The prevalence of Coxiella burnetii in ticks and animals in Slovenia

BACKGROUND: The obligate intracellular bacterium Coxiella burnetii causes globally distributed zoonotic Q fever. Ruminant livestock are common reservoirs of C. burnetii. Coxiella burnetii are shed in large numbers in the waste of infected animals and are transmitted by inhalation of contaminated aerosols. This study was conducted to evaluate the prevalence of C. burnetii infection in domestic animals and ticks in areas of Slovenia associated with a history of Q fever outbreaks. RESULTS: A total of 701 ticks were collected and identified from vegetation, domestic animals and wild animals. C. burnetii DNA was detected in 17 out of 701 (2.4%) ticks. No C. burnetii DNA was found in male ticks. Ticks that tested positive in the PCR-based assay were most commonly sampled from wild deer (5.09%), followed by ticks collected from domestic animals (1.16%) and ticks collected by flagging vegetation (0.79%). Additionally, 150 animal blood samples were investigated for the presence of C. burnetii-specific antibodies and pathogen DNA. The presence of pathogen DNA was confirmed in 14 out of 150 (9.3%) blood samples, while specific antibodies were detected in sera from 60 out of 150 (40.4%) animals. CONCLUSIONS: Our results indicate that ticks, although not the primary source of the bacteria, are infected with C. burnetii and may represent a potential source of infection for humans and animals. Ticks collected from animals were most likely found to harbor C. burnetii DNA, and the infection was not lost during molting. The persistence and distribution of pathogens in cattle and sheep indicates that C. burnetii is constantly present in Slovenia.