• Parasites, Hosts and Diseases
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• v.58 no.5
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• pp.559-564
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• 2020

A survey of rodents and chiggers associated with Orientia tsutsugamushi was conducted in a rural region of the Republic of Korea (Korea) between 2014 and 2018. Overall Apodemus agrarius 15.2% had the highest seropisitive for O. tsutsugamushi, followed by Myodes regulus 11.4%. Monthly risk factors using logistic regression analysis were not associated with O. tsutsugamushi infections in rodents. The overall prevalence rate of O. tsutsugamushi among chiggers was 0.3%. The chigger (Leptotrombidium scutellare) and monthly (October) risk factors were associated with O. tsutsugamushi human infections (P<0.05). Orientia tsutsugamushi infections are endemic in rodents in Korea and people, for example, soldiers who are active outdoors, must employ preventive measures, especially during October (P<0.05). When there are many reports of O. tsutsugamushi infections in Korea. The Boryong strain 85.7% (2/14) was the most common strain detected in chiggers, followed by the Shimokoshi 7.1% (1/14) and Karp 7.1% strains.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.232-235
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• 2005

Transcripts levels of superoxide dismutases increase slightly following infection of human dermal microvascular endothelial cells(HMEC-1) by the obligae intracellular bacterium Orientia tsutsugamushi, the causative agent of scrub typhus. In addition, fluorescence-activated cell sorter analysis demonstrates significant intracellular peroxide activity in infected cells within 5 hr after exposure to O. tsutsugamushi. Furthermore, infected cells experienced a significant depletion of glutathiones. These results support hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury.

• Journal of Yeungnam Medical Science
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• v.4 no.1
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• pp.173-176
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• 1987

Tsutsugamushi disease is an acute, febrile, typhus-like disease of rural Asia transmitted by the bite of larval trombiculid mites. The disease is caused by infection with Rickettsia tsutsugamushi. Recently the authors experienced a case of tsutsugamushi disease which was serologically confirmed. Here we reports a case of tsutsugamushi disease which successfully managed with doxycycline and reviewed literatures on it briefly.

• Parasites, Hosts and Diseases
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• v.59 no.3
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• pp.319-324
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• 2021

Incidence of tsutsugamushi disease (scrub typhus) caused by Orientia tsutsugamushi, is steadily increasing. It is a mite-borne disease transmitted by chigger mites. In this study, the chigger mites were collected from field small mammals in Hwaseong-si (city), Gyeonggi-do (province), Korea, 2019 and 2020. The field small mammals captured were 56 Apodemus agrarius (94.9%) and 3 Crocidura lasiura (5.1%). A total of 7,531 chigger mites were collected from the captured small mammals. Using PCR test, 153 chigger mite pools were examined and 17 pools were reported positive for O. tsutsugamushi. The O. tsutsugamushi were identified to 5 strains; Jecheon strain was most prevalent, followed by Boryong strain. The other strains were OI011, Taguchi, and Shimokoshi. Collectively, these results provide essential regional information on mite-borne tsutsugamushi disease in the Hwaseong-si, and further contribute to bring awareness and rapid diagnosis for the tsutsugamushi disease.

• The Journal of Korean Society of Virology
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• v.26 no.2
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• pp.235-244
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• 1996

We selected the adequate cell line to be used for propagation and plaquing of R. tsutsugamushi in laboratory and identified R. tsutsugamushi serotype cultured in LuMA cells by nested PCR. As in this study, we concluded that. 1. LuMA cell was suitable for the study of the biology of rickettsiae-host cell interaction. 2. The plaque-forming unit (PFU) per ml of R. tsutsugamushi Karp strain propagated in embryonated egg yolk sacs was $10^{8.8}$ and the PFU/ml of Gilliam strain was $10^{7.1}$. 3. The rate and extent of cytopathic changes depended on the PFU titer of R. tsutsugamushi. 4. PCR with nested primer pairs was useful for identification of R. tsutsugamushi serotype cultured in human embryonic lung cells.

• Biomedical Science Letters
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• v.13 no.4
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• pp.287-291
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• 2007

The factors and mechanisms by infection of Oriental Tsutsugamushi caused disease are not well understood. The onset of tsutsugamushi disease is characterized by chilliness, fever, malaise, headache and generalized aching. Infection of tsutsugamushi is the cause of impairment of function of a major organ often complicate the picture and immediately change the prognosis for the worse. Tsutsugamushi disease is reported that this disease is characterized by the histopathogenesis of liver, kidney, heart, and lung, but the variation of biochemical components in serum of tsutsugamushi disease patient are not clear. We analyzed total protein (TP), albumin (AL), aspartic aminotranferase (AST), alanine aminotransferase (ALT), alkaline phosphotase (ALP), urea nitrogen (UN), creatinine (CRE), glucose (GLD), cholesterol (CHOL) and total bilirubin (TB) in sera of patients with tsutsugamushi disease. In comparison with reference, total protein and albumin were abnormally decreased in 19.6% and 39.2% of patients, respectively. AST, ALT, ALP, creatinine, UN, glucose, cholesterol and total bilirubin were abnormally increased in 94.1 %, 72.5%, 25.5%, 15.7%, 9.8%, 62.7%, 25.5% and 6.0% of patients, respectively. The patients showed abnormal relative rate of protein electrophoretic fractions to total protein in serum compared to them of reference were 43.1% (albumin), 12.9% ($\alpha_1$-globulin), 58.8% ($\alpha_2$-globulin), 60.8% ($\beta$-globulin) and 70.6% ($\gamma$-globulin), respectively. These data suggest that infection of Oriental Tsutsugamushi causes impairment of function of a major organ and abnormal serum protein electrophoresis fractions to tsutsugamushi patients.

• The Journal of the Korean Society for Microbiology
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• v.35 no.1
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• pp.61-68
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• 2000

Among wild chipmunks, Tamias sibiricus, captured in Kyunggi and Kangwon province in Korea, 1997, seropositivity for Orientia tsutsugamushi was determined. Serological test for Orientia tsutsugamushi infection was performed using indirect immunofluorescent antibody technique (IFA). Of 243 wild chipmunks, 61 against Gilliam strain and 64 against Karp strain of Orientia tsutsugamushi were IFA positive. Seropositivity against Gilliam strain was shown 33.3% in Kyunggi and 23.5% in Kangwon province, and against Karp strain was shown 33.3% and 25.4%, respectively.

• Journal of Microbiology
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• v.39 no.2
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• pp.142-145
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• 2001

Changes in the Activities of several antioxidant enzymes in transformed human dermal microvascular endothelial Cells (HMEC-1) by infection with the obligate intracellular bacterium Orientia tsutsugamushi, the causative agent of scrub typhus, were investigated. The activities of glucose-6-phosphate dehydrogenase, catalase, and glutathione peroxidase were significantly decreased in HMEC-1 cells infected with Ο. tsutsugamushi. However, the level of superoxide dismutase increased slightly. Furthermore, Increased levels of intracellular peroxide was observed in HMEC-1 during infection. These results support the hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury that may eventually contribute to cell death.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.435-443
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• 1999

Orientia tsutsugamushi is obligate intracellular bacterium that grows within the cytoplasm of the eukaryotic host cells. Therefore capability of the attachment, entry into the host cell and intracellular survival should be critical process for oriential infection. In this study we investigated the cellular invasion mechanism of Orientia tsutsugamushi and the role of transmembrane heparan sulfate proteoglycan, which binds diverse components at the cellular microenvironment and is implicated as host cell receptors for a variety of microbial pathogens. First of all Orientia tsutsugamushi can invade a wide range of nonprofessional phagocytic cells including fibroblast, epithelial cells and endothelial cells of various host species, including Band T lymphocytes. Thus, it was postulated that the attachment of O. tsutsugamushi requires the recognition of ubiquitous surface structures of many kinds of host cells. Treatments with heparan sulfate and heparin inhibited the infection of Orientia tsutsugamushi in dose-dependent manner for L cell, mouse fibroblast, whereas other glycosaminoglycans such as chondroitin sulfate had no effect. Collectively, these findings provide strong evidence that initial interaction with heparan sulfate proteoglycan is required for the oriential invasion into host cells.

• Journal of agricultural medicine and community health
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• v.29 no.1
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• pp.177-184
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• 2004

Objectives: Tsutsugamushi disease is one of the most significant acute febrile illnesses, increasing in frequency of occurrence during the late autumn in rural areas of Korea. Methods: I have conducted a case-control study on 30 cases who had the fever as a chief complaint, then had been ruled out as having the Tsutsugamushi disease. Data was collected retrospectively by review of chart regarding their general characteristics, clinical and laboratory findings, then was analysed by chi-test. Results: Of 30 cases, 16 cases were seropositive and 14 cases were seronegative against O. tsutsugamushi. Of seropositive for tsutsugamushi disease, 56.3% were female; 37.5% were in their seventies; 50.0% were farmers; 62,6% had chances of exposure to fields or mountains. And 75.0% occurred in November. The main symptoms and signs were fever and chill(100.0%), headache(75.0%). weakness and fatigue(93.8%), and eschar(68.8%). The characteristic laboratory findings were elevated AST(50.0%), ALT(62.5%), and abnormal urinalysis(56.3%). On the other hand, of seronegative cases, 57.1% were male; 50.0% were in their fifties; 42.9% were farmers; 57.2% had chances of exposure to fields or mountains. And 71.4% occurred in November. The symptoms and signs were fever and chill(100.0%), headache(85.7%), eschar(64.3%). weakness, fatigue and skin(57.1%). The laboratory findings were elevated AST(71.4%) and ALT(64.3%), and abnormal urinalysis(42.9%). However, there were no significant differences between the seropositive and seronegative cases(P>.05). Conclusions: Acute febrile community inhabitants who have the epidemiological, clinical as well as laboratory features should be focused upon for the early diagnosis and treatment for tsutsugamushi disease whether or not possessing the serological antibody against O. tsutsugamushi.