Powassan virus disease

Powassan virus disease is a sometimes life-threatening illness transmitted to humans by infected ticks, particularly deer ticks. It is caused by the Powassan virus, an arbovirus related to West Nile virus. The illness typically presents with symptoms such as fever, headache, weakness, confusion, loss of coordination, seizures, and often encephalitis or meningitis. In severe cases, hospitalization may be required for respiratory support or to reduce brain swelling. The first case was reported in 2008, and the virus was first identified in Powassan, Ontario, in 1958. The disease is most commonly found in the northeastern U.S. and the Great Lakes region.1