Measles is a respiratory virus that can survive in the air for up to two hours. Up to 9 out of 10 people who are susceptible will get the virus if exposed, according to the U.S. Centers for Disease Control and Prevention.

The number of confirmed measles cases in western Texas grew to 146, and it is possibly spreading to the central part of the state and neighboring New Mexico, health officials said Friday.

Texas health officials say the number of people with measles has increased to 146 in rural West Texas outbreak that led this week to the death of a school-aged child who was not vaccinated