Cholera in the Dominican Republic. Dengue fever in the Caribbean. Measles in Ukraine.

'We see a lot of people who, after retirement, want to take the trek of a lifetime in Nepal, but it isn't the same as going to Kansas City, and a lot of them don't realize this,' says Phyllis Kozarsky, an infectious-disease expert at Emory University and travel health consultant for the Centers for Disease Control and Prevention, both in Atlanta. Many popular areas lack basic medical care, let alone easy access to a local drugstore.

See Your Doctor

'I walk through the aisles of my local pharmacy and carry the things I'd like to have with me in the event of a minor illness,' such as pain relievers and anti-diarrhea medication, says Dr. Kozarsky.

The CDC travel health website has a regularly updated list of health risks and vaccination recommendations and requirements for specific countries. Some clinics use a software program, Travax, which tracks disease risk data. Paul McKinney, developer of the program and medical director of the travel clinic at the University of Louisville in Kentucky, says it also helps identify vaccine requirements for travelers who may be going from one foreign country to another. For example, travelers going to India from the U.S. don't require a yellow-fever vaccination, but if they are first visiting countries where yellow fever is endemic, India may require them to be vaccinated.

Vaccine Risk

Live vaccines such as the one for yellow fever can be risky for those over 60 or 65, Dr. McKinney warns, because of a higher likelihood of side effects. Patients taking steroids, which lower resistance to viral infection of any kind, are also less likely to have a good response to a vaccine.

It's also important to be up-to-date on routine vaccinations such as flu and tetanus before leaving the U.S. A shingles vaccine for those over 65 can reduce the chance of being struck with a painful and debilitating case of the virus, which is related to childhood chickenpox. Measles are also a growing concern in Europe, Dr. Kozarsky says. If you're unsure whether you had measles or a childhood vaccination for it, a blood test can determine if there are antibodies to the disease.

For the worst-case scenario, it is also a good idea to consider an emergency medical evacuation program. Before a trip to Russia last year, Marvin Freedman, a retired Justice Department investigator and avid world traveler, bought a membership from MedjetAssist, on the recommendations of some fellow travelers. He admits he was skeptical it could deliver as promised: evacuation to the hospital of his choosing for the $260 plan.

While poking around historic towns in the Golden Ring area outside Moscow, Mr. Freedman picked up a bug that worsened by the time he got to St. Petersburg. Admitted to a hospital there, he was pumped full of antibiotics by doctors who diagnosed a bacterial infection. But he wasn't getting better. After a few days he placed a call to MedjetAssist, where he was connected to doctors at the University of Pittsburgh Medical Center who determined he needed to be brought home.

Ms. Landro is an assistant managing editor for The Wall Street Journal and writes the paper's Informed Patient column.

Laura Landro