Patterns of flea infestation in rodents and insectivores from intensified agro-ecosystems, Northwest Spain

Silvia Herrero-Cófreces,Manuel Fabio Flechoso,François Mougeot,Ruth Rodríguez-Pastor,Juan José Luque-Larena

doi:10.1186/s13071-020-04492-6

Silvia Herrero-Cófreces, Manuel Fabio Flechoso + Show 3 more

Open Access

https://doi.org/10.1186/s13071-020-04492-6

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Abstract

BackgroundFleas 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.MethodsWe 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.ResultsThree 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.ConclusionsThe 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.Graphical

Highlights

Fleas frequently infest small mammals and play important vectoring roles in the epidemiology of emerging zoonotic disease
Flea community The flea community included the following species: Ctenophthalmus apertus apertus (n = 2), C. a. gilcolladoi (n = 1879), C. baeticus baeticus (n = 11), Leptopsylla taschenbergi amitina (n = 460), Nosopsyllus fasciatus (n = 1903) and Rhadinopsylla beillardae (n = 8); in addition, two specimens were identified at genus level only (Ctenophthalmus spp.)
Shrews were only infested by C. a. gilcolladoi and N. fasciatus

Summary

Introduction

Fleas frequently infest small mammals and play important vectoring roles in the epidemiology of (re) emerging zoonotic disease. Fleas are abundant ectoparasites that frequently infest mammals and birds [1] These haematophagous insects can act as vectors of numerous pathogens transmitted through biting or by direct contact with their faeces [1] and often play a relevant role in the circulation and epidemiology of emerging and re-emerging diseases worldwide [1, 2]. Patterns of flea distribution and abundance in host communities, seasonal variation of such patterns, relationships with individual host characteristics (e.g., host sex, age, condition, immune function), the effect of environmental habitat and conditions (temperature, humidity) and co-infection, are all relevant aspects that need to be quantified to build any baseline knowledge required to understand flea life cycles and their relative ecological and epidemiological roles [5, 6]

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