Seroepidemiology of Coxiella burnetii in Domestic and Wild Ruminant Species in Southern Spain

The European Food Safety Authority has recently listed Q fever as a priority for setting up a coordinated surveillance system. Although Spain is the country with the highest human incidence of the disease in the European Union, updated data on <i>Coxiella burnetii</i> in ruminants are still limited. A total of 780 serum samples from small ruminants and 605 sera from wild ruminants were collected in the Mediterranean ecosystems of southern Spain during the period 2015-2023. Anti-<i>C. burnetii</i> antibodies were detected using a commercial indirect ELISA. The overall individual seroprevalence in the small ruminants was 49.1% (383/780; 95% CI: 45.6-52.6). Antibodies against <i>C. burnetii</i> were identified in 40.0% (156/390) of sheep and in 58.2% (227/390) of goats. At least one seropositive animal was observed in all sheep (100%) and in 92.3% of goat flocks. The species (goat) and the existence of reproductive disorders in primiparous females were potential risk factors for <i>C. burnetii</i> exposure in small ruminant farms. In the wild ruminants, the overall seroprevalence against <i>C. burnetii</i> was 1.5% (9/605; 95% CI: 0.8-2.8). Anti-<i>C. burnetii</i> antibodies were found in 1.8% (2/110) of mouflon, 1.5% (6/390) of red deer, and 1.0% (1/105) of Iberian ibex. The high exposure of the small ruminants to <i>C. burnetii</i>, particularly in goats, detected in the present study is of animal and public health concern. Our results denote that wild ruminants only play a minor role in the epidemiology of this bacterium in southern Spain and suggest an independent epidemiological cycle of <i>C. burnetii</i> in domestic and wild ruminant species in the study area.