Measles RNA detection in wastewater solids: longitudinal monitoring at a national scale

Abstract

Measles incidence has increased in recent years as vaccination rates have dropped globally, yet clinical surveillance is challenging due to misdiagnoses and a lag between infectivity and symptom onset. In this study, we applied a novel hydrolysis probe digital RT-PCR assay that is specific and sensitive to detect wild-type measles virus RNA in wastewater. Through pilot testing during an outbreak in the United States from December 2024–May 2025, we demonstrated that wild-type measles virus RNA can be detected in wastewater prior to clinical case reporting. We then conducted 6 months of measles RNA monitoring across the United States at 147 wastewater treatment plants including 11 598 samples. We detected measles RNA in 63 samples from 25 wastewater treatment plants across 17 states. Wastewater measles RNA detection was associated with clinical cases within 7 days (odds ratio: 14.7; 95% confidence interval: 8.6–24.6) and in the following 7 days (15.9, 9.6–27.3). Overall, national wastewater monitoring of measles RNA can fill clinical surveillance gaps and provide early warning of cases to supplement measles surveillance.