Powassan Virus Disease Statistics - Minnesota Dept. of Health

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.
  • 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 follow a similar pattern as other tickborne diseases with most cases becoming sick in May, June, and July.
  • In 2017, seven cases of Powassan virus disease were reported in Minnesota.
    • Six (86%) of seven cases were male.
    • Median age of cases was 61 years (range, 9 to 74 years).
    • All seven cases presented with severe illness affecting the central nervous system (meningitis or encephalitis).

On this page:
Charts and Graphs
Annual summaries
National statistics

Charts and Graphs


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.

Annual Summary Statistics

National Statistics

Updated Tuesday, 24-Jul-2018 07:40:44 CDT