At least 124 cases have been reported since late January, mostly among children and teenagers who were unvaccinated or whose vaccination status was unknown.

A child who tested positive for measles died in West Texas, the state health department said, marking the first death in an outbreak that has sickened nearly 140 people. The Texas Department of State Health Services said a school-age child died after being hospitalized in Lubbock.

Measles is a highly contagious disease. Here's what you should know about how to protect yourself against measles, as well as what's happening in Texas and New Mexico.