Optimizing Measles Wastewater Detections for Public Health Response — Oregon, 2024–2025
- Presentation Day/Time: Tuesday, April 21, 11:50 AM
- Presenter: Jeffrey Tamucci, PhD, MPH, Oregon Health Authority
The Issue
- Controlling measles transmission requires high immunization rates and early response to cases. Wastewater surveillance (WWS) can alert health authorities to the emergence of measles before clinical case detection.
What We Did
- We analyzed wastewater measles detections statewide to evaluate how four WWS thresholds could optimize public health response. Oregon conducted prospective measles WWS during October 2025–February 2026, testing samples 1–2 times weekly. We also looked at retrospective samples collected from four communities during a measles outbreak (March 19–September 26, 2024).
What We Found
- During the retrospective outbreak, Oregon detected 30 cases. Higher-sensitivity thresholds had positive results 4-10 weeks prior to case detection, while lower-sensitivity thresholds had no advance detection or a positive result one week after clinical detection. During the prospective period, Oregon detected measles in wastewater 100 times and reached every threshold in the absence of measles cases being reported in that area. Oregon detected six cases, but they lived outside the areas where we monitor wastewater.
What This Means
- In the absence of wastewater detections linked to clinical cases, the optimal threshold remains unclear. Currently, Oregon uses higher-sensitivity thresholds as an early warning to monitor syndromic surveillance and lower-sensitivity thresholds to alert counties and healthcare providers of elevated measles risk. Assessing WWS thresholds with other data sources like syndromic surveillance and laboratory reporting might help optimize use for public health response.
