|Group:||Group IV ((+)ssRNA)|
The Powassan virus is a tick-borne encephalitis (TBE) virus related to the classic TBE flavivirus. This disease had its earliest origins in the town of Powassan, Ontario, found in a young boy who eventually died from it.
Powassan virus is transmitted by Ixodes cookei among small mammals in eastern Canada and the United States, where it has been responsible for 39 deaths in the U.S. since 2008. Other ticks may transmit the virus in a wider geographic area, and there is some concern that Ixodes scapularis (also called I. dammini), a competent vector in the laboratory, may become involved as it becomes more prominent in the United States.
Powassan encephalitis generally shows first symptoms after 1–3 weeks. Powassan encephalitis is severe, and sequelae are common. In a mouse model, the Powassan virus can be transmitted in less than 15 minutes of tick attachment.
A genotype of the Powassan virus, called the deer tick virus, also called Powassan virus lineage II, is very closely related to Powassan virus and recent sequence analysis estimated that the two viruses diverged "approximately 200 years ago".
- Ebel GD, Kramer LD (2004). "Short report: duration of tick attachment required for transmission of powassan virus by deer ticks.". Am. J. Trop. Med. Hyg. 71 (3): 268–71. PMID 15381804.
- Kuno, G; Artsob H, Karabatsos N, Tsuchiya KR, Chang GJ. (November 2001). "Genomic sequencing of deer tick virus and phylogeny of powassan-related viruses of North America". Am J Trop Med Hyg 65 (5): 671–676. ISSN 0002-9637. PMID 11716135. Retrieved 5 July 2011.
- Pesko, KN.; Torres-Perez, F.; Hjelle, BL.; Ebel, GD. (Nov 2010). "Molecular epidemiology of Powassan virus in North America.". J Gen Virol 91 (Pt 11): 2698–705. doi:10.1099/vir.0.024232-0. PMID 20631087.
- Subbotina EL, Loktev VB (2012). "Molecular evolution of the tick-borne encephalitis and Powassan viruses". Mol. Biol. 46 (1): 75–84. doi:10.1134/S0026893311060148. PMID 22642104.
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