A teenage girl visiting from New Zealand was infectious with the measles virus when she visited Disneyland and Disney California Adventure Park and surrounding areas this month, CBS Los Angeles reports. According to the Orange County Health Care Agency, the teen was in the area from August 11 through August 15.

Orange County residents may have been exposed to measles at Disneyland and Disney's California Adventure on August 12 as well as at the Desert Palms Hotel from August 11 to 15.

The health care agency has been working with Disneyland and the nearby hotel to reach people believed to have had contact with the teen.

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Those who were at the theme parks and hotel around the same time should monitor themselves for illness with fever and/or an unexplained rash from 7 days to 21 days after potential exposure.

The agency has advised people who develop symptoms to stay at home and immediately call a health care provider.

In 2015, an outbreak involving dozens of cases of measles was traced to exposure to an infected visitor at Disneyland.

This has already been the worst year for measles in the U.S. in decades. The CDC reports at least 1,203 cases have been confirmed in 30 states, with the largest outbreak centered in the New York area.