As students return to school following spring break, Texas measles cases are continuing to grow with health officials warning of more cases to come.

HOUSTON — A measles outbreak in Texas has intensified, with the Texas Department of State Health Services now confirming 309 cases statewide since late January — up from 279 cases reported earlier this week. There's at least one confirmed case in 14 Texas counties.

Texas' outbreak, which has largely spread in undervaccinated Mennonite communities, could last a year, based on studies.