Survey of Japanese encephalitis virus in pigs and wild boars on Ishigaki and Iriomote Islands in Okinawa, Japan

A significant difference in Japanese encephalitis virus (JEV) seroprevalence was observed between pigs and wild boars across Ishigaki and Iriomote Islands in Okinawa, Japan. While only 3.1% of pigs on Ishigaki tested positive for JEV antibodies, a striking 44.4% of wild boars on nearby Iriomote Island showed evidence of exposure. This contrasts sharply with previous seroprevalence rates of 3.7% in Iriomote wild boars from 2000 and 2004, suggesting a potential increase in JEV transmission. Phylogenetic analysis further indicated that the JEV strain detected on Ishigaki (JEV/sw/Ishigaki/1/2005) was closely related to strains circulating in Taiwan between 2006 and 2008, hinting at possible inter-regional transmission dynamics. The study employed serological surveys of serum samples collected from pigs and wild boars over multiple years (2008–2010), providing critical insights into JEV distribution and potential spillover risks in these regions.

NIDAIRA, M., KYAN, H., TAIRA, K., OKANO, S., OSHIRO, T., KATO, T., KUDO, N., AZAMA, Y., MAHOE, Y., KUDAKA, J., TAMANAHA, K., & TAKASAKI, T. (2013). Survey of Japanese encephalitis virus in pigs and wild boars on Ishigaki and Iriomote Islands in Okinawa, Japan. Epidemiology and Infection, 142(4), 856–860. https://doi.org/10.1017/s0950268813001611