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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
['Herrero-Cófreces|Silvia|S|http://orcid.org/0000-0002-3463-2132', 'Flechoso|Manuel Fabio|MF|', 'Rodríguez-Pastor|Ruth|R|', 'Luque-Larena|Juan José|JJ|', 'Mougeot|François|F|']
D000818:Animals D003411:Arvicolinae D018556:Crops, Agricultural D017753:Ecosystem D007312:Eulipotyphla D058267:Flea Infestations D058507:Host Specificity D006790:Host-Parasite Interactions D051379:Mice D051189:Murinae D012376:Rodent Diseases D012621:Seasons D012737:Sex Factors D012788:Shrews D005423:Siphonaptera D013030:Spain D015047:Zoonoses
Microtus arvalis Apodemus sylvaticus Mus spretus Crocidura russula Aggregation Seasonal variations Ectoparasite Host sex effects Siphonaptera co-infection