Notes from the Field : Retrospective Analysis of Wild-Type Measles Virus in Wastewater During a Measles Outbreak — Oregon, March 24–September 22, 2024

In 2024, Oregon reported 31 measles cases in residents of three counties, the highest case count in Oregon since 1991.Thirty of these cases were associated with an outbreak in Clackamas and Marion counties, which included a close-knit community that did not readily seek health care; all cases occurred in unvaccinated persons.Illness onset for the person with the first confirmed case occurred on June 11, 2024, and the outbreak was declared over approximately 15 weeks later on September 26, a total of 42 days after illness onset in the last person with measles.Wastewater surveillance is a useful tool in the surveillance of emerging pathogens, including avian influenza A(H5) (1); however, wastewater surveillance for measles virus has not been well described in the context of clinical data.This retrospective study describes the detection of wild-type measles virus in wastewater samples collected during the 2024 measles outbreak.