Epidemiological study on Japanese encephalitis virus distribution in Ishikawa prefecture, Japan, by serological investigation using wild boar sera.

Thirty-seven specimens of wild boar sera were collected from August 2016 to March 2018 in Ishikawa prefecture, Japan. Thirty-two specimens (86.5%) were positive for neutralizing antibodies against Japanese encephalitis virus (JEV). Eight specimens (21.6%) were positive for IgM antibodies against JEV. One sample was obtained from a wild boar captured in February during the winter season. Four other serum specimens obtained during the winter season were positive using a JEV gene-specific PCR assay. Based on IgM and PCR assays, wild boars were infected with JEV during the winter season, suggesting that the prevalence of JEV antibodies in wild boars in Ishikawa is high and JEV activity is possible during winter in this region. In addition, wild boars may play an important role in the infection cycle of JEV.