A teenage girl from New Zealand sick with measles visited Disneyland and other popular tourist stops across Southern California earlier this month, possibly infecting others, local government health officials warned.

The alert comes amid the worst outbreak of measles in the United States in a quarter century, with more than 1,200 cases reported across 30 states since October 2018, according to the U.S. Centers for Disease Control and Prevention.

“The Los Angeles County Department of Public Health is looking to identify others who are at risk for measles and may have been exposed to a non-resident measles case that traveled to Los Angeles County while infectious,” the health department said in an advisory on Friday night.