Powassan virus (POWV) infection is a rare tickborne arbovirus infection, transmitted by the bite of infected deer/blacklegged tick (Ixodes scapularis), the same tick that causes other tickborne diseases in Wisconsin, including Lyme disease. POWV is the only tickborne virus that is part of the arbovirus group (including West Nile virus) occurring in Wisconsin and other parts of North America (Maine, Michigan, Minnesota, New Jersey, New York, Vermont, and Canada). The presence of POWV has been documented in several tick species (Ixodes spp., Dermacentor andersoni) and small and medium-sized mammal species (rodents, woodchucks, and skunks). The first case of Powassan identified in Wisconsin was in 2003.
People who are infected with POWV may experience a variety of symptoms, from mild illnesses to life-threatening complications; some people may not have any symptoms. Symptoms of illness usually begin 7-14 days (range 8-34 days) after being exposed to an infected tick bite. Signs and symptoms include acute onset of fever, muscle weakness, confusion, headache, nausea, vomiting, and stiff neck. Severe illness can include confusion, paralysis, speech difficulties, memory loss, and meningoencephalitis (inflammation of the brain and meninges).