel doctor six to eight weeks in advance so there is time to go over their travel plans, get them proper immunizations and teach them how to protect themselves."
Locally, hospitals including Mercy, Johns Hopkins and Union Memorial have centers focused on traveler health.
As for some of the do-it-yourself preventive supplements, there isn't proof that all of them work, said David Schardt, a senior nutritionist with the Center for Science in the Public Interest.
The maker of Airborne, a widely popular vitamin and herbal remedy, agreed in March to pay $23.3 million to settle a class-action lawsuit over false advertising, including claims it could fend off colds. The company didn't admit wrongdoing but said it would refund the purchase price to those who want it, and boxes now say Airborne "boosts your immune system." About $18 million has already been claimed.
Schardt said Airborne hasn't done much in the way of scientific studies. But three decades of other research into vitamin C, a main ingredient in Airborne and many other over-the-counter remedies, shows that it may shorten the duration of a cold but only slightly. And it doesn't prevent a cold.
"If you drink fluids with the Airborne, that's probably of more help," he said.
If travelers do take vitamin C, they should avoid megadoses that can cause an upset stomach, said Grace Keenan, a medical doctor and director of Nova Medical in Northern Virginia, which combines Western medicine with holistic treatments.
She and colleague Teerawong Kasiolarn, a naturopathic doctor and acupuncturist, say there are some other dietary supplements that can help keep natural defenses up: Vitamin D helps regulate the immune system, but most people are deficient. And they say probiotics, found in pill form and in some foods, can help boost your defenses by coating your system with good bacteria to fight the bad.
They also said to lay off dehydrating alcohol and junk food before and during the trip.
On the plane, which is filled with filtered air that tends to be dry, they suggest applying petroleum jelly in the nostrils - the moisture forms a barrier against bacteria. And upon arrival, they say, travelers could battle jet lag with a massage or melatonin, a sleep hormone.
As for water, many people react badly to any system's tap water that is different from their own, even if it's not unclean. Outside of the United States and Canada, Keenan suggests using bottled water for drinking and teeth cleaning, and avoiding ice cubes and salad that might be washed in tap water.
"The bottom line is to make sure your immune system is in good shape," said Keenan, "because that's your best defense."
Tips for the traveler
*Get plenty of rest, good nutrition and fluids before and during the trip.
*Wash your hands frequently.
*Pack prescriptions, common drugs such as Pepto Bismol, aspirin and even an antibiotic for travelers' diarrhea.
*Walk around on flights longer than two hours.
*Use petroleum jelly in your nostrils while on the plane for moisture that fends off bacteria.
*Consider a massage or melatonin to treat jet lag.
*When going overseas, check with the Centers for Disease Control and Prevention for general travel warnings.
*For exotic trips, see an experienced travel doctor six to eight weeks before for immunizations and advice.
*Drink bottled water even where the systems are clean but unfamiliar to your system.