Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708PB, Wageningen, The Netherlands.
Centre for Infectious Disease Control Netherlands, National Institute for Public Health and Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands.
Parasit Vectors. 2017 Sep 19;10(1):433. doi: 10.1186/s13071-017-2370-7.
Understanding which factors drive population densities of disease vectors is an important step in assessing disease risk. We tested the hypothesis that the density of ticks from the Ixodes ricinus complex, which are important vectors for tick-borne diseases, is determined by the density of deer, as adults of these ticks mainly feed on deer.
We performed a cross-sectional study to investigate I. ricinus density across 20 forest plots in the Netherlands that ranged widely in deer availability to ticks, and performed a deer-exclosure experiment in four pairs of 1 ha forest plots in a separate site.
Ixodes ricinus from all stages were more abundant in plots with deer (n = 17) than in plots without deer (n = 3). Where deer were present, the density of ticks did not increase with the abundance of deer. Experimental exclosure of deer reduced nymph density by 66% and adult density by 32% within a timeframe of two years.
In this study, deer presence rather than abundance explained the density of I. ricinus. This is in contrast to previous studies and might be related to the relatively high host-species richness in Dutch forests. This means that reduction of the risk of acquiring a tick bite would require the complete elimination of deer in species rich forests. The fact that small exclosures (< 1 ha) substantially reduced I. ricinus densities suggests that fencing can be used to reduce tick-borne disease risk in areas with high recreational pressure.
了解哪些因素驱动疾病媒介的种群密度是评估疾病风险的重要步骤。我们检验了这样一个假设，即鹿的密度决定了硬蜱属（Ixodes ricinus complex）的密度，因为这些蜱虫的成虫主要以鹿为食，而硬蜱属是蜱传疾病的重要媒介。
我们进行了一项横断面研究，在荷兰的 20 个森林样地中调查了硬蜱密度，这些样地在蜱虫获取鹿的能力方面差异很大，并在另一个地点的四个 1 公顷的森林样地对进行了 deer-exclosure 实验。
在有鹿（n=17）的样地中，所有阶段的硬蜱属数量都比没有鹿（n=3）的样地多。在有鹿的地方，蜱虫的密度并没有随着鹿的数量的增加而增加。在两年的时间内，对鹿进行实验性隔离减少了 66%的若虫密度和 32%的成虫密度。
在这项研究中，鹿的存在而不是数量解释了硬蜱属的密度。这与之前的研究结果相反，这可能与荷兰森林中相对较高的宿主物种丰富度有关。这意味着，要降低感染蜱虫的风险，就需要在物种丰富的森林中完全消灭鹿。事实上，小围栏（<1 公顷）大大降低了硬蜱属的密度，这表明在高娱乐压力的地区，围栏可以用来降低蜱传疾病的风险。
