To understand the virus’s re-emergence in America in 2025, some experts are looking to a past epidemic that had a high death rate in Philadelphia.

The Virginia Department of Health is sounding the alarm after a person who traveled through the Washington Dulles International Airport tested positive for measles.

Washington has seen 10 confirmed cases of measles so far in 2025, according to the state Department of Health, or DOH. The cases have all been on the west side, including six in King County and two each in Whatcom and Snohomish counties. The Whatcom County cases involved two family members in the same household.

Officials say a traveler from out of state who visited two Wisconsin gas stations may have exposed others to measles.

The Virginia Department of Health says someone with measles traveled through Washington Dulles International Airport on Tuesday, Aug. 12.

The out-of-state traveler visited the Flying J Travel Center in Roberts, Wisconsin, and the Pilot Travel Center in Beloit on Aug. 4.

The number of reported cases of the highly contagious disease has risen to 177 confirmed and 11 probable so far this year, according to provincial data updated every Wednesday. The data is up to Aug.

Officials from the CDPHE warned about a possible measles exposure at Denver International Airport in Concourse C.