Dpto. Ciencias Agroforestales, ETSIIAA, Universidad de Valladolid, Avda. de Madrid 44, 34004, Palencia, Spain.
Instituto Universitario de Investigación en Gestión Forestal Sostenible, Palencia, Spain.
Parasit Vectors. 2021 Jan 6;14(1):16. doi: 10.1186/s13071-020-04492-6.
Fleas frequently infest small mammals and play important vectoring roles in the epidemiology of (re)emerging zoonotic disease. Rodent outbreaks in intensified agro-ecosystems of North-West Spain have been recently linked to periodic zoonotic diseases spillover to local human populations. Obtaining qualitative and quantitative information about the composition and structure of the whole flea and small mammal host coexisting communities is paramount to understand disease transmission cycles and to elucidate the disease-vectoring role of flea species. The aims of this research were to: (i) characterise and quantify the flea community parasiting a small mammal guild in intensive farmlands in North-West Spain; (ii) determine and evaluate patterns of co-infection and the variables that may influence parasitological parameters.
We conducted a large-scale survey stratified by season and habitat of fleas parasitizing the small mammal host guild. We report on the prevalence, mean intensity, and mean abundance of flea species parasitizing Microtus arvalis, Apodemus sylvaticus, Mus spretus and Crocidura russula. We also report on aggregation patterns (variance-to-mean ratio and discrepancy index) and co-infection of hosts by different flea species (Fager index) and used generalized linear mixed models to study flea parameter variation according to season, habitat and host sex.
Three flea species dominated the system: Ctenophthalmus apertus gilcolladoi, Leptopsylla taschenbergi and Nosopsyllus fasciatus. Results showed a high aggregation pattern of fleas in all hosts. All host species in the guild shared C. a. gilcolladoi and N. fasciatus, but L. taschenbergi mainly parasitized mice (M. spretus and A. sylvaticus). We found significant male-biased infestation patterns in mice, seasonal variations in flea abundances for all rodent hosts (M. arvalis, M. spretus and A. sylvaticus), and relatively lower infestation values for voles inhabiting alfalfas. Simultaneous co-infections occurred in a third of all hosts, and N. fasciatus was the most common flea co-infecting small mammal hosts.
The generalist N. fasciatus and C. a. gilcolladoi dominated the flea community, and a high percentage of co-infections with both species occurred within the small mammal guild. Nosopsyllus fasciatus may show higher competence of inter-specific transmission, and future research should unravel its role in the circulation of rodent-borne zoonoses.
跳蚤经常寄生在小型哺乳动物身上，并在（重新）出现的人畜共患传染病的流行病学中发挥重要的媒介作用。西班牙西北部集约化农业生态系统中的啮齿动物暴发最近与周期性的人畜共患病溢出到当地人群有关。了解整个跳蚤和小型哺乳动物宿主共存群落的组成和结构的定性和定量信息对于理解疾病传播周期和阐明跳蚤物种的疾病媒介作用至关重要。本研究的目的是：（i）描述和量化寄生在西班牙西北部集约化农田小型哺乳动物群体中的跳蚤群落；（ii）确定和评估共感染模式以及可能影响寄生虫学参数的变量。
我们按季节和栖息地对寄生在小型哺乳动物宿主群体中的跳蚤进行了大规模调查。我们报告了寄生在 Microtus arvalis、Apodemus sylvaticus、Mus spretus 和 Crocidura russula 上的跳蚤物种的流行率、平均强度和平均丰度。我们还报告了宿主之间不同跳蚤物种的聚集模式（方差与均值比和差异指数）和共感染（Fager 指数），并使用广义线性混合模型根据季节、栖息地和宿主性别研究跳蚤参数的变化。
三种跳蚤物种占主导地位：Ctenophthalmus apertus gilcolladoi、Leptopsylla taschenbergi 和 Nosopsyllus fasciatus。结果表明，所有宿主的跳蚤都呈现出高度聚集的模式。所有宿主物种都共享 C. a. gilcolladoi 和 N. fasciatus，但 L. taschenbergi 主要寄生在老鼠（M. spretus 和 A. sylvaticus）上。我们发现，老鼠的感染模式存在显著的雄性偏倚，所有啮齿动物宿主（M. arvalis、M. spretus 和 A. sylvaticus）的跳蚤数量都存在季节性变化，而栖息在紫花苜蓿中的田鼠的感染值相对较低。三分之一的宿主同时发生了共感染，而 N. fasciatus 是最常见的寄生在小型哺乳动物宿主上的跳蚤。
普通的 N. fasciatus 和 C. a. gilcolladoi 主导着跳蚤群落，小型哺乳动物群体中同时存在两种跳蚤的高比例共感染。Nosopsyllus fasciatus 可能具有更高的种间传播能力，未来的研究应该揭示其在传播啮齿动物传播的人畜共患病中的作用。
