Powassan virus is a rare but serious virus transmitted primarily by ticks, particularly the black-legged tick and the groundhog tick. It can cause severe neurological disease, leading to symptoms such as fever, headache, and confusion. In some cases, it can result in long-term health issues or even death. The virus is named after the town of Powassan in Ontario, Canada, where it was first identified in 1958. While infections are uncommon, they are increasing in certain regions, particularly in the northeastern and north-central United States, as tick populations expand due to climate change and other factors.