Powassan Virus Encephalitis in Pediatric Patients.

Powassan virus is a tickborne flavivirus that is a rare cause of encephalitis in humans. The incidence of cases is increasing in North America. We present 6 cases of Powassan virus encephalitis in pediatric patients diagnosed between 2018 and 2023 in the New England region of the United States. The age at diagnosis ranged from 14 months to 11 years. All patients presented with fever and confusion, and the majority also presented with seizures. All patients had lasting neurologic sequelae including seizures, movement disorders, behavioral problems, attention-deficit hyperactivity disorder (ADHD), learning problems, anxiety, and sleep disturbances. This is the largest pediatric case series of Powassan virus encephalitis to date. These cases demonstrate the emergence of Powassan virus as a rare, but severe, cause of encephalitis in children that has long-term neurologic consequences. We recommend increased clinical surveillance and public awareness of this increasingly prevalent tickborne disease.