Colorado has had just one measles case this year, but that doesn’t mean Dr. Michelle Barron sleeps well at night.

With spring break around the corner, Barron worries out-of-state travelers will bring more than their luggage to the Centennial State.

“My big worry right now is DIA (Denver International Airport), said Barron, senior medical director of infection prevention and control for UCHealth.

Barron added, “Colorado’s big risk right now is it being imported from somebody visiting.”

The lone case out of Colorado was in Arapahoe County.

Last year, the state had 36 cases in 10 counties — including Denver. Of these, roughly one in four were associated with an out-of-state traveler who flew while infectious, according to the Colorado Department of Public Health and Environment.

The recent surge marks a sharp departure from the previous decade.

Between 2014 and 2024, Colorado only had six measles cases.

The maddening thing for health care professionals is that measles was considered eradicated in 2000. Health officials credit a highly affective vaccination campaign.

Before a vaccine was developed in the 1960s, an estimated 48,000 Americans were hospitalized with measles and 500 died each year.

While highly contagious, measles is a preventative respiratory illness. The disease is transmitted through direct contact with infected droplets or airborne when an individual breathes, coughs or sneezes.

Symptoms typically emerge within two weeks of exposure and include a spotty red rash, the telltale sign of a measles infection. In rare cases, measles can cause swelling of the brain and death.

The rise in measles cases follows growing vaccine skepticism.

In Colorado, 93.3% of students were vaccinated for measles, mumps and rubella, state vaccination shows.

To be protective in a community, 95% or more of students should be vaccinated against measles.

The United States has seen an unprecedented number of cases.

As of Feb. 20, there have been nearly 1,000 confirmed measles cases in 26 states with roughly 90% associated with an outbreak, according to the Centers for Disease Control and Prevention.

Last year, the U.S. had 2,281 confirmed measles cases in 45 states.