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 US in a quarter of a century, with more than 1,200 cases reported across 30 states since October 2018, according to the US Centers for Disease Control and Prevention (CDC).

“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.

The Orange county Health Care Agency said the girl was in southern California from 11 to 15 August.

During her stay in southern California the girl visited the Universal Studios theme park and several destinations in Hollywood and Santa Monica, LA health officials said, adding that anyone who was also at those locations may be at risk of developing measles.

Orange county health officials said the girl visited Disneyland in Anaheim on 12 August and stayed at the nearby Desert Palms Hotel. There was no information on her current condition.

So far in 2019 a total of 16 measles cases have been reported among Los Angeles county residents, and 11 infected people are known to have traveled through the county.

The CDC said earlier this week that there had been a 1.8% increase in the number of cases of the highly contagious and sometimes deadly virus in the US between 8 and 15 August.

The disease was declared eliminated in the US in 2000, meaning there was no continuous transmission for at least a year. CDC officials say the US risks losing its measles elimination status if the current outbreak, which began in October 2018 in New York, continues until October 2019.

Measles, considered one of the most contagious viruses in the world, infects 90% of exposed people who have not been immunized, according to the Los Angeles county health department.

Symptoms of the virus, which can cause severe complications and even death, include fever, cough, runny nose, red eyes and a characteristic rash which can appear up to three weeks following exposure.