The disease is relatively new and was discovered in Powassan, Canada in 1958 when a 5-year-old boy died from encephalitis caused by the Powassan virus. While very few cases have been reported in the past, the incident rate is slowly rising with most of the cases coming out of Minnesota and New York. According to the Centers for Disease Control and Prevention, there have been 17 reported cases of the disease from 2004 to 2013 in New York and 20 from Minnesota over the same time span. Pennsylvania reported only 1 case.
That doesn’t really tell the whole story. Those numbers only represent those that were tested and reported. Cases of Powassan virus are often mistaken for other health issues. The Powassan virus can act like Lyme Disease but it can also cause two very distinct diseases: encephalitis and meningitis. Both illnesses cause inflammation in the head and brain: encephalitis is an inflammation of the brain itself and meningitis is an inflammation of the membranes that surround the brain and spinal cord. Both are deadly.
There are various strains of encephalitis, but the one closely connected to Powassan is TBE – Tickborne Encephalitis. The Powassan virus is not always caused by TBE but the virus is often not tested for either. Of interest, the focal areas of TBE are Europe and Asia with an average of 8,500 cases reported annually. For the most part, it is travelers who are at greatest risk of bringing TBE back to the states, if they are infected.
While human cases of Powassan are low, there have been more cases of the virus discovered in at least 38 other mammals including rodents, woodchucks, skunks, dogs, and cats.
A blood or spinal fluid test would be able to determine if the virus was in the body. This test must specifically look for antibodies that the immune system would make in order to detect viral activity. Lyme disease is very different from Powassan in that there is a treatment. Lyme disease is a bacterial disease that antibiotics can effectively treat. Powassan is a flavivirus similar to West Nile or Dengue fever and does not have a cure or treatment regime.
The North American Powassan virus is being classified as coming from a newly evolved subtype of the deer tick. According to the Expert Review of Anti-Infective Therapy, a journal focused on infectious diseases, the Powassan virus is specific to three tick species: Ixodes cookei, I. marxi and I. spinipalpus. To the general population, the names are useless, but for those in the field, this provides crucial information to track and monitor the potential spread of Powassan-carrying ticks. As it appears that the disease incidence is slowly rising, it is critical to stop the spread of the culprit ticks.
One of the keys to keep the Powassan virus at bay is through routine monitoring and tracking. If we can avoid spreading the disease, we can keep the incidence rates low.
Those at high risk for Powassan are those who live in wooded areas, particularly the same locations as you might encounter ticks and Lyme disease. What makes this virus so deadly is that it often doesn’t come with symptoms. The person simply just develops encephalitis or meningitis after as long as a one-month incubation period.
The best way to reduce infection is to avoid contact with ticks – much like you would to reduce your risk of contracting Lyme Disease. Treating skin and clothing with insect repellents while in heavily wooded areas are recommended as well.
If you find a tick on your skin, remove it quickly before it has a chance to bite. After being in the woods, it is best to do a full body check before you walk into your home. Check all pets and equipment as well. Then, shower within two hours after being outdoors.
If you have been or believe you have been bit by a tick, consult your healthcare provider immediately. While it may not be Lyme disease or Powassan virus, you certainly want to make sure.
Works used for this article:
Centers for Disease Control and Prevention. (2015). Powassan virus. Retrieved from http://www.cdc.gov/powassan/index.html
EI Khoury, M. Y., Camargo, J. F., and Wormser, G. P. (2013). Changing epidemiology of Powassan encephalitis in North America suggest the emergence of the deer tick virus subtype. Expert Review of Anti-Infective Therapy, 11(10), 983-985.
El Khoury, M. Y., Camargo, J. F., White, J. L., Backenson, B. P., Dupuis II, A. P., Escuyer, K. L., Kramer, L., St. George, K., Chatterjee, D., Prusinski, M., Wormser, G. P., and Wong, S. J. (2013). Potential role of deer tick virus in Powassan encephalitis cases in Lyme Disease-endemic areas of New York, USA. Emerging Infectious Diseases, 19(12), 1926-1933.
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