Lyme neuroborreliosis and bird populations in northern Europe

Many vector-borne diseases are transmitted through complex pathogen-vector-host networks, which makes it challenging to identify the role of specific host groups in disease emergence. Lyme borreliosis in humans is now the most common vector-borne zoonosis in the northern hemisphere. The disease is caused by multiple genospecies of Borrelia burgdorferi sensu lato bacteria transmitted by ixodid (hard) ticks, and the major host groups transmit Borrelia genospecies with different pathogenicity, causing variable clinical symptoms in humans. The health impact of a given host group is a function of the number of ticks it infects as well as the pathogenicity of the genospecies it carries. B. afzelii, with mainly small mammals as reservoirs, is the most common pathogen causing Lyme borreliosis, and it is often responsible for the largest proportion of infected host-seeking tick nymphs in Europe. The bird-borne B. garinii, though less prevalent in nymphal ticks, is more likely to cause Lyme neuro...多种虫媒传染病（vector-borne diseases）通过复杂的病原体-媒介-宿主网络传播，这使得明确特定宿主类群在疾病出现中的作用极具挑战性。人类莱姆病（Lyme borreliosis）目前是北半球最常见的虫媒人畜共患病。该病由经硬蜱（ixodid ticks，又称硬蜱）传播的多种伯氏疏螺旋体广义群（Borrelia burgdorferi sensu lato）基因种引发；不同主要宿主类群所传播的疏螺旋体基因种致病力存在差异，进而导致人类出现各异的临床症状。某一宿主类群的健康影响，取决于其感染的蜱虫数量以及其所携带基因种的致病力。以小型哺乳动物为主要储存宿主的阿氏疏螺旋体（B. afzelii）是引发莱姆病的最常见病原体，在欧洲，它通常占感染寻宿主蜱若虫的最大比例。以鸟类为储存宿主的伽氏疏螺旋体（B. garinii）虽在蜱若虫中的流行率较低，但更易引发莱姆神经...