Wildlife Exposure Rates to Oz Virus vs. Severe Fever with Thrombocytopenia Syndrome Virus in Oita Prefecture, Japan

Oz virus (OZV) was first isolated from ticks in Japan in 2018, and human infections with OZV were reported in 2023. However, serosurveillance for OZV infections, compared with that for severe fever with thrombocytopenia syndrome (SFTS), is rarely performed among wild animals. We conducted a retrospective study on the epidemiology of SFTS virus and OZV infections in wild animals. Serum samples were collected from 289 deer, 158 raccoons, and 381 wild boars in this study. The positivity rates for the anti-OZV IgG antibody in deer (10.3%), raccoons (12%), and wild boars (12.1%) showed no difference. Both OZV and SFTS virus IgG antibodies were detected in wild animals. Wild animals in Oita Prefecture had anti-OZV antibodies, suggesting that human cases will occur in the future. We recommend educating the public about the tick-borne pathogen risks in this area and implementing tick bite prevention strategies.