• Parasites, Hosts and Diseases
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• 제59권3호
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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.

• Parasites, Hosts and Diseases
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• 제55권5호
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• pp.555-559
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• 2017

Chigger mites are parasites of rodents and other vertebrates, invertebrates, and other arthropods, and are the only vectors of scrub typhus, in addition to other zoonoses. Therefore, investigating their distribution, diversity, and seasonal abundance is important for public health. Rodent surveillance was conducted at 6 districts in Shandong Province, northern China ($114-112^{\circ}E$, $34-38^{\circ}N$), from January to December 2011. Overall, 225/286 (78.7%) rodents captured were infested with chigger mites. A total of 451 chigger mites were identified as belonging to 5 most commonly collected species and 3 genera in 1 family. Leptotrombidium scutellare and Leptotrombidium intermedia were the most commonly collected chigger mites. L. scutellare (66.2%, 36.7%, and 49.0%) was the most frequently collected chigger mite from Apodemus agrarius, Rattus norvegicus, and Microtus fortis, respectively, whereas L. intermedia (61.5% and 63.2%) was the most frequently collected chigger mite from Cricetulus triton and Mus musculus, respectively. This study demonstrated a relatively high prevalence of chigger mites that varied seasonally in Shandong Province, China.

• Parasites, Hosts and Diseases
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• 제59권4호
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• pp.377-392
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• 2021

This paper is to illustrate the infestation and related ecological characteristics of chigger mites on the Asian house rat (Rattus tanezumi). A total of 17,221 chigger mites were collected from 2,761 R. tanezumi rats, and then identified as 131 species and 19 genera in 2 families. Leptotrombidium deliense, the most powerful vector of scrub typhus in China, was the first major dominant species on R. tanezumi. All the dominant mite species were of an aggregated distribution among different individuals of R. tanezumi. The species composition and infestations of chiggers on R. tanezumi varied along different geographical regions, habitats and altitudes. The species-abundance distribution of the chigger mite community was successfully fitted and the theoretical curve equation was ${\hat{S}}(R)={37e^{-(0.28R)}}^2$. The total chigger species on R. tanezumi were estimated to be 199 species or 234 species, and this further suggested that R. tanezumi has a great potential to harbor abundant species of chigger mites. The results of the species-plot relationship indicated that the chig-ger mite community on R. tanezumi in Yunnan was an uneven community with very high heterogeneity. Wide geographi-cal regions with large host samples are recommended in the investigations of chigger mites.

• Parasites, Hosts and Diseases
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• 제52권1호
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• pp.63-67
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• 2014

This paper describes a new species of chigger mite (Acari: Trombiculidae), Gahrliepia cangshanensis n. sp., from rodents in southwest China. The specimens were collected from Yunnan red-backed voles, Eothenomys miletus (Thomas, 1914), and a Chinese white-bellied rat, Niviventer confucianus (Milne-Edwards, 1871) in Yunnan Province. The new species is unique mainly in its number of dorsal setae (n=21), and it has the following features: fT (formula of palpotarsus)=4B (B=branched), fp (formula of palpal seta)=B/N/N/N/B (N=naked), a broad tongue-shaped scutum with an almost straight posterior margin, and 17 PPLs (posterior posterolateral seta) with a length of 36-43 ${\mu}m$. This chigger mite may also infect other rodent hosts and may be distributed in other localities.

• 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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• 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.

• 한국토양동물학회지
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• 제11권1_2호
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• pp.16-19
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• 2006

A checklist on 61 species of chigger mites belonging to 12 genera and 2 families from Korean peninsula is suggested with Korean names of each taxon.

• 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.

• Parasites, Hosts and Diseases
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• 제52권2호
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• pp.225-229
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• 2014

A total of 9,281 larval chigger mites were collected from small mammals captured at Hwaseong-gun, Gyeonggi-do (Province) (2,754 mites from 30 small mammals), Asan city, Chungcheongnam-do (3,358 mites from 48 mammals), and Jangseong-gun, Jeollanam-do (3,169 for 62 mammals) from April-November 2009 in the Republic of Korea (= Korea) and were identified to species. Leptotrombidium pallidum was the predominant species in Hwaseong (95.8%) and Asan (61.2%), while Leptotrombidium scutellare was the predominant species collected from Jangseong (80.1%). Overall, larval chigger mite indices decreased from April (27.3) to June (4.9), then increased in September (95.2) and to a high level in November (169.3). These data suggest that L. pallidum and L. scutellare are the primary vectors of scrub typhus throughout their range in Korea. While other species of larval chigger mites were also collected with some implications in the transmission of Orientia tsutsugamushi, they only accounted for 11.2% of all larval chigger mites collected from small mammals.

• 대한임상검사과학회지
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• 제53권4호
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• pp.317-325
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• 2021

털진드기 발생감시를 위해 논, 밭, 수로, 초지 4지점에 채집기를 설치하여 조사하였다. 전체 채집 개체수는 7종 207마리가 채집되었다. 9월 5째주에 2마리를 시작으로 11월 3째주에 49마리로 가장 많이 채집되었다. 전체 채집 기간 중 지역별로는 초지, 수로, 논, 밭에서 각각 81, 52, 47, 27마리 채집된 털진드기를 표본 제작하여 동정한 결과 광릉털진드기(N. kwangneun) 73마리(35.3%)로 가장 많이 분리되었고, 수염털진드기(L. palpale)가 46마리(22.2%), 둥근혀털진드기(N. tamiyai)가 41마리(19.8%), 작은새방울털진드기(N. asakawai) 27마리(13.0%) 순으로 동정되었다. 야생설치류 44마리를 포획한 결과 등줄쥐(Apodemus agrarius) 35마리(79.5%), 땃쥐류(Crocidura spp.) 5마리(11.4%), 대륙밭쥐(Craseomys regulus) 2마리(4.5%)와 그동안 발견되지 않았던 흰넓적다리붉은쥐(Apodemus peninsulae) 2마리(4.5%)였다. 설치류에서 채집한 털진드기는 총 6,628마리 채집되어 chigger index는 150.6이었다. 시기별 chigger index는 10월에 234.2로 가장 높았고, 11월에 223.3, 4월에 75.6, 5월에 66.2 순으로 나타났다. 털진드기 검체로부터 쯔쯔가무시 병원체 PCR 검사는 모두 음성이었다.