Federal health officials are urging Americans to get vaccinated against measles before traveling abroad.

This follows a new report that the Centers for Disease Control and Prevention issued on Thursday showing that the number of measles cases nationwide has hit a 20-year high.

Dr. Anne Schuchat, the director of the CDC’s National Center for Immunization and Respiratory Diseases, said that many of the recent cases could be traced to the Phillippines, where a recent epidemic infected more than 30,000 people.

“These were Americans traveling to the Philippines and bringing the virus back and into communities where lots of people were not immunized,” said Dr. Schuchat.

So far this year, 288 measles cases have been identified in the U.S., including 26 in New York City, five across New York State, and three in New Jersey.