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.

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.

The ongoing measles outbreak in West Texas has doubled in size to 48 cases, mostly in children and teens, making it the state's worst in nearly 30 years. File video above: Doctor discusses impact of U.