• 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.

• Biomedical Science Letters
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• v.17 no.4
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• pp.367-370
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• 2011

Studies on the relative abundance of potential vectors of scrub typhus was conducted from April to October 2009 at the Jangseong of Jeonnam Province, Korea. Among the total 62 field rodents collected by the Sherman collapsible traps, 56 rodents were $Apodemus$ $agrarius$ (90.3%), 4 were $Crocidura$ $lasiura$ (6.4%) and 2 were $Cricetulus$ $triton$ $nester$ (3.2%). Out of the 62 field rodents, 39 were parasitized by chiggers, showing 62.9% of the infestation rate and 80.0 of the chigger index. Chigger index of $A.$ $agrarius$ and $C.$ $triton$ $nester$ were 79.9, 82.0, respectively. But chigger mite was not collected from $C.$ $lasiura$. From the trapped field rodents, 3,120 chiggers were collected and identified with 6 species of 2 genera. $Leptotrombidium$ $scutellare$, the vector species of tsutsugamushi disease, was the dominant species, showing 2,276 chiggers (72.9%). $L.$ $pallidum$ was the second dominant species showing 346 chiggers (11.0%). The distribution of chigger mites was showed the different dominant species according to seasons. $L.$ $pallidum$ was the predominant chigger collected in April (34.8%), May (77.8%) and Jun (39.3%), whereas $L.$ $scutellare$ was the predominant chigger collected in September (78.78%) and October (76.8%).

• 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.

• The Journal of the Korean Society for Microbiology
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• v.34 no.6
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• pp.591-594
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• 1999

Leptospirosis has been known as endemic disease in Korea since 1984. Wild rodent, mostly Apodemus agrarius, has been known as an important source of leptospiral infection especially in rainy circumstances in harvest reason of rural area. The infection rates of Leptospira interrogans in field rodents, Apodemus agrarius, was investigated by culture and PCR detection of leptospiral DNA, and compared with previous data. Furthermore, the serogroup and serovar were investigated. Two hundred twenty two Apodemus agrarius were captured during October to December 1996. Spirohaetes were isolated from 22 (9.9%) and leptospiral DNA was detected in an additional six rodents (12.6%). Subsequent cross-agglutinin absorption test, monoclonal antibody reactivity classified 21 cultures among 22 isolates as Leptospira interrogans serogroup Icterohemorrhagiae serovar lai. The above data did not differ from previous survey in 1984 to 1987. There was no significant change of Leptospira interrogans infection in field rodents in Korea.

• Parasites, Hosts and Diseases
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• v.34 no.1
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• pp.27-34
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• 1996

The geographical distribution and population density of rodents and chigger mites at six localities of Chollanam-do were investigated from October to December in 1993. Among total 142 field rodents collected by the modified Chemin wooden traps, 131 rodents were Aponemw usrari,us (92.3%) and 11 were Crocidurc losiurc (7.7%). Out of 142 field rodents, 92 were parasitized by chiggers, showing 69.0% of the infestation rate and 74.2 of the chiggor index. Infestation rate and chigger index of A. omfernrius and C. lusiurc were 73.3%, 80.4 and 18.2%, 0.5, respectively. From the trapped field rodents, 10,532 chiggers were collected and identified with 11 species of 4 genera. Leptotrombidium pcLLinun. the vector 3pecies of tsutsugamushi disease, was the dominant species, showing 8,038 chi99ers (76.31%). L. scutellnre was the second dominant species showing 1,359 chiggers (12.9%). The distribution of chigger mites was clearly localized by the species, showing the different dominant species according to localities. The predominant species was 1. scutellare (100%) in Changhung-gun, 1. scutellcre (41.5%) in Posong-gun, 1. pnllidum (88.8%) in Hwasun- gun, 1. pnLlidunl (59.2%) in Koksong-gun, 1. zetum (77.3%) in Hampyong-gun, and 1. pclpcle (63.4%) in Tamyang-gun. Regarding to the geographical distribution of chigger population density, the infestation rate and chigger index was most high in Hwasun-gun as 62.4% and 216.2 respectively, and next high in Koksong-gun as 22.4% and 77.7%, respectively.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.242-246
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• 2016

The distribution and population density of rodents and chigger mites were investigated between April 2013 and November 2013 in the Gokseong-gun of Jeollanam-do, Korea. A total of 79 rodents were collected using Sherman collapsible traps, and among them, 73 were Apodemus agrarius (92.4%), 4 were Crocidura lasiura (5.0%), and 2 were Microtus fortis (2.5%). Sixty-eight out of the 79 rodents were parasitized by chiggers, showing an infestation rate of 86.0% and a chigger index of 74.5; the chigger index of A. agrarius was 75.4. From the trapped field rodents, 5,063 chigger mites were collected and identified with 6 species of 2 genera. Leptotrombidium scutellare was the dominant species with 3,535 chiggers (69.8%), followed by L. pallidum with 777 chiggers (15.3%). This results showed that the distribution of chigger mites differ in dominant species according to seasons. L. pallidum was the predominant chigger collected in April (34.3%), May (70.0%), and June (55.1%); whereas L. scutellare was the predominant chigger collected in September (75.5%), October (71.8%), and November (74.2%).

• Journal of Korean Society of Forest Science
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• v.94 no.2 s.159
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• pp.108-111
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• 2005

This study was conducted to identify the road effect on small rodent populations within fragmented forest areas around the road from June to September 2002, in 9 study sites of Baekdugdaegan mountains, Korea. Two species of small rodents, Korean field mouse Apodemus peninsulae and striped field mouse Apodemus agrarius, were captured in this study. Korean field mouse preferred forest area, and striped field mouse generally has been found edge area around road. Mean body weight of Korean field mouse was significantly different, but that of striped field mouse was not between both distance from road. Korean field mouse is forest-dwelling species and their distribution is limited in forest area. In contrast, striped field mouse has wide distributional range around road. The effects of road is different in each small rodent species and their habitat preferences.

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.603-606
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• 2013

To determine geographical patterns of natural parasite infections among wild rodents, a total of 46 wild rodents from 3 different localities in northern Gangwon-do (Province), Korea were examined for intestinal parasite infections. Along with nematodes such as hookworms and Syphacia spp., Plagiorchis muris (2 specimens) (Trematoda) were collected from striped field mice, Apodemus agrarius. In a Korean wood mouse, Apodemus peninsulae, the overall nematode infections were similar to A. agrarius, but an adult worm of Echinostoma hortense (Trematoda) was collected. In addition, 2 species of cestodes, i.e., Hymenolepis nana and Hymenolepis diminuta, were collected from A. agrarius. Through this survey, A. agrarius and A. peninsule were confirmed as the natural definite hosts for zoonotic intestinal helminths, i.e., P. muris, E. hortense, H. nana, and H. diminuta, in northern Gangwon-do, Korea. Considering increased leisure activities around these areas, seasonal and further comprehensive surveys on wild rodents seem to be needed to prevent zoonotic parasite infections.

• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.331-336
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• 1986

A microbiological study for the isolation and characterization of Leptospira interrogans was performed in an attempt to define the characteristics of Leptospirosis in Korea. The results are summerised as follows. Thirty-five cultures were isolated from 11 patients with leptospirosis and 24 wild rodents captured in Paju area. The isolation rate of Leptospira from wild rodents reached 23.1%. All 35 cultures were identified as Leptospira interrogans by their characteristic morphology and motility in dark field microscopy, pathogenecity in Guinea pig and sensitivity to 8-Azaguanine. Cultures formed diffuse subsurface colonies with hazy margin and were catalase, peroxidase and oxdase positive. The fifty percent lethal dose of isolate HM 4 in Guinea pig was $8.9{\times}10^4$ org. Mouse passage method was sucecssfully applied in maintenance of fresh isolates without any loss of their original virulency.

• Proceedings of the PSK Conference
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• 2002.04a
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• pp.126.3-127
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• 2002