Regarding to diagnosis for bovine brucellosis, more than one serological test should be conducted to confirm the infection by Brucella with a reliable result due to various factors including false positive serological reactions. In this study, we compared confirmatory serological tests to determine the appropriate way to detect and confirm the Brucella infection in South Korea. Several serological tests, including serum agglutination test (SAT), indirect (I)- and competitive (C)-ELISA, and fluorescence polarization assay (FPA), for detection of bovine brucellosis were performed with sera from 537 cattle. In addition, comparison of diagnostic efficacy was performed with bacterial isolation represented true positive. Of 537 serum samples, 426 (79.3% of prevalence), 433 (80.6%), 414 (77.1%), and 409 (76.2%) sera were positive for SAT, C-ELISA, I-ELISA, and FPA respectively. Based on the results of serology, the correlation among the serological tests revealed observed agreements of more than 92% with kappa (k) value of more than 0.77. The correlation between serological tests with bacterial isolation appeared observed agreements of between 79.9% and 84.7% with k value of between 0.42 and 0.59. Particularly, FPA recorded almost perfect agreements with C-ELISA and I-ELISA as well as the highest correlation with bacterial isolation. Accordingly, this investigation presented the comparison of correlation and diagnostic efficacy of serological tests for bovine brucellosis in South Korea. We suggest this finding will be a useful data to re-establish the potential serological diagnostic methods that can apply to maintain the low prevalence.

Brucellosis is the most common zoonosis worldwide, which is caused by Brucella spp. In humans, it can be mainly occurred by direct contact with infected animals or consumption of contaminated dairy products. This study focused on human brucellosis caused by B. melitensis discovered from Chinese worker in Korea in 2015. We investigated molecular epidemiological evidence to find the infection source. We first performed several PCR methods including 16S rRNA PCR, multiplex PCR and real-time PCR to identify Brucella species. We also conducted MLVA typing for epidemiological trace-back analysis. The isolate from the patient was confirmed to B. melitensis through Brucella-specific PCR. In clustering analysis with B. melitensis from foreign countries, this human isolate was correlated with B. melitensis isolates from humans and sheep in China by 99.9% similarity. Thus, we assumed the brucellosis patient has been already infected in China followed by migration to Korea according to molecular epidemiological analysis with history evidence. Moreover, we suggest it needs to take measures to reduce the risk for intercountry transmission of brucellosis due to the influx of infected people from abroad.