Powassan Virus Symptoms: Encephalitis, Neurologic Damage and Long-Term Effects
Rare tick-borne viral infection
Can cause meningitis and encephalitis
May lead to long-term neurologic complications
Powassan virus is a rare but serious tick-borne infection. Many infected people have no symptoms, but others develop a febrile illness or severe neurologic disease involving the brain and nervous system.
Unlike Lyme disease, which is caused by bacteria, Powassan is caused by a virus. Experimental and case-report evidence suggests transmission may occur much more rapidly than with Lyme disease—potentially within minutes after an infected tick begins feeding.
What Are the Symptoms of Powassan Virus?
According to the Centers for Disease Control and Prevention, symptoms typically begin one week to one month after the bite of an infected tick. Many infected individuals do not develop symptoms.
Initial symptoms may include:
- Fever
- Headache
- Vomiting
- Weakness
Severe neurologic symptoms may include:
- Confusion or altered mental status
- Loss of coordination
- Difficulty speaking
- Seizures
- Muscle weakness or paralysis
Powassan Virus Encephalitis and Neurologic Complications
Powassan virus can cause inflammation of the brain, known as encephalitis, or inflammation of the membranes surrounding the brain and spinal cord, known as meningitis.
Approximately 1 in 10 people who develop severe Powassan virus disease die. About half of those who survive severe illness experience long-term health problems, which may include recurring headaches, muscle weakness, paralysis, coordination problems, or cognitive difficulties.
The resources below review Powassan virus symptoms, neurologic complications, pediatric infections, case reports, and related research.
Understanding Powassan Virus
Powassan Virus in Children
- Powassan virus in children: Case reports
- Young boy develops Powassan encephalitis after camping trip
Powassan Virus Case Reports
- Can you recover from Powassan virus? Four case reports
- Case report: Powassan meningoencephalitis
- Powassan virus infection causes polio-like illness
Powassan Virus Research
Frequently Asked Questions
What are the symptoms of Powassan virus?
Symptoms may include fever, headache, vomiting, weakness, confusion, loss of coordination, difficulty speaking, and seizures. Many people infected with Powassan virus have no symptoms.
Can Powassan virus cause encephalitis?
Yes. Powassan virus can cause encephalitis, a serious inflammation of the brain that may lead to seizures, weakness, cognitive difficulties, and other long-term neurologic complications.
What are the long-term effects of Powassan virus?
Some people who survive severe Powassan virus disease experience recurring headaches, muscle weakness, paralysis, coordination problems, memory loss, or other cognitive difficulties.
Clinical Takeaway
Powassan virus is uncommon, but severe infections can cause meningitis, encephalitis, and lasting neurologic complications. Early recognition and tick-bite prevention remain important because the virus may be transmitted rapidly after an infected tick begins feeding.
Powassan virus should be considered in patients with compatible neurologic symptoms and possible tick exposure, particularly in endemic regions.
Related Articles
- Tick-borne encephalitis
- Lyme disease and coinfections
- Tick-bite prevention
- What is the Powassan virus?
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
