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Powassan Virus Disease

What Is Powassan Virus Disease?

Powassan virus disease is an illness caused by a virus that can spread to people through the bite of an infected tick. It’s very rare, so isn’t as widely known as other infections that deer ticks can spread, like Lyme disease. But it’s good to know a little about it.

What Are the Signs & Symptoms of Powassan Virus Disease?

Powassan (puh-WAH-sen) virus infection may not cause any symptoms.

But about 1 week to 1 month after the tick bite, someone with an infection may have:

  • fever
  • headache
  • vomiting
  • weakness and confusion
  • seizures 
  • memory loss
  • meningitis (inflammation of the membranes that cover the brain and spinal cord)
  • encephalitis (swelling of the brain)

Most cases of Powassan have been in Canada, the Great Lakes and northeast areas of the United States, and Russia. People who spend a lot of time outdoors in these areas have a higher risk of getting the infection.

How Is Powassan Virus Infection Diagnosed?

A health care provider might suspect Powassan virus infection based on a person’s symptoms and tick exposure. If so, they’ll take a small sample of blood or cerebrospinal fluid (CSF, the fluid that surrounds the brain and spinal cord) to send to a lab for testing. To get a CSF sample, they’ll do a spinal tap (lumbar puncture).

How Is Powassan Virus Disease Treated?

There are no special medicines to treat or cure a Powassan virus infection. Someone with a serious infection might need treatment in a hospital. This could include getting medicine for headaches or nausea and IV fluids. If they’re very sick, they’ll get care in the ICU and might get medicines to ease brain swelling or help with breathing.

Can Powassan Virus Disease Be Prevented?

Preventing tick bites is the best way to avoid Powassan virus infection. These outdoor tips can help protect you and your kids:

  • Wear closed shoes or boots, long-sleeved shirts, and long pants.
  • Tuck pants into shoes or boots to prevent ticks from crawling up your legs.
  • Wear light-colored clothing to help you see ticks easily.
  • Keep long hair pulled back or wear a hat for added protection.
  • When outside, don't sit on the ground.
  • Use an insect repellent containing 10% to 30% DEET (N,N-diethyl-meta-toluamide).
  • While outdoors, check your family for ticks often. Check again after you go back inside (don't forget to check pets too).

Also, be sure you know how to remove a tick, just in case.

Reviewed by: Melanie L. Pitone, MD
Date Reviewed: May 10, 2022

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