Seroprevalence of Powassan Virus Infection in an Area Experiencing a Cluster of Disease Cases: Sussex County, New Jersey, 2019

A serosurvey of 273 residents of a New Jersey community with several recent Powassan virus neuroinvasive disease cases estimated IgM seroprevalence at <1% and that roughly one-quarter of infections result in neuroinvasive disease. In 2019, a geographically focal cluster of 3 Powassan virus neuroinvasive disease cases occurred in New Jersey. We conducted a serosurvey of 273 adult area residents and estimated that immunoglobulin M seroprevalence was 0.31% (95% confidence interval [CI], .04%-1.00%) and 23% (95% CI, 7%-100%) of infections result in neuroinvasive disease.