A trip to Universal Studios Hollywood came with a frightening plot twist after a measles-infected guest spent 11 hours inside the packed park, sparking a public health alert.

Health officials warned Wednesday that anyone who visited the Southern California attraction on Sunday between 10 a.m. and 9 p.m. may have been exposed to the highly contagious virus.

The alert comes as measles continues its dramatic resurgence across the US.

The country has recorded 2,371 confirmed cases in 2026 as of late July, the highest annual total since 1991, according to the US Centers for Disease Control and Prevention.

“With summer travel underway, the risk of exposure to infectious diseases may increase,” Muntu Davis, county public health officer wrote. “We urge everyone to confirm their immunity and get the MMR vaccine if needed, especially before traveling and attending crowded events.”

Measles spreads through the air when an infected person breathes, talks, coughs or sneezes.

The virus can remain in the air and on surfaces for hours after the infected person has left, making crowded spaces especially risky.

People with measles can spread the virus for up to four days before the signature rash appears and for four days afterward.

Infection happens by breathing contaminated air or by touching contaminated surfaces before touching the eyes, nose or mouth.

Officials said anyone who was at Universal Studios Hollywood during the exposure window could develop symptoms seven to 21 days after exposure.

“These individuals should confirm their protection against measles,” the department said in a news release. “Those who have had measles in the past or received the recommended measles vaccine are likely protected but should still monitor for symptoms.”

Visitors should monitor for symptoms through Aug. 16.

Anyone who remains symptom-free for more than 21 days after the exposure is no longer considered at risk.

Measles symptoms include fever, cough, runny nose and red, watery eyes, followed three to five days later by a rash that usually begins on the face before spreading across the body, according to the CDC.

The disease can cause severe complications, particularly in young unvaccinated children and pregnant people.

Serious cases can lead to pneumonia, encephalitis, hospitalization and, in some cases, death, according to the California Department of Public Health.

The latest exposure comes just months after another measles scare at another popular theme park. Orange County health officials warned that an infected international traveler had visited Disneyland and Goofy’s Kitchen while contagious, potentially exposing thousands of guests.

Officials at the time urged anyone who may have been exposed to verify their vaccination status, monitor for symptoms and contact a healthcare provider if they were not immune, underscoring how quickly the highly contagious virus can spread through crowded attractions.

Anyone who develops symptoms should stay home and avoid school, work and public gatherings to help prevent further spread of the virus.