Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan.
Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan.
Prev Vet Med. 2020 Feb;175:104873. doi: 10.1016/j.prevetmed.2019.104873. Epub 2019 Dec 19.
In September 2018, classical swine fever (CSF) reemerged in Japan after 26 years' absence. The first case was detected at a pig farm in Gifu Prefecture, in the center of Japan, and the disease spread to both domestic pigs and wild boar (Sus scrofa). The spread of CSF in wild boar is extremely difficult to control and is thus a great threat to domestic pig farms, and understanding the transmission risk from wild boar to domestic pigs is essential to implement effective control measures that will prevent domestic pig infection. Therefore, this study elucidates the transmission risk from wild boar to domestic pigs by introducing a transmission kernel that is dependent on the distance between infected wild boar and pig farms, and then estimating the risk area of infection from wild boar by describing the transmission probability. The study used epidemiological data from Gifu Prefecture in the period from September 2018 to March 2019, including a total of 171 1-km grid cells where an infected wild boar was detected and pig farm data from 13 infected and 34 uninfected farms. The estimated infection risk area within 28 days matched well with the observed data. The risk area widened gradually during the epidemic, and at the end of March, the risk area extended over a range of approximately 75 km from east to west and 40 km from north to south (almost 3000 km). Ten out of the 13 infected farms and four out of the 34 uninfected farms were located within the high-risk area (>60 % infection probability). In contrast, one infected farm and 18 uninfected farms were located within the low-risk area (<5 % infection probability). When several infected grid cells were detected within 5 km of a pig farm, the risk of infection from wild boar within 28 days was more than 5 %. This analysis provides an estimate of the potential spatial range over which CSF virus can spread between wild boar and domestic pig farms, and can be used to inform the early detection of CSF-suspected pigs and the strengthening of biosecurity measures that will effectively prevent and control the disease based on the infection risk level.
2018 年 9 月，时隔 26 年，经典猪瘟（CSF）在日本再次出现。首例病例发生在日本中部岐阜县的一个养猪场，疫情迅速蔓延至家猪和野猪（Sus scrofa）。野猪中 CSF 的传播极难控制，因此对养猪场构成巨大威胁，了解野猪向家猪传播的风险对于实施有效的防控措施以防止家猪感染至关重要。因此，本研究通过引入一个依赖于感染野猪和养猪场之间距离的传播核，阐明了野猪向家猪传播的风险，并通过描述传播概率来估计野猪感染的风险区域。该研究使用了 2018 年 9 月至 2019 年 3 月期间岐阜县的流行病学数据，包括总共 171 个 1 公里网格单元，在这些网格单元中检测到了感染的野猪，以及来自 13 个感染和 34 个未感染农场的数据。在 28 天内估计的感染风险区域与观察数据吻合良好。随着疫情的发展，风险区域逐渐扩大，到 3 月底，风险区域从东向西延伸约 75 公里，从北向南延伸约 40 公里（几乎 3000 公里）。在 13 个感染农场中，有 10 个农场和在 34 个未感染农场中，有 4 个农场位于高风险区域（感染概率>60%）。相比之下，一个感染农场和 18 个未感染农场位于低风险区域（感染概率<5%）。当养猪场附近 5 公里范围内检测到多个感染网格单元时，野猪在 28 天内感染的风险超过 5%。本分析提供了 CSF 病毒在家猪和野猪农场之间传播的潜在空间范围的估计，可以根据感染风险水平，用于早期发现疑似 CSF 的猪，并加强生物安全措施，有效预防和控制疾病。
