Powassan Virus Disease Statistics

• Since the first Minnesota case was reported in 2008, cases of Powassan virus disease have been reported every year except for 2014 and 2015. A peak of 11 cases was reported in 2011.
• In 2021, 5 cases of Powassan virus disease were reported in Minnesota.
  • All 5 cases were male, and ages ranged from 44 to 75 years.
  • All 5 cases presented with severe illness affecting the central nervous system (meningitis or encephalitis), and two cases died.
• Long-term sequelae occur in approximately half of those patients affected with encephalitis or meningitis and approximately 10-15% of cases are fatal.
• The majority of patients report being exposed to ticks in north-central Minnesota. Based on findings from routine tick surveillance activities, the virus appears to be widely distributed throughout the wooded areas of Minnesota.
• Illness onsets often follow a similar pattern as other tickborne diseases with most cases becoming sick in May, June, and July. Interestingly, four of the 2021 cases experienced illness onset in October, with the other patient first experiencing symptoms in June.

Charts and Graphs

• Reported Cases of Powassan virus disease in Minnesota by Year, 2008-2021 (PDF)
  Graph showing the number of reported cases of Powassan virus disease in Minnesota by year.

Maps

Most Powassan virus disease cases report likely exposure to blacklegged ticks in the same east-central, north-central, and southeast Minnesota counties where the risk of Lyme disease is greatest.

• High Risk Areas for Tickborne Diseases in Minnesota
  A map that shows counties of highest tickborne disease risk in Minnesota.

Annual Summary Statistics

• Arboviral Disease, 2019
  Minnesota Department of Health Disease Control Newsletter Annual Summary of Communicable Diseases
  • Arboviral Disease, 2018
  • Arboviral Disease, 2017
  • Arboviral Disease, 2016
  • Arboviral Disease, 2015
  • Arboviral Disease, 2014
  • Arboviral Disease, 2013
  • Arboviral Disease, 2012
  • Arboviral Disease, 2011
  • Arboviral Disease, 2010

National Statistics

• Powassan Virus Statistics & Maps
  Maps, charts, tables, and reports from the CDC.