Maryland health officials are investigating possible measles exposures after a person with a confirmed case traveled through the region on an Amtrak train.

The person traveled from Philadelphia on Jan. 7, the health department said on Sunday. Measles can be spread easily through the air when an infectious person breathes, coughs or sneezes. Health officials shared the following public places as possible points of exposure:

• Amtrak NE Regional Train from Philadelphia 30th Street Station to Washington, D.C. Union Station on Jan. 7 between 9 p.m. and 11:30 p.m.
• Amtrak BWI Shuttle to and from the BWI train station and the drop-off points outside of the lower-level of BWI Airport on Jan. 7 between 10:45 p.m. and 1:30 a.m. on Jan. 8.
• BWI Airport Parking Shuttle to and from outside of the lower-level outside of BWI Airport and the BWI Airport’s long-term parking lots on Jan. 7 between 11 p.m. and 2 a.m. on Jan. 8.

Officials said no exposures were identified inside the terminals of Baltimore-Washington International Thurgood Marshall Airport.

Measles had been eliminated in the U.S., but a decline in MMR (measles, mumps and rubella) vaccination rates among children has led the disease to resurface across the country. There were at least 2144 cases of measles in the U.S. in 2025, with 93% of the people being unvaccinated, according to the Centers for Disease Control and Prevention.

At least three cases of measles were identified in Maryland in 2025, according to health officials. One of them was in Howard County after a resident traveled abroad, and two cases were in Prince George’s County, also after international travel.

What to do if you think you’ve been exposed

If you think you may have been exposed, check your vaccination records. Health officials said you should be considered protected if you have received two doses of the measles vaccine or if you were born before 1957.

People who aren’t fully vaccinated should call their health care provider or local health department and monitor for any early signs of measles for 21 days. Watch out for a fever of more than 101 degrees, runny nose, cough and red, watery eyes.

Symptoms usually develop 10 to 14 days after exposure. People also develop a red rash on the face that spreads to the rest of the body one to four days after the early symptoms. The person is contagious beginning four days before the rash appears until four days after the rash surfaces, according to health officials.

“Vaccination remains essential to protecting ourselves, our families, and our communities against measles and other infectious diseases,” said Meg Sullivan, the Maryland Department of Health’s deputy secretary for Public Health Services. “These types of situations underscore the importance of knowing your vaccination status and ensuring you are up to date with all recommended vaccines.”