In north-western Europe, the common tick, Ixodes ricinus, is widely established, its distribution appears to be increasing and the spread of tick-borne diseases is of increasing concern. The project ‘Flått i Nord’ (Ticks in northern Norway) commenced in spring 2009 with the intention of studying the tick’s distribution and that of its pathogens in northern Norway. Several methods were used: cloth-dragging, collecting from trapped small mammals, and collecting from pets. Since 2010, the occurrence of ticks in the region of northern Norway was determined directly by cloth-dragging 167 times in 109 separate locations between the latitudes of 64 °N and 70 °N (included seven locations in the northern part of Trøndelag County). The northernmost location of a permanent I. ricinus population was found to be Nordøyvågen (66.2204 °N, 12.59 °E) on the Island of Dønna. In a sample of 518 nymphal and adult ticks, the Borrelia prevalence collected close to this distribution limit varied but was low (1–15 %) compared with the locations in Trøndelag, south of the study area (15–27 %). Five specimens (1 %) were positive for Rickettsia helvetica. The length of the vegetation growing season (GSL) can be used as an approximate index for the presence of established populations of I. ricinus. The present study suggests that the threshold GSL for tick establishment is about 170 days, because the median GSL from 1991 to 2015 was 174–184 days at sites with permanent tick populations, showing a clear increase compared with the period 1961–1990. This apparent manifestation of climate change could explain the northward extension of the range of I. ricinus.

在西北欧，常见的tick（Ixodes ricinus）已广泛建立，其分布似乎正在增加，而tick传播的疾病的传播日益引起人们的关注。该项目“弗拉特我诺德（蜱在挪威北部）在2009年春季开始与研究蜱的分布的意图和其在挪威北部的病原体。使用了几种方法：拖布，从被困的小型哺乳动物中收集和从宠物中收集。自2010年以来，挪威北部地区s虫的发生直接是通过在64°N和70°N纬度之间的109个单独位置（包括Trøndelag县北部的七个位置）拖曳167次来确定的。永久物的最北端I. ricinus种群被发现为登娜岛上的Nordøyvågen（66.2204°N，12.59°E）。在518个若虫和成年s的样本中，接近该分布极限的疏螺旋体患病率有所变化，但与研究区域南部特伦德拉格（15–27％）的位置相比较低（1–15％）。五份标本（1％）为立克次氏菌阳性。植被生长季节的长度（GSL）可以用作存在的蓖麻毒素种群的近似指标。。本研究表明，tick虫建立的门槛GSL约为170天，因为1991年至2015年from虫种群永久存在的地点的GSL中位数为174-184天，与1961-1990年相比明显增加。气候变化的这种明显表现可以解释蓖麻的范围向北扩展。