Powassan virus is spread to people by the bite of an infected Blacklegged Tick (Ixodes scapularis). Although still rare, the number of reported cases of people sick from Powassan virus has increased in recent years. Most cases in the United States occur in late spring through mid-fall when ticks are most active. Unlike other tick-borne diseases, a tick can transmit Powassan virus while being attached to a person for as little as 15 minutes.
Many people who become infected with Powassan virus do not develop symptoms. However, for those who do, symptoms usually appear within 1 to 4 weeks after the bite of an infected tick occurred.
Symptoms may include: Fever, vomiting, muscle weakness, headaches, confusion, lack of coordination, speech problems, memory problems, and seizures. When the infection spreads to the central nervous system, meningitis or encephalitis with seizures may occur, a low percentage of encephalitis cases result in death.