The number of measles cases in Gaines County, the epicenter of the outbreak, has grown to 107, nine more than the total reported four days prior.

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

As measles — a preventable disease the U.S. considered eliminated in 2000 — spreads through West Texas’ rural expanse, ...