Measles is one of the most contagious viruses known to humans, experts say. 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.

A child’s death this past week in Texas is the first U.S. death from measles, a highly contagious but preventable respiratory disease since 2015, according to the U.S. Centers for Disease

The measles outbreak in Texas has quickly grown to 146 cases. One child has died. NBC News answers readers' questions about the disease, vaccines and government response.