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.

Two separate outbreaks of measles in the U.S. Southwest have now accounted for nearly 100 confirmed cases and hospitalized 16 people.

As measles cases in Texas and New Mexico continue to increase, health officials are urging caution and vaccination. Here is what to know.

An ongoing measles outbreak that began in one of Texas' least vaccinated counties has mushroomed to 90 cases across a cluster of seven counties in the state, according to an update by the Texas Department of State Health Services on Friday.

A measles outbreak in rural West Texas, rising to 58 cases as of Tuesday (February 18), has spread to neighboring New Mexico. Eight people in eastern New Mexico have now contracted the highly contagious infection though a spokesperson for the state's health department says it hadn't “identified any direct contact” in cross-state cases.