Measles is spreading across the U.S., with an outbreak growing in Texas and cases reported in nearby states. Experts explain whether or not you should be concerned.

State health officials are seeking to confirm the vaccine status of the four self-reported cases, but no mutations of the virus have been recorded.

The measles outbreak in rural West Texas has grown to 58 cases as of Tuesday. Eight people in neighboring eastern New Mexico also have been diagnosed with the highly contagious disease.