Powassan Virus Disease

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Best Method for Tick Removal

The following is a step-by-step method that is suggested for safe and effective removal of all types of ticks.

  1. Wear hand protection such as gloves so you don't spread pathogens from the tick to your hands; use forceps or tweezers to grab the tick at skin level.
  2. Grasp the tick firmly with the tweezers as close to the skin as possible without crushing the tick. Apply gentle pulling motion upward until the tick comes free. Twisting or turning the tick does not make removal easier because the mouthparts are barbed; in fact, such actions may break off the head and mouthparts, thereby increasing the chances for infection. The second web citation illustrates the proper removal of a tick.
  3. Once the tick is removed, don't crush the tick because it may release pathogens. Consider keeping it in a tightly closed jar or taped to a piece of paper. Show the tick to the doctor if the person bitten becomes ill after the tick bite. Flush any removed ticks not kept for identification down the toilet or sink.

Powassan virus (POW virus) facts

  • Powassan viruses are members of the genus Flavivirus; there are two types, termed lineage 1 and lineage 2.
  • Powassan virus disease is an infection caused by these viruses that may result in a range of symptoms from none to encephalitis and death; the disease is relatively rare in the United States.
  • Both types of Powassan viruses cause the disease; however, these viruses require a vector to transmit them to humans. The vector is a tick.
  • The major risk factor is a tick bite from an infected tick.
  • Most incidences of this disease in the U.S. have occurred in the northeastern and Great Lakes regions.
  • If symptoms develop, they may include fever, headache, vomiting, weakness, confusion, loss of coordination, speech and memory problems, and seizures.
  • Besides the patient's history and physical examination (especially the history of a tick bite), blood and spinal fluid tests are needed to diagnose this infection.
  • There is no specific treatment for this disease; supportive care, including hospitalization, may be required for severe infections.
  • Home remedies to prevent tick bites may help prevent the disease.
  • Complications of Powassan virus disease may include permanent problems such as recurrent headaches, muscle wasting, and memory problems; severe infections may cause death the prognosis depends on the severity of the disease and may range from good to poor.
  • There is no vaccine available to prevent Powassan virus disease; however, it is possible to prevent transmission of the disease to humans if tick bites are prevented.

What are the types of Powassan virus (POW virus)?

Powassan (POW) virus is a Flavivirus, a genus in the family of Arbovirus; it is related to viruses such as West Nile virus. The virus is named after Powassan, Ontario, where it was first discovered in 1958. Two types of Powassan virus have been found in North America, including lineage 1 and lineage 2 (deer tick virus) types of POW viruses. Linage 1 type is associated with Ixodes cookeri, Ixodes marxi, and Ixodes scapularis tick species, while linage 2 virus is only associated with Ixodes scapularis ticks. Unfortunately, the tick that usually bites humans and is infected is Ixodes scapularis so humans can be infected with either virus type.

Medically Reviewed by a Doctor on 5/22/2017

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