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.

Texas health officials reported 17 new measles cases on April 29, bringing the total confirmed cases since late January to 663.

The measles outbreak centered in the South Plains region of Texas grew to 663 cases on Tuesday, according to health officials. The latest update from the Texas Department of State Health Services adds 17 new cases since the agency's last update on Friday.