Powassan virus is spread to people by the bite of an infected tick. Although still rare, the number of reported cases of people sick from Powassan virus has increased in recent years. Most cases in the United States occur in the northeast and Great Lakes regions from late spring through mid-fall when ticks are most active.

There are no vaccines to prevent or medicines to treat Powassan virus disease. Reduce your risk of infection from Powassan virus by avoiding ticks.

Powassan virus is spread to people by the bite of an infected tick. Ticks become infected when they feed on groundhogs, squirrels, mice, or other rodents that have the virus in their blood. Infected ticks can then spread Powassan virus to people and other animals by biting them. People do not develop high enough levels of the virus in their blood to infect biting ticks. As a result, people are considered “dead-end” hosts for Powassan virus.

The virus is not transmitted from person to person, except in rare instances by blood transfusion. Because the virus can be transmitted through blood, persons who were recently diagnosed with Powassan virus infection should not donate blood and bone marrow for 120 days following infection.

Three types of ticks spread Powassan virus and are primarily found in the eastern half of the United States.

• Ixodes cookei (groundhog tick)
• Ixodes marxi (squirrel tick), and
• Ixodes scapularis (blacklegged or deer tick)

The groundhog tick and the squirrel tick rarely bite people. The blacklegged, or deer tick, which feeds mainly on white-footed mice and deer, often bites people. These bites can result in several types of diseases (e.g., Lyme disease).

Ticks can attach to any part of the body but are often found in hard-to-see areas such as the groin, armpits, and scalp.

Prevent getting sick with Powassan virus by preventing tick bites.

Many people infected with Powassan virus do not have symptoms. For people with symptoms, the time from tick bite to feeling sick ranges from 1 week to 1 month.

• Initial symptoms can include fever, headache, vomiting, and weakness.
• Powassan virus can cause severe disease, including infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).
  • Symptoms of severe disease include confusion, loss of coordination, difficulty speaking, and seizures.
  • Approximately 1 out of 10 people with severe disease die.
  • Approximately half of the people who survive severe disease have long-term health problems such as recurring headaches, loss of muscle mass and strength, and memory problems.

If you think you or a family member might Powassan virus disease, talk to your healthcare provider.

• Healthcare providers diagnose Powassan virus infection 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 carry Powassan virus
  • Laboratory testing of blood or spinal fluid
• Your healthcare provider can order tests to look for Powassan virus infection or other infections that can cause similar symptoms.

There are no medications to prevent or treat Powassan virus infection. Antibiotics do not treat viruses.

Rest, fluids, and over-the-counter pain medications may relieve some symptoms.

People with severe disease often need to be hospitalized to receive support for breathing, staying hydrated, or reducing swelling in the brain.

Powassan virus is spread to people by the bite of an infected tick. There is no vaccine to prevent Powassan virus infection. Reduce your risk of getting sick by:

• Preventing tick bites
• Preventing ticks on your pets
• Preventing ticks in your yard

What is Powassan virus disease?

Powassan virus disease is a rare, but often severe disease caused by a virus spread to people by infected ticks. The number of reported cases of people sick from Powassan virus has increased in recent years. Powassan virus belongs to a group of viruses that can cause infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).

How do people get infected with Powassan virus?

Powassan virus is spread to people primarily by infected ticks. Rarely, Powassan virus has spread person-to-person through a blood transfusion. It does not spread through coughing, sneezing, or touching.

Where and when have most cases of Powassan virus disease occurred?

Most cases have occurred in the northeastern and Great Lakes regions of the United States from the late spring through mid-fall when ticks are most active.

Who is at risk for infection with Powassan virus?

Anyone bitten by a tick in an area where the virus is commonly found can be infected with Powassan virus. The risk is highest for people who live, work or recreate in brushy or wooded areas, because of greater exposure to potentially infected ticks.

How soon do people get sick after getting bitten by an infected tick?

The time from tick bite to feeling sick (incubation period) ranges from 1 week to 1 month.

What are the symptoms of Powassan virus disease?

Many people infected with Powassan virus do not have symptoms. For those who have them, initial symptoms can include:

• Fever
• Headache
• Vomiting
• Weakness

Powassan virus can cause severe disease, including infections of the brain (encephalitis) or the membranes that surround the brain and spinal cord (meningitis). Symptoms of severe disease can include:

• Confusion
• Loss of coordination
• Difficulty speaking
• Seizures

How is Powassan virus disease diagnosed?

Healthcare providers diagnose Powassan virus infection based on:

• Signs and symptoms
• History of possible exposure to the ticks that spread Powassan virus
• Laboratory testing of blood or spinal fluid

What is the treatment for Powassan virus disease?

There are no specific medicines to treat Powassan virus disease. People with severe disease often need to be hospitalized to receive support for breathing, staying hydrated, and reducing swelling in the brain.

How can I reduce the chance of getting infected with Powassan virus?

The best way to prevent Powassan virus disease is to protect yourself from tick bites. There is no vaccine to prevent Powassan virus infection. Reduce your risk of getting sick by:

• Preventing tick bites
• Preventing ticks on your pets
• Preventing ticks in your yard

What should I do if I think a family member might have Powassan virus disease?

If you think you or a family member might have Powassan virus disease, see your healthcare provider.