Powassan Virus Disease

Infected ticks can transmit the Powassan virus to humans.

Powassan virus disease facts written by John Cunha, DO, FACOEP

• Powassan virus disease is a rare and often severe viral disease spread to people by infected ticks.
• Most cases of Powassan virus disease occur from the late spring through mid-fall in the northeastern and Great Lakes regions of the U.S.
• Those at highest risk of infection from Powassan virus disease are people who live, work, or vacation in brushy or wooded areas, because of greater exposure to potentially infected ticks.
• The incubation period for Powassan virus disease ranges from 1 week to 1 month.
• Powassan virus disease may cause no symptoms. When symptoms and signs do occur, they can include fever, headache, vomiting, and weakness.
• In severe cases, the Powassan virus can cause infections of the brain (encephalitis) or the membranes that surround the brain and spinal cord (meningitis). Symptoms and signs of severe disease may include confusion, loss of coordination, difficulty speaking, and seizures.
• Doctors make a diagnosis of Powassan virus infection based on a patient's history, signs and symptoms, and laboratory testing of blood or spinal fluid.
• There is no specific treatment for Powassan virus disease. Those with severe disease may need hospitalization to receive support for breathing, hydration, and reduction of brain swelling.
• Protecting yourself from tick bites is the best way to help prevent 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).

Powassan virus is spread to people by infected ticks. It does not spread through coughing, sneezing, or touching.

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.

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.

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

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

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

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.

The best way to prevent Powassan virus disease is to protect yourself from tick bites. There is no vaccine to prevent Powassan virus infection.

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