At least 124 cases of measles have been identified in Texas since late January, mostly among children and teenagers who are either unvaccinated or whose vaccination status is unknown, officials say.

A measles outbreak in the southwestern United States has infected nearly 100 people in recent weeks. The deadly illness has sickened dozens of people in west Texas and New Mexico since late January. The Texas Department of State Health Services confirmed 90 cases of measles,

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.