Sandoval County wastewater detected measles five days before first case

Sandoval County’s wastewater picked up wild-type measles five days before the county’s first confirmed cases, giving public health officials an early heads-up in a year when New Mexico was already fighting a larger outbreak elsewhere.

A research letter published in JAMA Network Open says the New Mexico Department of Health and Rice University’s Stadler Laboratory worked together during the spring 2025 outbreak, which the paper places between February 11 and August 10, 2025. Sampling began March 12 and covered nine wastewater treatment plants in six counties: Luna, Chaves, Santa Fe, Sandoval, Bernalillo and Doña Ana.

In Sandoval County, that wastewater signal came before the first two cases were announced on May 15, 2025. Those cases were an adult of unknown vaccination status and an unvaccinated child under age 4. State health officials said the Sandoval County cases were the first New Mexico measles cases identified outside the Southeast and Southwest regions in 2025.

The early warning mattered because measles moves fast once it is circulating. Health officials used the signal to prepare vaccines, alert providers and deploy an outbreak response team before the county cases were publicly confirmed. NMDOH later issued exposure notices for places in Rio Rancho, Albuquerque and Cedar Crest, including Presbyterian Rust Hospital Emergency Department, Presbyterian Rust Medical Center Hematology/Oncology Clinic, Trader Joe’s in Albuquerque and Ribs Hickory Pit BBQ in Cedar Crest.

The department also urged an early MMR dose for infants 6 to 11 months old who live in or travel to higher-risk areas, including Sandoval County. Measles can spread from four days before a rash appears through four days after, which makes advance notice especially important for clinics, daycares and families trying to avoid exposure.

State health officials have been careful not to overstate what wastewater can tell them. The system cannot identify exactly when someone was infected, where the infection happened or how many people were sick. What it can show is that at least one unidentified measles infection was likely present in the area before anyone walked into a clinic.

That warning came during New Mexico’s first measles outbreak since 1996. By May 8, 2025, the Centers for Disease Control and Prevention had reported 1,001 cases in 31 jurisdictions nationwide, most among people who were unvaccinated or whose vaccination status was unknown. In New Mexico, wastewater surveillance later expanded statewide, but Sandoval County’s signal stood out for what it did first: it gave local officials time to act before the outbreak became visible.