Medical Definition of Powassan Virus

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Powassan virus: an arbovirus (arthropod-borne) virus that is transmitted to humans through infected ticks. Person-to-person transmission does not occur. The infection is rare, with 60 cases reported in the U.S. over the past 10 years. Most U.S. cases have occurred in the Northeast and Great Lakes areas. Severe infection can lead to encephalitis (inflammation of the brain), requiring hospitalization. Signs and symptoms of Powassan infection can include fever, headache, vomiting, weakness, confusion, seizures, and memory loss. Long-term neurologic problems can develop after infection. There is no specific treatment available. Prevention of infection involves taking precautions to avoid exposure to ticks and tick bites.

Reviewed on 12/21/2018


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United States. Centers for Disease Control and Prevention. "Powassan Virus." Feb. 9, 2015. <>.

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