Key points
- Powassan virus infection can result in mild febrile illness or severe neurologic disease, including meningitis or encephalitis.
- If you think you or a family member might have Powassan virus disease (Powassan), talk to your healthcare provider.
Symptoms
Many people infected with Powassan virus do not have symptoms. For people with symptoms, the time from tick bite to feeling sick (incubation period) ranges from 1 week to 1 month.
Initial symptoms
Initial symptoms can include:
- Fever
- Headache
- Vomiting
- Weakness
Severe illness
Powassan virus can cause severe illness, including inflammation of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).
Symptoms of severe illness include:
- Confusion
- Loss of coordination
- Difficulty speaking
- Seizures
Outcomes and complications
Approximately 1 out of 10 people with severe illness die.
Approximately half of the people who survive severe illness have long-term health problems. These can include recurring headaches, loss of muscle mass and strength, or memory problems.
Risk factors
Anyone can develop severe illness if infected with Powassan virus, but some people are at higher risk, including:
- Older adults
- Children, including infants
- People with a weakened immune system
Testing and diagnosis
If you think you or a family member might have Powassan, talk to your healthcare provider.
Healthcare providers diagnose Powassan based on:
- Signs and symptoms
- History of living in or traveling to an area where Powassan virus is known to circulate
- History of possible exposure to the ticks that can spread Powassan virus
- Laboratory testing
Your healthcare provider can order tests to look for Powassan virus or other infections that can cause similar symptoms.