Research and Innovation Centre, Fondazione Edmund Mach, San Michele All'Adige, TN, Italy.
Azienda Provinciale Servizi Sanitari, Trento, Italy.
Sci Rep. 2023 May 22;13(1):8262. doi: 10.1038/s41598-023-35478-w.
Tick-borne encephalitis (TBE) is caused by a flavivirus that infects animals including humans. In Europe, the TBE virus circulates enzootically in natural foci among ticks and rodent hosts. The abundance of ticks depends on the abundance of rodent hosts, which in turn depends on the availability of food resources, such as tree seeds. Trees can exhibit large inter-annual fluctuations in seed production (masting), which influences the abundance of rodents the following year, and the abundance of nymphal ticks two years later. Thus, the biology of this system predicts a 2-year time lag between masting and the incidence of tick-borne diseases such as TBE. As airborne pollen abundance is related to masting, we investigated whether inter-annual variation in pollen load could be directly correlated with inter-annual variation in the incidence of TBE in human populations with a 2-year time lag. We focused our study on the province of Trento (northern Italy), where 206 TBE cases were notified between 1992 and 2020. We tested the relationship between TBE incidence and pollen load collected from 1989 to 2020 for 7 different tree species common in our study area. Through univariate analysis we found that the pollen quantities recorded two years prior for two tree species, hop-hornbeam (Ostrya carpinifolia) and downy oak (Quercus pubescens), were positively correlated with TBE emergence (R = 0.2) while a multivariate model with both tree species better explained the variation in annual TBE incidence (R = 0.34). To the best of our knowledge, this is the first attempt at quantifying the correlation between pollen quantities and the incidence of TBE in human populations. As pollen loads are collected by widespread aerobiological networks using standardized procedures, our study could be easily replicated to test their potential as early warning system for TBE and other tick-borne diseases.
蜱传脑炎（TBE）是由一种黄病毒引起的，该病毒感染包括人类在内的动物。在欧洲，TBE 病毒在自然疫源地的蜱和啮齿动物宿主中循环传播。蜱的数量取决于啮齿动物宿主的数量，而啮齿动物宿主的数量又取决于食物资源的可利用性，如树的种子。树木的种子产量会出现很大的年际波动（结实），这会影响到次年啮齿动物的数量，以及两年后幼蜱的数量。因此，该系统的生物学预测，结实和蜱传疾病（如 TBE）的发生之间存在 2 年的时间滞后。由于空气传播花粉的数量与结实有关，我们调查了花粉负荷的年际变化是否可以与人类 TBE 发病率的年际变化直接相关，时间滞后为 2 年。我们的研究集中在意大利北部的特伦蒂诺省（Trento），在 1992 年至 2020 年间，该地区共报告了 206 例 TBE 病例。我们测试了从 1989 年到 2020 年采集的 7 种常见树种的花粉负荷与 TBE 发病率之间的关系。通过单变量分析，我们发现两种树种（山毛榉和柔毛栎）的花粉量在两年前记录与 TBE 出现呈正相关（R = 0.2），而同时包含这两种树种的多变量模型更好地解释了年度 TBE 发病率的变化（R = 0.34）。据我们所知，这是首次尝试量化花粉数量与人类 TBE 发病率之间的相关性。由于花粉负荷是通过使用标准化程序的广泛空气生物学网络收集的，我们的研究可以很容易地复制，以测试它们作为 TBE 和其他蜱传疾病的预警系统的潜力。
