Department of Veterinary Sciences, University of Turin, Largo Braccini, 2, 10095 Grugliasco, TO, Italy.
Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, 3720 BA Bilthoven, the Netherlands.
Ticks Tick Borne Dis. 2020 Sep;11(5):101489. doi: 10.1016/j.ttbdis.2020.101489. Epub 2020 Jun 8.
In mountain areas of northwestern Italy, ticks were rarely collected in the past. In recent years, a marked increase in tick abundance has been observed in several Alpine valleys, together with more frequent reports of Lyme borreliosis. We then carried out a four-year study to assess the distribution and abundance of ticks and transmitted pathogens and determine their altitudinal limit in a natural park area in Piedmont region. Ixodes ricinus and Dermacentor marginatus were collected from both the vegetation and hunted wild ungulates. Tick abundance was significantly associated with altitude, habitat type and signs of animal presence, roe deer's in particular. Ixodes ricinus prevailed in distribution and abundance and, although their numbers decreased with increasing altitude, we recorded the presence of all active life stages of up to around 1700 m a.s.l., with conifers as the second most infested habitat after deciduous woods. Molecular analyses demonstrated the infection of questing I. ricinus nymphs with B. burgdorferi sensu lato (15.5 %), Rickettsia helvetica and R. monacensis (20.7 %), Anaplasma phagocytophilum (1.9 %), Borrelia miyamotoi (0.5 %) and Neoehrlichia mikurensis (0.5 %). One third of the questing D. marginatus were infected with R. slovaca. We observed a spatial aggregation of study sites infested by B. burgdorferi s.l. infected ticks below 1400 m. Borrelia-infected nymphs prevailed in open areas, while SFG rickettsiae prevalence was higher in coniferous and deciduous woods. Interestingly, prevalence of SFG rickettsiae in ticks doubled above 1400 m, and R. helvetica was the only pathogen detected above 1800 m a.s.l. Tick infestation on hunted wild ungulates indicated the persistence of tick activity during winter months and, when compared to past studies, confirmed the recent spread of I. ricinus in the area. Our study provides new insights into the population dynamics of ticks in the Alps and confirms a further expansion of ticks to higher altitudes in Europe. We underline the importance of adopting a multidisciplinary approach in order to develop effective strategies for the surveillance of tick-borne diseases, and inform the public about the hazard posed by ticks, especially in recently invaded areas.
在意大利西北部的山区，过去很少采集蜱虫。近年来，在几个阿尔卑斯山谷中观察到蜱虫数量明显增加，同时莱姆病的报告也更加频繁。因此，我们进行了一项为期四年的研究，以评估蜱虫和传播病原体的分布和丰度，并确定它们在皮埃蒙特地区自然公园地区的海拔极限。从植被和被猎捕的野生动物中采集了蓖子硬蜱和边缘革蜱。蜱虫的丰度与海拔、栖息地类型和动物存在的迹象显著相关，特别是獐鹿。蓖子硬蜱在分布和丰度上占主导地位，尽管随着海拔的升高其数量减少，但我们记录了所有活动阶段的存在，直至海拔约 1700 米，以针叶林为仅次于落叶林的第二大受感染栖息地。分子分析表明，在莱姆病螺旋体属（15.5%）、瑞士无芽胞杆菌和单胞菌属（20.7%）、嗜吞噬细胞无形体（1.9%）、伯氏疏螺旋体（0.5%）和新立克次体（0.5%）感染的蓖子硬蜱若虫中存在感染。三分之一的边缘革蜱受瑞士无芽胞杆菌感染。我们观察到，在海拔低于 1400 米的受感染的蜱虫研究点存在空间聚集。在开阔区域中，感染伯氏疏螺旋体的若虫占优势，而 SFG 立克次体的流行率在针叶林和落叶林中更高。有趣的是，在海拔高于 1400 米的地方，SFG 立克次体的流行率增加了一倍，而瑞士无芽胞杆菌是海拔高于 1800 米的唯一检测到的病原体。在被猎捕的野生动物中，蜱虫的感染表明蜱虫活动在冬季期间持续存在，与过去的研究相比，这证实了莱姆病螺旋体属在该地区的近期传播。我们的研究提供了阿尔卑斯山地区蜱虫种群动态的新见解，并证实了蜱虫向更高海拔地区在欧洲的进一步扩张。我们强调了采用多学科方法的重要性，以便制定有效的监测策略来控制蜱传疾病，并向公众宣传蜱虫带来的危害，特别是在最近被入侵的地区。
