CIRAD, UMR ASTRE, Montpellier, France.
ASTRE, Univ Montpellier, CIRAD, INRAE, Montpellier, France.
Transbound Emerg Dis. 2022 Sep;69(5):e2351-e2365. doi: 10.1111/tbed.14578. Epub 2022 May 19.
We developed a correlative model at high resolution for predicting the distribution of one of the main vectors of Crimean-Congo haemorrhagic fever virus (CCHFV), Hyalomma marginatum, in a recently colonised area, namely southern France. About 931 H. marginatum adult ticks were sampled on horses from 2016 to 2019 and 2021 in 14 southern French departments, which resulted in the first H. marginatum detection map on a large portion of the national territory. Such updated presence/absence data, as well as the mean number of H. marginatum per examined animal (mean parasitic load) as a proxy of tick abundance, were correlated to multiple parameters describing the climate and habitats characterising each collection site, as well as movements of horses as possible factors influencing tick exposure. In southern France, H. marginatum was likely detected in areas characterised by year-long warm temperatures and low precipitation, especially in summer and mostly concentrated in autumn, as well as moderate annual humidity, compared to other sampled areas. It confirms that even in newly invaded areas this tick remains exclusively Mediterranean and cannot expand outside this climatic range. Regarding the environment, a predominance of open natural habitats, such as sclerophyllous vegetated and sparsely vegetated areas, were also identified as a favourable factor, in opposition to urban or peri-urban and humid habitats, such as continuous urban areas and inland marshes, respectively, which were revealed to be unsuitable. Based on this model, we predicted the areas currently suitable for the establishment of the tick H. marginatum in the South of France, with relatively good accuracy using internal (AUC = 0.66) and external validation methods (AUC = 0.76 and 0.83). Concerning tick abundance, some correlative relationships were similar to the occurrence model, as well as the type of horse movements being highlighted as an important factor explaining mean parasitic load. However, the limitations of estimating and modelling H. marginatum abundance in a correlative model are discussed.
我们在高分辨率下开发了一个相关模型，用于预测克里米亚-刚果出血热病毒（CCHFV）的主要传播媒介之一，边缘硬蜱（Hyalomma marginatum）在最近殖民化地区的分布情况，该地区为法国南部。2016 年至 2019 年和 2021 年，我们在法国南部的 14 个省份从马身上采集了约 931 只成年边缘硬蜱，这是首次在法国大部分地区绘制边缘硬蜱的分布图。这些更新的存在/缺失数据，以及每只检查动物的边缘硬蜱平均数（平均寄生负荷）作为蜱丰度的替代指标，与描述每个采集点气候和栖息地特征的多个参数以及马的运动（可能影响蜱暴露的因素）相关。在法国南部，边缘硬蜱可能在全年温暖和低降水的地区被检测到，尤其是在夏季，主要集中在秋季，而年湿度适中，与其他采样地区相比。这证实了即使在新入侵的地区，这种蜱仍然是地中海特有的，不能在这个气候范围内扩张。至于环境，开放的自然栖息地（如硬叶植被和稀疏植被区）占主导地位，这也被认为是一个有利因素，而城市或城乡结合部和潮湿的栖息地（如连续的城市地区和内陆沼泽地）则被认为是不适宜的。根据这个模型，我们预测了法国南部目前适合边缘硬蜱建立的区域，使用内部（AUC = 0.66）和外部验证方法（AUC = 0.76 和 0.83），预测结果具有较好的准确性。关于蜱丰度，一些相关关系与发生模型相似，马的运动类型也被强调为解释平均寄生负荷的一个重要因素。然而，在相关模型中估计和模拟边缘硬蜱丰度的局限性也进行了讨论。
