Rodent-borne bacterial infections in Gwangju, Korea

Abstract Background This study investigated the prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum, and Leptospira interrogan in wild rodents through molecular detection in organ samples collected from two distinct sites in Gwangju Metropolitan City, Republic of Korea. Methodology/Principal Findings A total of 47 wild rodents, identified as Apodemus agrarius (A. agrarius) , were captured from June to August 2016. The seroprevalence of antibodies against bacterial pathogens in rodent sera was analyzed; 17.4% (8/46) were identified as O. tsutsugamushi through indirect immunofluorescence assay and 2.2% (1/46) were identified as Leptospira spp. through passive hemagglutination assay. Using molecular methods, the spleen, kidney, and blood samples were evaluated for the presence of O. tsutsugamushi, A. phagocytophilum , and L. interrogans . Out of 47 wild rodents, 25.5% (12/47) were positive for bacterial pathogens by PCR, where 19.1% (9/47) were positive for A. phagocytophilum and 6.4% (3/47) were positive for L. interrogans , while none were positive for O. tsutsugamushi . In addition, testing for bacterial infection in different tissues indicated that 8.7% (4/46) were positive for A. phagocytophilum in the blood, 13.3% (6/45) were positive for A. phagocytophilum in the spleen, and 6.4% (3/47) and 2.1% (1/47) were positive for L . interrogans and A. phagocytophilum , respectively, in the kidney. Conclusions/Significance In this study, tropisms for A. phagocytophilum in the spleen and L. interrogans in the kidney were identified. Notably, A. phagocytophilum and L. interrogans were detected in wild rodents living in close proximity to humans in the metropolitan suburban areas. Results of the present study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban area of Republic of Korea. Author Summary Many zoonotic diseases are spreading not only in the Republic of Korea (ROK), but also worldwide. Scrub typhus, anaplasmosis, and leptospirosis are well known diseases that are considered common, widespread rodent-borne infectious diseases. Rodents serve as important reservoirs for zoonotic pathogens such as O. tsutsugamushi, A. phagocytophilum , and L. interrogans, which may be fatal to humans. Our study demonstrated the prevalence of these pathogens in wild rodents, through molecular assays and seroprevalence in organ samples. We captured 47 wild rodents in the Gwangju metropolitan city area of ROK. All were identified as A. agrarius . The prevalence of rodent-borne bacteria was 17.4% in the sera, where 25.5% was positively detected as bacterial pathogens via polymerase chain reaction. Our results indicate the importance of detecting rodent-borne bacteria in wild rodents living close to humans in suburban areas of ROK. Our data was limited to only a few samples of rodents in two regions. More samples may have to be collected over longer periods of time, to investigate the infectious nature of these pathogens in detail.