Symptoms, Diagnosis, and Treatment


  • Many people infected with Powassan virus do not have symptoms.
  • For people with symptoms, the time from tick bite to feeling sick ranges from 1 week to 1 month.
  • Initial symptoms can include fever, headache, vomiting, and weakness.
  • Powassan virus can cause severe disease, including infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).
  • Symptoms of severe disease include confusion, loss of coordination, difficulty speaking, and seizures.
  • Approximately 1 out of 10 people with severe disease die.
  • Approximately half of the people who survive severe disease have long-term health problems such as recurring headaches, loss of muscle mass and strength, and memory problems.


  • Healthcare providers diagnose Powassan virus infection based on:
    • Signs and symptoms
    • History of possible exposure to the ticks that can carry Powassan virus
    • Laboratory testing of blood or spinal fluid
  • More information on diagnostic testing is available here.


  • There is no medication to treat Powassan virus infection.
  • People with severe disease often need to be hospitalized to receive support for breathing, staying hydrated, or reducing swelling in the brain.
  • If you think you or a family member might have Powassan virus disease, see your healthcare provider.
  • To learn more about treatment, visit our Healthcare Provider page.