PORTLAND, Ore.--A new data tracking tool Oregon Health Authority (OHA) launched today shows the five confirmed measles cases identified in the state since Jan. 1 likely represent only a portion of infections occurring statewide, public health officials say.  

To strengthen early detection, OHA today published a new measles wastewater surveillance dashboard showing viral concentrations by county and categorizing activity as very low, low, moderate or high over two-week periods. 

Wastewater monitoring began Oct. 1, 2025, and complements traditional case reporting. Oregon submits data to the Centers for Disease Control and Prevention’s National Wastewater Surveillance System, which uses a high threshold for labeling samples as a “detection.” While that approach has shown sporadic detections of measles over time, Oregon’s analysis of viral concentrations indicates low-level measles activity across the state that has been increasing. For the two-week period ending Feb. 7, low levels of measles virus were observed in wastewater from nine counties. 

“Wastewater surveillance serves as an early warning signal system, which gives communities a head start to prepare and empowers everyone to make informed decisions about immunization. Wastewater testing looks for the actual measles virus that causes illness in people, so it provides an early signal of community spread,” said Howard Chiou, M.D., Ph.D., medical director for communicable diseases and immunizations at OHA’s Public Health Division. 

“Measles is here in Oregon and spreading in the United States,” Chiou added, “and vaccination remains the best way for people to protect themselves. We encourage everyone to talk with a healthcare provider to ensure they and their families are fully protected.” 

Measles is a highly contagious respiratory virus spread through the air when an infected person breathes, speaks, coughs or sneezes. The virus can linger in the air for up to two hours, allowing it to infect up to 90% of unprotected close contacts and potentially cause serious complications, including pneumonia, brain inflammation and death. 

Measles has been increasing nationwide since early 2025, with nearly 2,300 cases reported last year. Most cases occurred among unvaccinated children. 

Guidance for providers and the public

Symptoms typically begin seven to 21 days after exposure and include cough, runny nose and conjunctivitis with high fever, followed by a rash that starts on the head or neck and spreads downward. People are contagious from four days before the rash appears until four days afterward. 

Health care providers should report suspected cases immediately and consider post-exposure prophylaxis for exposed patients: 

• MMR vaccine, within 72 hours of exposure.
• Immunoglobulin, within six days.