Study Finds Higher Hantavirus Levels in Pacific Northwest Rodents

Washington State University researchers found higher than expected levels of Sin Nombre virus in rodents across farms and forests in the Palouse region of eastern Washington and north-central Idaho. The team collected samples from 189 deer mice, voles and chipmunks at eight farms and two forest sites in summer 2023.

Nearly 30 percent of the rodents showed evidence of prior exposure and about 10 percent had active infections.

The findings were published in 2026 in Emerging Infectious Diseases, a peer-reviewed journal from the Centers for Disease Control and Prevention. Infections appeared in both agricultural and natural settings and across multiple rodent species. Stephanie Seifert, the study's corresponding author, said researchers were surprised by how common the virus was locally and by how little prior data existed for the Northwest.

Expert Context Dr.

Sonja Bartolome of UT Southwestern Medical Center noted that 864 hantavirus cases were reported nationwide between 1993 and 2022, with most occurring in western states. She said precautions remain essential when cleaning areas with rodent activity. Pilar Fernandez, a co-author and disease ecologist, said people may be exposed more often than realized, though severe cases are more likely to be tested.

The study measured infection only in rodents and did not assess human transmission risk. Samples were limited to one season in the Palouse region.