Francisella tularensis in a wild population of common vole (Microtus arvalis) from agricultural landscapes of SW Europe

Resumen del trabajo presentado al 15th Rodens et Spatium: International Conference on Rodent Biology, celebrada en Olomouc (Czech Republic) del 25 al 29 de julio de 2016.In many European regions, most microtine rodents exhibit multi-annual fluctuations in abundance and can cause significant crop damage and economical losses when they are overabundant during population outbreaks. In addition, they can be reservoirs of multiple pathogens responsible of serious zoonotic diseases to humans and livestock. Therefore, understanding the relationships between rodents and their pathogens under a dynamic perspective (density-dependent patterns of prevalence) may be particularly relevant in terms of effective public health management. In NW Spain, the outbreaking common vole (Microtus arvalis) recently colonized intensive agricultural landscapes where it has been pointed as a main amplification and spill-over host of Francisella tularensis (the etiological agent of tularemia). However, the epidemiological role of these fluctuating vole populations with regard to zoonotic diseases remains largely unknown. Here we describe for the first time the patterns of prevalence of F. tularensis along a complete fluctuation in abundance in a wild common vole population. Voles were captured seasonally (March, July and November) during a population outbreak between 2013 and 2015 and were screened for the occurrence of the pathogen. From a total of 243 captured voles, 46 individuals were infected, but prevalence greatly varied in time (range from 0 to 30%).We found a strong effect of vole abundance on tularemia prevalence, in a direct positive density-dependent way. We discuss the implications of the findings for our understanding of vole population regulation and public health. The increasing frequency of zoonotic disease events in rodents encourage us to go on studying the co-infection in common vole populations with other relevant pathogens.Peer Reviewe