Los Angeles, California — California health officials are warning travelers who may have been exposed to measles after an unvaccinated passenger traveled through six counties by Amtrak train and connecting buses earlier this month before eventually leaving the state for Denver, Colorado.
The California Department of Public Health said Friday that the passenger later required hospitalization after developing measles. Officials are now working with county health departments and federal health authorities to identify people who may have been exposed during the person’s journey.
The passenger arrived in California on Sept. 10 aboard an Amtrak train traveling from Chicago to Los Angeles. The trip then continued through Southern and Northern California before the passenger left the state several days later.
Six California Counties Included in the Travel Route
According to the California Department of Public Health, the passenger’s journey included multiple trains, stations and connecting buses between Sept. 10 and Sept. 15.
The affected travel routes passed through Los Angeles, Kern, San Joaquin, Butte, Sacramento and Alameda counties.
The passenger’s California itinerary included:
Sept. 10-12: Chicago to Los Angeles, arriving at Los Angeles Union Station.
Sept. 12: Los Angeles to Bakersfield, arriving at Bakersfield Station.
Sept. 12: Bakersfield to Stockton, arriving at Stockton-San Joaquin Street Station.
Sept. 12: Stockton to Oroville by thruway bus.
Sept. 13: Oroville to Sacramento by thruway bus, arriving at Sacramento Valley Station.
Sept. 13: Sacramento to Emeryville, arriving at Emeryville Station.
Sept. 14-15: Emeryville to Denver.
Health officials said people who were aboard the affected trains or buses or present at the listed stations during the specified periods may have been exposed.
California Officials Are Contacting Potentially Exposed Travelers
The CDPH said it is coordinating with local health departments and federal health officials to determine who may have been exposed during the journey.
Because measles is highly contagious, identifying potentially exposed passengers is an important part of the public health response.
Dr. Rita Nguyen, assistant state public health officer, emphasized the importance of vaccination following the case and other measles activity in California this year.
“This case, along with previous measles outbreaks in California this year, serve as reminders of the importance of vaccination against measles. Measles is one of the most contagious infections that can lead to severe life-long consequences including permanent brain damage and can also be fatal, especially for children,” said Dr. Rita Nguyen, assistant state public health officer.
What Travelers Should Do After a Possible Exposure
Health officials are urging anyone who may have been exposed to check their measles vaccination status.
Two doses of the measles, mumps and rubella vaccine provide full immunization against measles. People who are not fully vaccinated or are uncertain about their immunity should contact a health care provider to discuss vaccination.
Anyone who may have been exposed should also monitor for symptoms for 7 to 21 days following exposure.
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Possible measles symptoms include fever, cough, runny nose, red or watery eyes and a rash.
The illness can initially resemble other respiratory infections, making it important for people who may have been exposed to pay close attention to developing symptoms.
Call Before Going to a Medical Facility
People who develop symptoms after a possible exposure should take precautions before seeking medical care.
The CDPH advises anyone who suspects they may have measles to call a health care provider before arriving at a medical facility.
That advance call is important because measles can spread easily to other people in waiting rooms, offices and other health care settings.
Health officials can then provide guidance on how to receive appropriate medical attention while reducing the possibility of exposing others.
California Has Reported 59 Measles Cases in 2026
The latest case comes as California continues to monitor measles activity across the state.
As of Sept. 14, California had reported 59 measles cases across 13 counties in 2026, according to the CDPH. The department said 94% of those patients were either unvaccinated or had an unknown vaccination status.
The CDPH also noted that roughly 90% of unvaccinated people who are exposed to measles will contract the disease.
Were you or someone you know traveling through any of these California stations during the listed dates? Share your experience or questions in the comments.