Prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum and Leptospira interrogans in striped field mice in Gwangju, Republic of Korea.

Mi-Seon Bang,Choon-Mee Kim,Na Ra Yun,Jung Wook Park,Dong-Min Kim,Jae Keun Chung

doi:10.1371/journal.pone.0215526

Abstract

This study investigated the prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum, and Leptospira interrogans in wild rodents through molecular detection using organ samples and through serological assay using blood samples of mice collected from two distinct sites in Gwangju Metropolitan City, Republic of Korea (ROK). 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 A. agrarius 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 species through passive hemagglutination assay. Using polymerase chain reaction, the spleen, kidney and blood samples were investigated for the presence of O. tsutsugamushi, A. phagocytophilum, and L. interrogans. Out of the 47 A. agrarius, 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. Four out of 46 (8.7%) blood samples, six out of 45 (13.3%) spleen samples, and one out of 47 (2.1%) kidney samples were positive for A. phagocytophilum. Three out of 47 (6.4%) kidney samples were positive for L. interrogans. The sequencing results of PCR positive samples demonstrated > 99% similarity with A. phagocytophilum and L. interrogans sequences. A. phagocytophilum was mostly detected in the spleen, whereas L. interrogans was mostly detected in the kidneys. Notably, A. phagocytophilum and L. interrogans were detected in A. agrarius living in close proximity to humans in the metropolitan suburban areas. The results of this study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban areas of ROK.

Highlights

Rodents are known carriers of zoonotic pathogenic agents that are usually transmitted to humans through direct or indirect contact [1].Scrub typhus, caused by Orientia tsutsugamushi, is an infectious disease and has become one of the most prevalent human diseases in the Asia-Pacific region, including in the Republic of Korea (ROK) [2]
A. phagocytophilum and L. interrogans were detected in A. agrarius living in close proximity to humans in the metropolitan suburban areas
The results of this study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban areas of ROK

Summary

Introduction

Scrub typhus, caused by Orientia tsutsugamushi, is an infectious disease and has become one of the most prevalent human diseases in the Asia-Pacific region, including in the Republic of Korea (ROK) [2]. In 1995, 274 cases of scrub typhus were reported in ROK, whereas 10,365 cases were reported in 2013, indicating a 38.1-fold increase in the incidence of this disease [4]. Anaplasma phagocytophilum causes human granulocytic anaplasmosis (HGA). A. phagocytophilum has been detected in Hemaphysalis longicornis (H. longicornis), Ixodes nipponensis (I. nipponensis), and Ixodes persulcatus (I. persulcatus) ticks in ROK [5]. The incidence of anaplasmosis has increased from 1.4 cases per million in 2000 to 6.1 cases per million in 2010 [7, 8]. The first HGA case in ROK was reported in 2013 [9]

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Conclusion