Powassan Virus Seroprevalence in a U.S. Servicemember Population at High Risk for Tick Exposure

Powassan virus (POWV) is an emerging tick-borne flavivirus that can cause severe encephalitis in humans. Currently no vaccines or therapeutics are approved to treat POWV. POWV is spread by the deer tick, Ixodes scapularis, which is ubiquitous across the Northeastern United States. To better understand POWV prevalence in high-risk populations, we examined POWV seroprevalence in Cadets at United States Military Academy (USMA) in West Point, New York. Cadets at USMA, located in a heavily wooded area, are at high risk for tick exposure during outdoor military training. 1,051 serum samples from the Cadet class of 2017 were screened for POWV seropositivity using a POWV Envelope (E) DIII ELISA. A seropositivity rate of 1.3% was determined. Several ELISA-positive samples were also able to neutralize both reporter virus particles bearing the POWV E protein and authentic POWV. This study demonstrates populations at risk for tick exposure may have significant seroprevalence of POWV.