Ruth Rodríguez-Pastor

Tularemia Outbreaks and Common Vole (Microtus arvalis) Irruptive Population Dynamics in Northwestern Spain, 1997-2014.

During the last decades, large tularemia outbreaks in humans have coincided in time and space with population outbreaks of common voles in northwestern Spain, leading us to hypothesize that this rodent species acts as a key spillover agent of Francisella tularensis in the region. Here, we evaluate for the first time a potential link between irruptive vole numbers and human tularemia outbreaks in Spain. We compiled vole abundance estimates obtained through live-trapping monitoring studies and official reports of human tularemia cases during the period 1997-2014. We confirm a significant positive association between yearly cases of tularemia infection in humans and vole abundance. High vole densities during outbreaks (up to 1000 voles/hectare) may therefore enhance disease transmission and spillover contamination in the environment. If this ecological link is further confirmed, the apparent multiannual cyclicity of common vole outbreaks might provide a basis for forecasting the risk of tularemia outbreaks in northwestern Spain.

Density-Dependent Prevalence of Francisella tularensis in Fluctuating Vole Populations, Northwestern Spain

Tularemia in humans in northwestern Spain is associated with increases in vole populations. Prevalence of infection with Francisella tularensis in common voles increased to 33% during a vole population fluctuation. This finding confirms that voles are spillover agents for zoonotic outbreaks. Ecologic interactions associated with tularemia prevention should be considered.

Irruptive mammal host populations shape tularemia epidemiology

Funding: This work was funded by Programa Estatal de I+D+i Orientada a los Retos de la Sociedad; Ministerio de Economia y Competitividad, Gobierno de Espana (Spain). This publication is part of the project ECOTULA (reference: CGL2015-66962-C2-1-R). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.