Stable prevalence of Coxiella burnetii in wildlife after a decade of surveillance in northern Spain

Abstract

Coxiella burnetii is an obligate intracellular zoonotic bacterium widespread in nature that causes Q fever in animals and humans. The most common sources of human infection are domestic ruminants, but wildlife can also act as reservoir. Here, spleen samples from 652 wild ungulates and 218 wild birds collected in 2011-2019 in the Basque Country (northern Spain) were analysed by real-time PCR (IS1111 gene) and the results compared with data from a past study in 2001-2006. Among wild ungulates, C. burnetii DNA was detected in 7.0% (6/86) of roe deer (Capreolus capreolus), 1.9% (9/484) of wild boar (Sus scrofa) and 2.4% (2/82) of red deer (Cervus elaphus). The prevalence in roe deer was significantly higher compared to wild boar (p = 0.006). Among wild birds, only one white stork (Ciconia ciconia) tested positive. SNP-typing of C. burnetii-positive samples showed that wild ungulates shared SNP 2, SNP 6 and SNP 8 genotypes with domestic ruminants of the region. However, the white stork harboured a C. burnetii genotype (SNP 3) never identified in the studied area before. Comparing these results with those obtained in the same area a decade before (2001-2006), no significant differences were observed in the prevalence of C. burnetii in any of the wildlife species, indicating stability in C. burnetii prevalence. Nevertheless, continuous surveillance is needed to monitor any future changes in the reservoir role of roe deer and wild boar considering the increase in density of both species observed in Europe in the last decades.

Keywords: Birds; Coxiella burnetii; Q fever; SNP-typing; Ungulates; Zoonoses.