Powassan virus disease: Symptoms and treatment

On this page

• Symptoms of Powassan virus disease
• If you become ill
• Diagnosing Powassan virus disease
• Treating Powassan virus disease

Symptoms of Powassan virus disease

Signs and symptoms of Powassan virus disease can vary from person to person after being bitten by an infected blacklegged tick (deer tick), groundhog tick or squirrel tick. The first symptoms can appear within 1 week to 4 weeks.

Many people with Powassan virus disease have no symptoms or develop mild to moderate symptoms.

Early signs and symptoms of Powassan virus disease may include:

• non-specific flu-like symptoms such as:
  • chills
  • fever
  • fatigue
• vomiting
• headaches
• general weakness

Powassan virus disease can progress to neuroinvasive disease, including encephalitis and meningitis. Symptoms may include:

• seizures
• confusion
• difficulty speaking
• loss of coordination

Encephalitis is inflammation of the brain. Meningitis is an infection and inflammation of the fluid and membranes surrounding the brain and spinal cord.

People with neurological complications of severe Powassan virus disease may have long-term issues such as:

• memory problems
• recurring headaches
• loss of muscle mass and strength

Death occurs in approximately 1 in 10 people who have severe Powassan virus disease.

If you become ill

Early diagnosis of Powassan virus disease can prevent complications. See your health care provider right away if you've been:

• bitten by a tick and develop symptoms of Powassan virus disease
• to an area where blacklegged ticks, groundhog ticks, or squirrel ticks may be found and develop symptoms of Powassan virus disease

Tell your health care provider:

• where on your body the tick was attached
• how long you think the tick was attached to you
• where you were (area, city, province, and country) when you were bitten by the tick or may have been exposed to ticks

Learn more about:

• Ticks in Canada
• How to remove a tick
• How to prevent tick bites
• Provincial and territorial public health authorities

Diagnosing Powassan virus disease

A diagnosis of Powassan virus disease is based on:

• signs and symptoms
• exposure to blacklegged ticks, groundhog ticks, or squirrel ticks
• travel or exposure to an area where blacklegged ticks, groundhog ticks, or squirrel ticks may be found
• blood tests or lumbar puncture, when appropriate

Only get tested by a licensed public health laboratory. Testing by private, non-licensed laboratories may not be reliable.

Treating Powassan virus disease

There is no treatment for Powassan virus disease.

People with severe Powassan virus disease will often need to receive supportive care such as:

• respiratory support
• medications to reduce swelling in the brain
• intravenous fluids
• medications to treat vomiting and nausea
• pain control for headaches