An outbreak of measles has spread to 48 cases across four counties in the South Plains region of northwestern Texas, doubling in scope from earlier this week, health officials said. Most of the cases are in school-aged children,

At least 49 cases have been confirmed. Health officials — who are scrambling to get a handle on the vaccine-preventable outbreak — suspect 200 to 300 people may be infected.

Texas state health officials confirmed 24 cases of measles, as New Mexico announced its first case this year in a county on the state border.