Powassan Virus: Symptoms, Encephalitis, and Neurologic Complications

Powassan virus is a rare but serious tick-borne infection.
It may cause meningitis, encephalitis, and long-term neurologic injury.
Unlike Lyme disease, transmission may occur rapidly after a tick bite.

Powassan virus is a rare but serious tick-borne illness that can cause inflammation of the brain (encephalitis) and the membranes surrounding the brain and spinal cord (meningitis).

Unlike Lyme disease, Powassan virus may be transmitted very rapidly after tick attachment.

Patients searching for Powassan virus symptoms are often concerned about neurologic complications including encephalitis, weakness, confusion, headaches, seizures, or long-term neurologic impairment.

Patients with Powassan virus infection may initially develop fever, headache, vomiting, or generalized weakness before neurologic symptoms appear.

For a broader overview, see What is Powassan virus?.

Powassan Virus Symptoms

Powassan virus symptoms may initially resemble other viral or tick-borne illnesses.

Reported symptoms include:

• Fever
• Headache
• Vomiting
• Weakness
• Confusion
• Loss of coordination
• Speech difficulties
• Seizures

Severe cases may progress to meningitis, encephalitis, or meningoencephalitis.

Powassan Virus Encephalitis

Powassan virus encephalitis can lead to significant neurologic injury.

Several published case reports describe patients developing severe brain inflammation following tick exposure.

Some survivors of Powassan virus encephalitis may experience long-term neurologic effects including weakness, memory problems, headaches, or difficulty with coordination.

For additional discussion, see:

• Can Powassan virus cause encephalitis or other neurologic damage?
• 4 cases of Powassan virus encephalitis
• Powassan virus encephalitis contracted during winter months
• Case report: Powassan meningoencephalitis

Powassan Virus in Children

Children may also develop serious neurologic complications from Powassan virus infection.

Case reports have described encephalitis and prolonged neurologic recovery following camping trips and outdoor exposure.

• Powassan virus in children: Case reports
• Young boy develops Powassan encephalitis after camping trip

Powassan Virus and Lyme Disease

Ticks may carry more than one pathogen simultaneously.

Patients exposed to ticks may develop Lyme disease, Babesia, Anaplasmosis, or Powassan virus from the same tick bite.

Research from Maine has examined the prevalence of both Borrelia infections and Powassan virus in ticks.

Read more: Prevalence of Borrelia infections and Powassan virus in Maine.

Frequently Asked Questions

What is Powassan virus?

Powassan virus is a rare tick-borne flavivirus that can infect the brain and nervous system.

Can Powassan virus cause encephalitis?

Yes. Powassan virus may cause meningitis, encephalitis, seizures, weakness, and long-term neurologic complications.

How quickly can Powassan virus spread after a tick bite?

Unlike Lyme disease, Powassan virus transmission may occur rapidly after tick attachment.

Can the same tick carry Lyme disease and Powassan virus?

Yes. Some ticks may carry multiple pathogens simultaneously, including Lyme disease bacteria and Powassan virus.

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Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention