Texas’ health commissioner told lawmakers Monday they are still trying to determine the origin of a South Plains-Panhandle measles outbreak more than a month after the first patients reported symptoms.

Measles has been spreading across the U.S. for the last several weeks, sickening people in at least nine states amid a growing outbreak in western Texas. Several people have been hospitalized and at least one unvaccinated school-aged child in Texas has died,

Public health reporter Fenit Nirappil traveled to the epicenter of the measles outbreak in West Texas to learn what is behind the rise in cases of a disease once thought eradicated in the U.S.

The Montgomery County Department of Health and Human Services' Office of Public Health is investigating a confirmed case of measles in an unvaccinated Montgomery County child.