Overview
- A Washington State University study published in May 2026 analyzed 189 rodents trapped in the Palouse in summer 2023 and found about 30% showed past infection and roughly 10% were actively infected with Sin Nombre virus.
- Researchers produced the first full Sin Nombre genomes from the Northwest and found high genetic diversity with signs of viral reassortment and infection across multiple rodent species.
- Sin Nombre virus does not spread person to person, but the study’s authors warn that higher rodent prevalence could mean more human exposures that go undetected because only severe cases are usually tested.
- The study is limited to one season and a confined area, and the authors call for expanded, longer-term surveillance, human-exposure studies, and sustained funding to clarify risk and drivers like land use or climate.
- Public health guidance remains the same: ventilate and wet-clean spaces with rodent activity to reduce inhalation of virus from droppings, urine, or nesting materials; U.S. records show 864 hantavirus cases from 1993–2022 with a roughly 36% fatality rate.