Have small mammals been neglected as Coxiella burnetii reservoirs?

Presentado a la 12th Conference of the European Wildlife Disease Association (EWDA), celebrada en Berlin (Alemania) del 26 al 31 de agosto de 2016.Several wild species are potential hosts of Coxiella burnetii, the causal agent of Q fever in humans and other mammals. Yet, those that present wide geographic distribution ranges, are abundant, reach high population densities, are gregarious and live in humanized environments are most prone to be relevant reservoirs. Accordingly, previous studies on C. burnetii in Iberia targeted on dense, widely distributed and gregarious species such as the red deer (Cervus elaphus) and the European wild rabbit (Oryctolagus cuniculus). Many other wild animals may be good candidates as reservoirs of C. burnetii. Herein, we analysed the status of C. burnetii infection in wild small mammal species to estimate their role in the ecology of C. burnetii. From 2004 to 2015, spleen samples were collected from 10 species of small mammals captured along different research projects. Small mammals were collected from 16 locations covering peninsular Spain from south to north. Eight- hundred and sixteen samples from 571 (70%) common voles (Microtus arvalis), 138 (17%) wood mice (Apodemus sylvaticus), 47 (5.8%) black rats (Rattus rattus), 27 (3.3%) greater white-toothed shrews (Crocidura russula), 17 (2%) Algerian mice (Mus spretus), 10 (1.2%) house mice (M. musculus), 2 (0.2%) yellow-necked mice (A. flavicollis), 2 (0.2%) garden dormice (Eliomys quercinus), 1 (0.1%) European water vole (Arvicola amphibius) and 1 (0.1%) red squirrel (Sciurus vulgaris) were analysed by real-time semi-quantitative PCR (qPCR) and a sub- sample characterized by single nucleotide polymorphism (SNP) and PCR/RLB analysis. Microtus arvalis displayed the highest average infection prevalence (Mean (M): 10.9%; 95% Confidence Interval (CI): 8.4-13.7; Inter-population prevalence range (IPR): 0.0-23.3) followed by A. sylvaticus (M: 8.7%; 95%CI: 4.6-14.7; IPR: 0.0- 21.2), C. russula (M: 7.4%; 95%CI: 0.9-24.3; IPR: 0.0-33.3) and R. rattus (M: 6.4%; 95%CI: 1.3-17.5). Coxiella burnetii DNA was absent in the rest of small mammal species. Prevalence ranges in M. arvalis and A. sylvaticus - surveyed in 8 and 13 of the study locations, respectively - widely diverged among locations, suggesting - as evidenced from red deer long-time series data - that local population and environmental factors influence the spatio-temporal dynamics of C. burnetii. This study points out the relevance of small mammals in the ecology of C. burnetii. The role of the common vole - a small mammal experiencing cyclic population changes with intense density peaks - in the transmission of C. burnetii to livestock and humans shouldn’t be dismissed and should be better understood.Peer Reviewe