An unvaccinated child has died as measles cases in rural West Texas continue to surge, making it the largest outbreak in the US in six years. Initially confined to a close-knit Mennonite community, the outbreak has now spread to other under-vaccinated groups.

A Texas measles outbreak has doubled in the last week to 124 cases, state health officials said Tuesday, a day after they warned a person infected with the highly contagious disease had traveled from the outbreak zone.

A child in Texas has died from measles, officials said Wednesday, the first known death in the current large outbreak in West Texas and the first death from measles in the country since 2015. The individual, described as a school-aged child, was not vaccinated. The gender and previous health status of the child was not disclosed.