Powassan Virus Disease Information for Health Professionals - Minnesota Dept. of Health

Powassan Virus Disease Information for Health Professionals

Powassan virus is a tickborne flavivirus, that includes a strain (lineage II or “deer tick virus”) that is transmitted by blacklegged ticks (Ixodes scapularis). The virus can cause encephalitis or meningitis, and long-term sequelae occur in approximately 50% of patients. Approximately 10-15% of cases are fatal.

On this page:
Clinical Presentation/Diagnosis

May 31, 2018: Minnesota Laboratory System (MLS) Update
Powassan and Arbovirus Testing for the 2018 Season

May 31, 2018: Tickborne Disease Health Alert
Tickborne Disease Risk Season is Here

June 29, 2011: Tickborne Disease Health Alert
Minnesota Records First Death from Tickborne Powassan Virus

Clinical Presentation/Diagnosis

  • Medical providers should consider Powassan virus disease in patients with encephalitis or meningitis of probable unknown etiology that occurs during the tickborne disease transmission season (May to October).
  • Signs and symptoms of Powassan encephalitis or meningitis may include:
    • fever
    • headache
    • vomiting
    • weakness
    • confusion
    • loss of coordination
    • speech difficulties
    • memory loss
  • Long-term sequelae are common, and the case-fatality rate in reported cases is approximately 10%.


  • There is no specific treatment available for Powassan virus disease.
  • Care for patients is typically supportive and may include intravenous fluids and respiratory support.


  • Reporting Powassan Virus
    Minnesota Rules Governing Communicable Diseases require health care providers to report confirmed or suspected cases of Powassan virus disease to the Minnesota Department of Health (MDH) within 1 working day.

MDH staff also are available to provide clinical consultation regarding testing and diagnosis of Powassan virus disease and other tickborne diseases. Call 651-201-5414 for a clinical consultation.


Updated Friday, 30-Nov-2018 10:01:15 CST