Thousands potentially exposed to measles at multiple transportation hubs nationwide

Health officials have warned of a potential measles exposure across multiple transportation hubs, possibly exposing thousands of travelers to the highly contagious virus.

In Pennsylvania, which is battling a measles outbreak connected to four deaths, Philadelphia International Airport is facing a possible measles exposure after an unidentified infected individual traveled through the location. 

The possible exposure took place from September 13 to 14 at Terminals B and F, as well as areas that connect other terminals in C, D, and E. Health officials said they did not leave the airport, which sees more than 30 million passengers per year.

This is the second measles-related incident in Philadelphia. On September 11, the main campus at Children’s Hospital of Philadelphia (CHOP) reported a possible exposure. Officials say the two cases are unrelated. 

On the West Coast, California public health officials are also warning about a possible measles exposure across multiple counties. 

An infected and unvaccinated passenger traveled through the state between September 12 and 14, using Amtrak trains and buses with transfers in at least six populated counties. About 10 to 12 million passengers ride Amtrak trains in California each year. 

Missouri has also had a confirmed case of measles in a patient who used public transportation. In late August, an infected individual boarded an Amtrak train in western Missouri and traveled through the St Louis area. 

These exposures come as the nation is hit with the worst measles resurgence in 35 years.

As of Thursday, the Centers for Disease Control and Prevention (CDC) reported 3,471 confirmed cases of measles in the US, the most in three decades and 1,182 more cases than all of last year, when there were 2,289 cases.

There have been 39 new outbreaks reported in 2026, and 95 percent of confirmed cases are outbreak-associated.

Travelers at the Philadelphia airport who were in the impacted areas at the time of the possible exposure are urged to check their immunity and vaccination status and seek medical care if they are not immune, officials said. 

‘This week’s measles exposures are a reminder of how important it is for all of us to be up to date on our vaccinations,’ said Philadelphia Health Commissioner Dr Palak Raval-Nelson in a statement.

‘Every Philadelphian who is fully vaccinated has little to fear from the situation at CHOP and the airport. Even more importantly, every one of those people is doing their part to help protect our most vulnerable from measles,’ Raval-Nelson continued.

As of Monday, Pennsylvania has seen a total of 792 measles cases, including 97 new cases in the last seven days, per state data.

Of those cases, 155 people have been hospitalized and four have died from measles-associated complications. Children under the age of 18 account for 31 percent of cases.

California health officials are also working with county and federal officials to identify and notify anyone who may have been exposed during the Amtrak incident. 

‘This case, along with previous measles outbreaks in California this year serve as reminders of the importance of vaccination against measles,’ Dr Rita Nguyen, assistant state public health officer, said in a statement.

‘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,’ she added.

The unidentified passenger arrived in California aboard an Amtrak train from Chicago, Illinois, to Los Angeles from September 10 through 12.

After arriving, the passenger got onboard another Amtrak train from Los Angeles to Bakersfield, California, arriving at Bakersfield Station.

From there, they traveled to Stockton, arriving at Stockton-San Joaquin Street Station. They then took a bus to Oroville, and the next day they traveled from Oroville to Sacramento by bus, arriving at Sacramento Valley Station.

The passenger then traveled from Sacramento to Emeryville, arriving at Emeryville Station.

From September 14 through 15, the passenger traveled from Emeryville, California toward Denver.

The travel routes show the passenger traveled through Alameda, Butte, Kern, Los Angeles, Sacramento and San Joaquin counties.

California has already reported 59 measles cases across 13 counties thus far in 2026. The vast majority, 94 percent, of those patients were either unvaccinated or did not know their vaccination status.

In Missouri, an unidentified infected individual boarded an Amtrak train in Sedalia, Missouri on August 27. The train made stops at stations across Missouri and Illinois, including Washington, Kirkwood, downtown St Louis and Alton. 

A St Louis County resident has tested positive for measles, the county’s first confirmed case in 20 years, health officials announced on Thursday. The case appears to be the second infection linked to the Amtrak exposure, St Louis Post-Dispatch reported.

Popular sightseeing destinations in Missouri are also dealing with possible measles exposures. 

Missouri state health officials said eight businesses, including Busch Stadium, may have had a possible exposure after an infected individual visited several locations between September 12 and 14. Officials declined to say whether it was linked to the late August Amtrak exposure. 

Missouri physicians have reported 10 measles cases to the state in 2026, compared to an average of two cases per year. 

Measles is one of the most infectious diseases known to man – for unvaccinated people, nine in ten of those exposed to the virus will get infected.

It is preventable, however, with the measles, mumps, and rubella (MMR) vaccine.

The shot is typically given once between ages 12 and 15 months and again between ages four and six. Two doses slash the risk of measles infection by 97 percent, according to the CDC. 

The vast majority of measles cases in both 2025 and 2026 were in individuals who had not received both doses of the measles, mumps and rubella (MMR) vaccine.

Measles can cause serious illness in adults – complications are more common in children younger than five years and adults older than 20 years, according to the CDC.

An unvaccinated adult who contracts measles faces a higher risk of severe complications and hospitalization than school-aged children. The death rate for unvaccinated adults who contract measles is one to three deaths per 1,000 cases.

Measles is characterized by cough, fever, a distinctive blotchy rash that starts on the face before spreading down the body and tiny white spots inside the mouth called Koplik spots.

The virus spreads through direct contact with infectious droplets or through the air. Patients with a measles infection are contagious from four days before the rash through four days after the rash appears.

Enclosed areas like airports and planes are extremely risky locations for disease transmission.