• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.241-249
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• 2004

As a part of epidemiologic investigation of tsutsugamushi disease, the wild rodents which were captured in Gyeongnam area were diagnosed with indirect immunofluorescent antibody assay (IFA) and Polymerase Chain Reaction (PCR) to find if they have an antibody against Orientia tsutsugamushi. The conclusion was drawn as followings. (1) The captured 58 wild rodents showed that the subspecies distribution of Apodemus agrarius was 86.2%, Microtus fortis was 8.6% and Crocidura lasiura was 5.2%. (2) The antibody positive rate of O. tsutsugamushi Gilliam, Karp, Karto and Boryong by IFA method was 32.0% in Apodemus agrarius among 50 wild rodents and 40.0% in Microtus fortis among 5 wild rodents, respectively. It was negative in the case of all the 3 Crocidura lasiura. (3) The antibody titers on Apodemus agrarius, Microtus fortis and Crocidura lasiura against Gilliam, Karp, Karto and Boryong were measured between 1:20 and 1:640. The antibody titer against each antigen was in the order Boryong>Gilliam>Karp. (4) O. tsutsugamushi was detected from the blood, spleen and kidney from the artificially infected mice by IFA and PCR. IFA showed the positive response between 3 and 18 days after inoculation. On the other hand, positive response was found from all the samples by PCR. (5) From PCR of the genomic DNA extracted from the blood, spleen and kidney samples of the captured wild rodents, Boryong-specific amplification product with size of 210 bp, which is particular in Boryong, was detected from spleen and kidney samples, but not detected in the blood. (6) Boryong-specific amplification product was detected from spleen and kidney samples which were obtained at 3, 6, 12, 18 and 24 days after the infection with Boryong. But, it wasn't detected from the uninfected samples. (7) From PCR of spleen and kidney samples of the captured wild rodents, it was found that positive rate of O. tsutsugamushi in Apodemus agrarius and Microtus fortis were 25.0% (4/16) and 20.0% (1/5), respectively. From the above results, it can be concluded that Apodemus agrarius resided in Gyeongnam area carried O. tsutsugamushi and PCR method might be a simple, precise, rapid and useful diagnostic tool than IFA for the diagnosis of O. tsutsugamushi.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.344-350
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• 2019

We investigated the distribution of chigger mites in Seogwipo, Jeju Island to conduct surveillance for the presence of Orientia tsutsugamushi. Using a total of 20 samplers, chigger mite larvas were sampled weekly from September to November in Rice field, Field, Waterway, and Glass field (4 locations), and we found up to 51 larvas of 3 different species of chigger mites. 64 field mice were captured when sampling for chigger mite-infested rodents in rice fields, waterways, fields, reservoirs and hills (5 locations) for 9 months from March, 2018 to November, using 100 Sherman traps with placing 20 traps in each location, and in each location the trap index was 0.08. Only back-striped field mice (Apodemus agrarius) were captured one at a time. They were most frequently captured in April with 15 mice, and then 436 chigger mites were collected from the total of 64 captured wild rodent, showing a chigger index of 6.8. The chigger index was the highest in November at 46.0, followed by 6.8 in July and 4.6 in June. PCR was performed to investigate if there were any O. tsutsugamushi hosts among the 487 chigger mites sampled from the captured rodents and this turned out to be negative.

• The Journal of Korean Oriental Chronic Disease
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• v.10 no.1
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• pp.32-38
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• 2005

Scrub typhus is a acute febrile illness by Orientia tsutsugamushi that is endemic in Asian-Pacific areas. It is characterized by fever, rash, eschar, lymphadenopathy. Therapy with Tetracycline, Doxycycline, Chloramphenicol is currently recommended. Here we report a case of tsutsugamushi disease in a 66 year old man had fever, nausea, vommitting, dyspnea, who was successfully treated with East-West intergrative medicine therapy - Antibiotics therapy and Korean traditional medicine(Sasang medicine and acupuncture treatment) - and symptoms improved.

• The Journal of the Korean Society for Microbiology
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• v.35 no.5_6
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• pp.373-373
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• 2000

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.71-71
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• 2008

• Korean Journal of Veterinary Service
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• v.35 no.3
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• pp.183-189
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• 2012

Tsutsugamushi disease or scrub typhus cause by Orientia tsutsugamushi is an endemic disease in Korea. Chigger mites and field rodents play roles in transmission of the disease by the vector and host of the agent. The purpose of this study is to investigate the density of the chigger mites and field rodents due to environmental factors such as temperature, relative humidity, soil thickness and the various vegetations to the 9 field rodent collection sites. The total 62 field rodents was captured by the Sherman collapsible traps from April to October 2009 at the Jangseong of Jeonnam Province, Korea. The trapping rate of the field rodents by the different collecting sites was dominant at subside storage water (24%), bush near by dam (22%), bank around field (20%), followed by 18% of grassy field and surround cattle shed. The distribution of chigger mites by the different collecting sites was the highest at Bush near by dam (28.7%). And the sites of subside storage water, bank around field and surround cattle shed were 20.4%, 18.8%, 16.4%, respectively. On the other hand the collecting sites of stream bank and ridges between rice paddies were not collected. The temperature to the collecting sites was showed $24.1^{\circ}C$ in June and $24.2^{\circ}C$ in October which was higher than April ($10.6^{\circ}C$), whereas lower than May ($25.3^{\circ}C$) and September ($26.8^{\circ}C$). The highest number of mites was collected at $24.2^{\circ}C$ and 46.6% relative humidity in October. The chigger mites and field rodents were highly collected between 18 and 24% at the sites where are loosely in the superficial layers of the soil from 8.0 cm to 10.2 cm. Total 25 species of vegetation were distributed at the collecting sites. In the present study, strong evidence was found that bank around field and grassy field were provided for the prevalence sites of tsutsugamushi disease.

• Parasites, Hosts and Diseases
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• v.58 no.3
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• pp.301-308
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• 2020

Owing to global climate change, the global resurgence of vector-borne infectious diseases and their potential to inflict widespread casualties among human populations has emerged as a pivotal burden on public health systems. Tsutsugamushi disease (scrub typhus) in the Republic of Korea is steadily increasing and was designated as a legal communicable disease in 1994. The disease is a mite-borne acute febrile disease most commonly contracted from October to December. In this study, we tried to determine the prevalence of tsutsugamushi disease transmitted by chigger mites living on rodents and investigated their target vector diversity, abundance, and distribution to enable the mapping of hotspots for this disease in 2015. A total of 5 species belonging to 4 genera (109 mites): Leptotrombidium scutellare 60.6%, L. pallidum 28.4% Neotrombicula tamiyai 9.2%, Euschoengastia koreaensis/0.9%), and Neoschoengastia asakawa 0.9% were collected using chigger mite collecting traps mimicking human skin odor and sticky chigger traps from April to November 2015. Chigger mites causing tsutsugamushi disease in wild rodents were also collected in Hwaseong for the zoonotic surveillance of the vector. A total of 77 rodents belonging to 3 genera: Apodemus agrarius (93.5%), Crocidura lasiura (5.2%), and Micromys minutus (1.3%) were collected in April, October, and November 2015. The most common mite was L. pallidum (46.9%), followed by L. scutellare (18.6%), and L. orientale (18.0%). However, any of the chigger mite pools collected from rodent hosts was tested positive for Orientia tsutsugamushi, the pathogen of tsutsugamushi disease, in this survey.

• Parasites, Hosts and Diseases
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• v.58 no.4
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• pp.445-450
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• 2020

Trombiculid "chigger" mites (Acari) are ectoparasites that feed blood on rodents and another animals. A crosssectional survey was conducted in 7 ecosystems of southern Vietnam from 2015 to 2016. Chigger mites were identified with morphological characteristics and assayed by polymerase chain reaction for detection of rickettsiaceae. Overall chigger infestation among rodents was 23.38%. The chigger index among infested rodents was 19.37 and a mean abundance of 4.61. A total of 2,770 chigger mites were identified belonging to 6 species, 3 genera, and 1 family, and pooled into 141 pools (10-20 chiggers per pool). Two pools (1.4%) of the chiggers were positive for Orientia tsutsugamushi. Ricketsia spp. was not detected in any pools of chiggers. Further studies are needed including a larger number and diverse hosts, and environmental factors to assess scrub typhus.

• Korean Journal of Veterinary Service
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• v.26 no.3
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• pp.203-214
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• 2003

Scrub typhus and murine typhus are common endemic febrile illness in the fall in Korea. Scrub typhus is caused by Orientia tsutsugomushi, murine typhus is caused by Rickettsia typhi. Trombiculid mites are known as both the vector and the reservoir host of O tsutsugamushi, the mites which transmit O tsutsugomushi have been reported to be Leptotrombidium pallidum and L scutellare. The author carried out an epidemiological study of scrub typhus and murine typhus in Kyodong-Myeon, Kanghwa-Gun, Incheon in relation to the residents and the host rodents, such as their distribution, seroepidemiology, and population density of chigger mites. 1. Out of 900 residents, 33(3.7%) showed positive reaction to O tsutsugamushi, 24(2.7%) to R typhi. 2. In the seropositives to O tsutsugamushi or R typhi, between the sixties and the seventies of the age were dominant. 3. In the seropositives to O tsutsugamushi serotypically Gilliam was dominant. 4. Among the total 42 field rodents trapped by the sherman traps, 18 rodents were Apodemus agrarius(42.9%), 13 rodents were Crocidura lasiura(31.0%), 5 rodents were Musmusculus(11.9%), 2 rodents(4.8%) were Crocidura suaveolens, Rattus norvegicus, Tscherskia triton, respectively. 5. Out of 42 field rodents, 25 were parasitized by 4,419 chigger mites, showing 59.5% of the infestation rate and 98.8 of the chigger index. L pallidum parasitized in A agrarius, C lasiura, M musculus, R norvegicus and T triton, and L scutellare parasitized only C lasiura. 6. Antibodies in the sera of field rodents against O tsutsugamushi and R typhi were investigated by indirect immunofluorescent antibody technique. Positive rate of antibody against O tsutsugamushi were 11.9(5 of 42) and all of the positive is A agrarius. Antibody against R typhi was not detected. These results might provide the basic information for the management of scrub typhus and murine typhus in Kyodong-myeon, where the epidemiological studies on scrub typhus and murine typhus was not carried out enough.

• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.137-137
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• 2007