The next two weeks will determine whether a single measles case in Colorado fizzles out or starts an outbreak.
An unvaccinated adult who lives in Pueblo developed measles after visiting a part of Mexico that has an ongoing outbreak, according to the Colorado Department of Public Health and Environment.
The infection, which comes amid outbreaks in multiple states, marks the first confirmed measles case in Colorado in two years and only the seventh case since 2014, according to state records.