The U.S. declared measles eliminated 25 years ago. But the growing outbreak of the disease centered in West Texas poses a threat to this coveted status—and signals the possibility of measles becoming more common.

Since the measles outbreak began in West Texas, 87 people in Texas have been hospitalized, and two school-aged children have died.

As more counties are being impacted by the ongoing measles outbreak and added to the growing list of counties across Texas, here's what to know.