A case of the virus has emerged in Washington DC, the Department of Health confirmed as they say a contagious individual traveled on Amtrak to visit.

(Bloomberg) -- A measles patient traveled to Washington, DC, on an Amtrak train without knowing their health status on March 19, further exposing people to the highly infectious disease as the national outbreak grows.

A measles patient traveled from New York to Washington, DC, on an Amtrak train on the evening of March 19, exposing people along the heavily traveled route to the highly infectious disease.