Center for Infectious Diseases Epidemiology and Prevention Research, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
Center for Surveillance, Immunization and Epidemiologic Research, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
Viruses. 2024 Aug 9;16(8):1273. doi: 10.3390/v16081273.
Pigs are the most common amplifying hosts of the Japanese encephalitis virus (JEV). In 2016, four residents on Tsushima Island who did not own pig farms were diagnosed with JE. Therefore, a serosurvey was conducted to estimate the risk and seroprevalence of JEV after the outbreak. Sera collected from 560 Tsushima Island residents between January and September 2017 were tested for neutralizing antibodies against JEV strains JaGAr01 (genotype 3) and Muar (genotype 5). Sera collected from six wild boars between June and July 2022 were tested. The seroprevalence rates of neutralizing antibodies against JaGAr01 and Muar were 38.8% and 24.6%, respectively. High anti-JEV neutralizing antibody titers of ≥320 were identified in 16 residents, including 3 younger than 6 years with prior JEV vaccination, 2 in their 40s, and 11 older than 70. However, no anti-JEV-specific IgM was detected. Residents who engaged in outdoor activities had higher anti-JEV antibody titers. Sera from wild boars were negative for JEV RNA, but four of six samples contained neutralizing antibodies against JEV. Therefore, JEV transmission continues on Tsushima Island, even in the absence of pig farms, and wild boars might serve as the amplifying hosts.
猪是日本脑炎病毒（JEV）最常见的扩增宿主。2016 年，在对马岛上的 4 位非养猪户居民被诊断出患有日本脑炎。因此，在疫情爆发后进行了血清学调查，以评估 JEV 的风险和血清流行率。2017 年 1 月至 9 月，从 560 名对马岛居民中采集了血清，用于检测针对 JEV 株 JaGAr01（基因型 3）和 Muar（基因型 5）的中和抗体。同时，对 2022 年 6 月至 7 月采集的 6 只野猪血清进行了检测。针对 JaGAr01 和 Muar 的中和抗体血清阳性率分别为 38.8%和 24.6%。在 16 位居民中发现了高抗 JEV 中和抗体滴度≥320，其中 3 位年龄小于 6 岁，曾接种过 JEV 疫苗，2 位年龄在 40 多岁，11 位年龄大于 70 岁。然而，未检测到抗 JEV 特异性 IgM。从事户外活动的居民具有更高的抗 JEV 抗体滴度。野猪血清中未检测到 JEV RNA，但 6 个样本中有 4 个含有针对 JEV 的中和抗体。因此，即使没有养猪场，JEV 仍在对马岛传播，野猪可能充当了扩增宿主。
