Powassan Virus: Symptoms, Ticks and Prevention

Quick answer

Powassan virus is spread mainly by the bite of infected Ixodes ticks, including the blacklegged (deer) tick, in the Northeast and Great Lakes regions. It is rare, but reported cases are climbing. It can cause encephalitis or meningitis. There is no vaccine and no specific treatment, so preventing tick bites is the main protection.

What Powassan virus is

Powassan is a virus. That is the big difference from Lyme disease, which is caused by bacteria and treated with antibiotics. Because Powassan is a virus, antibiotics cannot clear it, and care focuses on supporting the body while it fights the infection.

Infections have been found in the United States, Canada and Russia. CDC has collected U.S. case data since 2004. Powassan is one of several germs grouped as Lyme co-infections, because the blacklegged tick that spreads Lyme can also carry it.

Which ticks spread it

• Blacklegged (deer) tick, the same tick that spreads Lyme disease in the East and Midwest. See our blacklegged tick guide.
• Groundhog tick (Ixodes cookei).
• Squirrel tick (Ixodes marxi).

Not sure which tick bit you? Our types of ticks page shows how common U.S. ticks differ.

How fast can a tick pass it on?

CDC’s current patient and clinician pages do not give a minimum attachment time for Powassan. A 2017 CDC report in MMWR noted that the virus can be passed as quickly as 15 minutes after a tick attaches, citing an earlier laboratory study. Compare that with Lyme disease, where CDC says a tick generally has to be attached for more than 24 hours (see how long a tick needs to be attached). The practical lesson: check for ticks after time outdoors and remove any you find right away, rather than relying on a tick having been attached only briefly.

Where it occurs, and rising cases

Most U.S. cases come from the northeastern states and the Great Lakes region. Illness shows up from late spring through mid-fall, when ticks are most active. Anyone in an area with Powassan activity can be infected; people who work or play outdoors there face more risk.

Cases are still uncommon, but CDC says reported numbers have gradually increased since 2004. CDC’s national report on 2024 data (MMWR, July 2026) described a new record high:

Powassan virus symptoms

Symptoms usually begin 1 to 5 weeks after the tick bite, according to CDC’s clinician guidance. Some infected people never feel sick, and some have only a fever-type illness. When symptoms do appear, early ones include:

• Fever
• Headache
• Vomiting
• Weakness

Signs that the virus may be affecting the brain or spinal cord include confusion, loss of coordination, trouble speaking and seizures. CDC also lists weakness or paralysis, movement problems and problems with the nerves of the face and eyes in people with encephalitis. Older adults, children and people with weakened immune systems are more likely to develop this severe form.

These symptoms overlap with many other illnesses, which is why telling your provider about any tick bite or time in tick habitat matters. For how Lyme symptoms compare, see our Lyme disease symptoms guide.

Severe disease and recovery

When Powassan infects the brain or its lining, it can be life-threatening. CDC estimates that about 1 in 10 people with this neuroinvasive disease die. About half of survivors have long-lasting nerve or brain problems, such as recurring headaches, muscle weakness, paralysis in one area or trouble with thinking and memory.

If you or someone you care for is living with after-effects, our pages on caring for someone and support groups may help, even though they focus on Lyme.

Treatment

There is no medicine that targets Powassan virus. Care is supportive:

• Milder illness: rest, fluids and over-the-counter pain relievers may ease some symptoms.
• Severe illness: people are often hospitalized for help with breathing, fluids and reducing brain swelling. Clinicians watch closely for seizures and pressure inside the skull.

People with weakened immune systems, including those on medicines that suppress the immune system, face a higher risk of serious illness and death. After a confirmed infection, CDC advises not donating blood for 120 days (4 months).

How to prevent Powassan

With no vaccine, prevention means avoiding tick bites:

• Use an EPA-registered insect repellent.
• In areas where the virus spreads, avoid wooded and bushy areas with high grass.
• Check your body, clothing and pets for ticks after being outdoors, and remove ticks promptly. See what to do after a tick bite.

More practical steps are on our tick bite prevention, hiking and yard pages. Knowing the warning signs is part of step 3 of our plan, recognize the signs.

Frequently asked questions