Šujanová Alžbeta, Čužiová Zuzana, Václav Radovan
Institute of Zoology, Slovak Academy of Sciences, Dúbravská Cesta 9, 84506 Bratislava, Slovakia.
Microorganisms. 2022 Dec 25;11(1):60. doi: 10.3390/microorganisms11010060.
Birds are known to maintain and spread human pathogenic borreliae, but they are common hosts of diverse parasite communities, notably haemosporidians. Only a few studies examined whether tick infestation and/or prevalences vary with hosts' haemosporidian infection status.
Here, we study whether infestation rates and infection rates in bird-feeding ticks vary according to haemosporidian infection status in a community of free-living avian tick hosts.
Birds of six avian species harbored the majority of ticks. Both the tick infestation prevalence and the intensity peaked during spring and summer, but while bird-feeding nymphs prevailed in spring, bird-feeding larvae dominated in summer. Almost half of the bird-feeding ticks were found to be positive for s.l. Although the majority of infections involved bird-associated and , appears to be the dominant strain circulating in locally breeding avian species. We detected a negative link between the hosts' haemosporidian infection status and the infection rate of bird-feeding ticks, but the association was dependent on the host's age.
Our results on tick infestation intensity support the idea that more immunologically vulnerable hosts harbor more ticks but suggest that different mechanisms may be responsible for tick infestation rates among immunologically naïve and experienced avian hosts. The results on infection rates in bird-feeding ticks are consistent with studies revealing that intracellular parasites, such as haemosporidians, can benefit from the host immune system prioritizing immune responses against extracellular parasites at the expense of immune responses against intracellular parasites. The findings of our study urge for a more robust design of parasitological studies to understand the ecology of interactions among hosts and their parasites.
已知鸟类会携带并传播人类致病性疏螺旋体，但它们也是多种寄生虫群落的常见宿主，尤其是血孢子虫。仅有少数研究考察了蜱虫侵染情况和/或患病率是否会因宿主的血孢子虫感染状况而有所不同。
在此，我们研究在一个自由生活的鸟类蜱虫宿主群落中，以鸟类为食的蜱虫的侵染率和感染率是否会根据血孢子虫感染状况而有所变化。
六种鸟类宿主身上寄生着大部分蜱虫。蜱虫的侵染患病率和强度在春季和夏季达到峰值，但以鸟类为食的若虫在春季占主导，而以鸟类为食的幼虫在夏季占主导。几乎一半以鸟类为食的蜱虫被检测出伯氏疏螺旋体狭义种呈阳性。尽管大多数感染涉及与鸟类相关的伯氏疏螺旋体狭义种和伽氏疏螺旋体，但伯氏疏螺旋体狭义种似乎是在当地繁殖的鸟类物种中传播的主要菌株。我们检测到宿主的血孢子虫感染状况与以鸟类为食的蜱虫的伯氏疏螺旋体感染率之间存在负相关，但这种关联取决于宿主的年龄。
我们关于蜱虫侵染强度的研究结果支持了这样一种观点，即免疫功能更脆弱的宿主身上寄生的蜱虫更多，但表明不同机制可能导致免疫未成熟和有经验的鸟类宿主之间蜱虫侵染率存在差异。关于以鸟类为食的蜱虫感染率的研究结果与其他研究一致，这些研究表明，细胞内寄生虫，如血孢子虫，可受益于宿主免疫系统优先针对细胞外寄生虫的免疫反应，而以牺牲针对细胞内寄生虫的免疫反应为代价。我们的研究结果促使寄生虫学研究采用更严谨的设计，以了解宿主及其寄生虫之间相互作用的生态学。
