Additional measles cases "are likely to occur" as an outbreak of the virus grows, the Texas Department of State Health Services said in its latest update.

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.