Herd prevalence and genotypes of Coxiella burnetii in dairy cattle bulk tank milk in Gyeongsang provinces of South Korea.

Coxiella burnetii is the causative agent of the zoonotic Q fever, and its reservoirs include ticks and livestock, which are key sources of transmission to humans. Although there have been several studies on the prevalence of C. burnetii antibodies in dairy cattle bulk tank milk (BTM), there is a lack of information on the molecular detection of C. burnetii in BTM in South Korea. Thus, this study was designed to assess milk shedding of C. burnetii in BTM from dairy cattle herds. Among the 607 BTM samples collected from 41 counties in Gyeongsang provinces in 2015, 108 (17.8%) from 23 (56.1%) counties tested positive for C. burnetii by PCR. Because the 16S rRNA sequences of C. burnetii from all 108 PCR-positive samples were identical, two representative samples (BTM-GB-10 and BTM-GN-63) are described in this paper. These sequences showed high identity (96.9-100%) to other C. burnetii sequences deposited in GenBank. Phylogenetic analysis showed that these two sequences were clustered with existing C. burnetii strains. The relatively high prevalence rates of C. burnetii in BTM detected in this study suggest that C. burnetii is prevalent among dairy cattle herds in South Korea. Thus, implementation of continuous monitoring and control strategies for domestic animals is needed to prevent disease transmission and protect public health.