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Powassan Virus

  • Powassan virus is a rare, yet often serious disease that is spread by the bite of infected ticks. 
  • Most human cases in the U.S. occur in the northeast and Great Lakes regions from late spring through mid-fall when ticks are most active. 
  • While rare, the number of reported human cases of people sick from Powassan virus has increased in recent years.
  • There has only been one reported case of Powassan virus disease in Michigan to date. 
  • The signs and symptoms of Powassan virus range from no symptoms to encephalitis (inflammation of the brain) and meningitis (inflammation of the membranes that surround the brain and spinal cord). 
  • The best way to prevent infection is to protect yourself from tick bites. 
Powassan Virus image
  • Got A TICK? SUBMIT IT FOR ID, Information on identifying and testing ticks

    GOT A TICK? SUBMIT A PIC! Click here for more information on picture ID

    MiTracking, Michigan Environmental Public Health Tracking

    Emerging and Zoonotic Disease Surveillance Summary

    Link to 2021 Michigan Trends in Tickborne Disease Report

    • The majority of Powassan virus cases have occurred during the late spring, early summer, and mid-fall when ticks are most active in the northeastern and Great Lakes regions of the United States. 
    • Anyone who is bitten by an infected Ixodes scapularis, Ixodes cookei, or Ixodes marxi tick, in an area where the virus is commonly found, can become infected. 
    • Individuals who live, work, or recreate in brushy or wooded habitats are at greater risk due to the increased chance of being bitten by an infected tick.     


    • After being bitten by an infected tick, the onset of illness can range from one week to one month. 
    • Many people who become infected with Powassan virus do not develop any signs or symptoms. 
    • Initial symptoms can include fever, headache, vomiting, and weakness. 
    • Powassan virus can cause severe disease including infection of the brain (encephalitis) or the membranes that surround the brain and spinal cord (meningitis).
      • Symptoms of severe disease include confusion, loss of coordination, difficulty speaking, and seizures.
      • Approximately 10% of people with severe disease die. 
      • About half of the individuals who survive severe disease have long-term health problems such as  recurrent headaches, loss of muscle mass and strength, and memory problems. 


  • Powassan virus is diagnosed by a healthcare provider using a combination of:

    • Signs and symptoms
    • History of possible exposure to ticks that an carry Powassan virus
    • Laboratory tests of blood or spinal fluid.     

    What should I do if I have a tick that I want to identify?

    Knowing what kind of tick bit you may be important in knowing what your risk of disease is.  The Michigan Department of Health and Human Services (MDHHS) provides tick identification at no charge to Michigan citizens. There are two ways to have a tick identified, 1) By submitting a photo of your tick, or, 2) by sending the tick to the MDHHS for microscopic identification.  If you want to submit a photo of your tick, the MDHHS will make all attempts to identify the tick based on the condition of the tick and the condition of the photos.  However, definitive tick identification may only be made by sending the tick for microscopic examination.  

    Click HERE for instructions on how to submit a photo of your tick for identification

    Click HERE for instructions on how to ship a tick to the MDHHS for microscopic identification


    • There are no medications that can be used to prevent or treat Powassan virus infection. 
    • People with severe illness from Powassan virus usually need to be hospitalized to receive support for breathing, intravenous fluids, and medications to help decrease brain swelling. 
    • See your health care provider if you think that you or a family member may have Powassan virus.   


    • Powassan virus is spread to people through the bite of an infected tick. 
    • There is no vaccine to prevent Powassan virus infection.
    • Reduce your risk of getting sick by: