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
    • 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
    • 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
    • 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.