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

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.