An outbreak of measles in California – traced back to the state’s Disney parks – has prompted state health officials to warn local residents about exposure to international travellers at theme parks.

Since the outbreak started in December, around 59 cases of Measles have been reported in California. Of those, 42 have been linked to initial exposure at the Disneyland or Disney California Adventure Park. Overall, including four other US states and Mexico, 70 cases have been linked to the Disney parks.

Any patient with measles-like symptoms who has been to places where tourists congregate, such as theme parks and airports, should “be considered to have a plausible exposure to measles,” said a statement from the California Department of Public Health (CDPH). Meanwhile, state epidemiologist Gil Chavez told the Associated Press that any adults who haven’t been immunised, or children that are too young, should avoid Disneyland California.

According to the CDPH, more cases are expected and health officials have urged people to get vaccinations.

“California has many international attractions and visitors come from many parts of the world,” continued the CDPH statement. “It is important for health care providers and the public to be aware that measles transmission can occur in California, and they can prevent transmission by receiving the MMR vaccine.”