Powassan Virus (POWV) and Deer Tick Virus (DTV)

What are Powassan Virus (POWV) and Deer Tick Virus (DTV)?

Powassan virus (POWV) and Deer Tick Virus (DTV)  are tick transmitted viruses that can cause meningoencephalitis. Deer tick virus is a flavivirus closely resembling Powassan virus. Because they are so related, deer tick virus is thought to be a genotype of Powassan virus, and is also called Powassan virus lineage II. 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. Powassan virus will be transmitted to human host within 15 minutes of tick attachment. The time from tick bite to feeling sick (incubation period) ranges from 1 week to 1 month. 

  Initial symptoms can include: 

  • Fever
  • Headache
  • Vomiting
  • 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
  • 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
  • Memory problems


Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD)

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