Powassan Virus Disease Statistics - Minnesota Dept. of Health

Powassan Virus Disease Statistics

Since 2008, 27 cases (2 fatal) of Powassan virus disease have been reported in Minnesota residents. Most of these patients had neuroinvasive disease (15 encephalitis and 10 meningitis) but 2 were non-neuroinvasive fever cases. Twenty (74%) cases have been male, and the median age is 61 years (range, 3 mos. to 75 years). Similar to other tickborne diseases, the majority of patients (20, or 74%) reported illness onsets between May and August. Seven patients (26%) had onset dates in October or November. With the exception of 2014 and 2015, cases have been reported every year since 2008, with a peak of 11 in 2011 (range, 1 to 11), and 5 cases in 2016. Cases were exposed to ticks in several north-central Minnesota counties. MDH has also identified Powassan virus-positive ticks at sites in the six counties that have been investigated to date (Anoka, Clearwater, Cass, Houston, Morrison, and Pine). Thus, the virus appears to be widely distributed in the same wooded parts of the state that are endemic to other pathogens transmitted by blacklegged (deer) ticks.

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 Friday, 06-Apr-2018 10:07:36 CDT