Despite the presence of several microorganisms, other than Borrelia burgdorferi sensu lato (Bbsl) and TBE virus, in Ixodes ricinus ticks from the Nordic countries, data is lacking on their pathogenic potential in humans. In this study, we wanted to investigate the aetiology and clinical manifestations of tick-transmitted infections in individuals seeking medical care following a tick-bite.

The sampling frame was participants of a large-scale, prospective, multi-centre, follow-up study of tick-bitten volunteers recruited in Sweden, Finland and Norway in the years 2007–2015. Participants who sought medical care during the three-month follow-up period and from whom blood samples were collected during this healthcare visit (n = 92) were tested, using PCR, for exposure to spotted fever group (SFG) Rickettsia spp., Anaplasma phagocytophilum and Babesia spp. Moreover, 86 of these individuals had two serum samples, collected three months apart, tested serologically for six tick-borne microorganisms. The selected organisms – Bbsl, SFG rickettsiae, Anaplasma phagocytophilum, TBE virus, Babesia microti and Bartonella henselae – have all been detected in field-collected ticks from the Nordic countries. Medical records were reviewed and questionnaires were completed to determine clinical manifestations.

We found Lyme borreliosis to be the most common tick-transmitted infection as seen in 46 (54%) of the 86 participants with available medical records. Among the 86 participants with paired sera, serological or molecular evidence of recent exposure to other microorganisms than Bbsl could be demonstrated in eight (9%). Five participants (6%) exhibited serological evidence of recent concomitant exposure to more than one tick-borne microorganism. Clinical presentations were mild with one exception (TBE).

In conclusion, our data suggest a low risk of infection with tick-borne microorganisms, other than Bbsl, in immunocompetent tick-bitten persons from the examined regions, a low occurrence of co-infection and mostly mild or no overt clinical signs of infection in immunocompetent persons exposed to the studied agents.

尽管在北欧国家的蓖麻（Ixodes ricinus）s中存在除伯氏疏螺旋体（Borrelia burgdorferi sensu lato，Bbsl）和TBE病毒以外的几种微生物，但仍缺乏有关其对人类致病潜力的数据。在这项研究中，我们想调查tick叮咬后寻求医疗护理的个体中tick传播的感染的病因和临床表现。

样本框架是2007-2015年在瑞典，芬兰和挪威招募的对tick虫叮咬志愿者进行的大规模，前瞻性，多中心，后续研究的参与者。在三个月的随访期内寻求医疗服务并在这次医疗保健就诊时收集了血液样本的参与者（n = 92）使用PCR检测了暴露于斑点发烧组（SFG）立克次体，无形体吞噬细胞和巴贝虫属 此外，这些人中有86人有两个血清样本，间隔三个月收集一次，对六种ological传微生物进行血清学检测。选定的生物-Bbsl，SFG立克次体，吞噬性无浆膜，TBE病毒，在北欧国家的田tick中都检测到了小巴贝斯虫和亨通巴尔通体。查阅病历并完成问卷调查以确定临床表现。

我们发现莱姆病（Lyme borreliosis）是最常见的壁虱传播感染，在有可用医疗记录的86位参与者中，有46位（54％）看到了。在具有配对血清的86名参与者中，有八名（9％）证明了近期暴露于Bbs1之外的其他微生物的血清学或分子证据。五名参与者（6％）显示出近期同时接触一种以上ser传播微生物的血清学证据。临床表现较轻，只有一个例外（TBE）。

总之，我们的数据表明，来自检查区域的具有免疫能力的被tick咬的人感染B传播的微生物（除Bbsl以外）的风险较低，同时感染的发生率较低，并且在该地区感染的症状大多为轻度或没有明显的临床体征具有研究能力的免疫能力强的人。