The ongoing measles outbreak in West Texas has doubled in size to 48 cases. It's the state's worst in nearly 30 years.

The measles outbreak first reported in Gaines County, Texas, has doubled to 48 cases in the last four days, the Texas Department of State Health Services said in a statement Friday.

The measles outbreak in the South Plains region, in West Texas, has expanded to at least 48 people, most of them children.