The measles outbreak in 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.

Texas reported 90 cases this week, while New Mexico reported nine. A majority of the cases have been in a Texas county where vaccination rates have lagged behind the rest of the state.

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