Los Angeles County health officials warned Friday that train passengers and visitors at Union Station may have been exposed to measles last weekend by an infected traveler arriving from Chicago, adding to a nationwide surge that has reached 3,471 confirmed cases this year.
The Amtrak Journey and Union Station Exposure Timeline
Public health authorities trace the exposure risk to a traveler who arrived in California on September 10 after riding an Amtrak train from Chicago. The passenger subsequently boarded Amtrak’s Southwest Chief Train 3, arriving at Los Angeles Union Station at 7:03 a.m. on Saturday.
During the stop in Los Angeles, the infected individual spent hours at the transit hub before departing at 10:55 a.m. aboard Amtrak Thruway Bus Route 5717 bound for Bakersfield. Health officials specify that anyone present at Union Station between 8 a.m. and noon on Saturday falls into the window of potential exposure, with the final day to monitor for symptoms set for October 3.
A Statewide Transit Route Across Six Counties
The journey did not end in Southern California. State public health officials note that the traveler passed through at least six counties, moving through Bakersfield, Stockton, Oroville, and Sacramento before reaching Emeryville on the evening of September 13. By Monday morning, the infected passenger boarded another train from Emeryville to Denver.
That cross-country movement directly tied into a parallel warning issued in Colorado. State health officials announced that an out-of-state visitor with measles potentially exposed crowds at Denver’s Union Station on Tuesday, September 15, between 6 p.m. and 9 p.m., followed by a stay at the La Quinta Inn in Steamboat Springs the next morning.
Official Guidance and Public Health Warnings
As jurisdictions coordinate tracing efforts, health leaders emphasize the extreme contagiousness of the virus, which spreads through the air when an infected person breathes, talks, coughs, or sneezes. Common early signs include a fever, cough, runny nose, and red, watery eyes.
“The MMR vaccine is the safest and most reliable way to prevent measles and protect yourself, your family, and your community.”
Dr. Muntu Davis, Los Angeles County Health Officer
In California, Assistant Public Health Director Dr. Rita Nguyen underscored the severity of the illness, noting that measles is one of the most contagious infections that can lead to severe lifelong consequences including permanent brain damage and can also be fatal, especially for children
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Vaccination Status and Nationwide Statistics
Health agencies point to immunization as the primary defense, noting that two doses of the measles-mumps-rubella vaccine offer 97% effectiveness, while a single dose provides 93% protection. Unimmunized individuals or those with unknown vaccination histories face the highest risk and are advised to monitor themselves for up to 21 days.
The recent exposures arrive during a sharp uptick in national transmission. Nationwide figures stand at 3,471 confirmed measles cases and four associated deaths across 39 outbreaks this year, with approximately 9% of patients requiring hospitalization for complications or isolation.
Next Steps for Potentially Exposed Travelers
Individuals who believe they crossed paths with the infected passenger are instructed to stay home, avoid public gatherings, and contact a healthcare provider immediately by phone before visiting any medical facility. Unvaccinated individuals exposed within the past 72 hours may receive the MMR vaccine to prevent infection, while antibody treatment remains an option if administered within six days of exposure.