Health authorities warned of further spread. Most U.S. measles cases this year involved people 19 and under and those without a confirmed vaccination.

Lea County, New Mexico, is now reporting an outbreak of measles, according to the New Mexico Department of Health (NMDOH). Lea County is near Gaines County, Texas, where measles cases continue to rise as part of the original outbreak.

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.