National Veterinary Institute, Kemitorvet, building 202, 2800, Kgs. Lyngby, Denmark.
National Veterinary Institute, Kemitorvet, building 202, 2800, Kgs. Lyngby, Denmark.
Ticks Tick Borne Dis. 2019 Apr;10(3):546-552. doi: 10.1016/j.ttbdis.2019.01.007. Epub 2019 Jan 24.
Presently, it is uncertain to what extent seasonal migrating birds contribute to the introduction of ticks and tick-associated pathogens in Denmark. To quantify this phenomenon, we captured birds during the spring and autumn migration at three field sites in Denmark and screened them for ticks. Bird-derived ticks were identified to tick species and screened for 37 tick-borne pathogens using real-time PCR. Overall, 807 birds, representing 44 bird species, were captured and examined for ticks during the spring (292 birds) and autumn migrations (515 birds). 10.7% of the birds harboured a total of 179 Ixodes ricinus ticks (38 ticks in spring and 141 in the autumn) with a mean infestation intensity of 2.1 ticks per bird. The European robin (Erithacus rubecula), the common blackbird (Turdus merula), and the common redstart (Phoenicurus phoenicurus) had the highest infestation intensities. 60.9% of the ticks were PCR-positive for at least one tick-borne pathogen. Borrelia DNA was found in 36.9% of the ticks. The Borrelia species detected were B. spielmanii (15.1%), B. valaisiana (13.4%), B. garinii (12.3%), B. burgdorferi s.s. (2.2%), B. miyamotoi (1.1%), and B. afzelii (0.6%). In addition, 10.6% and 1.7% of the samples were PCR-positive for spotted fever group rickettsiae and Candidatus Neoehrlichia mikurensis. All of the tick-borne pathogens that we found in the present study are known to occur in Danish forest populations of I. ricinus. Our study indicates that migrating birds can transport ticks and their pathogens from neighboring countries to Denmark including sites in Denmark without a sustainable tick population. Thus, a tick-borne pathogen affecting human or animal health emerging at one location in Europe can rapidly be introduced to other countries by migrating birds. These movements are beyond national veterinary control. The current globalization, climatic and environmental changes affect the potential for introduction and establishment of ticks and tick-borne pathogens in Northern Europe. It is therefore important to quantify the risk for rapid spread and long distance exchange of tick-borne pathogens in Europe.
目前，尚不清楚季节性迁徙鸟类在丹麦传播蜱虫和蜱虫相关病原体的程度。为了量化这一现象，我们在丹麦的三个野外地点，在春季和秋季迁徙期间捕获鸟类，并对它们进行蜱虫筛查。从鸟类身上采集的蜱虫，鉴定到种，并用实时 PCR 检测 37 种蜱传病原体。总的来说，在春季（292 只鸟）和秋季迁徙（515 只鸟）期间，我们共捕获并检查了 807 只鸟类，代表 44 种鸟类，共发现了 179 只蓖子硬蜱（春季 38 只，秋季 141 只），平均每只鸟携带 2.1 只蜱虫。欧洲知更鸟（Erithacus rubecula）、普通乌鸦（Turdus merula）和红腹灰雀（Phoenicurus phoenicurus）的感染强度最高。60.9%的蜱虫至少对一种蜱传病原体 PCR 呈阳性。36.9%的蜱虫检测到伯氏疏螺旋体 DNA。检测到的疏螺旋体种类为 B. spielmanii（15.1%）、B. valaisiana（13.4%）、B. garinii（12.3%）、B. burgdorferi s.s.（2.2%）、B. miyamotoi（1.1%）和 B. afzelii（0.6%）。此外，10.6%和 1.7%的样本对斑点热群立克次体和候选新立克次体呈 PCR 阳性。本研究中发现的所有蜱传病原体，均已知在丹麦的蓖子硬蜱森林种群中存在。我们的研究表明，迁徙鸟类可以将蜱虫及其病原体从邻国传播到丹麦，包括丹麦没有可持续蜱虫种群的地区。因此，在欧洲一个地方出现的影响人类或动物健康的蜱传病原体，可以通过迁徙鸟类迅速传播到其他国家。这些迁徙已经超出了国家兽医控制的范围。目前的全球化、气候和环境变化影响了蜱虫和蜱传病原体在北欧的传入和建立的可能性。因此，量化欧洲蜱传病原体快速传播和远距离交换的风险非常重要。
