Powassan encephalitis explained

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Powassan encephalitis, caused by the Powassan virus (POWV), a flavivirus also known as the deer tick virus, is a form of arbovirus infection that results from tick bites. It can occur as a co-infection with Lyme disease, as both are transmitted to humans by the same species of tick.^[1] Over the last decade, there has been a surge in the number of cases and an expansion of its geographic range. In the United States, cases have been documented primarily in the northeast.^[2] The disease was first isolated from the brain of a boy who died of encephalitis in Powassan, Ontario, in 1958.^[3] This disease is classified as a zoonosis, originating in animals, often found in rodents and ticks, with subsequent transmission to humans. The virus shares antigenic similarities with the Far Eastern tick-borne encephalitis viruses.^[4]

Presentation

Symptoms manifest within 7–10 days and include fever, headache, partial paralysis, confusion, nausea and even coma.

Treatment

There is currently no established treatment.^[5]

Prognosis

Half of all cases results in permanent neurological damage and 10-15% result in death.

Notes and References

1. Caulfield. AJ. Pritt. BS. Lyme Disease Coinfections in the United States.. Clinics in Laboratory Medicine. December 2015. 35. 4. 827–46. 26593260. 10.1016/j.cll.2015.07.006.
2. Web site: Cumulative human disease cases reported to CDC ArboNET for 2015. United States Geological Survey. 2015-11-27. https://web.archive.org/web/20161215234534/http://diseasemaps.usgs.gov/mapviewer/. 2016-12-15. dead.
3. McLEAN. DM. DONOHUE. WL. Powassan virus: isolation of virus from a fatal case of encephalitis.. Canadian Medical Association Journal. 1 May 1959. 80. 9. 708–11. 13652010. 1830849.
4. CASALS. J. Antigenic relationship between Powassan and Russian spring-summer encephalitis viruses.. Canadian Medical Association Journal. 13 February 1960. 82. 7. 355–8. 13808112. 1937779.
5. Hinten SR, Beckett GA, Gensheimer KF, etal . Increased recognition of Powassan encephalitis in the United States, 1999-2005 . Vector Borne Zoonotic Dis. . 8 . 6 . 733–40 . December 2008 . 18959500 . 10.1089/vbz.2008.0022 . Smith.