University of Wisconsin–Madison

Powassan virus/deer tick virus

Powassan virus is a rare infection that is transmitted by deer ticks in Wisconsin.  It is most common in older individuals.  We find very few infected ticks: about 1-3% of adult deer ticks may be infected in some areas.  The map and graph on this page show human case data by year and location and are from the Wisconsin Department of Health Services.  Visit their site for more information:  https://www.dhs.wisconsin.gov/tickborne/powassan.htm