5 Hidden Dangers in International Travel

Jeffrey B. Nemhauser, MD; Sue K. Partridge, MPH; Amanda A. Akosa, MPH


August 26, 2019

Editorial Collaboration

Medscape &

We live in an interconnected world. In fact, tourism is now the world's third largest export.[1] A few hot spots attracted most US travelers in the past, but your patients will increasingly be visiting far-flung locations that are truly global.

Travel puts all of us at potential risk for preventable illnesses, but most people do not seek out health advice as they plan their next adventure. Including travel questions in routine visits opens an opportunity to assess possible risks as well as provide important patient education, vaccinations, and medications.

What are the five areas that will provide the biggest return on the investment of your limited time and best prepare your patients for safe and healthy international travel?

1. Vaccination

Make sure your patients are up to date on all routine vaccines, including measles, mumps, and rubella (MMR); varicella (chickenpox); and the seasonal flu vaccine. Determine what specific vaccines are recommended for the destinations your patient will be visiting by searching the Centers for Disease Control and Prevention's (CDC's) Destinations pages.

Note about measles: Measles remains a common disease in many parts of the world. Most of the outbreaks in the United States have started with an infected US traveler returning to an undervaccinated community and spreading the disease. From January 1 to June 27, 2019, 1095 cases of measles were confirmed in 28 states. This is the highest number of reported US cases since 1992, and the number continues to climb.

Check to see that patients ≥ 12 months of age who are traveling internationally have presumptive evidence of immunity against measles before departure. For those who do not, administer measles-containing vaccine, primarily as the MMR vaccine. Infants 6-11 months of age who will be traveling internationally should receive one dose of MMR vaccine, although this dose does not count toward the routine Advisory Committee on Immunization Practices schedule. Additional vaccine recommendations for international travelers are available on the CDC Measles website.

2. Insect Bites

Depending on your patient's destination, insect bites can transmit a variety of pathogens, including mosquito-borne Zika, dengue, yellow fever, or malaria; tick-borne Lyme disease or spotted fevers; fly-borne leishmaniasis or sleeping sickness; and flea-borne typhus or plague. Encourage patients to use an Environmental Protection Agency-registered insect repellent with one of the following active ingredients: DEET (N,N-diethyl-meta-toluamide), picaridin, IR3535, oil of lemon eucalyptus, para-menthane-3,8-diol, or 2-undecanone. Sleeping in a room without screens or air conditioning increases risk for insect bites, so use of a mosquito net in those cases is advised.

Note about Zika: Zika is and will continue to be a potential risk in many countries in the Americas and around the world.

In February 2019, after an extensive review of available scientific data on all countries of the world, CDC updated the Zika map and recommendations for travel to areas with past or current Zika transmission. The new Zika travel recommendations rely on shared patient-provider decision-making. CDC encourages you to review the recommendations that accompany the updated map and equip yourself with information to appropriately counsel pregnant women, couples considering pregnancy, and patients of reproductive age about travel to areas with past or current Zika transmission (indicated by purple on the Zika map).

When counseling pregnant women or couples planning pregnancy about travel to these areas, factors to consider include unknown level of risk, potential delays in identifying an outbreak, willingness to take protective measures, type of accommodations during travel, type and length of possible exposure, and individual preferences. If a Zika outbreak does occur, CDC recommends that pregnant women not travel to the affected area.

3. Food and Water Safety

Contaminated food or drinks can cause travelers' diarrhea, the most common travel-related illness, and other gastrointestinal diseases. Travelers to developing countries are especially at risk.

Encourage patients to choose food that is cooked and served hot, food from sealed packages, peeled fruits and vegetables, and pasteurized dairy. In most developing countries, travelers should avoid drinking tap water, even in cities. The same applies to ice, which is probably made with tap water. Bottled and canned drinks are safer choices.

4. Blood Clots During Long-Distance Travel

More than 300 million people travel on long-distance flights (generally > 4 hours) each year.[2] Deep vein thrombosis (DVT) can be a serious risk for some long-distance travelers, regardless of the mode of transportation (air, car, bus, or train).

Patients planning long-distance travel should be counseled about associated risks that increase their chances of developing DVT. People at higher risk include those who were recently hospitalized or had recent surgery, pregnant women, and those in the postpartum period (up to 3 months after childbirth). Other risk factors include history of previous DVT; family history of DVT; obesity; increased estrogen; indwelling catheters; cancer; and certain chronic medical illnesses, such as heart or lung disease.

A prevention plan is key. Educate patients on the symptoms of blood clots and what to do if they have concerns. Remind patients to move their legs frequently and to walk around every 2-3 hours while traveling.

5. Road and Traffic Risks

Did you know that motor vehicle crashes are the number-one killer of healthy US citizens in foreign countries? Nearly half of medical evacuations back to the United States are the result of a car crash, and a medical evacuation can cost upward of $100,000.

Roads in developing countries may be poorly maintained, and traffic laws may be followed haphazardly or not enforced. A crash in a developing country is more likely to be fatal because of lack of readily available emergency care. It may take a long time to get to a center that can provide appropriate attention, and care may not be up to US standards.

Encourage patients who plan to travel internationally to:

  • Always wear seat belts;

  • Avoid riding in a car in a developing country at night, if possible;

  • Avoid riding motorcycles;

  • Know local traffic laws before driving;

  • Ride only in marked taxis that have seat belts;

  • Avoid overcrowded or top-heavy buses or vans; and

  • Be alert when crossing the street.

Travelers with small children should plan to bring car seats because these may not be available in many countries or may not meet US safety standards.

Use CDC's Yellow Book: Health Information for International Travel, updated for 2020, for more information on these topics and many others related to your patients' international travel needs.

The Yellow Book 2020 compiles the US government's most current travel health guidelines, including pretravel vaccine recommendations; destination-specific health advice; and easy-to-reference maps, tables, and charts.

The Yellow Book is available free online or can be purchased through any major bookseller.

Web Resources

CDC Yellow Book 2020

Measles Vaccine Travel Assessment Tool

International Road Safety

Blood Clots and Long-Distance Travel: Advising Patients

Can I Eat This? CDC app

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