Japanese Journal of Veterinary Research;Volume 67 Number 2


Epidemiological survey of tick-borne encephalitis virus infection in wild animals on Hokkaido and Honshu islands, Japan

Jamsransuren, Dulamjav;Yoshii, Kentaro;Kariwa, Hiroaki;Asakawa, Mitsuhiko;Okuda, Kei;Fujii, Kei;Fukumoto, Shinya;Umemiya-Shirafuji, Rika;Sasaki, Motoki;Matsumoto, Kotaro;Yamaguchi, Emi;Ogawa, Haruko;Imai, Kunitoshi

Permalink : http://hdl.handle.net/2115/74797
JaLCDOI : 10.14943/jjvr.67.2.163
KEYWORDS : Deer;Raccoon;Sentinel;Seroprevalence;Tick-borne encephalitis (TBE)


The first human case of tick-borne encephalitis (TBE) in Japan was recorded in southern Hokkaido in 1993 and was followed by four further cases in southern, central, and northern Hokkaido during 2016-2018. However, the distribution of TBE virus (TBEV) foci in Japan is unclear. Therefore, here, we serologically examined raccoons (Procyon lotor), sika deer (Cervus nippon), and wild boars (Sus scrofa) as sentinels of TBEV infection in Hokkaido and in Fukushima and Tochigi Prefectures in Honshu. A total of 1,649 serum samples collected between 2003 and 2018 were screened by enzyme-linked immunosorbent assay using subviral particles and confirmed using the virus neutralization test. In raccoons, the seroprevalence of TBEV was 5.9% (39/662 samples) in central Hokkaido in 2003-2005 and 0.8% (3/368 samples) in eastern Hokkaido in 2010-2018, revealing the presence of TBEV foci in these areas. In addition, 0.5% (2/414) of deer sampled in eastern Hokkaido in 2010-2017 and 2.4% (1/42) of deer sampled in Tochigi Prefecture in 2016-2018 were seropositive. On Honshu, seropositive rodents have previously been detected only in Shimane Prefecture. Therefore, the detection of seropositive animals in Tochigi Prefecture may indicate the widespread distribution of TBEV foci throughout Japan. TBEV and viral genes were not detected in 507 ticks collected in the same area of eastern Hokkaido where seropositive animals were found, reemphasizing the value of using serological examination of wild animals as a tool for revealing unknown TBE risk areas. Our findings also indicate that raccoons may be particularly useful sentinels.