As measles cases rise in Arizona and other states, could U.S. lose its measles-free status?

The growing measles outbreak in Arizona and Utah could be putting the United States at risk of losing its status as a country that has eliminated the highly infectious virus.

The World Health Organization considers measles to be eliminated when a country has no outbreaks that last an entire year. The U.S. has been considered measles-free since the year 2000.

Measles began spreading in Texas at the beginning of this year. That outbreak has been considered over since August. But it remains unclear if other outbreaks around the country are related to the Texas cases.

According to the U.S. Centers for Disease Control and Prevention, 1,753 cases of measles have been reported nationwide this year — the highest total since 1992.

The largest ongoing outbreak in the country is in northern Arizona and southern Utah. Arizona’s Mohave County has reported 133 cases since August. Another 68 cases have been reported in neighboring communities in Utah.

If transmission continues through January — one year since the start of the Texas outbreak — the U.S. could lose its measles-free status.

The Pan American Health Organization, a WHO agency, already declared that the region of the Americas has lost its elimination status. The region-wide announcement came after Canada had one continuous year of measles transmissions from October 2024 to October 2025.

PAHO reports other outbreaks are ongoing in the United States, Mexico, Bolivia, Brazil, Paraguay, and Belize. The agency is encouraging countries throughout the Americas to ramp up measles surveillance, diagnosis and vaccination campaigns.

“This loss [of measles-free status] represents a setback — but it is also reversible,” PAHO director, Dr. Jarbas Barbosa said in a statement. “As we have demonstrated before, with political commitment, regional cooperation, and sustained vaccination, the region can once again interrupt transmission and reclaim this collective achievement.”