Measles is still a risk for travelers, regardless of destination, and vaccination remains the best way to prevent it, according to travel health experts.

Data from 57 travel and tropical medicine clinics on six continents shows that between 2000 and 2014, there were 94 reported measles cases in these clinics, with two-thirds occurring after 2010. Measles affected tourists, business travelers, and people visiting friends or family.

"We think measles is definitely something people should be concerned about, specifically getting vaccinated against," said lead author Mark J. Sotir of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.

The measles virus is highly contagious, spread by respiratory droplets in sneezes and coughs. Measles can cause diarrhea, pneumonia and even death.

According to CDC recommendations, all children should have had two doses of measles vaccine by age 6, which will be 97 percent effective at preventing infection. Children and adults traveling internationally should have evidence of these vaccines.

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Infants ages 6 months through 11 months can receive a dose of the vaccine in case of international travel, and will receive two more doses after age 1 year on the regular vaccine schedule.

"There have been reports of people getting measles in airports and on airplanes," as well as in destination countries, Sotir told Reuters Health.

The year with the most cases was 2011, when 11 were reported in Asia, eight in Europe, four in Africa and one in the Middle East or Caribbean.

Over the whole study period, exposures were reported in 30 countries, most often in Thailand, followed by India, Singapore, Nepal, China and the Philippines.

Almost 90 percent of measles infections happened to adults, the researchers report in Clinical Infectious Diseases.

Although the measles vaccine has greatly reduced the number of cases, there are still 20 million cases annually worldwide, Sotir said.

There have been recent outbreaks in Germany, France, Croatia and Bosnia-Herzegovina, the authors write.

A measles infection becomes symptomatic with fever, eye irritation, cough and a blotchy red rash between seven and 21 days after exposure to the virus.

"Measles is a really contagious virus," said coauthor Dr. Douglas H. Esposito, also of the CDC. "The best way to protect against it is to be fully vaccinated."

Declining vaccination rates are a "broad public health issue," Esposito told Reuters Health.

"We feel that people should probably be evaluated by a healthcare provider four to six weeks before they go," Sotir said.

"We recommend people be up to date on routine vaccinations as well as destination-specific vaccinations," like those for tropical climates, Esposito said.