Here’s a souvenir you don’t want to bring home from your travels abroad: measles.
The United States declared that measles had been eliminated–no continuous spread of the disease for more than 12 months–in 2000. Unfortunately, though, periodic measles outbreaks continue to occur in the United States, because air travel makes it easy for unvaccinated people to import the highly contagious disease from countries that have not yet eliminated it.
Based on the findings of a study out Tuesday, millions of U.S. residents each year fly to foreign destinations without first getting their recommended measles immunization, placing themselves and the people with whom they come in contact back home at risk for the disease and its complications.
More than half of imported cases occur in unvaccinated U.S. travelers who became infected outside the country. For example, in 2015, a large measles outbreak in multiple states was thought to have started with a traveler who contracted the disease overseas and then visited Disneyland while infected. The traveler was never identified, but scientists at the Centers for Disease Control and Prevention showed that the type of measles virus in the Disneyland-centered outbreak was identical to the one that caused a large 2014 measles outbreak in the Philippines. Worldwide each year, about 267,000 cases of measles are reported and an estimated 146,000 people, mainly children, die of the disease, according to the CDC.
Because people are more likely to contract measles outside the United States than in it, the Advisory Committee on Immunization Practices (ACIP) recommends that U.S. travelers to other countries get vaccinated against the disease if they haven’t already had it or been been immunized against it.