Hantavirus in Wisconsin.
Wisconsin reports occasional Sin Nombre HPS cases linked to cabin and outbuilding exposure in the northern half of the state. The 2025 case in Iron County renewed attention to deer-mouse populations following a wet spring; Wisconsin Department of Health Services circulated clinician-alert materials and a wet-cleanup protocol for cabin owners.
Frequently asked
How many hantavirus cases has Wisconsin reported?
Wisconsin has reported 1 confirmed hantavirus pulmonary syndrome cases year-to-date in 2026, against a 5-year average of 0.4 per year. Case counts vary year-on-year with rodent population cycles.
What rodent carries hantavirus in Wisconsin?
Deer mouse (Peromyscus maniculatus). Northern hardwood and pine barren rural areas; cabin and outbuilding exposure.
Which strain causes hantavirus in Wisconsin?
Sin Nombre virus is the dominant hantavirus strain in Wisconsin. It causes hantavirus pulmonary syndrome (HPS) with case fatality typically 30–40%.
Related
Disclaimer. State case counts reflect what CDC NNDSS publishes. The state health department is the authoritative real-time source.