• 대한임상검사과학회지
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• 제48권3호
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• pp.242-246
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• 2016

2013년 4월부터 11월까지 전라남도 곡성군 지역을 대상으로 들쥐를 포획하고 기생하는 털진드기의 분포를 조사하였다. 597개의 trap에서 79마리를 포획하여 포획률은 13.2%였고, 종류별로는 등줄쥐가 92.4%를 차지하여 절대 우점종이었다. 79마리의 들쥐중 68마리에 털진드기가 기생하고 있어 86.0%의 기생률을 보였고, 74.5개체의 chigger index를 보였다. 5,063개체의 채집한 털진드기는 2속 6종으로 동정되었고, 활순털진드기가 3,535개체(69.8%)로 절대적인 우점종이었다. 계절별로 봄철에는 대잎털진드기, 가을철에는 활순털진드기가 높은 밀도로 채집되어 진드기종의 분포가 채집시기에 따라 차이가 있었다.

• 대한임상검사과학회지
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• 제51권3호
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• pp.344-350
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• 2019

Orientia tsutsugamushi 감시를 위한 털진드기 분포를 제주도 서귀포시 일원에서 조사 하였다. 총 20개의 채집기를 이용하여 논, 밭, 수로, 초지(4개 지점)에서 털진드기 유충을 9~11월까지 매주 1회씩 채집한 결과 개체수는 3종 51마리가 채집되었다. 설치류에 기생하는 털진드기 분포 감시를 2018년 3월부터 11월까지 한달에 한번씩 9개월 동안 논, 수로, 밭, 저수지, 야산(5개 지점)에서 Sherman traps 각 20개씩 100개를 설치해서 채집한 결과 64마리의 들쥐를 포획해서 trap index 0.08 이였다. 포획된 들쥐는 한 종류인 등줄쥐(Apodemus agrarius)로만 확인되었다. 시기별로는 4월에 15마리로 가장 많았고, 포획된 64마리의 야생 설치류에서 털진드기가 436마리 채집되어 chigger index는 6.8이었으며 시기별 chigger index는 11월 46.0로 가장 높았고, 7월에 6.8, 6월에 4.6 순으로 나타났다. 채집기와 포획된 설치류에서 채집한 털진드기 총 487마리에 대한 쯔쯔가무시 보유여부를 확인하기 위해서 PCR을 실시한 결과 모두 음성으로 나타났다.

• 한국동물위생학회지
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• 제35권3호
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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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• 제59권6호
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• pp.625-634
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• 2021

Based on the field investigations in 91 investigation sites (counties) in southwest China between 2001 and 2019, the present paper reported the chigger mites on A. agrarius mice in southwest China for the first time by using a series of statistical methods. From 715 striped field mice captured in 28 of 91 investigated sites, only 255 chiggers were collected, and they were identified as 14 species, 6 genera in 3 subfamilies under 2 families. Of 715 A. agrarius mice, only 24 of them were infested with chigger mites with low overall prevalence (P_M=3.4%), overall mean abundance (M_A=0.36 mites/host) and overall mean intensity (M_I=10.63 mites/host). The species diversity and infestation of chiggers on A. agrarius were much lower than those previously reported on some other rodents in southwest China. On a certain species of rodent, A. agrarius mouse in southwest China seems to have a very low susceptibility to chigger infestations than in other geographical regions. Of 14 chigger species, there were 3 dominant species, Leptotrombidium sialkotense, L. rupestre and Schoengastiella novoconfuciana, which were of aggregated distribution among different individuals of A. agrarius hosts. L. sialkotense, one of 6 main vectors of scrub typhus in China, was the first dominant on A. agrarius. The species similarity of chigger mites on male and female hosts was low with C_SS=0.25, and this reflects the sex-bias of different genders of A. agrarius mice in harboring different chigger species.

• Journal of Ecology and Environment
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• 제41권3호
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• pp.107-113
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• 2017

Background: As the habitat changes in Korea due to climate change, the emergence of disease-mediated vectors is increasing rapidly. Thus for the surveillance of mosquito- and chigger mite-borne disease, their seasonal prevalence and species composition were investigated at seven locations in Daegu, Gunwi and Sangju. Methods: Mosquitoes were collected twice every month from five collection sites using a black light and BG sentinel traps in Daegu and Gunwi from April through November. Chigger mites were investigated twice per month from wild rodents caught with Sherman live traps in Gunwi and Sangju from April through May and September through November. Results: A total of 2,361 female mosquitoes were collected. Cowshed (626 individuals, Trap index (TI) 44.7) and Kyungpook National University campus (846 individuals, TI 60.4) in Daegu had the highest number of mosquitoes in the black light and BG sentinel trap, respectively. The mosquitoes were collected more by BG sentinel trap than the black light trap. Nine mosquito species were trapped, and the Culex pipiens complex was the most commonly mosquito (1,397 individuals, 59.2%), followed by Anopheles sinensis (554 individuals, 23.5%). Anopheles sinensis (531 individuals, 51.9%) and Culex pipiens complex (1,142 individuals, 85.4%) were the most mosquitoes from black light and BG sentinel trap, respectively. In terms of seasonal prevalence, the highest abundance was in July, with 824 individuals collected. In chigger mites, eighty-one wild rodents of five species that are hosts of chigger mites were collected; among them, 53 and 25 individuals of Apodemus agrarius and Crocidura suaveolens, respectively were trapped. Leptotrombidium pallidum was a dominant species, with 2,467 individuals collected (67.8%). Conclusions: The mosquito was the dominant species in Culex pipiens complex and the highest in July and August. Apodemus agrarius was most abundant in wild rats and Leptotrombidium pallidum was dominant in the collected chigger mites.

• Parasites, Hosts and Diseases
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• 제61권3호
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• pp.263-271
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• 2023

The present study aimed to survey the prevalence of chigger mites and Orientia tsutsugamushi (O. tsutsugamushi) infection in the northern regions of Gangwon-do, Korea. From early February to early June 2015, a total of 17,050 chiggers were collected from striped field mice, Apodemus agrarius, in Cheorwon-gun, Hwacheon-gun, Yanggu-gun, and Goseong-gun, which are well-known endemic areas of scrub typhus in Korea. The chiggers were analyzed using molecular genomic methods, as previously described. Among the 7,964 identified chiggers, the predominant species was Leptotrombidium pallidum (76.9%), followed by L. zetum (16.4%), L. orientale (4.3%), L. palpale (0.3%), L. tectum (0.2%), and Neotrombicula tamiyai (1.8%). The chigger index (CI) was highest in Hwacheon (115.58), followed by Cheorwon (97.02), Yanggu (76.88), and Goseong (54.68). Out of the 79 O. tsutsugamushi-positive chigger pools, 67 (84.8%) were identified as the Boryong strain, 10 (12.7%) as the Youngworl strain, and only 2 were the Jecheon strain. Based on the high infestation of chiggers in striped field rodents and the high rate of O. tsutsugamushi infection in chigger mites, Hwacheon-gun and Cheorwon-gun are presumed to be high-risk areas for scrub typhus. Furthermore, L. pallidum, a major vector of scrub typhus, and the dominant O. tsutsugamushi serotype, the Boryong strain, were found in the northern regions of Gangwon-do, Korea.

• Parasites, Hosts and Diseases
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• 제58권3호
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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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• 제27권2호
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• pp.141-144
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• 1989

1987년 10월부터 12월에 걸쳐 경기도 포천군 이개 부락과 경상남도 진해시 일개 부락에 서 채집한 등줄쥐(Apedemus agrariuscoreae)의 이개에 기생한 털진드기유를 조사하여 다음과 같은 결과를 얻었다. 채집된 171필의 등줄쥐 중 58필에서 털진드기가 잡혀 기생률은 33.9%이었다. 그 중 한 종만 발견된 숙주가 27필(46.6%)로 가장 많았고, 기생 종수가 많아질수록 감소하였으며 5종이 기생하는 쥐는 2필(3.4%)뿐이었다. 총 865개체의 털진드기 유충을 동정한 결과 Leptotrombidium Pallidum (4.3%), L. palpate(23.0%), L. orientalis(20.2%), L. wetum(19.0%), Neotrombicula tamiyai (32.9%), N. japonica(0.2%) 및 Euschongastia koreaensis(0.3%)의 7종이 확인되었다. 그 중 N. tamiyai가 285개체(32.9%)로 가장 많았으나 이 종은 일개 지역에서 12월에만 집중 채집되었으므로 우리 나라 우점종은 전 조사지역과 기간에 고루 분포되어 있는 것으로 나타난 L. palpale라 추측된다. 쭈쭈가무시병의 매개종인 L. pallidum은 37개체가 채집되어 전체의 4.3%에 불과하였다. 한 숙주에 기생하는 털진드기의 밀도는 1개체로부터 최고 207개체까지 심한 차이를 보였는데 개체마다 한 두 종이 집중 기생하는 경향을 나타내었다.

• Parasites, Hosts and Diseases
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• 제50권4호
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• pp.327-331
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• 2012

Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.

• Parasites, Hosts and Diseases
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• 제56권4호
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• pp.313-324
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• 2018

This article reviews Leptotrombidium deliense, including its discovery and nomenclature, morphological features and identification, life cycle, ecology, relationship with diseases, chromosomes and artificial cultivation. The first record of L. deliense was early in 1922 by Walch. Under the genus Leptotrombidium, there are many sibling species similar to L. deliense, which makes it difficult to differentiate L. deliense from another sibling chigger mites, for example, L. rubellum. The life cycle of the mite (L. deliense) includes 7 stages: egg, deutovum (or prelarva), larva, nymphochrysalis, nymph, imagochrysalis and adult. The mite has a wide geographical distribution with low host specificity, and it often appears in different regions and habitats and on many species of hosts. As a vector species of chigger mite, L. deliense is of great importance in transmitting scrub typhus (tsutsugamushi disease) in many parts of the world, especially in tropical regions of Southeast Asia. The seasonal fluctuation of the mite population varies in different geographical regions. The mite has been successfully cultured in the laboratory, facilitating research on its chromosomes, biochemistry and molecular biology.