WASHINGTON (AP) — Public health officials are warning travelers and workers at four U.S. airports early last week that they may have been exposed to measles from a traveler arriving from London.

Authorities said Saturday that a passenger later confirmed to have the infectious disease arrived at Washington Dulles International Airport late on Feb. 20. Two days later, she flew from BWI airport near Baltimore on an evening flight to Denver, Colo., and on to Albuquerque, N.M.

Spokesman Tom Skinner at the Centers for Disease Control and Prevention says officials are notifying travelers who sat close to the infected passenger. People who might have been exposed should see a doctor if they develop symptoms of the highly contagious respiratory disease that has been virtually eliminated in the U.S. People are considered immune if they’ve been vaccinated, were born before 1957 or previously had the disease.

Copyright 2011 The Associated Press.