Measles has sickened nearly 150 mostly unvaccinated people in rural West Texas, and a school-age child has died.

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.

When the local hospital warned of a brewing measles outbreak, Kaleigh Brantner urged fellow residents of this rural West Texas community to beware of vaccinating their children. Two weeks later, her unvaccinated 7-year-old son came home from school with a fever.

The number of people with measles in Texas increased to 146 in an outbreak that led this week to the death of an unvaccinated school-aged child, health officials said Friday. The number of cases — Texas’ largest in nearly 30 years — increased by 22 since Tuesday.

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.

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,

At least 146 measles cases have been identified in West Texas so far, including 20 hospitalizations and one death.

As the measles outbreak in West Texas continues to grow, North Texas doctors say they’re fielding a growing number of questions from concerned parents. Dr. Christopher Dreiling, a pediatrician at Pediatric Associates of Dallas,