Serological Evidence of Widespread Coxiella burnetii Exposure Among Small Ruminants in Western Romania

Q fever, caused by Coxiella burnetii, remains an important zoonotic disease with significant implications for animal health, livestock production, and public health. Epidemiological data regarding the circulation of C. burnetii in Romania remain limited, particularly in the western region of the country. This study aimed to assess the observed seropositivity and geographic distribution of anti-C. burnetii antibodies among sampled small ruminants from Western Romania. A cross-sectional sero-epidemiological survey was conducted using 546 serum samples collected from sheep (n = 451) and goats (n = 95) originating from five counties (Timiș, Arad, Bihor, Caraș-Severin, and Hunedoara). Sera were tested for IgG antibodies against C. burnetii using a commercial indirect enzyme-linked immunosorbent assay (ELISA). Overall, 87 animals were seropositive, corresponding to an observed seropositivity of 15.9% (87/546). Species-specific seropositivity was significantly higher in goats (25.3%) than in sheep (14.0%) (p = 0.006). Seropositive animals were detected in all surveyed counties, with prevalence ranging from 5.1% in Arad County to 21.3% in Timiș County. Significant geographic variation in seroprevalence was also observed among the investigated counties (p = 0.040). These findings indicate widespread serological evidence of exposure to Coxiella burnetii among the sampled small-ruminant population in Western Romania and reveal heterogeneous exposure patterns associated with both host species and geographic location. Continued surveillance integrating serological and molecular approaches is warranted to better characterize the epidemiology and transmission dynamics of C. burnetii within a One Health framework.