Measles cases linked to a West Texas outbreak have now been confirmed in two North Texas counties, marking the virus's continued spread across the state. State health officials said cases have been identified in Collin and Rockwall counties,

Texas health officials reported eight new measles cases on Tuesday, with the outbreak spreading to three new counties. The Texas Department of State Health Services has reported 717 measles cases amid the largest outbreak in the United States in at least 25 years.

There’s been a second straight single-digit increase in new measles cases tied to the West Texas outbreak, but the state health department also says three new counties reported one case each. Two of the three new counties are just north of Dallas.