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. Here, we present wastewater monitoring for measles viral RNA as a tool to fill in gaps in clinical surveillance. In this study, we applied a recently-designed assay that is specific and sensitive to detect wild-type measles virus in wastewater. Through pilot testing during an outbreak in the United States from December 2024 -May 2025, we demonstrated that measles virus RNA can be detected in wastewater prior to clinical case reporting. We then conducted 6 months of measles monitoring across the United States at 147 wastewater treatment plants. We detected measles virus RNA in 63 samples from 25 wastewater treatment plants across 17 states. Wastewater measles RNA detections are associated with clinical cases within 30 days (odds ratio: 14.7; 95% confidence interval: 8.6 -24.6) and in the following 30 days (15.9, 9.6 -27.3). Overall, wastewater monitoring of measles virus can fill in clinical surveillance gaps and provide early warning of cases to supplement measles surveillance.