| Summary: | This study was conducted to determine the prevalence of <i>Coxiella burnetii</i> in cattle and how that prevalence is influenced by cattle breed and growth type. A total of 491 cattle [cattle breed: 216 dairy cattle and 275 beef cattle; growth type: indoor housed (<i>n</i> = 294) and grazing (<i>n</i> = 197)] were used. The presence of <i>C. burnetii</i> DNA and antibodies was detected from blood and serum samples using polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The overall prevalence of <i>C. burnetii</i> was: 10.8% (95% CI: 8.0–13.5%) using PCR and 8.8% (95% CI: 6.3–11.3%) using ELISA. The prevalence of <i>C. burnetii</i> was significantly higher in beef cattle than in dairy cattle using both PCR (13.5% vs. 7.4%; <i>P</i> = 0.032) and ELISA (14.5% vs. 1.4%; <i>P</i> = 0.000), respectively. Comparison by growth type revealed that <i>C. burnetii</i> infection was significantly higher in grazing cattle than in housed cattle when using both PCR (24.9% vs. 1.4%; <i>P</i> = 0.000) and ELISA (21.3% vs. 0.3%; <i>P</i> = 0.000). Beef cattle were at a significantly higher risk of contracting <i>C. burnetii</i> compared with dairy cattle (odds ratio = 3.20, 95% CI: 1.80–5.67; <i>P</i> = 0.000). The risk of contracting <i>C. burnetii</i> in grazing cattle was increased by 32.57-fold (95% CI: 12.84–82.61; <i>P</i> = 0.000) compared with indoor housed cattle. The phylogenetic analysis based on the IS1111 gene revealed that our sequences grouped with human, tick, goat, and cattle isolates/strains found in several countries. <i>C. burnetii</i> sequences circulating in the Republic of Korea exhibit genetic variations. Thus, grazing is a high risk factor for the prevalence and transmission of <i>C. burnetii</i>.
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