West Nile Virus Maps and Statistics
2025 Update: Minnesota is seeing high West Nile Virus Activity This Year
West Nile virus activity increases in late summer and early fall. MDH urges everyone to protect themselves from mosquito bites.
For the most up to date data on West Nile virus human disease cases, infections in blood donors, and non-human activity please visit ArboNET, the national arboviral surveillance system managed by CDC and state health departments.
CDC: Current Year Data (2025) | West Nile Virus
ArboNET human data are reported by county of residence. Current season data are updated every one to two weeks from June through December.
West Nile virus (WNV) was first found in Minnesota in 2002 and has since become the most commonly reported mosquitoborne disease in the state. The highest risk areas for WNV in Minnesota include the western and central portions of the state. Open areas, such as farmland and prairie, provide the best habitat for Culex tarsalis, the primary mosquito vector of the virus. Similar to other arboviruses, most WNV cases occur later in the summer when infected vector populations are at their highest level.
In 2024, 35 WNV disease cases were reported in Minnesota. The majority of cases, 71%, reported symptom onset in August or September.
- 25 (71%) cases were male
- Median age was 64 years (range, 32 to 86 years)
- 28 (80%) cases were hospitalized
- 26 (74%) cases had a severe illness affecting the central nervous system (encephalitis or meningitis) and one case died
- 7 WNV-positive blood donors who did not have any symptoms of illness were also identified