Powassan virus
Encyclopedia
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 20 recognized cases of human disease. 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.
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".
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.
Flavivirus
Flavivirus is a genus of the family Flaviviridae. This genus includes the West Nile virus, dengue virus, tick-borne encephalitis virus, yellow fever virus, and several other viruses which may cause encephalitis....
. This disease had its earliest origins in the town of Powassan, Ontario
Powassan, Ontario
Powassan is a municipality in the Canadian province of Ontario, located near North Bay. Powassan is located in the Parry Sound District, at its easternmost boundary with the Nipissing District....
, found in a young boy who eventually died from it.
Powassan virus is transmitted by Ixodes cookei
Ixodes cookei
Ixodes cookei is a species of tick in the genus Ixodes. It is normally a parasite of carnivorans, such as raccoons, foxes, and weasels, but has also been recorded on the groundhog and the marsh rice rat...
among small mammals in eastern Canada and the United States, where it has been responsible for 20 recognized cases of human disease. Other ticks may transmit the virus in a wider geographic area, and there is some concern that Ixodes scapularis
Ixodes scapularis
Ixodes scapularis is commonly known as the deer tick or blacklegged tick , and in some parts of the USA as the bear tick. It is a hard-bodied tick of the eastern and northern Midwestern United States...
(also called I. dammini), a competent vector in the laboratory, may become involved as it becomes more prominent in the United States.
A genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
of the Powassan virus, called the deer tick virus
Deer tick virus
Deer tick virus is a virus causing tick-borne encephalitis.Deer tick virus is a flavivirus closely resembling Powassan 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".
Time of transmission
Powassan encephalitisEncephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
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.