Travelers visiting some popular cruise destinations are at an increased risk of contracting a concerning illness that’s spreading in the Caribbean, Mexico, and other areas.

The U.S. Centers for Disease Control and Prevention is advising those planning to travel internationally to make sure they’re vaccinated against measles. The warning, issued last week, says cases of the highly contagious disease are on the rise around the world.

Measles cases are on the rise in many countries around the world, prompting the U.S. Centers for Disease Control and Prevention to update its travel warning.