Mysterud Atle, Stigum Vetle Malmer, Linløkken Harald, Herland Anders, Viljugrein Hildegunn
Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, 0316, Oslo, Norway.
Evolutionary Ecology Group, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium.
Oecologia. 2019 May;190(1):115-126. doi: 10.1007/s00442-019-04411-2. Epub 2019 May 6.
The pathogens causing Lyme disease are all vectored by generalist tick species found on a wide range of vertebrates, but spatial and annual variation in host use has rarely been quantified. We here compare the load of Ixodes ricinus (the vector) on small mammals and investigate the infection prevalence of Borrelia burgdorferi s.l. (the pathogen) involved in the enzootic transmission cycle of Lyme disease in two contrasting ecosystems in Norway from 2014 to 2016. The most common larval tick host in the eastern region was the bank vole, while the common shrew dominated in the western region of Norway. However, the wood mouse and the bank vole had consistently higher larval tick loads than the common shrew in both ecosystems. Hence, the evidence indicated that species are differently suitable as hosts, regardless of their abundances. The pathogen infection prevalence was similar among small mammal species, but markedly higher in the region with larger small mammal populations and higher tick loads, while the seasonal and annual variation was less marked. Our study indicated that the generalist I. ricinus shows consistent patterns of load on species of small vertebrate hosts, while B. burgdorferi s.l. (B. afzelii) was a true generalist. The similar roles of host species across regions suggest that disease dynamics can be predicted from host community composition, but predicting the role of host community composition for disease dynamics requires a detailed understanding of the different species population limitations under global change.
引起莱姆病的病原体均由广泛存在于多种脊椎动物身上的普通蜱虫传播，但宿主利用情况的空间和年度变化很少被量化。我们在此比较了蓖麻硬蜱（传播媒介）在小型哺乳动物身上的负载情况，并调查了2014年至2016年期间挪威两个不同生态系统中参与莱姆病动物传播循环的伯氏疏螺旋体（病原体）的感染率。东部地区最常见的幼蜱宿主是田鼠，而普通鼩鼱在挪威西部地区占主导地位。然而，在两个生态系统中，林姬鼠和田鼠身上的幼蜱负载量始终高于普通鼩鼱。因此，有证据表明，尽管物种数量不同，但它们作为宿主的适宜性也有所不同。小型哺乳动物物种之间的病原体感染率相似，但在小型哺乳动物数量较多且蜱负载量较高的地区明显更高，而季节性和年度变化则不太明显。我们的研究表明，普通的蓖麻硬蜱在小型脊椎动物宿主物种上的负载呈现出一致的模式，而伯氏疏螺旋体（阿氏疏螺旋体）是一种真正的普通病原体。不同地区宿主物种的相似作用表明，可以从宿主群落组成预测疾病动态，但预测宿主群落组成对疾病动态的作用需要详细了解全球变化下不同物种的种群限制。
