Clark County finds measles virus in wastewater, urges vaccination

The Southern Nevada Health District announced Thursday it has detected the measles virus in Clark County wastewater.

Clark County has no confirmed measles cases and has not since 2018. However, wastewater surveillance can indicate undiagnosed viral infections.

The health district is urging Clark County residents to stay up to date on their children’s measles-mumps-rubella (MMR) vaccines, which are 97 percent effective at preventing measles after two doses, according to the Centers for Disease Control and Prevention.

“While a single wastewater detection does not mean we have confirmed measles cases or community transmission, it is a signal that shouldn’t be ignored,” Cassius Lockett, district health officer for the Southern Nevada Health District, wrote in a Thursday statement.

A subsequent wastewater sample tested negative for the virus.

Brian Labus, an infectious disease epidemiologist and associate professor at UNLV, said the county regularly tests for measles to alert clinicians to test for the virus.

“All this announcement tells us is that somebody is shedding measles in the community. It could be that they had the disease somewhere else and came back here at the very end of their recovery stage,” Labus said. “It doesn’t mean that there’s somebody necessarily sick walking around with measles, but it is the kind of thing that the medical community needs to pay attention to so we can respond to any actual cases of measles quickly.”

Measles is a highly contagious disease that can be serious for small children. The World Health Organization declared measles eliminated in the U.S. in the year 2000. Vaccination rates have been declining, however, and an early-2025 outbreak in west Texas caused the highest number of reported cases in the U.S. since the disease was declared eliminated.

The health district said MMR is one of several vaccinations required for school enrollment, and vaccinations are still available before the first day of school, which is Monday.

“Kids should be fully immunized for measles if they’re going to school,” Labus said. “The vaccine is the best way to prevent yourself or your loved ones from getting this disease.”

Contact Isaiah Steinberg at isteinberg@reviewjournal.com. Follow @IsaiahStei27 on X.