Veterinary Epidemiology Unit, Department of Preventive Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
Division of Transboundary Animal Disease Research, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan.
PLoS Comput Biol. 2022 Oct 6;18(10):e1010510. doi: 10.1371/journal.pcbi.1010510. eCollection 2022 Oct.
Understanding the impact of vaccination in a host population is essential to control infectious diseases. However, the impact of bait vaccination against wildlife diseases is difficult to evaluate. The vaccination history of host animals is generally not observable in wildlife, and it is difficult to distinguish immunity by vaccination from that caused by disease infection. For these reasons, the impact of bait vaccination against classical swine fever (CSF) in wild boar inhabiting Japan has not been evaluated accurately. In this study, we aimed to estimate the impact of the bait vaccination campaign by modelling the dynamics of CSF and the vaccination process among a Japanese wild boar population. The model was designed to estimate the impact of bait vaccination despite lack of data regarding the demography and movement of wild boar. Using our model, we solved the theoretical relationship between the impact of vaccination, the time-series change in the proportion of infected wild boar, and that of immunised wild boar. Using this derived relationship, the increase in antibody prevalence against CSF because of vaccine campaigns in 2019 was estimated to be 12.1 percentage points (95% confidence interval: 7.8-16.5). Referring to previous reports on the basic reproduction number (R0) of CSF in wild boar living outside Japan, the amount of vaccine distribution required for CSF elimination by reducing the effective reproduction number under unity was also estimated. An approximate 1.6 (when R0 = 1.5, target vaccination coverage is 33.3% of total population) to 2.9 (when R0 = 2.5, target vaccination coverage is 60.0% of total population) times larger amount of vaccine distribution would be required than the total amount of vaccine distribution in four vaccination campaigns in 2019.
了解宿主群体中疫苗接种的影响对于控制传染病至关重要。然而，很难评估针对野生动物疾病的诱饵疫苗接种的影响。野生动物的宿主动物的疫苗接种史通常是不可观察的，并且很难将疫苗接种引起的免疫力与疾病感染引起的免疫力区分开来。由于这些原因，针对日本野猪中古典猪瘟（CSF）的诱饵疫苗接种的影响尚未准确评估。在这项研究中，我们旨在通过模拟 CSF 在日本野猪种群中的动力学和疫苗接种过程来估计诱饵疫苗接种的影响。该模型旨在估计诱饵疫苗接种的影响，尽管缺乏有关野猪的人口统计学和运动的数据。使用我们的模型，我们解决了疫苗接种对感染野猪比例和免疫野猪比例时间序列变化的影响之间的理论关系。利用该推导关系，估计了 2019 年疫苗接种活动导致 CSF 抗体流行率增加了 12.1 个百分点（95%置信区间：7.8-16.5）。参考先前关于日本以外野猪中 CSF 的基本繁殖数（R0）的报告，还估计了通过将有效繁殖数降低到 1 以下来消除 CSF 所需的疫苗分配量。与 2019 年四次疫苗接种活动的总疫苗分配量相比，大约需要多 1.6 倍（当 R0 = 1.5 时，目标疫苗接种覆盖率为总人口的 33.3%）到 2.9 倍（当 R0 = 2.5 时，目标疫苗接种覆盖率为总人口的 60.0%）的疫苗分配量。
