Confirmed measles cases in Mesa County last week are providing a case study for Pitkin County in the importance of using wastewater surveillance systems to identify the viral infection.

Both an unvaccinated adult with no travel or connection to other cases and another adult of unknown vaccination status who shared a workplace tested positive for measles, Pitkin County Epidemiology Program Administrator Carly Senst confirmed. It is currently uncertain how the individuals were exposed.

According to Senst, wastewater testing is what allowed Mesa County to be ready for the measles cases before they were confirmed in any individuals.

“What makes (the Grand Junction cases) so interesting is that roughly a week before these cases were identified, Mesa County was able to pick up a wastewater sample for an active infection before the case was ever identified,” she said. “It really allowed them to set the stage for response.”

There are currently seven confirmed cases of measles in Mesa County, according to the county’s website.

While Pitkin County still has zero confirmed measles cases, the Colorado Department of Public Health & Environment and local wastewater district’s wastewater treatment system is sampling refuse in the wastewater over the course of a set amount of hours twice a week. The samples are sent to the Colorado State Public Health Laboratory for sequencing — testing not only for measles, but also for COVID-19, the flu, and RSV.

“The work that is being done is remarkable (in Colorado),” Senst said of wastewater surveillance. “”Wastewater can play a critical role in giving us a potential heads up.”

As for the risk Pitkin County faces with new cases in Mesa County, she said it’s still low.

“I would say pretty low, but I’m not going to say the risk is zero,” she said. “We have a lot of individuals who come into Pitkin County for work. That’s where we see some of our risk coming from.”

Senst sees the risk potentially increasing going into the winter season, especially as winter tourism increases. Vaccination is the number one way community members can protect against measles, in addition to avoiding traveling to areas where measles outbreaks are occurring.