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West Nile Virus Maps and Statistics

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  • West Nile virus (WNV) was first found in Minnesota in 2002 and has since become the most commonly reported mosquito-transmitted 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 farm land 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 (July through September) when infected vector populations are at their highest level.
  • In 2014, 21 cases of WNV disease were reported in Minnesota. There were no deaths, but 6 (29%) had neuroinvasive presentations including encephalitis or meningitis. The other 15 (71%) cases had West Nile (WN) fever. Five WNV-positive blood donors, who had no symptoms, were also identified in 2014.

Annual summaries:

Archive of maps:

National statistics:

Updated Tuesday, September 15, 2015 at 09:43AM